There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
(11-02-2023, 01:03 AM)Balam Wrote: @GuateGojira that's a great find. Orinoco crocodiles surpass in size both American crocodiles and black caimans with modern records of 5+ meter specimens, despite the massive overhunting.
A mature Orinoco male from the Patrullero de Chávez breeding facility in Venezuela is claimed to measure 4.9 meters in lenght but with a weight of 730 kg. Orinocos are notorious for their weight relative to lenght as well.
The Nile crocodile is popularly regarded as the second largest crocodile in the world, but that's greatly disputed when we consider the historical sizes of Orinoco crocodiles which challenged even the largest salties. For context, no reliable record exists of a Nile crocodile above 6.1 meters in lenght, where despite their massive populations, males above 4.5 meters are very rare to come by.
The Neotropical crocodiles certainly deserve their dues in this regard.
Ohhhh, I did not knew that. So Orinoco crocs are real giants. I believe that some of the biggest crocodiles in America are as large as some of the largest crocs in Africa/Asia. The problem is that very few has been actually measured and even less weighed. Litterature are full of estimations and doubtfull measurements.
(11-02-2023, 01:03 AM)Balam Wrote: @GuateGojira that's a great find. Orinoco crocodiles surpass in size both American crocodiles and black caimans with modern records of 5+ meter specimens, despite the massive overhunting.
A mature Orinoco male from the Patrullero de Chávez breeding facility in Venezuela is claimed to measure 4.9 meters in lenght but with a weight of 730 kg. Orinocos are notorious for their weight relative to lenght as well.
The Nile crocodile is popularly regarded as the second largest crocodile in the world, but that's greatly disputed when we consider the historical sizes of Orinoco crocodiles which challenged even the largest salties. For context, no reliable record exists of a Nile crocodile above 6.1 meters in lenght, where despite their massive populations, males above 4.5 meters are very rare to come by.
The Neotropical crocodiles certainly deserve their dues in this regard.
Ohhhh, I did not knew that. So Orinoco crocs are real giants. I believe that some of the biggest crocodiles in America are as large as some of the largest crocs in Africa/Asia. The problem is that very few has been actually measured and even less weighed. Litterature are full of estimations and doubtfull measurements.
Yes we have a few giants here in Venezuela, in a breeding facility in Estado Guarico we had two big ones one very close to 5 meters long that died a few years back after fighting with another a little smaller about 4,70 with out a part of the tail. I saw a huge wild one at least 5 meters long a few years back in Hato El Frio, Apure, Venezuela. You are right not many are measured and their numbers are very low. According to Mr Omar Hernandez one of the experts working very hard to preserve them only about 100 females Orinoco Crocodiles breed in Venezuelan Llanos today.
(11-02-2023, 01:03 AM)Balam Wrote: @GuateGojira that's a great find. Orinoco crocodiles surpass in size both American crocodiles and black caimans with modern records of 5+ meter specimens, despite the massive overhunting.
A mature Orinoco male from the Patrullero de Chávez breeding facility in Venezuela is claimed to measure 4.9 meters in lenght but with a weight of 730 kg. Orinocos are notorious for their weight relative to lenght as well.
The Nile crocodile is popularly regarded as the second largest crocodile in the world, but that's greatly disputed when we consider the historical sizes of Orinoco crocodiles which challenged even the largest salties. For context, no reliable record exists of a Nile crocodile above 6.1 meters in lenght, where despite their massive populations, males above 4.5 meters are very rare to come by.
The Neotropical crocodiles certainly deserve their dues in this regard.
Do the administrators at Patrullero de Chávez actually claim to have measured that crocodile, or just estimated it's lenght?
While I find it plausible that Orinoco crocodiles and even American crocodiles can grow to the same size as niles, I have a few points of contention regarding the possible size of Orinoco crocodiles relative to niles and saltwaters
Firstly, it is of course to be expected most nile crocodiles are under 5 meters. Most crocodiles of all species, even saltwaters, are under 5 meters. Crocodiles in excess of this are uncommon. Do you have a source for the statement that nile crocodiles over 4.5 meters are "very rare". Ideally this source should focus on mature males, since that is the only relevant demographic for the discussion. I'm interested to know if 4.5 plus mature males are any rarer in the nile species than in the Orinoco. Ideally that would have to be substantiated with data, which I don't personally have, and not just anecdotes about specific individual crocodiles. There is a video on youtube "Finding the largest nile crocodile" or something like that, where a guy measures several 4.5 plus niles at a single croc farm. I suspect that any of the four largest croc species will throw a few 4.5 meter plus individuals, but their species specific abundance would need to actually be quantified if you want to make that kind of comparison.
Regarding the largest skulls on record, the highest recorded DCLs for acutus and intermedius are quite high, but it should be remembered that the DCL to TL ratio might be different in the new world species than in the nile and saltwater. This is the case in tomistoma, the crocodilian with the largest recorded skulls. Personally, when I scale pics of acutus, niloticus and porososus taken from above, the head definitely seems to acocunt for a larger portion of the body length in the new world species, and if that appearance is real then that complicates exprapolating 6meter + TLs from the largest new world skulls.
Re the effect of hunting on the modern sizes of new world crocodiles: I can believe that hunting could have eliminated potential 6 meter crocs form C. acutus and C. intermedius. However, I don't believe hunting can explain why these two species have never been measured in excess of 5 meters in the modern era. All the large crocodiles were hunted extensively, yet you can still find 5.4 meter plus niles and saltwaters occasionally. Until we have a confirmed 5.5 meter measurement from the Orinoco and American crocodiles, I am also prepared to believe that these species simply top out at a lower TL (though perhaps similar DCL) to the giant old world crocodiles.
11-02-2023, 07:00 AM( This post was last modified: 11-02-2023, 07:06 AM by epaiva )
(11-02-2023, 06:47 AM)KRA123 Wrote: @Balam I just realized you stated there are modern 5 meter plus records for Orinocos. Were those records published? I would love to see them if so.
@KRA123
A Biologist measured all Orinoco Crocodiles in that place but they told me that I must wait to place them here until he publishes his paper. I saw them pictured them and have videos of the two larger ones and took two pictures of the huge wild Orinoco Crocodile but sadly I could not take better pictures of it. Larger Orinoco Crocodiles today measure about 5 meters long, you can find very few Orinoco Crocodile skulls in Museums with larger ones close to 70 centimeters long.
The breeding facility Patrullero de Chávez, dedicated to the conservation of Orinoco crocodiles, plays an active role in managing these reptiles for breeding purposes, with the distinct advantage of having them in captivity. Such facilities follow strict protocols, including regular veterinary assessments to ensure the well-being and accurate measurements of the crocodiles. It's important to note that this measurement is particularly reliable because it pertains to one of the largest breeding males in the facility which fell well within the range of large contemporary males as mentioned by @epaiva.
It's also true that all crocodile species face challenges when it comes to surpassing the 5-meter length threshold, and this is a reflection of the natural constraints on their growth. However, the main point of contention is not that Nile crocodiles are unable to achieve such lengths but rather that despite their widespread reputation as the "second-largest" crocodile species in the world, they appear to encounter comparable hurdles in reaching this notable milestone. What adds to the intrigue is that American and, particularly, Orinoco crocodiles have grappled with overhunting, which has led to significant impacts on their average sizes due to genetic diversity erosion.
Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greter proportional frequency. In contrast, Nile crocodiles boast a larger population and healthier genetic diversity, yet they seem to exhibit a comparatively lower frequency in achieving these impressive lengths. This intriguing observation casts a shadow of doubt on the claim that Nile crocodiles are unequivocally the second-largest in the world, as their counterparts from the Neotropics show a remarkable ability to achieve similar sizes despite their less favorable conservation status.
Now in terms of size, this is the information I have:
In the 2017 Growth rates of the American crocodile paper by Andrés E. Seijas, growth rates for American crocodiles were analyzed from various regions. The von Bertalanffy growth model predicted an asymptotic size of 4.39 meters for males in Florida. As for females, asymptotic sizes were 2.617 meters for those in Florida and 2.274 meters for those in the mangroves of Venezuela.
The Comportamiento reproductivo del caimán del Orinoco by Colvée (1999) reported that in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms. Females reach up to 3.2 meters in length and weigh around 211 kilograms.
Experts generally estimate a maximum total length of up to 7 meters for Orinocos. This estimation is substantiated by the accounts of seasoned "caimaneros" or crocodile hunters, such as those cited by Medem in 1981. Even historical explorers like Humboldt and Bonpland, who ventured along the banks of the Apure River in 1880, recorded their encounters with remarkably large Orinoco crocodiles. One account describes a specimen measuring 16 feet 8 inches (508 cm) in length, while another, identified as a male, stretched to an impressive 22 feet 3 inches (678 cm). Further back in time, the narrative continues with Fray Jacinto de Carvajal, who, in 1618, chronicled a colossal crocodile of 25 feet, which, adjusted for the "pie de Castilla" measurement system (27.85 cm per foot), translates to an astonishing 696 cm. These historical and contemporary records paint a vivid picture of the remarkable size potential of the Orinoco crocodiles during a time when they were not critically endangered.
Humboldt and Bonpland are as reliable as a naturalist could get for the 19th century, which is why they are quoted by modern authorities in the field, like in the Commercial Hunting of the Orinoco Crocodile, Crocodylus intermedius, in Venezuela thesis by Ernesto Boede and Rafael Hoogesteijn (2017) where they detail Alexander von Humboldt's extraordinary journey to the Orinoco region in detail. He noted that crocodiles were abundant and that sizes ranged between 5.08 meters to 7.31 meters. It's possible that the 7.31 meters value is an incorrect conversion belonging to the 6.78 meters specimen to be clear.
For Nile crocodiles, we have B. Cott's paper, Scientific results of an inquiry into the ecology and economic status of the Nile Crocodile (Crocodilus niloticus) in Uganda and Northern Rhodesia which sheds light on the challenges associated with assessing the size of Nile crocodiles. The study underscores the skepticism surrounding the validity of size records and highlights the unreliability of visual estimates, such as those provided by herpetologists like Brue (7.62 meters) and Barbot (9.14 meters). While some herpetologists have erred on the side of caution, accepting a conservative estimate of 4.88 meters, this figure is notably lower than the measurements reliably reported from historical accounts.
Cott's work presents a range of maximum lengths reported for Nile crocodiles from different African regions. In Central Africa, reports suggest that large crocodiles over 4.99 meters in length have been encountered. For instance, the largest crocodile measured in Northern Rhodesia reached 5.05 meters. Similarly, a crocodile in Nyasaland was reported to measure an impressive 5.74 meters.
In East Africa, particularly in Uganda, the study highlights the presence of exceptionally large Nile crocodiles. Crocodiles in the Lower Semliki and the Murchison reach of the Victoria Nile achieved notable sizes. In 1950, two males measured 5.13 meters and 5.54 meters, according to measurements taken by a Game Ranger. Additionally, in 1952, the Marketing Corporation received a skin measuring 5.94 meters from the Lower Semliki, signifying the substantial size of Nile crocodiles in this region.
So what does contemporary data says? A. D. Graham's 1968 study, The Lake Rudolf Crocodile (Crocodylus niloticus Laurenti) Population, provides valuable insights into the population and growth characteristics of Nile crocodiles in the Lake Rudolf region. The study reveals that sexual maturity in this population is reached by over 50% of males at approximately 2.7 meters in length. However, there is substantial variability in the size at which crocodiles become sexually mature, with some individuals reaching maturity as early as 1.89 meters, while others require up to 3.38 meters.
The study records that among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters. Notably, in the Lake Rudolf area surveyed by the Kenya Game Department in Ferguson's Gulf, no crocodiles larger than this maximum size were encountered.
Additionally, A. D. Graham references findings from B. Cott's study in Uganda and Zambia, which examined 324 males. Cott's study reported that only seven of these males had lengths ranging from 4.3 to 4.75 meters. But as I showed before Cott's work also cites several seemingly authentic records of Nile crocodiles reaching lengths of up to 6 meters. Graham highlights personal records of crocodiles exceeding 5 meters in length from the Grumeti River in Tanzania as well. This suggests that while there is a common upper limit for Nile crocodile size, exceptionally large individuals occasionally surpass this threshold, but they are far from common.
I believe that the idea of Nile crocodiles being the undisputed runner-up for sizes in crocodiles is just a lazy generalization that has been accepted through time, particularly when we take into account that Nile crocodiles are significantly better-known and documented than Orinoco crocodiles, this generates a bias to place more importance to them even when the empirical data doesn't support those assertions.
I believe that under the right conditions, all four of the largest crocodiles in the world can attain similarly gigantic sizes: salt-water, Orinoco, Nile, and American, but we don't live in a perfect world and the degrees of conservation between these species vary greatly, so we must have a large degree of nuance when we make definitive claims about their sizes.
The breeding facility Patrullero de Chávez, dedicated to the conservation of Orinoco crocodiles, plays an active role in managing these reptiles for breeding purposes, with the distinct advantage of having them in captivity. Such facilities follow strict protocols, including regular veterinary assessments to ensure the well-being and accurate measurements of the crocodiles. It's important to note that this measurement is particularly reliable because it pertains to one of the largest breeding males in the facility which fell well within the range of large contemporary males as mentioned by @epaiva.
It's also true that all crocodile species face challenges when it comes to surpassing the 5-meter length threshold, and this is a reflection of the natural constraints on their growth. However, the main point of contention is not that Nile crocodiles are unable to achieve such lengths but rather that despite their widespread reputation as the "second-largest" crocodile species in the world, they appear to encounter comparable hurdles in reaching this notable milestone. What adds to the intrigue is that American and, particularly, Orinoco crocodiles have grappled with overhunting, which has led to significant impacts on their average sizes due to genetic diversity erosion.
Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greter proportional frequency. In contrast, Nile crocodiles boast a larger population and healthier genetic diversity, yet they seem to exhibit a comparatively lower frequency in achieving these impressive lengths. This intriguing observation casts a shadow of doubt on the claim that Nile crocodiles are unequivocally the second-largest in the world, as their counterparts from the Neotropics show a remarkable ability to achieve similar sizes despite their less favorable conservation status.
Now in terms of size, this is the information I have:
In the 2017 Growth rates of the American crocodile paper by Andrés E. Seijas, growth rates for American crocodiles were analyzed from various regions. The von Bertalanffy growth model predicted an asymptotic size of 4.39 meters for males in Florida. As for females, asymptotic sizes were 2.617 meters for those in Florida and 2.274 meters for those in the mangroves of Venezuela.
The Comportamiento reproductivo del caimán del Orinoco by Colvée (1999) reported that in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms. Females reach up to 3.2 meters in length and weigh around 211 kilograms.
Experts generally estimate a maximum total length of up to 7 meters for Orinocos. This estimation is substantiated by the accounts of seasoned "caimaneros" or crocodile hunters, such as those cited by Medem in 1981. Even historical explorers like Humboldt and Bonpland, who ventured along the banks of the Apure River in 1880, recorded their encounters with remarkably large Orinoco crocodiles. One account describes a specimen measuring 16 feet 8 inches (508 cm) in length, while another, identified as a male, stretched to an impressive 22 feet 3 inches (678 cm). Further back in time, the narrative continues with Fray Jacinto de Carvajal, who, in 1618, chronicled a colossal crocodile of 25 feet, which, adjusted for the "pie de Castilla" measurement system (27.85 cm per foot), translates to an astonishing 696 cm. These historical and contemporary records paint a vivid picture of the remarkable size potential of the Orinoco crocodiles during a time when they were not critically endangered.
Humboldt and Bonpland are as reliable as a naturalist could get for the 19th century, which is why they are quoted by modern authorities in the field, like in the Commercial Hunting of the Orinoco Crocodile, Crocodylus intermedius, in Venezuela thesis by Ernesto Boede and Rafael Hoogesteijn (2017) where they detail Alexander von Humboldt's extraordinary journey to the Orinoco region in detail. He noted that crocodiles were abundant and that sizes ranged between 5.08 meters to 7.31 meters. It's possible that the 7.31 meters value is an incorrect conversion belonging to the 6.78 meters specimen to be clear.
For Nile crocodiles, we have B. Cott's paper, Scientific results of an inquiry into the ecology and economic status of the Nile Crocodile (Crocodilus niloticus) in Uganda and Northern Rhodesia which sheds light on the challenges associated with assessing the size of Nile crocodiles. The study underscores the skepticism surrounding the validity of size records and highlights the unreliability of visual estimates, such as those provided by herpetologists like Brue (7.62 meters) and Barbot (9.14 meters). While some herpetologists have erred on the side of caution, accepting a conservative estimate of 4.88 meters, this figure is notably lower than the measurements reliably reported from historical accounts.
Cott's work presents a range of maximum lengths reported for Nile crocodiles from different African regions. In Central Africa, reports suggest that large crocodiles over 4.99 meters in length have been encountered. For instance, the largest crocodile measured in Northern Rhodesia reached 5.05 meters. Similarly, a crocodile in Nyasaland was reported to measure an impressive 5.74 meters.
In East Africa, particularly in Uganda, the study highlights the presence of exceptionally large Nile crocodiles. Crocodiles in the Lower Semliki and the Murchison reach of the Victoria Nile achieved notable sizes. In 1950, two males measured 5.13 meters and 5.54 meters, according to measurements taken by a Game Ranger. Additionally, in 1952, the Marketing Corporation received a skin measuring 5.94 meters from the Lower Semliki, signifying the substantial size of Nile crocodiles in this region.
So what does contemporary data says? A. D. Graham's 1968 study, The Lake Rudolf Crocodile (Crocodylus niloticus Laurenti) Population, provides valuable insights into the population and growth characteristics of Nile crocodiles in the Lake Rudolf region. The study reveals that sexual maturity in this population is reached by over 50% of males at approximately 2.7 meters in length. However, there is substantial variability in the size at which crocodiles become sexually mature, with some individuals reaching maturity as early as 1.89 meters, while others require up to 3.38 meters.
The study records that among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters. Notably, in the Lake Rudolf area surveyed by the Kenya Game Department in Ferguson's Gulf, no crocodiles larger than this maximum size were encountered.
Additionally, A. D. Graham references findings from B. Cott's study in Uganda and Zambia, which examined 324 males. Cott's study reported that only seven of these males had lengths ranging from 4.3 to 4.75 meters. But as I showed before Cott's work also cites several seemingly authentic records of Nile crocodiles reaching lengths of up to 6 meters. Graham highlights personal records of crocodiles exceeding 5 meters in length from the Grumeti River in Tanzania as well. This suggests that while there is a common upper limit for Nile crocodile size, exceptionally large individuals occasionally surpass this threshold, but they are far from common.
I believe that the idea of Nile crocodiles being the undisputed runner-up for sizes in crocodiles is just a lazy generalization that has been accepted through time, particularly when we take into account that Nile crocodiles are significantly better-known and documented than Orinoco crocodiles, this generates a bias to place more importance to them even when the empirical data doesn't support those assertions.
I believe that under the right conditions, all four of the largest crocodiles in the world can attain similarly gigantic sizes: salt-water, Orinoco, Nile, and American, but we don't live in a perfect world and the degrees of conservation between these species vary greatly, so we must have a large degree of nuance when we make definitive claims about their sizes.
This is a very thorough reply, thanks. I will break my response into two parts:
Nile crocodile vs Orinoco crocodile average sizes
I was actually aware of the review by Cott of nile crocodile sizes, what I had actually hoped for was a similar empirical breakdown of Orinoco crocodile sizes, based exclusively on actual measurements. You state “Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greater proportional frequency.” But consider the data we have. “in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms”. @epaiva states that the largest Orinocos in these populations are around 5 meters. Meanwhile for Nile crocodiles “among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters” and “Cott's study reported that only seven of these 324 males had lengths ranging from 4.3 to 4.75 meters.” Neither of these two Nile datasets are precisely comparable to the Orinoco one, because they are giving us number of males in certain size classes while the Orinoco data is a population average. In any case, I would not describe the two species’ datasets as “Orinoco’s attaining close to five meters with greater proportional frequency”. I don’t think the data here justifies that claim. At best, I would say that this data suggests the two species have comparable size distributions on average, since the fact that relatively few male Niles are attaining 4.3 plus meters implies the bulk are in the 4.29 and lower range, while the average for male Orinoco crocodiles was 4.1.
Why people say that the Nile crocodile is the second largest species
Your second and third paragraphs on Orinoco crocodile sizes consist of historical anecdotes and some reported measurements on very large Orinocos. I feel that when people are making a list of largest crocodilians, there are a few considerations which cause people to rank the Orinoco crocodile third. People will be looking at the largest reliable sizes, and placing each species as high in the list as it can go based on verified, reproducible high-end measurements. This reproducibility issue is, IMO, the main reason why the order of size is typically given as saltwater-nile-others. If we are to accept the 6 meter plus Orinoco measurements then we would have to actually consider C. intermedius to be the largest crocodilian, because not even salties have reliable measurements of that length on record. However, how large is the data, especially modern data, to substantiate those sizes? By my count we have at least one saltwater crocodile definitively measured at 6 plus meters (Lolong) and two others that were measured piecemeal and can reasonably be expected to have been in that range as well (Old Charlie and the Fly River Crocodile) No other species has verified 6-meter records. Could other species potentially reach this length? I think so, but the measurements aren’t there to support that, so we say that the Saltwater crocodile is the largest. I think we’re really saying that this species has the highest verified upper size range based on the data we have. For the second largest species, there is only one other crocodile with many verified measurements over 5.3 meters, and that is C. niloticus. Brady Barr was able to capture a 5.36-meter Nile crocodile on camera, and the SCI record book has a few specimens over 17 feet as well, including at least two 5.6 meter plus specimens. A dataset set of verified measurements in this size class doesn’t exist for any of the remaining crocodiles, so the Nile is said to be the second largest. No Orinoco or American crocodile has been measured to exceed 5.2 meters (I’ve actually never seen a confirmed measurement over 5 meters) so one of these species is typically said to be the third largest.)
Of course, all these large crocodiles are uncommon, and the bulk of the ecology of these species is mediated by smaller individuals. I think we both agree that the four largest crocodiles are of broadly comparable size and the potential exist for the new world species to one day be measured above 5.5 meters; but, when we want to make a ranked list of species based on size, we have to make reasonable judgement calls based on the empirical measurements, and I think it is this consideration that leads to the commonly cited order of crocodilian sizes.
11-02-2023, 09:56 PM( This post was last modified: 11-02-2023, 09:57 PM by KRA123 )
An addendum to my previous reply: The saltwater is apparently a bit longer on average than the nile as well, so that, as well as the maximum recorded sizes, supports placing it as the largest species. The Nile, Orionoco and American may be closer in average size than any of the three is to the saltwater. In that case, ranking them would fall to the maximum reliable sizes.
The breeding facility Patrullero de Chávez, dedicated to the conservation of Orinoco crocodiles, plays an active role in managing these reptiles for breeding purposes, with the distinct advantage of having them in captivity. Such facilities follow strict protocols, including regular veterinary assessments to ensure the well-being and accurate measurements of the crocodiles. It's important to note that this measurement is particularly reliable because it pertains to one of the largest breeding males in the facility which fell well within the range of large contemporary males as mentioned by @epaiva.
It's also true that all crocodile species face challenges when it comes to surpassing the 5-meter length threshold, and this is a reflection of the natural constraints on their growth. However, the main point of contention is not that Nile crocodiles are unable to achieve such lengths but rather that despite their widespread reputation as the "second-largest" crocodile species in the world, they appear to encounter comparable hurdles in reaching this notable milestone. What adds to the intrigue is that American and, particularly, Orinoco crocodiles have grappled with overhunting, which has led to significant impacts on their average sizes due to genetic diversity erosion.
Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greter proportional frequency. In contrast, Nile crocodiles boast a larger population and healthier genetic diversity, yet they seem to exhibit a comparatively lower frequency in achieving these impressive lengths. This intriguing observation casts a shadow of doubt on the claim that Nile crocodiles are unequivocally the second-largest in the world, as their counterparts from the Neotropics show a remarkable ability to achieve similar sizes despite their less favorable conservation status.
Now in terms of size, this is the information I have:
In the 2017 Growth rates of the American crocodile paper by Andrés E. Seijas, growth rates for American crocodiles were analyzed from various regions. The von Bertalanffy growth model predicted an asymptotic size of 4.39 meters for males in Florida. As for females, asymptotic sizes were 2.617 meters for those in Florida and 2.274 meters for those in the mangroves of Venezuela.
The Comportamiento reproductivo del caimán del Orinoco by Colvée (1999) reported that in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms. Females reach up to 3.2 meters in length and weigh around 211 kilograms.
Experts generally estimate a maximum total length of up to 7 meters for Orinocos. This estimation is substantiated by the accounts of seasoned "caimaneros" or crocodile hunters, such as those cited by Medem in 1981. Even historical explorers like Humboldt and Bonpland, who ventured along the banks of the Apure River in 1880, recorded their encounters with remarkably large Orinoco crocodiles. One account describes a specimen measuring 16 feet 8 inches (508 cm) in length, while another, identified as a male, stretched to an impressive 22 feet 3 inches (678 cm). Further back in time, the narrative continues with Fray Jacinto de Carvajal, who, in 1618, chronicled a colossal crocodile of 25 feet, which, adjusted for the "pie de Castilla" measurement system (27.85 cm per foot), translates to an astonishing 696 cm. These historical and contemporary records paint a vivid picture of the remarkable size potential of the Orinoco crocodiles during a time when they were not critically endangered.
Humboldt and Bonpland are as reliable as a naturalist could get for the 19th century, which is why they are quoted by modern authorities in the field, like in the Commercial Hunting of the Orinoco Crocodile, Crocodylus intermedius, in Venezuela thesis by Ernesto Boede and Rafael Hoogesteijn (2017) where they detail Alexander von Humboldt's extraordinary journey to the Orinoco region in detail. He noted that crocodiles were abundant and that sizes ranged between 5.08 meters to 7.31 meters. It's possible that the 7.31 meters value is an incorrect conversion belonging to the 6.78 meters specimen to be clear.
For Nile crocodiles, we have B. Cott's paper, Scientific results of an inquiry into the ecology and economic status of the Nile Crocodile (Crocodilus niloticus) in Uganda and Northern Rhodesia which sheds light on the challenges associated with assessing the size of Nile crocodiles. The study underscores the skepticism surrounding the validity of size records and highlights the unreliability of visual estimates, such as those provided by herpetologists like Brue (7.62 meters) and Barbot (9.14 meters). While some herpetologists have erred on the side of caution, accepting a conservative estimate of 4.88 meters, this figure is notably lower than the measurements reliably reported from historical accounts.
Cott's work presents a range of maximum lengths reported for Nile crocodiles from different African regions. In Central Africa, reports suggest that large crocodiles over 4.99 meters in length have been encountered. For instance, the largest crocodile measured in Northern Rhodesia reached 5.05 meters. Similarly, a crocodile in Nyasaland was reported to measure an impressive 5.74 meters.
In East Africa, particularly in Uganda, the study highlights the presence of exceptionally large Nile crocodiles. Crocodiles in the Lower Semliki and the Murchison reach of the Victoria Nile achieved notable sizes. In 1950, two males measured 5.13 meters and 5.54 meters, according to measurements taken by a Game Ranger. Additionally, in 1952, the Marketing Corporation received a skin measuring 5.94 meters from the Lower Semliki, signifying the substantial size of Nile crocodiles in this region.
So what does contemporary data says? A. D. Graham's 1968 study, The Lake Rudolf Crocodile (Crocodylus niloticus Laurenti) Population, provides valuable insights into the population and growth characteristics of Nile crocodiles in the Lake Rudolf region. The study reveals that sexual maturity in this population is reached by over 50% of males at approximately 2.7 meters in length. However, there is substantial variability in the size at which crocodiles become sexually mature, with some individuals reaching maturity as early as 1.89 meters, while others require up to 3.38 meters.
The study records that among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters. Notably, in the Lake Rudolf area surveyed by the Kenya Game Department in Ferguson's Gulf, no crocodiles larger than this maximum size were encountered.
Additionally, A. D. Graham references findings from B. Cott's study in Uganda and Zambia, which examined 324 males. Cott's study reported that only seven of these males had lengths ranging from 4.3 to 4.75 meters. But as I showed before Cott's work also cites several seemingly authentic records of Nile crocodiles reaching lengths of up to 6 meters. Graham highlights personal records of crocodiles exceeding 5 meters in length from the Grumeti River in Tanzania as well. This suggests that while there is a common upper limit for Nile crocodile size, exceptionally large individuals occasionally surpass this threshold, but they are far from common.
I believe that the idea of Nile crocodiles being the undisputed runner-up for sizes in crocodiles is just a lazy generalization that has been accepted through time, particularly when we take into account that Nile crocodiles are significantly better-known and documented than Orinoco crocodiles, this generates a bias to place more importance to them even when the empirical data doesn't support those assertions.
I believe that under the right conditions, all four of the largest crocodiles in the world can attain similarly gigantic sizes: salt-water, Orinoco, Nile, and American, but we don't live in a perfect world and the degrees of conservation between these species vary greatly, so we must have a large degree of nuance when we make definitive claims about their sizes.
This is a very thorough reply, thanks. I will break my response into two parts:
Nile crocodile vs Orinoco crocodile average sizes
I was actually aware of the review by Cott of nile crocodile sizes, what I had actually hoped for was a similar empirical breakdown of Orinoco crocodile sizes, based exclusively on actual measurements. You state “Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greater proportional frequency.” But consider the data we have. “in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms”. @epaiva states that the largest Orinocos in these populations are around 5 meters. Meanwhile for Nile crocodiles “among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters” and “Cott's study reported that only seven of these 324 males had lengths ranging from 4.3 to 4.75 meters.” Neither of these two Nile datasets are precisely comparable to the Orinoco one, because they are giving us number of males in certain size classes while the Orinoco data is a population average. In any case, I would not describe the two species’ datasets as “Orinoco’s attaining close to five meters with greater proportional frequency”. I don’t think the data here justifies that claim. At best, I would say that this data suggests the two species have comparable size distributions on average, since the fact that relatively few male Niles are attaining 4.3 plus meters implies the bulk are in the 4.29 and lower range, while the average for male Orinoco crocodiles was 4.1.
Why people say that the Nile crocodile is the second largest species
Your second and third paragraphs on Orinoco crocodile sizes consist of historical anecdotes and some reported measurements on very large Orinocos. I feel that when people are making a list of largest crocodilians, there are a few considerations which cause people to rank the Orinoco crocodile third. People will be looking at the largest reliable sizes, and placing each species as high in the list as it can go based on verified, reproducible high-end measurements. This reproducibility issue is, IMO, the main reason why the order of size is typically given as saltwater-nile-others. If we are to accept the 6 meter plus Orinoco measurements then we would have to actually consider C. intermedius to be the largest crocodilian, because not even salties have reliable measurements of that length on record. However, how large is the data, especially modern data, to substantiate those sizes? By my count we have at least one saltwater crocodile definitively measured at 6 plus meters (Lolong) and two others that were measured piecemeal and can reasonably be expected to have been in that range as well (Old Charlie and the Fly River Crocodile) No other species has verified 6-meter records. Could other species potentially reach this length? I think so, but the measurements aren’t there to support that, so we say that the Saltwater crocodile is the largest. I think we’re really saying that this species has the highest verified upper size range based on the data we have. For the second largest species, there is only one other crocodile with many verified measurements over 5.3 meters, and that is C. niloticus. Brady Barr was able to capture a 5.36-meter Nile crocodile on camera, and the SCI record book has a few specimens over 17 feet as well, including at least two 5.6 meter plus specimens. A dataset set of verified measurements in this size class doesn’t exist for any of the remaining crocodiles, so the Nile is said to be the second largest. No Orinoco or American crocodile has been measured to exceed 5.2 meters (I’ve actually never seen a confirmed measurement over 5 meters) so one of these species is typically said to be the third largest.)
Of course, all these large crocodiles are uncommon, and the bulk of the ecology of these species is mediated by smaller individuals. I think we both agree that the four largest crocodiles are of broadly comparable size and the potential exist for the new world species to one day be measured above 5.5 meters; but, when we want to make a ranked list of species based on size, we have to make reasonable judgement calls based on the empirical measurements, and I think it is this consideration that leads to the commonly cited order of crocodilian sizes.
@KRA123
Totally agree with you about their size, Orinoco Crocodiles and American Crocodiles are behind Nile Crocodiles in size, Nile Crocodiles are the heaviest of them all for their size, I am sure a few of them (Nile Crocodiles) go over 5 meters long in Lake Chamo in Ethiopia, Mr Rhom Whitaker went to Lake Chamo a few years back (you can see it in youtube) and found a few giant Crocs and very large skulls in their collection that belonged to big males over 5 meters long.
@epaiva at least seven of the twelve 17- to 19-foot nile crocodiles in the SCI record book are from Lake Chamo, including the top two specimens. The crocodile caught by Brady Barr was in Tanzania though. I suspect you'll find a few five meter plus specimens throughout east Africa. Not sure about southern Africa though.
The breeding facility Patrullero de Chávez, dedicated to the conservation of Orinoco crocodiles, plays an active role in managing these reptiles for breeding purposes, with the distinct advantage of having them in captivity. Such facilities follow strict protocols, including regular veterinary assessments to ensure the well-being and accurate measurements of the crocodiles. It's important to note that this measurement is particularly reliable because it pertains to one of the largest breeding males in the facility which fell well within the range of large contemporary males as mentioned by @epaiva.
It's also true that all crocodile species face challenges when it comes to surpassing the 5-meter length threshold, and this is a reflection of the natural constraints on their growth. However, the main point of contention is not that Nile crocodiles are unable to achieve such lengths but rather that despite their widespread reputation as the "second-largest" crocodile species in the world, they appear to encounter comparable hurdles in reaching this notable milestone. What adds to the intrigue is that American and, particularly, Orinoco crocodiles have grappled with overhunting, which has led to significant impacts on their average sizes due to genetic diversity erosion.
Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greter proportional frequency. In contrast, Nile crocodiles boast a larger population and healthier genetic diversity, yet they seem to exhibit a comparatively lower frequency in achieving these impressive lengths. This intriguing observation casts a shadow of doubt on the claim that Nile crocodiles are unequivocally the second-largest in the world, as their counterparts from the Neotropics show a remarkable ability to achieve similar sizes despite their less favorable conservation status.
Now in terms of size, this is the information I have:
In the 2017 Growth rates of the American crocodile paper by Andrés E. Seijas, growth rates for American crocodiles were analyzed from various regions. The von Bertalanffy growth model predicted an asymptotic size of 4.39 meters for males in Florida. As for females, asymptotic sizes were 2.617 meters for those in Florida and 2.274 meters for those in the mangroves of Venezuela.
The Comportamiento reproductivo del caimán del Orinoco by Colvée (1999) reported that in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms. Females reach up to 3.2 meters in length and weigh around 211 kilograms.
Experts generally estimate a maximum total length of up to 7 meters for Orinocos. This estimation is substantiated by the accounts of seasoned "caimaneros" or crocodile hunters, such as those cited by Medem in 1981. Even historical explorers like Humboldt and Bonpland, who ventured along the banks of the Apure River in 1880, recorded their encounters with remarkably large Orinoco crocodiles. One account describes a specimen measuring 16 feet 8 inches (508 cm) in length, while another, identified as a male, stretched to an impressive 22 feet 3 inches (678 cm). Further back in time, the narrative continues with Fray Jacinto de Carvajal, who, in 1618, chronicled a colossal crocodile of 25 feet, which, adjusted for the "pie de Castilla" measurement system (27.85 cm per foot), translates to an astonishing 696 cm. These historical and contemporary records paint a vivid picture of the remarkable size potential of the Orinoco crocodiles during a time when they were not critically endangered.
Humboldt and Bonpland are as reliable as a naturalist could get for the 19th century, which is why they are quoted by modern authorities in the field, like in the Commercial Hunting of the Orinoco Crocodile, Crocodylus intermedius, in Venezuela thesis by Ernesto Boede and Rafael Hoogesteijn (2017) where they detail Alexander von Humboldt's extraordinary journey to the Orinoco region in detail. He noted that crocodiles were abundant and that sizes ranged between 5.08 meters to 7.31 meters. It's possible that the 7.31 meters value is an incorrect conversion belonging to the 6.78 meters specimen to be clear.
For Nile crocodiles, we have B. Cott's paper, Scientific results of an inquiry into the ecology and economic status of the Nile Crocodile (Crocodilus niloticus) in Uganda and Northern Rhodesia which sheds light on the challenges associated with assessing the size of Nile crocodiles. The study underscores the skepticism surrounding the validity of size records and highlights the unreliability of visual estimates, such as those provided by herpetologists like Brue (7.62 meters) and Barbot (9.14 meters). While some herpetologists have erred on the side of caution, accepting a conservative estimate of 4.88 meters, this figure is notably lower than the measurements reliably reported from historical accounts.
Cott's work presents a range of maximum lengths reported for Nile crocodiles from different African regions. In Central Africa, reports suggest that large crocodiles over 4.99 meters in length have been encountered. For instance, the largest crocodile measured in Northern Rhodesia reached 5.05 meters. Similarly, a crocodile in Nyasaland was reported to measure an impressive 5.74 meters.
In East Africa, particularly in Uganda, the study highlights the presence of exceptionally large Nile crocodiles. Crocodiles in the Lower Semliki and the Murchison reach of the Victoria Nile achieved notable sizes. In 1950, two males measured 5.13 meters and 5.54 meters, according to measurements taken by a Game Ranger. Additionally, in 1952, the Marketing Corporation received a skin measuring 5.94 meters from the Lower Semliki, signifying the substantial size of Nile crocodiles in this region.
So what does contemporary data says? A. D. Graham's 1968 study, The Lake Rudolf Crocodile (Crocodylus niloticus Laurenti) Population, provides valuable insights into the population and growth characteristics of Nile crocodiles in the Lake Rudolf region. The study reveals that sexual maturity in this population is reached by over 50% of males at approximately 2.7 meters in length. However, there is substantial variability in the size at which crocodiles become sexually mature, with some individuals reaching maturity as early as 1.89 meters, while others require up to 3.38 meters.
The study records that among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters. Notably, in the Lake Rudolf area surveyed by the Kenya Game Department in Ferguson's Gulf, no crocodiles larger than this maximum size were encountered.
Additionally, A. D. Graham references findings from B. Cott's study in Uganda and Zambia, which examined 324 males. Cott's study reported that only seven of these males had lengths ranging from 4.3 to 4.75 meters. But as I showed before Cott's work also cites several seemingly authentic records of Nile crocodiles reaching lengths of up to 6 meters. Graham highlights personal records of crocodiles exceeding 5 meters in length from the Grumeti River in Tanzania as well. This suggests that while there is a common upper limit for Nile crocodile size, exceptionally large individuals occasionally surpass this threshold, but they are far from common.
I believe that the idea of Nile crocodiles being the undisputed runner-up for sizes in crocodiles is just a lazy generalization that has been accepted through time, particularly when we take into account that Nile crocodiles are significantly better-known and documented than Orinoco crocodiles, this generates a bias to place more importance to them even when the empirical data doesn't support those assertions.
I believe that under the right conditions, all four of the largest crocodiles in the world can attain similarly gigantic sizes: salt-water, Orinoco, Nile, and American, but we don't live in a perfect world and the degrees of conservation between these species vary greatly, so we must have a large degree of nuance when we make definitive claims about their sizes.
This is a very thorough reply, thanks. I will break my response into two parts:
Nile crocodile vs Orinoco crocodile average sizes
I was actually aware of the review by Cott of nile crocodile sizes, what I had actually hoped for was a similar empirical breakdown of Orinoco crocodile sizes, based exclusively on actual measurements. You state “Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greater proportional frequency.” But consider the data we have. “in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms”. @epaiva states that the largest Orinocos in these populations are around 5 meters. Meanwhile for Nile crocodiles “among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters” and “Cott's study reported that only seven of these 324 males had lengths ranging from 4.3 to 4.75 meters.” Neither of these two Nile datasets are precisely comparable to the Orinoco one, because they are giving us number of males in certain size classes while the Orinoco data is a population average. In any case, I would not describe the two species’ datasets as “Orinoco’s attaining close to five meters with greater proportional frequency”. I don’t think the data here justifies that claim. At best, I would say that this data suggests the two species have comparable size distributions on average, since the fact that relatively few male Niles are attaining 4.3 plus meters implies the bulk are in the 4.29 and lower range, while the average for male Orinoco crocodiles was 4.1.
Why people say that the Nile crocodile is the second largest species
Your second and third paragraphs on Orinoco crocodile sizes consist of historical anecdotes and some reported measurements on very large Orinocos. I feel that when people are making a list of largest crocodilians, there are a few considerations which cause people to rank the Orinoco crocodile third. People will be looking at the largest reliable sizes, and placing each species as high in the list as it can go based on verified, reproducible high-end measurements. This reproducibility issue is, IMO, the main reason why the order of size is typically given as saltwater-nile-others. If we are to accept the 6 meter plus Orinoco measurements then we would have to actually consider C. intermedius to be the largest crocodilian, because not even salties have reliable measurements of that length on record. However, how large is the data, especially modern data, to substantiate those sizes? By my count we have at least one saltwater crocodile definitively measured at 6 plus meters (Lolong) and two others that were measured piecemeal and can reasonably be expected to have been in that range as well (Old Charlie and the Fly River Crocodile) No other species has verified 6-meter records. Could other species potentially reach this length? I think so, but the measurements aren’t there to support that, so we say that the Saltwater crocodile is the largest. I think we’re really saying that this species has the highest verified upper size range based on the data we have. For the second largest species, there is only one other crocodile with many verified measurements over 5.3 meters, and that is C. niloticus. Brady Barr was able to capture a 5.36-meter Nile crocodile on camera, and the SCI record book has a few specimens over 17 feet as well, including at least two 5.6 meter plus specimens. A dataset set of verified measurements in this size class doesn’t exist for any of the remaining crocodiles, so the Nile is said to be the second largest. No Orinoco or American crocodile has been measured to exceed 5.2 meters (I’ve actually never seen a confirmed measurement over 5 meters) so one of these species is typically said to be the third largest.)
Of course, all these large crocodiles are uncommon, and the bulk of the ecology of these species is mediated by smaller individuals. I think we both agree that the four largest crocodiles are of broadly comparable size and the potential exist for the new world species to one day be measured above 5.5 meters; but, when we want to make a ranked list of species based on size, we have to make reasonable judgement calls based on the empirical measurements, and I think it is this consideration that leads to the commonly cited order of crocodilian sizes.
On Average Sizes and Conservation:
The Nile crocodile's data is often presented in size classes, showing that only a limited number of male Nile crocodiles reach lengths between 4.3 and 4.7 meters, hence why I initially stated that despite their reputation as "giants", they struggle to surpass the 4.5-meter threshold. This distribution may also imply that the majority fall below the 4.3-meter threshold. It's essential to consider this variation, but I'd agree that stating Orinoco's attaining sizes close to 5 meters with "greater proportional frequency" might not be entirely accurate as we need more data, but I will elaborate on why I said that further down. The available data indeed supports that these two species have comparable size distributions on average, with male Orinocos from Venezuela at 4.1 meters and Nile crocodiles from East Africa predominantly below 4.3 meters.
My argument emphasizes the genetic predisposition for Orinoco crocodiles to achieve sizes that Nile crocodiles often struggle to attain. This phenomenon becomes all the more striking when we consider the significant population differences between these two species. The Orinoco crocodile population ranges between 250 and 1500 individuals, while Nile crocodiles number between 50,000 and 70,000. The vast contrast in population size should logically favor Nile crocodiles achieving the larger sizes we're discussing with potentially more frequency due to sheer numbers and better genetic diversity, not because they are inherently a larger species.
Despite their very different conservation statuses, Orinocos have somehow managed to produce contemporary specimens that reach the impressive 5+ meter threshold. In this context, I based my claim that Orinocos are proportionally more capable of reaching these larger sizes, and this genetic predisposition is a critical factor to consider in discussions about their size potential.
Validating Historical Claims, Especially Humboldt's:
You've raised a pertinent point about historical claims regarding crocodile sizes. It's essential to acknowledge the credibility of these claims and recognize that esteemed naturalists like Humboldt and Bonpland would not have provided specific measurements without solid experience. Their meticulous scientific approaches add weight to their records, and their observations, though from another era, remain valuable in assessing the potential size of these creatures.
I included the second-hand information provided to B. Cott's that relies largely on hunting records from the 20th century to give an overview in favor of large Nile crocodiles, but I do find it interesting that you did not challenge the validity of these records as you did with Humboldt and Bonpland.
In contrast, more contemporary records, such as those found in the Safari Club International (SCI) record book, have demonstrated inaccuracies, as hunters occasionally exaggerate the sizes of their kills. This pattern of exaggeration is not unique to crocodile records and has been observed in other species, such as big cats, where even skull measurements have been manipulated or measured in incorrect ways. As such, these modern records must be viewed with a degree of skepticism I'd argue even greater than those from reputable scientists from past centuries.
In regards to the 5+ meter Orinoco crocodiles, here's Mexican naturalist René Villanueva at the Roberto Franco Biological Station in Colombia showcasing the skull of a huge Orinoco crocodile they have in their collection which he states measured 5.5 meters in length when alive, presumably information provided by the collection officials. I included subtitles but other members can verify that's what he's saying:
@“Balam”
Great to see that you are doing great with crocodiles too. Ask the person that gave you the Information of the Giant Orinoco if he has pictures of that animal and information of its skull, I posted a picture of the largest skull of a Orinoco Crocodile in Colombia and it does not correspond with a Giant Croc over 5 meters long, it is as large as the largest one in Venezuelan Collections.
(11-03-2023, 07:30 PM)epaiva Wrote: @“Balam”
Great to see that you are doing great with crocodiles too. Ask the person that gave you the Information of the Giant Orinoco if he has pictures of that animal and information of its skull, I posted a picture of the largest skull of a Orinoco Crocodile in Colombia and it does not correspond with a Giant Croc over 5 meters long, it is as large as the largest one in Venezuelan Collections.
I will ask and contact the museum directly as well. I'd like to know the year that specimen was harvested as well.
(11-03-2023, 07:30 PM)epaiva Wrote: @“Balam”
Great to see that you are doing great with crocodiles too. Ask the person that gave you the Information of the Giant Orinoco if he has pictures of that animal and information of its skull, I posted a picture of the largest skull of a Orinoco Crocodile in Colombia and it does not correspond with a Giant Croc over 5 meters long, it is as large as the largest one in Venezuelan Collections.
I will ask and contact the museum directly as well. I'd like to know the year that specimen was harvested as well.
@Balam I will respond to your last post soon; been busy recently.
The breeding facility Patrullero de Chávez, dedicated to the conservation of Orinoco crocodiles, plays an active role in managing these reptiles for breeding purposes, with the distinct advantage of having them in captivity. Such facilities follow strict protocols, including regular veterinary assessments to ensure the well-being and accurate measurements of the crocodiles. It's important to note that this measurement is particularly reliable because it pertains to one of the largest breeding males in the facility which fell well within the range of large contemporary males as mentioned by @epaiva.
It's also true that all crocodile species face challenges when it comes to surpassing the 5-meter length threshold, and this is a reflection of the natural constraints on their growth. However, the main point of contention is not that Nile crocodiles are unable to achieve such lengths but rather that despite their widespread reputation as the "second-largest" crocodile species in the world, they appear to encounter comparable hurdles in reaching this notable milestone. What adds to the intrigue is that American and, particularly, Orinoco crocodiles have grappled with overhunting, which has led to significant impacts on their average sizes due to genetic diversity erosion.
Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greter proportional frequency. In contrast, Nile crocodiles boast a larger population and healthier genetic diversity, yet they seem to exhibit a comparatively lower frequency in achieving these impressive lengths. This intriguing observation casts a shadow of doubt on the claim that Nile crocodiles are unequivocally the second-largest in the world, as their counterparts from the Neotropics show a remarkable ability to achieve similar sizes despite their less favorable conservation status.
Now in terms of size, this is the information I have:
In the 2017 Growth rates of the American crocodile paper by Andrés E. Seijas, growth rates for American crocodiles were analyzed from various regions. The von Bertalanffy growth model predicted an asymptotic size of 4.39 meters for males in Florida. As for females, asymptotic sizes were 2.617 meters for those in Florida and 2.274 meters for those in the mangroves of Venezuela.
The Comportamiento reproductivo del caimán del Orinoco by Colvée (1999) reported that in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms. Females reach up to 3.2 meters in length and weigh around 211 kilograms.
Experts generally estimate a maximum total length of up to 7 meters for Orinocos. This estimation is substantiated by the accounts of seasoned "caimaneros" or crocodile hunters, such as those cited by Medem in 1981. Even historical explorers like Humboldt and Bonpland, who ventured along the banks of the Apure River in 1880, recorded their encounters with remarkably large Orinoco crocodiles. One account describes a specimen measuring 16 feet 8 inches (508 cm) in length, while another, identified as a male, stretched to an impressive 22 feet 3 inches (678 cm). Further back in time, the narrative continues with Fray Jacinto de Carvajal, who, in 1618, chronicled a colossal crocodile of 25 feet, which, adjusted for the "pie de Castilla" measurement system (27.85 cm per foot), translates to an astonishing 696 cm. These historical and contemporary records paint a vivid picture of the remarkable size potential of the Orinoco crocodiles during a time when they were not critically endangered.
Humboldt and Bonpland are as reliable as a naturalist could get for the 19th century, which is why they are quoted by modern authorities in the field, like in the Commercial Hunting of the Orinoco Crocodile, Crocodylus intermedius, in Venezuela thesis by Ernesto Boede and Rafael Hoogesteijn (2017) where they detail Alexander von Humboldt's extraordinary journey to the Orinoco region in detail. He noted that crocodiles were abundant and that sizes ranged between 5.08 meters to 7.31 meters. It's possible that the 7.31 meters value is an incorrect conversion belonging to the 6.78 meters specimen to be clear.
For Nile crocodiles, we have B. Cott's paper, Scientific results of an inquiry into the ecology and economic status of the Nile Crocodile (Crocodilus niloticus) in Uganda and Northern Rhodesia which sheds light on the challenges associated with assessing the size of Nile crocodiles. The study underscores the skepticism surrounding the validity of size records and highlights the unreliability of visual estimates, such as those provided by herpetologists like Brue (7.62 meters) and Barbot (9.14 meters). While some herpetologists have erred on the side of caution, accepting a conservative estimate of 4.88 meters, this figure is notably lower than the measurements reliably reported from historical accounts.
Cott's work presents a range of maximum lengths reported for Nile crocodiles from different African regions. In Central Africa, reports suggest that large crocodiles over 4.99 meters in length have been encountered. For instance, the largest crocodile measured in Northern Rhodesia reached 5.05 meters. Similarly, a crocodile in Nyasaland was reported to measure an impressive 5.74 meters.
In East Africa, particularly in Uganda, the study highlights the presence of exceptionally large Nile crocodiles. Crocodiles in the Lower Semliki and the Murchison reach of the Victoria Nile achieved notable sizes. In 1950, two males measured 5.13 meters and 5.54 meters, according to measurements taken by a Game Ranger. Additionally, in 1952, the Marketing Corporation received a skin measuring 5.94 meters from the Lower Semliki, signifying the substantial size of Nile crocodiles in this region.
So what does contemporary data says? A. D. Graham's 1968 study, The Lake Rudolf Crocodile (Crocodylus niloticus Laurenti) Population, provides valuable insights into the population and growth characteristics of Nile crocodiles in the Lake Rudolf region. The study reveals that sexual maturity in this population is reached by over 50% of males at approximately 2.7 meters in length. However, there is substantial variability in the size at which crocodiles become sexually mature, with some individuals reaching maturity as early as 1.89 meters, while others require up to 3.38 meters.
The study records that among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters. Notably, in the Lake Rudolf area surveyed by the Kenya Game Department in Ferguson's Gulf, no crocodiles larger than this maximum size were encountered.
Additionally, A. D. Graham references findings from B. Cott's study in Uganda and Zambia, which examined 324 males. Cott's study reported that only seven of these males had lengths ranging from 4.3 to 4.75 meters. But as I showed before Cott's work also cites several seemingly authentic records of Nile crocodiles reaching lengths of up to 6 meters. Graham highlights personal records of crocodiles exceeding 5 meters in length from the Grumeti River in Tanzania as well. This suggests that while there is a common upper limit for Nile crocodile size, exceptionally large individuals occasionally surpass this threshold, but they are far from common.
I believe that the idea of Nile crocodiles being the undisputed runner-up for sizes in crocodiles is just a lazy generalization that has been accepted through time, particularly when we take into account that Nile crocodiles are significantly better-known and documented than Orinoco crocodiles, this generates a bias to place more importance to them even when the empirical data doesn't support those assertions.
I believe that under the right conditions, all four of the largest crocodiles in the world can attain similarly gigantic sizes: salt-water, Orinoco, Nile, and American, but we don't live in a perfect world and the degrees of conservation between these species vary greatly, so we must have a large degree of nuance when we make definitive claims about their sizes.
This is a very thorough reply, thanks. I will break my response into two parts:
Nile crocodile vs Orinoco crocodile average sizes
I was actually aware of the review by Cott of nile crocodile sizes, what I had actually hoped for was a similar empirical breakdown of Orinoco crocodile sizes, based exclusively on actual measurements. You state “Even in the face of this adversity, American and Orinoco crocodiles continue to produce individuals that attain asymptotic sizes of 5 meters or close to it with greater proportional frequency.” But consider the data we have. “in Venezuela, adult males of Orinoco crocodiles reach 4.1 meters in length on average with a weight of 369 kilograms”. @epaiva states that the largest Orinocos in these populations are around 5 meters. Meanwhile for Nile crocodiles “among the 202 males examined during the survey, the largest individual measured 4.72 meters, with an additional 11 crocodiles falling within the range of 4.3 to 4.7 meters” and “Cott's study reported that only seven of these 324 males had lengths ranging from 4.3 to 4.75 meters.” Neither of these two Nile datasets are precisely comparable to the Orinoco one, because they are giving us number of males in certain size classes while the Orinoco data is a population average. In any case, I would not describe the two species’ datasets as “Orinoco’s attaining close to five meters with greater proportional frequency”. I don’t think the data here justifies that claim. At best, I would say that this data suggests the two species have comparable size distributions on average, since the fact that relatively few male Niles are attaining 4.3 plus meters implies the bulk are in the 4.29 and lower range, while the average for male Orinoco crocodiles was 4.1.
Why people say that the Nile crocodile is the second largest species
Your second and third paragraphs on Orinoco crocodile sizes consist of historical anecdotes and some reported measurements on very large Orinocos. I feel that when people are making a list of largest crocodilians, there are a few considerations which cause people to rank the Orinoco crocodile third. People will be looking at the largest reliable sizes, and placing each species as high in the list as it can go based on verified, reproducible high-end measurements. This reproducibility issue is, IMO, the main reason why the order of size is typically given as saltwater-nile-others. If we are to accept the 6 meter plus Orinoco measurements then we would have to actually consider C. intermedius to be the largest crocodilian, because not even salties have reliable measurements of that length on record. However, how large is the data, especially modern data, to substantiate those sizes? By my count we have at least one saltwater crocodile definitively measured at 6 plus meters (Lolong) and two others that were measured piecemeal and can reasonably be expected to have been in that range as well (Old Charlie and the Fly River Crocodile) No other species has verified 6-meter records. Could other species potentially reach this length? I think so, but the measurements aren’t there to support that, so we say that the Saltwater crocodile is the largest. I think we’re really saying that this species has the highest verified upper size range based on the data we have. For the second largest species, there is only one other crocodile with many verified measurements over 5.3 meters, and that is C. niloticus. Brady Barr was able to capture a 5.36-meter Nile crocodile on camera, and the SCI record book has a few specimens over 17 feet as well, including at least two 5.6 meter plus specimens. A dataset set of verified measurements in this size class doesn’t exist for any of the remaining crocodiles, so the Nile is said to be the second largest. No Orinoco or American crocodile has been measured to exceed 5.2 meters (I’ve actually never seen a confirmed measurement over 5 meters) so one of these species is typically said to be the third largest.)
Of course, all these large crocodiles are uncommon, and the bulk of the ecology of these species is mediated by smaller individuals. I think we both agree that the four largest crocodiles are of broadly comparable size and the potential exist for the new world species to one day be measured above 5.5 meters; but, when we want to make a ranked list of species based on size, we have to make reasonable judgement calls based on the empirical measurements, and I think it is this consideration that leads to the commonly cited order of crocodilian sizes.
On Average Sizes and Conservation:
The Nile crocodile's data is often presented in size classes, showing that only a limited number of male Nile crocodiles reach lengths between 4.3 and 4.7 meters, hence why I initially stated that despite their reputation as "giants", they struggle to surpass the 4.5-meter threshold. This distribution may also imply that the majority fall below the 4.3-meter threshold. It's essential to consider this variation, but I'd agree that stating Orinoco's attaining sizes close to 5 meters with "greater proportional frequency" might not be entirely accurate as we need more data, but I will elaborate on why I said that further down. The available data indeed supports that these two species have comparable size distributions on average, with male Orinocos from Venezuela at 4.1 meters and Nile crocodiles from East Africa predominantly below 4.3 meters.
My argument emphasizes the genetic predisposition for Orinoco crocodiles to achieve sizes that Nile crocodiles often struggle to attain. This phenomenon becomes all the more striking when we consider the significant population differences between these two species. The Orinoco crocodile population ranges between 250 and 1500 individuals, while Nile crocodiles number between 50,000 and 70,000. The vast contrast in population size should logically favor Nile crocodiles achieving the larger sizes we're discussing with potentially more frequency due to sheer numbers and better genetic diversity, not because they are inherently a larger species.
Despite their very different conservation statuses, Orinocos have somehow managed to produce contemporary specimens that reach the impressive 5+ meter threshold. In this context, I based my claim that Orinocos are proportionally more capable of reaching these larger sizes, and this genetic predisposition is a critical factor to consider in discussions about their size potential.
Validating Historical Claims, Especially Humboldt's:
You've raised a pertinent point about historical claims regarding crocodile sizes. It's essential to acknowledge the credibility of these claims and recognize that esteemed naturalists like Humboldt and Bonpland would not have provided specific measurements without solid experience. Their meticulous scientific approaches add weight to their records, and their observations, though from another era, remain valuable in assessing the potential size of these creatures.
I included the second-hand information provided to B. Cott's that relies largely on hunting records from the 20th century to give an overview in favor of large Nile crocodiles, but I do find it interesting that you did not challenge the validity of these records as you did with Humboldt and Bonpland.
In contrast, more contemporary records, such as those found in the Safari Club International (SCI) record book, have demonstrated inaccuracies, as hunters occasionally exaggerate the sizes of their kills. This pattern of exaggeration is not unique to crocodile records and has been observed in other species, such as big cats, where even skull measurements have been manipulated or measured in incorrect ways. As such, these modern records must be viewed with a degree of skepticism I'd argue even greater than those from reputable scientists from past centuries.
In regards to the 5+ meter Orinoco crocodiles, here's Mexican naturalist René Villanueva at the Roberto Franco Biological Station in Colombia showcasing the skull of a huge Orinoco crocodile they have in their collection which he states measured 5.5 meters in length when alive, presumably information provided by the collection officials. I included subtitles but other members can verify that's what he's saying:
"Genetic Predisposition"
You stated “My argument emphasizes the genetic predisposition for Orinoco crocodiles to achieve sizes that Nile crocodiles often struggle to attain” You clearly mean a greater predisposition than Niles, and my argument is that this greater predisposition is not evident at all. You are mixing two arguments in your second and third paragraphs. The first is that Orinocos attain 5 meter lengths with more frequency than Niles. That is not supported. In fact so far we have not established any modern records of five meter plus Orinoco crocodiles at all (n=0) while there are several such records (modern and reliable) for Niles. The second argument you’re making is that the distribution of five-plus meter crocodiles between the two species doesn’t necessarily imply that Niles are inherently bigger. This argument is correct, IMO. The argumentative framework you’ve constructed around this, when you consider it, is weirdly all or nothing. If we do eventually find a few five meter plus C. intermedius, that would then establish that both species can reach this size class. A greater proportional frequency of giant crocs in Orinoco crocodiles is an extraordinary claim for which you seem to be willing to accept a very low bar of evidence. I mean, consider Lake Chamo. According to the Crocodile Specialist Group, the population of C. niloticus in Lake Chamo (LC) has been estimated between 2,000 to 4,000. A minimum of seven 5-meter plus crocodiles have been measured from this lake when we consider only the most reliable records. So, this single water body has produced more crocodiles in this size range than the entire population of Orinoco crocodiles (which may be comparable to the LC population) has. And keep in mind that these records were made when hunting was still permitted on the lake. I guess I just don’t see how you can interpret the data (possible absence of the five meter-plus size class in C. intermedius) as evidence for a completely opposite conclusion (proportional overrepresentation of the 5 -meter plus size class in C. intermedius). I should mention that I expect the southernmost populations of C. niloticus to attain the largest sizes relatively rarely compared to the east African ones. The west African populations living in dry unproductive areas might never attain them for all I know. I think this discussion really concerns mostly the east African subset of the C. niloticus population.
C. intermedius almost certainly does have a genetic potential to attain a size that C. niloticus struggles to - because C. intermedius can probably attain a length of five meters, and all the crocodile species including C. niloticus struggle to attain this length. The comparable statement would be true of C. acutus, C. niloticus, and C. porosus as well. It’s a nothing burger. If/when a few giant C. intermedius show up, this will be a realization of the potential I’m sure we all agree is there.
I think that some more involved statistics than what we have been doing here are required for the type of argument you want to make anyway. Statistics isn’t an area of expertise for me, but I think you would ideally want to quantify the frequency of giant individuals in large samples of both species, perhaps their entire respective populations, and then statistically test your data with an appropriate test and note the significance of the results. Something like that would be the gold standard, I think. Alternatively, we could measure a bunch of crocodiles in some comparable samples of each species and have a look at their size distributions. I don’t think this has been done, and based on the data I see no reason to believe the result would show C. intermedius having a greater proportional frequency of giant individuals.
Even if this were to be done, the question of “second largest species” would still be based on which one has the highest verified reproducible measurements, which, if we go on reproducible figures, is C. niloticus. Reliability of Records
As for SCI records, I have not encountered a convincing argument that these are unreliable, especially for something as straightforward as measuring the TL of a crocodile over the curves. The SCI themselves state “All entries are submitted by hunters and verified by Master Measurers to ensure accuracy.” Unless we have a reason to doubt the veracity of this (and I do not) I feel it appropriate to treat the SCI records as corroborated and reliable. It’s not as if a hunter can simply inform SCI that they shot a five-meter crocodile and have that entered into the records. To be honest, the SCI record book doesn’t seem to bear the hallmarks of inflation to me; the records of giant crocodiles are relatively few compared to the total number, and we don’t see any suspicious measurements like seven plus meters popping up.
Btw, it’s not that I didn’t want to challenge those secondhand accounts of giant Niles from Cott’s study, it’s that I ignored them because they weren’t relevant to any point I was making. For the record, if I’m remembering the nature of those reports correctly, I would not consider the secondhand reports to be verified measurements either.
Finally, re Humboldt’s measurement. It’s not that I’m saying Humboldt’s assistant falsified that figure (assuming it has been reported and converted correctly from whatever format it was originally issued in) I’m saying that it has not been reproducible. This may be because all crocodiles in that size class have been killed off but, even so, it still stands that giving too much weight to a non-reproducible figure is statistically and epistemologically non-ideal. This is what I was getting at when I gave a rundown of the number of salties measured at 6 meters and Niles at 5-plus meters. Those ranges of measurements have been reproducible for those species so we can consider them firmly established. However, no one has since been able to measure and verify an Orinoco crocodile of the size of the one described by Humboldt. So, what should we make of this. We can appreciate that Humboldt’s record suggests a potential for C. intermedius of that size to one day show up, but I think that for most intents and purposes we should stick to facts with more robust corroboration whenever possible.
Also, it was unclear if the crocodile from Fray Jacinto de Carvajal you posted was a measurement or just an estimate. Estimates shouldn’t even be considered in a discussion like this IMHO, even if they are made by “seasoned” people. In general, the days before mass hunting of crocodilians are rife with large reported sizes which may or may not have been real. I think the best we can do is base our analyses on the measurements we can substantiate in the modern day, even if we don’t rule anything out.
American crocodile (Crocodylus acutus)
