WildFact
›
Information Section
›
Terrestrial Wild Animals
›
Reptiles and Birds
Komodo Dragons (Varanus komodoensis)
Komodo Dragons (Varanus komodoensis)
|
Komodo Dragons (Varanus komodoensis)
|
Credits to Act for Wildlife.
NEW KOMODO DRAGON POPULATIONS FOUND: Our lead keeper of lower vertebrates and invertebrates, Matt Cook, previously travelled out to Indonesia where he joined our field partners, the Komodo Survival Program (KSP), to conduct Komodo dragon surveys.  *This image is copyright of its original author Flores is home to several populations of Komodo dragon which is listed as Vulnerable on the IUCN Red List; however the exact number of individuals is unclear. With our support, KSP have expanded their work further and are now in their second year of a complete population survey of the Indonesian island of Flores and its surrounding islands. At the end of the study, the data will be used to create a long-term conservation action plan for the Komodo dragon across the whole of Indonesia. So far, two new populations of Komodo dragon have already been identified. Their latest discovery happened earlier this year on a small island off Flores called Longos where a previously undescribed population of the critically endangered yellow crested cockatoo was also discovered! Surveying Flores is no mean feat – the island spans 5,228mi2 not including all the small surrounding islands which are also being included in the survey. The field team at KSP have sent us some incredible footage of Ontole island, it shows the type of terrain they have to tackle during their field work, plus we thought it was too good not to share with you. The survey work is on-going so there is potential for even more discoveries over the coming months; we can’t wait to bring you more exciting news from this project! 
The claim that average adult male ora weigh 40-50kg is inaccurate and not well based. Now i've communicated with Dr. Tim Jessop on the matter, and this is what he had to say( the original question dealt with what a large ora could weigh without supplemental food, hence the 87kg figure).
 *This image is copyright of its original author Claims made earlier in this post that a 73kg male would be fully gorged and not an empty stomach measurement are false; the figures given by Wood appear to be well based 
Welcome to the forum @Paleosuchus
It is nice that you started with good information We hope to see such more information
Thank you, it is nice to be here :)
Here is some research on the prey preferences and niche segregation in sizes classes: Ecological allometries and niche use dynamics across Komodo dragon ontogeny Abstract Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons (Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ∼20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon’s transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels. "Between December 2002 and April 2015, we collected regurgitated stomach contents (N= 52) and direct observations of prey kills (N= 25) from Komodo dragons (with known identity and body mass) across field sites during routine trapping and telemetry studies (∼1100 field days). Production of vomited prey items was an induced response to normal trapping activities, and stomach flushing was not needed. All prey items collected were identified to species level in situ. Prey items were categorized into four prey size classes (<0.1, 0.1– 1, 1–5 and ≥50 kg). These size categories were deemed ecologically appropriate as they reflected the natural and the somewhat discontinuous body size categories representative of prey species occupying terrestrial habitats in Komodo National Park (Auffenberg 1981). Here, insects and small reptiles comprised the smallest prey body size class, followed by snakes, rodents and birds in the 0.1–1 kg prey class, next juvenile ungulates and palm civets (Paradoxurus hermaphroditus) dominated the 1–5 kg prey size class, and adult ungulates comprised the heaviest prey body mass class (≥50 kg). To assign prey to their respective size class, intact whole prey was weighted to the nearest gram using a digital hanging scale. For dietary records that comprised the partial prey remains large ungulates (i.e. Rusa deer and pigs) that could not be fully consumed, we inferred prey mass from the dentition class or using the diameter of long bones to assign ungulates into juveniles or adults, following methods described by Auffenberg (1981)." " body size-related niche use and overlap To consider ontogenetic difference in niche requirements, we categorized Komodo dragons into four body mass classes (<1 kg [hatchlings to small juveniles], 1–10 kg [large juveniles], 10–25 kg [sub-adult to small adults], >25 kg [large adults]) that reflected key life stages differences in this species (Auffenberg 1981; Imansyah et al. 2008; Laver et al. 2012). To qualify the size-related differences in niche use, we compiled data on four important measures of habitat use:
ingestion of larger prey body mass categories (GAM: EDF = 5.30; F = 59.45; P < 0.001, R2 (adj) = 0.84; Fig. 2a). Juvenile lizards selected smaller and lighter prey (e.g. supplementary material), but as lizards increased in size, they increased their preference for larger prey. This transition seemed relatively abrupt with preference of large lizards (>20 kg) contained only the largest prey mass class (e.g. including adult Rusa deer estimated to weight more than 50 kg). Using telemetry, we monitored dragons for a mean period of 151.7 ± 31.9 days resulting in 2108 movement data points. Dragon hourly movement rates varied significantly with lizard body mass (GAMM: EDF = 3.89; F1, 2106= 37.35; P< 0.001, R2 (adj)= 0.12; Fig. 2b). There was a clear non-linear pattern with hourly movement rates increasing in Komodo dragons between the body mass ranges of 1.4–20 kg. Above this movement rates asymptote and then decreased in largest individuals. A mean number of 286 ± 77 location fixes was recorded among individuals. The minimum number of fixes required to assess home range size was determined by plotting the cumulative home range size per number of fixes recorded until the home range reaches an asymptote. In this study, the average minimum fixes needed to determine home range was 82.7 ± 6.5 fixes. Home range area (1.71–1178.54 ha estimated from 95 % Kernel analysis) exhibited a significant non-linear increase with body size (GAM: EDF = 2.79; F1,19 = 24.41; P < 0.001, R2 (adj) = 0.62; Fig. 2c). Home range areas appeared small and relatively invariant in area until lizards exceeded 20 kg body mass. Above this mass, Komodo dragon home range substantially increased with the large adult male animals."  *This image is copyright of its original author "The effects of body size on prey size preferences were clearly evident with small lizards that preferentially consumed small prey, whilst large adults targeted large ungulate prey. Rather than a continuous increase for larger prey with increased lizard body size, there was body size-dependent threshold effect at which Komodo dragons ceased consumption of small prey and preferentially switched entirely to killing large prey. Similar thresholds of prey size switching appear common in interspecific comparisons of mammalian predators. In carnivores, a body mass threshold of ∼20 kg is advocated as the body mass threshold at which predators switch from hunting small prey to targeting large prey (Carbone et al. 1999; Ray and Sunquist 2001). Our study also suggested that there were distinct transitions in lizard prey preferences at ∼20 kg. Our results support the notion that large ontogenetic changes in body mass necessitate abrupt change in prey size to optimize energy flux between energy expenditure and intake (Carbone et al. 2007). Importantly, many other functional processes would be associated with body size that could further delimit the threshold at which Komodo dragons switch to killing large ungulate prey. In particular, larger lizards being heavier and stronger could better dispatch larger prey items with increased gape size, bite force and physical attack strength (Auffenberg 1981; Pianka and Vitt 2003; McCurry et al. 2015)." Link to study
Well, when you have to go you have to go...
 *This image is copyright of its original author
@Paleosuchus, nice to meet you and welcome to the forum.
I think that you are confused about past posts, and certainly words like "inaccurate and not well based" or "false" are to harsh. Please, let me explain to you the correct statements made in past posts. If you take a look to post No. 2, 7 and 9, you can see that my conclusions were based in the study of Dr Auffenberg, published in his book of 1981 "The Behavioral Ecology of the Komodo Monitor", which as far I know, seems to be the most complete study of this animal in the past century. In that study, the average weight of the largest males, captured by him, was of 47 kg (n=12), with the heaviest been of 54 kg. More recently, the heaviest male reported by Jessop et al. (no date) was of 81.5 kg, without apparent stomach content. So, an average large male should weight between 40-50 kg, in the best case, based in the study of 1981, but the new figures reported by Jessop et al. (no date) suggest that modern male Komodo dragons could be heavier than in the 80's. In fact, @Pckts in post No. 8 already stated that an average male would be between 70-80 kg. Now, check the post No. 7: "In fact, both of you are right. Pckts has a good point here, every statement most came with its backup. Now, the facts of Chaos are actually correct. Auffenberg (1981) showed that Komodos can eat up to 80% of they own weight, and Wood (1978) present the record of the huge "captive" male of 365 lb (165.5 kg ). Now, taking together both facts, this large male Ora could weight as low as 73 kg, IF it was fully gorged. However, extreme obese animals are well know in captivity, so this was probably just a huge overfeed reptile. A wild Ora will be very lucky if manage to reach 90 kg, from my point of view." As you can see, this was part of a little debate between two posters. The conclusion was that in fact, Komodo dragons can eat up to 80% of its own weight, which means that the large captive male that weighed c.166 kg could weigh as low as 73 kg, if it was gorged. This is what I tried to state, in any moment I am saying that a fully gorged dragon weights only 73 kg, that is nonsense. Finally, in any moment I am discrediting Gerard Wood, check post No. 4: "Finally, but no less important, the book of Gerard Wood (1977) and the Guinness Records of Komodo dragons. The data is very important for comparison. Check that the weights presented in the first paragraph are not averages but a range, after all, a male dragon of 90 kg and a female of 73 kg, will be clearly exceptionally large specimens." I am just mentioning that the figures that he presents are ranges, not average figures. Now, check this in post No. 9: "The weight range of 79-91 kg (Wood, 1977) are by no means an average figure, like Wikipedia claims." I am criticizing Wikipedia, not Wood, because in Wikipedia they stated that those weights are "averages", when in fact, Wood never say that. We can clearly see that the average figure is the length, not the weight, which is presented in ranges. As you can see, there is not "inaccurate and not well based" statements, and certainly there is no "false" information here. Now that I have clarified these two points, let's check your email of Dr. Tim Jessop:  *This image is copyright of its original author It is very interesting that his estimation of weights-range match the one of @Pckts, which means that modern adult males oras are heavier than those at 1981, and this is a good actualization of information. Maybe you could ask to Dr Jessop about the average figures for males only, because in the document that I posted from him, he mixed males and females in the average. Now, it is also interesting that he "think" that the heaviest male, not gorged or obese, could reach up to 87 kg (his heaviest male actually captured was of 81.5 kg). So, Wood stated that male Komodo dragons weigh between 79-91 kg, and now Dr Jessop present a range of 65-80 kg (up to 81.5 kg actually weighed and up to 87 kg hypothetically). We can see that the figures of Gerard Wood are still higher than those of Dr Jessop. Now, if we include the "obese" males which eat supplemental food, then it is possible for an ora to reach over 100 kg, but those are not normal specimens. Conclusion: Dr Auffenberg study in the decade of the 80's stated that adult male oras had an average weight of 47 kg (n=12), with the heaviest been of 54 kg. Now, since the 2000, new studies from Dr Jessop suggest higher figures, with a mode (not average) among males between 65-80 kg (based in your email), with a maximum figure, actually recorded, of up to 81.5 kg "empty" and an hypothetical of up to 87 kg, for males that forage naturally. Gerard Wood (1977) presented a range of weights between 79-91 kg, which is higher than the studies of Auffenberg and Jessop. However, his figures are still valuable, as the higher figure (90 kg or more) are plausible, but only when the males had supplemental food source. Hope this helps to clarify the situation. Again, welcome to the forum. 
Quote:I think that you are confused about past posts, and certainly words like "inaccurate and not well based" or "false" are to harsh. Please, let me explain to you the correct statements made in past posts.No, no, i read your statements fine. They aren't too harsh of words, but don't take it personally. I read auffenberg's book too( i have an open access copy i you'd like); Auffenberg's sample of 12 displays no segregation between sexes or age in his small sample so to definitely state "males average 40-50kg" in the face of that is in fact not well based.  *This image is copyright of its original author  *This image is copyright of its original author As you can see, No "average weight of males was 47kg" is displayed in the section about weight, what you have is a mixed sample that includes smaller, recently sexually matured(~attained at ~1.7m TBL, one animal had a total body length of 2.2m) and/ or females, nevermind the fact that twelve is far too small a sample to give anything super definitive. In regards to my email Jessop is referring to what most adult males will weigh with the 65-80kg range, not the largest, as i believe he had made that distinction in his email. Anything in excess of 80kg is what is to be expected for the largest of males, at least this is what the data indicates.
@Paleosuchus, just a few remarks:
1. To say that a person is posting "false" or "inaccurate and not well based" information do sound harsh and believe me, it only provoke problems with the people. Is better to say "incorrect information" or "incorrect interpretation", it is just my advice. By the way, I am not taking it personal, don't worry.  I am interested more in the data than in discussions. 2. Yes, the figure of 47 kg don't specifically say "males", but in page 23 Dr Auffenberg mentioned a sample of 10 largest males and 10 largest females measured by his team, which suggest some separation of sexes at some point. When we see that the maximum weight of his study (54 kg) is just 7 kg less than the average of 47 kg, and taking in count that the average is of the "largest specimens", I believed that the figure certainly belonged to "male" specimens. It is also interesting that other males of the same length than the longest-heaviest specimen, weighed as low as 35 kg. So, it was logic to conclude that the figure of 47 kg certainly belonged to males. However, I see that you have more knowledge of the reptile world, so your conclusions may be more accurate and I respect them. 3. Finally, on the email of Dr Jessop, please read again my post. I am not saying anything contrary to the statements of Jessop. He clearly says that "most adult males are probably 65 - 80 kg", this is obviously a "range", not an "average". Also, he clearly mentions that he thinks that a large male would weight up to 87 kg. Also, I addressed the fact that, as far I know, the heaviest dragon weighed by him is of 81.5 kg. Again, no contradiction at all. I see that you have a good knowledge of reptiles, so I would like to see if you can ask to Dr Jessop about specific figures of the Komodo dragons like: 1. Average of males and ranges. 2. Average of females and ranges. 3. Body lengths, separated by sexes. Etc.... Any data that you could provide will be excellent, and will enrich our database. Greetings.
Here are a few images to give us an idea of the size of a large ora:
 *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author Impressive! 
@GuateGojira ,
I will work on emailing jessop soon, as soon as i can get my work load cleared. Thank you for the kind words by the way, it is nice to be here with some people who know a lot about some species of animals like yourself :)
What’s jaws is mine: Komodo dragon sticks its head inside another one’s mouth to snatch its food
"Startling images from Indonesia captured the moment a ravenous Komodo dragon placed its entire head into the mouth of his bigger and potentially deadly reptile pal in a fierce battle over a deer carcass. The giant lizards, which can only be found on a few Indonesian islands, are renowned for their feisty temper and insatiable appetite and these photos show the lengths a dragon will go to get a meal. Russian photographer Andrey Gudkov, 44, from Moscow visited Rinca Island, close to Komodo island, recently and caught the sharp teethed beasts battling out for a new kill. It seems the brave dragon avoided serious injury in its daring move to to appease his appetite. Considering the lizards have poisonous saliva and have been noted for cannibalistic tendencies this boy was very lucky to escape unscathed. "  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author http://www.dailymail.co.uk/news/article-3781467/What-s-jaws-Komodo-dragon-sticks-head-inside-one-s-mouth-snatch-food.html |
| Users browsing this thread: |
| 4 Guest(s) |