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RE: A Discussion on the Reliability of Hunting Records - WaveRiders - 05-01-2016
Peter
I can’t see reasons for me to post replies often nearly entirely forced to be oriented to clarify points and concepts made by me in the previous post. This is what I meant in my previous post, adding again that I am not saying I am blameless for this my nearly regular necessity in spite of my posts generally definitely not short on average.
On the topics discussed I agree that we made arguments detailed enough to allow readers to make their own opinions if these arguments have been caught in their entireness and correct meaning. No real need to add anything else.
Below, while awaiting for your accurate and reliable reports of extra-large tigers measuring 11.0-11.5 ft and over in total length over curves, I make a few points on your last post. I will be equally interested to read about any report of tiger weights from scales claimed to be in excess of 570 lb (258.5 kg). I can only include 5 scale weights (they would be 6 ones if considering a scale weight coming from a scale estimated to have bottomed by 20 lb) in the range 570+ lb (over 570 lb) to 705 lb which are possibly sufficiently accurate and reliable as hunting records.
3a – I would personally state most / very most modern biologists measure big cats 'over curves' and not 'between pegs'. There are a few modern data from zoologists clearly stated to have been taken in straight line, such as for instance the lengths of the radio-collared leopards from the Phinda-Mkhuze Complex in northern KwaZulu-Natal, South Africa (Balme et al., 2012).
3d – I disagree on your suggestion that today's tigers appear maybe a bit shorter than a century ago. In my opinion this is the apparent result of measurements taken on narcotized animals in the wild not stretched to the same amount (if perhaps “stretched” at all and not just straightened up raising the head) sportsmen generally used to apply on dead animals during the hunting era. I am talking only of fair stretching by hunters, not overstretching due to padding on elephant back or sort of similar artificial operation. Concerning likely higher average weight I believe it could be the result of very most of animals weighed by zoologists living in core areas of protected parks with plenty of game available throughout all their life from fetal stage maximing the genetic potential of their average bulkiness and body size.
3e – The average of 235 kg for supposed 7 distinct adult male individual tigers reported by Smith et al. (1983) for Chitawan NP, Nepal, is clearly faulty. I explained in details why in 3 of my recent posts in Carnivora of late March together with further digression on the topic. As you stated you are aware of those posts, I deduce you disagree on my analyses and results even just circumscribing them to the issue of how many distinct individuals can be considered, the resulting correct average weight and how many individual weights are known from Chitawan (including those taken by D. Smith and H. Mishra reported in Mishra, 2010). Therefore an issue not related to adjusting weights or not and in case by how much (we evidently disagree on that too).
3f – The results of the probabilistic computation results I briefly presented is based on all accurate and reliable enough adult male Bengal tiger lengths and scale weight reported in historical literature as from approximately 1800 to 1970. From after 1860/1880 or so I only excluded the ca. 11.5 ft Lord Hardinge’s and Lord Reading’s tigers as evidently unreliable and dismissed by either Brander and Hewett. This result in including all lengths up to 11 ft over curves and equivalent if reported in straight line between pegs and in including all scale weights up to the 705 lb Nepal tiger (as I stated above I can include only 5 wild Bengal tiger adult male scale weights from historical literature in excess of 570 lb).
3e – The average of 235 kg for supposed 7 distinct adult male individual tigers reported by Smith et al. (1983) for Chitawan NP, Nepal, is clearly faulty. I explained in details why in 3 of my recent posts in Carnivora of late March together with further digression on the topic. As you stated you are aware of those posts, I deduce you disagree on my analyses and results even just circumscribing them to the issue of how many distinct individuals can be considered, the resulting correct average weight and how many individual weights are known from Chitawan (including those taken by D. Smith and H. Mishra reported in Mishra, 2010). Therefore an issue not related to adjusting weights or not and in case by how much (we evidently disagree on that too).
3f – The results of the probabilistic computation results I briefly presented is based on all accurate and reliable enough adult male Bengal tiger lengths and scale weight reported in historical literature as from approximately 1800 to 1970. From after 1860/1880 or so I only excluded the ca. 11.5 ft Lord Hardinge’s and Lord Reading’s tigers as evidently unreliable and dismissed by either Brander and Hewett. This result in including all lengths up to 11 ft over curves and equivalent if reported in straight line between pegs and in including all scale weights up to the 705 lb Nepal tiger (as I stated above I can include only 5 wild Bengal tiger adult male scale weights from historical literature in excess of 570 lb).
The limit of 11 ft in total length over curves (3353 mm) has not been selected by me. It is pretty much the one that comes out from existing accurate and reliable enough records and, not for case, the limit considered by Brander (1923) over curves and not in straight line as I have seen stated in a relatively recent past post from you (I am confident it was just an unintentional inadvertency from you).
Concerning the 857 lb (388.7 kg) Hasinger Bengal tiger total length of 11 ft 1 inches over curves (3378 mm) and/or 10 ft 7 inches in straight line between pegs (3226 mm) the probability of the total length of that tiger to match its skull 14” x 9” - 355.6 x 228.6 mm, a skull of merely average length and quite small width, quite close to the minimum of the range for a Bengal tiger adult male, is virtually zero. Therefore I believe the total length of the Hasinger tiger is unreliable, but it could be considered if one wants. Including the Hasinger tiger total length or not makes virtually zero difference in my probabilistic calculations as we are not talking of possible upper exceptions of 1 or perhaps 2 inches above 11 ft. Needless to say that I absolutely instantly reject the ridiculous weight of the Hasinger tiger even if for a fully gorged tiger.
All in all I included several hundreds total lengths and some 150 individual weights of adult male Bengal tigers. In terms of sample size they are both samples by far large more then enough to make reliable statistics analyses and theoretical probabilistic calculations.
I cannot absolutely see how you would include those unreliable reports of tigers measuring in total length over curves 11 ft 6 inches or so and over. In any case it is not including a handful of Bengal tigers supposed to have measured 11.5 – 12.5 ft over curves within a very large sample that makes these Bengal tiger length sufficiently realistic. The theoretical probabilities are still so very low that if anything suggest those kind of lengths are non-trustable. I would also argue that hunting records in spite of those cases when hundreds of them are available could be slightly skewed towards a size slightly larger then the actual average, apart from issue of aging and physical conditions, as generally hunters are less prone to record unimpressive animals.
If you argue that among thousands or tenths of thousands or more adult male individuals a few true outliers can occur, I argue that the larger the sample the more is the continuous spread of the population distribution of body size as outliers show themselves as such particularly in relatively smaller samples.
The above is exactly what accounts of probabilistic calculation theories in statistics, which also suggest that to compute reliable enough indicative theoretical probabilities it is needed only a reliable, random, homogenous large enough sample, not mandatorily made by many hundreds or thousands of individuals, with pretty much straightforward sample distribution properties generally verified in the very most of cases to more then a sufficient extent.
If you argue that all statistics should be based on tigers measured before 1860 or so to validate possible existence of tigers 11.5 ft and over before 1860, well, you are right, but we know that this is impossible to do reliably enough and the debate will keep going lasting for the eternity as at the end it is a question of trusting or not trusting reports of pre-1860 or so.
Personally I see absolutely no-science in trusting those reports. Suggestions that Bengal tigers before 1860 were appreciably genuinely larger on average and that some extra-large animals in excess of 11-11.5 ft or so in total length over curves could realistically occur on the basis of a hunting pressure significantly lower then a threshold implicating a non-existence of extra-large tigers have no proven solid enough scientific basis. What would be this threshold for tigers? What the correspondent population number? What the correspondent population density? What the correlation? Etc. etc.
I could provide you examples of large carnivore species living in a hunting area and hunted being bigger on average then the same animal living in an adjacent protected area. There are a number of such examples for brown bear populations in North America for instance. There is not a strict rule for animal species within some boundaries of course. There are examples for other carnivore species where anthropogenic factors influence body size changes either way. While generally hunting selection for largest size appears as a factor contributing to decrease average body size in a population, an inverse correlation between population density and body size may become predominant in case of limited food resources thus resulting in a larger average size for hunted populations. In a study on brown bears in Northern Europe it is suggested the existence of a negative correlation between female body size variation and density-dependent factors while density-independent fluctuations in the environment would be positive correlated to body size. Hard hunting pressure on brown bears in Northern Europe has instead possibly caused some populations to decrease in body size over the last few centuries due to forcing them to live in less productive habitats inducing a phenotype change and causing genetic depression due to a higher level of inbreeding inducing a genotype change. Furthermore human pressure during the course of 1800 / 1900 has also partly caused selective breeding on some populations of brown bears in Western Europe favouring reproduction of less aggressive animals systematically removing those ones too much aggressive.
Can we equivalently state that human civilization in British India in the middle of the XIX Century was in a position to systematically remove the largest Bengal tigers after 1860 causing an irremediable loss in the genetic pool among the likely still well over 40000 Bengal tigers living over there after 1860? Could have not been possible instead that a still moderate hunting pressure on tigers till late 1800s changed instead the population density to a more favourable conditions for larger average body size at least till late 1800s with respect of 1700s to mid 1800s when there have possibly been too many tigers and not enough food resources for them?
The most important factors to be considered are abundance, quality and general characteristics of food resources and the balance of mortality and recruitment within the population for each age class. For instance if hunters would just select mostly fully grown adult past-prime individuals, it is well possible that those individuals would have been killed in territory/resources/mating rights battles in any case by younger and therefore possibly stronger adults. In this case mortality due to hunting would nearly perfectly be equivalent to a natural mortality factor.
As already mentioned there are also and primarily biomechanical and ecological constraints limiting body size and mass particularly stringent for terrestrial hyper-carnivore mammalian predators preventing the occurrences in historical time of Panthera individuals larger and bigger then the limits suggested by those accurate and reliable enough reports of late 1800s and 1900s for tigers and lions and substantially confirmed by modern zoological data.
The only valid arguments are possibly the ones I already expressed, meaning that within a substantially undisturbed population of larger number the actual occurrences of a theoretical probability can be verified or can be verified with more real individuals. However it does not necessarily mean at all that the theoretical probabilities will definitely get higher. True outliers among a larger number of a population is another argument. If we want to discuss reports of true outliers at the end it is just a question or trusting or not trusting those reports as already said.
Can we equivalently state that human civilization in British India in the middle of the XIX Century was in a position to systematically remove the largest Bengal tigers after 1860 causing an irremediable loss in the genetic pool among the likely still well over 40000 Bengal tigers living over there after 1860? Could have not been possible instead that a still moderate hunting pressure on tigers till late 1800s changed instead the population density to a more favourable conditions for larger average body size at least till late 1800s with respect of 1700s to mid 1800s when there have possibly been too many tigers and not enough food resources for them?
The most important factors to be considered are abundance, quality and general characteristics of food resources and the balance of mortality and recruitment within the population for each age class. For instance if hunters would just select mostly fully grown adult past-prime individuals, it is well possible that those individuals would have been killed in territory/resources/mating rights battles in any case by younger and therefore possibly stronger adults. In this case mortality due to hunting would nearly perfectly be equivalent to a natural mortality factor.
As already mentioned there are also and primarily biomechanical and ecological constraints limiting body size and mass particularly stringent for terrestrial hyper-carnivore mammalian predators preventing the occurrences in historical time of Panthera individuals larger and bigger then the limits suggested by those accurate and reliable enough reports of late 1800s and 1900s for tigers and lions and substantially confirmed by modern zoological data.
The only valid arguments are possibly the ones I already expressed, meaning that within a substantially undisturbed population of larger number the actual occurrences of a theoretical probability can be verified or can be verified with more real individuals. However it does not necessarily mean at all that the theoretical probabilities will definitely get higher. True outliers among a larger number of a population is another argument. If we want to discuss reports of true outliers at the end it is just a question or trusting or not trusting those reports as already said.
Suggestions that tigers or other big cats grow in body size to “old age” is another myth. Skeletal developments of big cats completes by approximately 5 years of age as all major cartilages defining bone lengths have been observed to have fused by about that age. The only bones that keep growing for longer time are the ones defining the zygomathic width of the skull and the sagittal crest. Big cats generally keep adding body mass after 5 years of age into prime age, but body mass is not body size which is to be expressed by the head-and-body length, shoulder height and, intraspecifically, possibly by total length including tail.
In my opinion the above concepts in this specific case are just myths like many myths and legends existing in human culture. This also no doubt applies to all those extra large Amur tigers in excess of 11-11.5 ft in total length over curves claimed to exist in the hunting era of pre-1970. Please you and other people do not get offended if I may sound harsh on this, as it is definitely not my intention and just my (firm) opinion on the matter.
In my opinion the above concepts in this specific case are just myths like many myths and legends existing in human culture. This also no doubt applies to all those extra large Amur tigers in excess of 11-11.5 ft in total length over curves claimed to exist in the hunting era of pre-1970. Please you and other people do not get offended if I may sound harsh on this, as it is definitely not my intention and just my (firm) opinion on the matter.
I will make further comments should you or anybody else present details of the reports of claims of total length over curves of 11-11.5 ft and over (12 ft, 12.5 ft and possibly even more) wild Bengal, Amur and Indochinese tigers and on which basis you believe these reports are accurate and reliable enough to be trusted. Same for any wild tiger scale weight claimed in excess of 570 lb (258.5 lb) as I sufficiently trust 5 ones at most.
I believe to be aware of most or possibly virtually all of these reports and I am curious to see your arguments.
I believe to be aware of most or possibly virtually all of these reports and I am curious to see your arguments.
WaveRiders
RE: A Discussion on the Reliability of Hunting Records - Pckts - 05-02-2016
@WaveRiders
As what you wrote is directed to Peter, i'll let him respond in kind.
But this caught my eye
"Suggestions that tigers or other big cats grow in body size to “old age” is another myth. Skeletal developments of big cats completes by approximately 5 years of age as all major cartilages defining bone lengths have been observed to have fused by about that age. The only bones that keep growing for longer time are the ones defining the zygomathic width of the skull and the sagittal crest. Big cats generally keep adding body mass after 5 years of age into prime age, but body mass is not body size which is to be expressed by the head-and-body length, shoulder height and, intraspecifically, possibly by total length including tail."
We posted a study here on lions that showed as they aged they tended to be both longer in body and taller at the shoulder.
I wish I can find it but it involved a few members on this forum so I'm sure they'll remember as well.
As is the case with a few assumptions of yours, to determine this you would first need to take all cat sizes (body length, height and weight)
Find their ages at the time of each measuring then log it into a data base and compare. You'd also need to take any and all big cats captured multiple times over the years and compare measurements of them as well.
Since to my knowledge, that has never been done, I think the idea of you saying it is a "myth" is unfounded. And the only study I have seen on the matter tends to show that lions grow up until the age of 8 which seems to be their largest or prime age. I'll try to find the study...
RE: A Discussion on the Reliability of Hunting Records - Pckts - 05-10-2016
Here you can see a few of what I stated above...
Age generally dictates size, not just mass but length and shoulder height as well.
*This image is copyright of its original author
Notice 101 never grows in length but she is stated as "adult" throughout the study, so she could of well been into her prime during capture.
Next Notice
Male 102- Grows in mass and length
Obviously 103 since she was caught as a cub so she of course will grow
Male 105 you see the same pattern
106 same pattern
Here you see a similar pattern in Waza lions when it comes to age and body dimensions
*This image is copyright of its original author
I still can't find the main study of lions size and ages, I searched everywhere.
I'll continue to look around, I know its around here somewhere, its like the pot of gold at the end of the rainbow.