Modern Weights and Measurements of Wild Lions

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CHEST CIRCUMFERENCE OF NGORONGORO CRATER LIONS. 

From Dr. Craig Packer, we have following two equations for estimating weight of lions using their chest circumference - 
   

First equation is based on Dr. Bertram et al. 1975 (Weights and measures of lions from Serengeti) and the second one comes from Smithsonian (as told by Dr. Packer). Correct me if I'm wrong, it is unsure which one was implemented in the research study of Dr. Brown et al. 1991.

We also have two ranges for chest circumference of lions from this area. First one is 127 - 134 cm (apparently this was the range included in Dr. Brown et al. 1991) and second one is 120 - 143 cm which was told by Dr. Packer recently.

It may also be possible that the range from 1991 research study is a misprint, as to my knowledge there hasn't been any other research on crater lions since then and the research study has other misprints too (eg. - the equation mentioned). The total range may be 120 - 143 cm only.

From the second range, we know the exact value of chest circumference of 5 largest lions - 134.5 cm, 135 cm, 136 cm, 138 cm and 143 cm. These are large but nothing exceptional. This has been reached by lions from other regions too eg. 148 cm (Namibia) and 139 cm (Rhodesia / Zimbabwe). Value of smaller ones (under 130 cm) is unknown. So if one tries to calculate the mean from available individuals (n = 8) the result will be 133.4 cm which is false, leaning to the higher side. 

Other way one can try to find the mean is through using the estimated mean weight from Dr. Brown et al. 1991, which was 212 kg (n = 6) adult lions and then reversing the equations provided by Dr. Packer. 

1. Using equation 1
  a. When implementing the estimated weight of 212 kg, we get a mean chest circumference of 126.3 cm. 
     - This is only possible if the range was 120 - 143 cm. In the other smaller range, the smallest value was 127 cm which alone makes the mean of 126.3 cm impossible. 

2. Using equation 2
  a. When we implement the estimated weight of 212 kg here, we get a mean chest circumference of 127.7 cm. 
     - This is possible only in the case that 5 out of 6 lions in the range of 127 - 134 cm had chest circumference of 127 cm which is highly unlikely. 
  
  b. Assuming that lions of 120 cm, 134.5 cm, 135 cm, 136 cm, 138 cm and 143 cm were NOT included, the final is 131 cm (n = 12). This is again not the proper result as the chest circumference of smaller lions is unknown. 
 

Conclusion - 
The lions used in Dr. Brown et al. 1991 most likely already include all the lions ranging from 120 - 143 cm. Based on the regression equation used, mean chest circumference of lions from Ngorongoro Crater is 126.3 - 127.7 cm (n = 6-12+) and up to 131 cm (n = 12). 131 cm is based on the assumption that larger lions aren't already included in the 1991 research study, and is not the proper result as it is based on larger individual lions. Hence the proper value will be lesser than 130 cm. This is negligibly larger than lions from other region (difference of only 1-3 cm). Reply