ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

[peter]

ON THE SIZE OF CAPTIVE AMUR TIGERS - IV

IV.1 - Introduction

In this post, another recent study will be briefly discussed. I'm referring to 'Per- and polyfluoroalkyl substances (PFASs) in blood of captive Siberian tigers in China: Occurrence and association with biochemical parameters', Wang (Y), Yao (J), Dai (J), Ma (L), Liu (D), Xu (H), Cui (Q), Ma (J) and Zhang (H), in: Environmental Pollution (2020).

Our member 'Betty' (thanks again) sent me the link to the article. This time, I'll only post the title page, a credit author statement, the abstract and a table I found in the 'Supporting Information'. I'm referring to table S1 ('Information on sample collection, sex, age, and weight of captive Siberian tigers in Harbin Tiger Park, China').

IV.2 - Scans

*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

  
IV.3 - Table S1 

This article was published about a year before the study discussed in the previous post was published. Like in that study, the tigers used for this study were measured in the Harbin Siberian Tiger Park, China. I'm not saying the sample could have been identical, but it's quite likely some of the tigers used for the study discussed in the previous post were used for this one as well. Or the other way round. 

In order to refresh your memory and prevent a lot of clicking, I decided to repost Figures 3 and 4 of that study. This time, both Figures are a bit larger. The larger size will enable you to see all details. 

Here's Figure 3 (trends in male tigers):

*This image is copyright of its original author

And here's Figure 4 (trends in female Amur tigers):

*This image is copyright of its original author

In this study, 54 young adult male tigers (4-5 years of age) averaged 214,7 kg (475 pounds). In the previous study, young adult males averaged about 200 kg (442 pounds). 

Young adult tigresses (3-4 years of age) used for this study averaged about 140 kg (310 pounds). In the previous study, they also averaged about 140 kg. 

Young adult males used for this study are 33 pounds heavier than those used for the study discussed in the previous post, but one has to remember individual variation in this age category (young adults) is quite pronounced (see Figure 3). The difference could be a result of selection or coincidence, that is. 

The thing to remember is young adult male Amur tigers in the Harbin Siberian Tiger Park, depending on the way the sample is selected, average 200-215 kg (433-475 pounds), whereas young adult females in that Park average 135-140 kg (300-310 pounds). 

I'm not sure how young adult males and females, weightwise, compare to mature tigers (females of 5 years and older and males of 6 years and older), because only few mature tigers were weighed. Based on the study discussed in the previous post, I think it's safe to conclude mature tigers and tigresses start growing again after they reach 5 (females) or 6 years (males) of age. In male tigers, this new period of growth doesn't seem to be as prolonged as in females. This conclusion, however, is based on small samples. 

IV.4 - Conclusions

The study discussed in this post is well written and interesting. Interesting, because it shows that some chemical substances (referring to PFASs) not only affect marine mammals, but also terrestrial mammals like captive Amur tigers. 

In the Amur tigers in the Harbin Siberian Tiger Park, dietary food accounted for over 70% of the total daily intake of PFASs, indicating that " ... meat consumption is a predominant exposure pathway in tigers ... ". The researchers also found " ... positive associations between higher exposure to PFASs ... and elevated serum levels of alanine transaminase (ALT), a marker of liver damage ... " (abstract). 

As it's very likely pollution also affects terrestrial wild animals, " ... comprehensive health assessments of PFAS burdens in wildlife are needed ... " (abstract). 

The tigers used for this study were young adults. The 54 males (4,57 years of age) averaged 214,7 kg (475 pounds), whereas the 62 females (3,77 years of age) averaged 140,7 kg (310 pounds). Reply