Abiotic factors can affect fecal glucocorticoid metabolite level of Panthera tigris altaica (Felidae) in the wild in the Russian Far East

An estimation of welfare/stress level in wild animals helps to determine the factors affecting their conditions.Panthera tigris is a species, that has evolved in tropical Asia, but its subspecies Panthera tigris altaica (hereinafter -Amur tiger) lives under extreme climatic conditions in the Russian Far East.The aim of this study was to estimate the effect of low air temperature and high snow level as potential stressors for Amur tigers.Changes in glucocorticoids levels may be a good indicator to evaluate an animal's welfare/stress level.We collected a total of 209 fecal samples from Amur tigers.The samples were kept frozen until analysis.We used previously validated commercial kits to quantify fecal glucocorticoid metabolites (FGCM) in Amur tigers.We determined Amur tigers' FGCM levels in four Protected Areas, situating from the north to the south, suggesting that FGCM will be different in northern and southern locations (depending on weather conditions).We did not find significant differences in FGCM level related to the Amur tigers' location.However, we found correlation with the climatic conditions for these geographical points.Air temperature had a significant effect on FGCM levels in Amur tigers both in the study period as a whole (F = 4.16; df = 1; p = 0.043) and in the snowy period taken separately (F = 4.92; df = 1; p = 0.028).The FGCM level in Amur tigers increased significantly when the ambient temperature dropped.This correlation was significant over the whole studied period and during the snowy period.We assume that low ambient temperature should intensify the metabolic rate in such tropical species as the Amur tiger.The snow level did not affect considerably the FGCM level.However, we discovered a positive correlation between the level of hormones and snow depth.When the snow level exceeded 60 cm, FGCM concentrations declined by more than a half (from 1441 561 ng/g to 668 125 ng/g).Especially high snow depth led to a low FGCM level in Amur tigers, which may be related to the changes in their movement patterns and hunting efficiency.FGCM monitoring is an effective tool for the estimation of the Amur tiger's physiological status in the wild.However, the air temperature per se might affect significantly the FGCM level in the Amur tiger (tropical species) and it should be taken into account when scientists interpret the results.