Effect of captive environment on plasma cortisol level and behavioral pattern of Bengal tigers (Panthera tigris tigris)

Captive environment in zoological parks often does not provide optimum conditions for natural behaviors due to spatial constraints and negative public reaction. These factors elicit stereotypic behavior in tigers such as pacing, head bobbing and aimless repetition of some movements, and are considered to be an indication of stress. The present study was conducted to assess the effect of captivity on the plasma cortisol level and behavioral pattern in Bengal tigers (Panthera tigris tigris). Tigers kept in captivity at the Lahore zoo (n=4) and in semi natural environment at the Lahore Wildlife Park (n=6) were used for this study, and standard protocols of housing and sampling were observed. The mean plasma cortisol values for the captive animals and those kept in a semi natural environment were 34.48 plus minus 1.33 and 39.22 plus minus 3.16 mug/dl, respectively. The difference was statistically non significant. Similarly, no significant differe nce in the plasma cortisol levels was observed among the individuals within each form of captivity. From the behavioral survey it was observed that the time spent in pacing and resting was much longer for captive animals than animals confined to the semi natural environment. Thus, technically monitored "Environmental Enrichment" plans need to be devised which are as close as possible to the natural environment of the captive animals in order to achieve their utmost performance.