Does Observer Presence Modify the Behavior and Enclosure Use of Captive Edwards’ Pheasants?

Abstract

It is well known that captive animals alter their behavior and space use when observed by visitors, with the concept coined the ‘visitor effect’. The ‘observer effect’, described as any alteration in behavior and enclosure use as a result of a quiet, stationary observer, has been less studied. This study investigates the observer effect in two pairs of Edwards’ pheasants (Lophura edwardsi) and their offspring at Sparsholt College, United Kingdom. The impact of an observer (as opposed to camera) on behavior and enclosure use of pheasants was observed, using instantaneous focal sampling. Enclosure use was measured by converting both enclosures into unequal zones and then assessing the evenness of enclosure use through modified Spread of Participation Index. Poisson regression analysis was used to investigate observer impact, alongside the additional variables of keeper and visitor presence, temperature, and individual bird differences. Overall, the behaviors of resting and clustering were significantly increased during observer presence, whereas feeding and locomotion were significantly decreased. The behaviors of preening and standing were not affected by observer presence, though they were influenced by keeper and visitor presence. Enclosure use was also affected by observer presence, though the effect size was small. This suggests that pheasants may perceive the presence of humans near their enclosures as a potential threat, and may alter their behavior to reduce detection, similar to their wild counterparts. Animal researchers should consider the potential impact of observer presence on their subjects, particularly when observing species such as pheasants.