The influence of camera-trap flash type on the behavioural response, detection rate and individual recognition of Eld's deer

Context. Camera traps are available with infrared or white flash, with the former being more commonly used. However, white flash produces colour night-time photographs that can be critically useful for both species and individual identification. White flash was thought to cause more disturbance to wildlife than was infrared and this may lead to camera avoidance. Evaluating the extent of this response, and differences between the flash types, is useful to develop improved survey designs. Aims. This research aimed to quantify the behavioural responses of Eld's deer to white and infrared flash, to determine whether white-flash cameras were suitable for use in population surveys of this species. Methods. A behavioural ethogram was used to quantify the responses of the deer to the two flash types, as well as the responses of different sex-age classes and group sizes when encountering a camera trap. Additionally, the detection rate for white flash and infrared flash cameras was compared through time, to determine any pattern of avoidance. Key results. While deer were more likely to observe and be startled by white flash than infrared, this did not adversely affect the detection of the deer, with no significant change in the detection rate between the two different flash types over time. Group size was found not to influence behavioural response when encountering camera traps, whereas different age-sex classes of deer showed very few differences in response to camera traps. Conclusions. White flash cameras were found to be suitable for Eld's deer population surveys and were beneficial in providing colour night-time photos that allow for spotted female deer to be individually identified. Implications. Practitioners should not be concerned about the influence of white flash when using camera traps to monitor populations of Eld's deer, and using white flash is recommended when individual identification is required.