Using camera traps to study the age-sex structure and behaviour of crop-using elephants Loxodonta africana in Udzungwa Mountains National Park, Tanzania

Abstract

Crop losses from elephants are one of the primary obstacles to the coexistence of elephants and people and one of the contributing causes to elephant population decline. Understanding if some individuals in an elephant population are more likely to forage on crops, and the temporal patterns of elephant visits to farms, is key to mitigating the negative impacts of elephants on farmers. We used camera traps as a novel technique to study elephant crop foraging behaviour in farmland adjacent to the Udzungwa Mountains National Park in southern Tanzania from October 2010 to August 2014. Camera traps placed on elephant trails into farmland captured elephants on 336 occasions over the four-year study period. We successfully identified individual elephants from camera trap images for 126 of these occasions. All individuals detected on the camera traps were independent males, and we identified 48 unique bulls aged between 10 and 29 years. Two-thirds of the bulls identified were detected only once by camera traps over the study period, a pattern that also held during the last year of study when camera trapping effort was continuous. Our findings are consistent with previous studies that found that adult males are more likely to adopt high-risk feeding behaviours such as crop foraging, though young males dispersing from maternal family units also consume crops in Udzungwa. Our study found a large number of occasional crop-users (32 of the 48 bulls identified) and a smaller number of repeat crop-users (16 out of 48), suggesting that lethal elimination of crop-using elephants is unlikely to be an effective long-term strategy for reducing crop losses from elephants.