Anthropogenic Influences on Distance Traveled and Vigilance Behavior and Stress-Related Endocrine Correlates in Free-Roaming Giraffes

Watching giraffes can make them walk farther. Following an animal to learn about its daily life may change the very behaviour being recorded. For giraffes, extra walking could also take time away from feeding and resting, making the presence of a quiet observer more consequential than it appears.

Ciska Scheijen, Sean van der Merwe, André Ganswindt and Francois Deacon followed seven GPS-tagged giraffes at South Africa’s Rooipoort Nature Reserve. Over a year, they compared hourly movement with and without observers on foot, recorded how much time giraffes spent watching people, and analysed hormone breakdown products in dung. They also tracked accumulated exposure to observers and whether less accustomed giraffes were present in the herd.

With observers present, the giraffes travelled about two-thirds farther per hour after accounting for factors including season and time of day. That response weakened with repeated exposure, but time spent watching observers did not. Unaccustomed companions were associated with extra movement and vigilance. Hormone levels also declined with growing exposure, although the overall elevation with observers was statistically uncertain. These were initially unhabituated giraffes in a reserve with a history of hunting on foot, not tourist-vehicle encounters. Becoming accustomed to researchers was gradual, and did not mean ignoring them.