title: Human Activity Dampens the Benefits of Group Size on Vigilance in Khulan (Equus hemionus) in Western China.
abstract: Animals receive anti-predator benefits from social behavior. As part of a group, individuals spend less time being vigilant, and vigilance decreases with increasing group size. This phenomenon, called "the many-eyes effect", together with the "encounter dilution effect", is considered among the most important factors determining individual vigilance behavior. However, in addition to group size, other social and environmental factors also influence the degree of vigilance, including disturbance from human activities. In our study, we examined vigilance behavior of Khulans (Equus hemionus) in the Xinjiang Province in western China to test whether and how human disturbance and group size affect vigilance. According to our results, Khulan showed a negative correlation between group size and the percentage time spent vigilant, although this negative correlation depended on the groups' disturbance level. Khulan in the more disturbed area had a dampened benefit from increases in group size, compared to those in the undisturbed core areas. Provision of continuous areas of high-quality habitat for Khulans will allow them to form larger undisturbed aggregations and to gain foraging benefits through reduced individual vigilance, as well as anti-predator benefits through increased probability of predator detection.
authors.affiliation: Key Laboratory of Biogeography and Bioresources in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 830011 Urumqi, Xinjiang, China.
authors.forename: Mu-Yang
authors.initials: MY
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive Northwest, Calgary, AB T2N 1N4, Canada; Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom.
authors.forename: Kathreen E
authors.initials: KE
authors.lastname: Ruckstuhl
authors.affiliation: Key Laboratory of Biogeography and Bioresources in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 830011 Urumqi, Xinjiang, China.
authors.forename: Wen-Xuan
authors.initials: WX
authors.lastname: Xu
authors.affiliation: Key Laboratory of Biogeography and Bioresources in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 830011 Urumqi, Xinjiang, China.
authors.forename: David
authors.initials: D
authors.lastname: Blank
authors.affiliation: Key Laboratory of Biogeography and Bioresources in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 830011 Urumqi, Xinjiang, China.
authors.forename: Wei-Kang
authors.initials: WK
authors.lastname: Yang
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002681:China; D018397:Equidae / Q000502:physiology*; D005843:Geography; D006802:Human Activities; D006801:Humans; D016014:Linear Models; D011156:Population Density; D012919:Social Behavior