Vigilance strategy differentiation between sympatric threatened and common crane species

• Published in: Behavioural processes Vol. 176; p. 104119
• Main Authors: Kong, Dejun, Luo, Weixiong, Møller, Anders Pape, Zhang, Yanyun, Yang, Xiaojun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2020; Elsevier
• Subjects: Animals; Antipredator behavior; Biodiversity and Ecology; Birds; Collective vigilance; Ecosystem; Endangered Species; Environmental Sciences; Fear; Group size effect; Grus; Individual vigilance; Sympatry; Wakefulness; Collective vigilance; Group size effect; Antipredator behavior; Grus; Individual vigilance
• ISSN: 0376-6357; 1872-8308
• DOI: 10.1016/j.beproc.2020.104119

•Common Grus grus is more vigilant than threatened G. nigricollis.•G. grus has diverse antipredation tactics than G. nigricollis.•G. grus could obtain vigilance benefits by foraging with other species.•Group size and distribution area have common effects on vigilance for both species. Studies have indicated that threatened species may show reduced or elevated antipredator behavior compared with their close common relatives, but remarkably few studies revealed such differences in behavior among populations. Exploring factors affecting behavior between phylogenetically related common and threatened species could help understand such discrepancy. We tested for effects of external and internal variables including month, time of day, habitat type, distribution area, group composition status and group size on vigilance behavior (including group scan frequency and level) of two sympatric common Grus grus and threatened G. nigricollis cranes with generalized linear models. We detected significant species effect on group scan level, and grus was more vigilant than nigricollis. Model tests also indicated that group size had common effect on group scan frequency for both species, and distribution area significantly correlated with the vigilance of nigricollis, while grus was more affected by time of day and group composition status in areas of sympatry with nigricollis. But when nigricollis was absent, time had no effects on behavior by individuals belonging to grus, implying existence of inter-specific competition. We also found that grus decreased individual vigilance efforts by foraging with other species (e.g., Bar-headed Goose Anser indicus) to share large group alertness benefits (collective vigilance). As our results demonstrated, we argued that, with diverse antipredation tactics e.g., foraging with other species, alternating time rhythm or partitioning spatial utilization to mitigate inter-specific competition, reducing time allocation to preening while maintaining foraging efforts, common grus could maintain high level of vigilance, which may benefit their survival and population increase. Whereas less time spent vigilant antipredation strategy adopted by threatened nigricollis, this may have negative effects on their populations.