Seasonal and Sexual Variation in Vigilance Behavior of Goitered Gazelle (Gazella subgutturosa) in Western China

Animals receive benefits from social behavior. As part of a group, individuals spend less time having to be vigilant. This phenomenon, called the ‘‘group size effect,’’ is considered the most dominant factor in an animal’s demonstrated level of vigilance. Studies on vigilance have shown sex to be an important factor influencing vigilant behavior.

Researchers from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, used the goitered gazelle, Gazella subgutturosa, as a study animal to test the group size effect and examine its possible changes over seasons and between males and females. They hypothesized that: 1) gazelles would spend more time being vigilant in summer due to an abundance of food, and less time being vigilant in winter because of a lower quality and a lower density of suitable food; 2) goitred gazelles would be more vigilant in smaller groups than in larger groups for both sexes, and across all seasons, according to the ‘‘group size effect.” Their research showed that, for females, the percentage vigilance was highest in summer (6.9%) and winter (7.0%); for males, it was highest in winter (19.2%) and lowest in summer (2.8%). Significant differences were found among seasons in females, except between summer and winter, and the difference was significantly higher in males in winter than in any other season. The duration of vigilance was significantly different among all seasons, except between summer and autumn in females and between spring and summer in males.

By research they found that seasonal factors were not a substantial influence on a gazelle’s level of vigilance, while group size had a tangible effect. In comparison, the yearly breeding cycle (a natural phenomenon) was the most powerful factor: it significantly changed the degree of vigilance in females during birthing and males during rut. Anthropogenic factors (unnatural phenomena) were also potential causes of increased vigilance in both sexes during winter.

This study was supported by the International Science &Technology Cooperation Program of China (2010DFA92720), the Sino–Italian Cooperation Project (0866031) and Chinese Academy of Sciences (which funded Visiting Professorships for Senior International Scientists-2009Z2-5). This work has been published on Journal of Ethology, 2011, 29(3): 443–451. It can be link from: http://www.springerlink.com/content/3822w448nl8x31w1/.

Effect of group size on the percentage vigilance (a spring, b summer, c autumn, d winter; filled triangles females, open circles males, continuous lines trendline for females, dashed lines trendline for males)