Group scan sampling and focal animal sampling was used to evaluate the relationship between the vigilance and group size of Mongolian gazelle (
Procapra gutturosa) from July to August 2012 around Lake Dalai, Inner Mongolia, China. We recorded 348 groups, including 107 mixed groups, 54 male groups, and 187 female groups with juveniles. The total number of individuals observed was 2026, including 4 solitary males, and the group average size was 5.76 individuals. The index of the models for curve fitting revealed that the power model Y= 2291.40–0.821 (R2 = 0.846, P = 0.013, Y
= vigilance distance and X = group size) was the best-fit model to represent
the relationship between vigilance distance and group size. The cubic model
Y = 108.1 – 16.95X + 1.09X2 – 0.023X3 (R2 = 0.826, P = 0.019, Y = vigilance rate and X = group size) was the best-fit model to represent the relationship between vigilance rate and group size. While, the logarithmic model Y =35.84 – 6.26lnX (R2 = 0.792, P = 0.024, Y = vigilance time and X = group size) was the best-fit model to represent the relationship between individual vigilance time and group size. Results indicate that vigilance rate, individual vigilance
time, and vigilance distance of Mongolian gazelle decreased significantly with increasing group size. Our research provides data on Mongolian gazelles’ vigilance and which will further benefit gazelle conservation.