Vigilance, staring and escape running in antipredator behavior of goitered gazelle.

Predation is a very powerful force that shapes many ungulate traits. It is widely known that increasing vigilance intensity is costly and leads to a decline of forage intake. Consequently, ungulates gather into larger groups to reduce an individual vigilance burden by using the "many eyes" effect and to enhance their survival through the "safety in numbers" effect. Vigilance rate and related aggregation changes are two of the most discussed antipredator responses of ungulates to predation risk, but less considered factors also have a significant impact. To enhance our knowledge on these impact factors, I investigated the antipredator responses (vigilance, staring, and escape running) of goitered gazelles. I found that: a) adult females demonstrated vigilance, staring and escape running significantly more often than adult males, sub-adults and fawns; b) adult gazelles (females and males), having more experience in responding to threats, were more vigilant than young individuals (sub-adults and fawns), having likely more involvement in finding food; c) during the birthing and hiding periods, mothers displayed higher rates of vigilance than in other seasons, while staring and escape running were observed most often at the end of the hiding period, when fawns altering their hiding strategy to following one, started to walk a lot in the absence of mothers, as well; and d) goitered gazelles changed their vigilance rate in response to predation risks before changing group size. The events of the yearly biological cycle (birthing/rearing young for females; rutting for males) also had significant impacts on the antipredator responses (vigilance rate and aggregation) in adult gazelles.