In some monogamous birds, males invest more time in vigilance than females, especially during the pre-incubation period. As behaviors are time costly, there is a tradeoff between vigilance and feeding behavior. Male vigilance can be regarded as a male investment in their mates and may benefit the female by reducing the danger of predation, increasing her probability of survival, and allowing more time for her to forage to obtain more resources for egg production and incubation. In this study, we documented the proportion of time spent in vigilance and feeding by Chinese grouse Tetrastes sewerzowi with their mates and alone during the pre-incubation period, and then estimated male vigilance under more severe predation pressures through predator call playback. Our results indicated that paired male Chinese grouse spend more time in vigilance than unpaired males and paired females and could alter their activity budgets in response to the social context (i.e. with and without their mate) and an experimental e...
