Food supply fluctuations constrain group sizes of kangaroos and in turn shape their vigilance and feeding strategies

摘要: Seasonal variation in food resources and predation risk imposes major constraints on herbivores, which must adjust their behaviour to maximize energy intake survival. In seasonally driven landscapes, it is not yet clear what the primary drivers are that shape seasonal vigilance feeding rates. These rates have been shown vary relation various environmental, social individual factors, but many of these factors also through year, due supply. We studied wild female eastern grey kangaroos, Macropus giganteus, under low over a year investigate whether varied this was mainly by quantity or quality, group size individuals' reproductive states. Both seasonally, as did quality size. Vigilance, including antipredator (head orientation away from group) exclusive (i.e. without chewing) vigilance, decreased rate increased with increasing However, because quantity, emerged driver behavioural strategies. results suggest observed effects trade-off between acquisition safety fact corollaries supply our study system, adults low, hence by-products foraging choices made kangaroos response dynamics food.