Food and safety as determinants of foraging behavior in a desert granivore bird community

Perceived risk in an environment depends on the interactions of the escape strategy of the prey, and the physical structures of the landscape. Among birds two main escape modalities are common, some prefer vegetative cover for safety (e.g. Sparrows), others the open habitats (e.g. Larks). Most antipredator studies on birds have focused on a single species and hence on one perception of cover, thereby ignoring the community perspective. They have used traditional techniques of vigilance behavior and flock size. Currently other tools are available to evaluate risk. In this study we tried to understand the perceived risk of predation, at different distances from cover and time, in a community of birds of the Negev desert, Israel. Apart from using the traditional techniques, we also used the giving-up density (GUD) approach, a more “fitness true” version of the patch model, to investigate the trade-offs between foraging and predation risk. This allowed us to understand the use of time allocation (decisions such as when, where and how long to forage) and apprehension (attention redirected from foraging to predator detection) by the birds. We found perceived risk increased with increase in distance from cover. The birds took more risk in the morning by foraging in the open patches with high apprehension. Surprisingly they did not use vigilance for managing risk. Our study emphasizes the need for use of additional techniques such as GUDs along with traditional measures of vigilance behavior.