Effects of habitat on avian productivity in abandoned pecan orchards in southern Georgia
Daily survival rates (DSRs) of nests, eggs and nestlings were determined for Mourning Doves (Zenaida macroura), Northern Cardinals (Cardinalis cardinalis), Brown Thrashers (Toxostoma rufum) and Northern Mockingbirds (Mimus polyglottos) occupying abandoned pecan orchards in a highly fragmented and intensively farmed area of southern Georgia. The effects of nest placement parameters, seasonal factors and habitat disruptions on DSRs for all species combined were statistically analyzed. Egg and nestling DSRs varied significantly by month of nesting, percent cover, vegetative form and position of nest in substrate. Causes of nest failure (no fledglings produced) in order of decreasing importance were predation by small mammals/snakes, avian predation, predation by large mammals, and abandonment. Results provide further evidence that the importance of nest placement and habitat disruptions in nesting success is influenced by foraging strategies of the predator community. Site-specific predator/habitat complexes may be a more appropriate criterion than habitat conditions alone for evaluating avian nesting habitat