Reproductive success of grassland sparrows on a reclaimed surface mine in West Virginia.

Abstract

Examines the reproductive success of grasshopper sparrows Ammodramus savannarum, savannah sparrows Passerculus sandwichensis, vesper sparrows Pooecetes gramineus and field sparrows Spizella pusilla. Only vesper sparrows showed significant annual differences in clutch size. Predation was the major cause of egg and nestling losses. The study site, surrounded by woodlots and pastureland, concentrated predators. Northern black racers Coluber constrictor constrictor and common crows Corvus brachyrhynchos were the major predators. Variable nesting success reflects differential predation pressure. Adults are not replacing themselves and immigration is necessary to maintain a stable population. Environmental cues are sufficient to elicit a settling response, but, due to predation, reproductive success is low. Although surface mining is providing new nesting habitat, inadequate reproductive success suggests that these man-made grasslands may not be of benefit to the sparrow populations. -from Authors