1982/01/01 by Thomas Wray, II, Ii +2 · 114 citations
Environmental Science · #Avian clutch size #Avian ecology and behavior #Biology #Demography #Ecology #Habitat #Population #Predation #Reproduction #Reproductive success #Sparrow #Wildlife Conservation and Criminology Analyses
paper · pdf · doi:10.2307/4086032
published in The Auk 99(1), 157-164 (Oxford University Press)
openalex publication_date 1982/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/26
Abstract The reproductive success of Grasshopper Sparrows (Ammodramus savannarum), Savannah Sparrows (Passerculus sandwichensis), Vesper Sparrows (Pooecetes gramineus), and Field Sparrows (Spizella pusilla) breeding on a reclaimed surface mine in northern West Virginia was studied from 1978 through 1980. Only Vesper Sparrows showed significant (P < 0.05) annual differences in clutch size. Predation was the major cause of egg and nestling losses during all 3 yr. Of 185 nests located, 80 (43%) were presumed lost to predators. Our study site, surrounded by woodlots and pastureland, apparently concentrated predators. We believe northern black racers (Coluber constrictor constrictor) and Common Crows (Corvus brachyrhynchos) were the major predators. Generally, predators were equally successful in locating nests during the incubation and nestling periods. Variable nesting success, calculated from exposure for the species during the 3 yr, reflects differential predation pressure. Productivity estimates suggest that adults are not replacing themselves and immigration is necessary to maintain a stable population. Apparently, 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 for these species, the inadequate reproductive success experienced on our site suggests that these manmade grasslands may not be of benefit to the sparrow populations in this area. Breeding densities during the 3 yr were variable and may reflect poor breeding success, changes in the vegetation, availability of more suitable nesting habitat, and differential mortality during migration and on the wintering grounds.