Survival of grasshopper sparrows (Ammodramus savannarum) during two important life stages in grassland managed with fire and grazing
نویسندگان
چکیده
Patch-burn grazing is a management framework that promotes heterogeneity in grasslands, similar to the structure grasslands birds evolved inhabiting. Published studies on patch-burn grazing have been conducted on large, contiguous grasslands and only one of these studies has investigated the reproductive success of grassland birds. We assessed the effects of patch-burn grazing (grazing, one third of the pasture burned annually) compared with a more traditional graze-and-burn treatment (grazing, entire pasture burned every third year) on nests of grasshopper sparrows (Ammodramus savannarum) in fragmented grasslands. We modeled grasshopper sparrow nest survival as a function of multiple biological and ecological factors. Constant daily survival rates were greater in patch-burn grazing pastures than in graze-and-burn pastures (patch-burn grazing rate = 0.930, burnand-graze rate = 0.907). Multiple factors were significant in survival models including year, stage of nest, a negative effect of nest age, and a negative effect of cool-season grass abundance within five meters of the nest. Our findings represent grassland bird survival in small-scale, fragmented grassland similar to many found throughout the corn-belt region of the United States. Results showed that survival rates were the highest in pastures managed with patch-burn grazing, but multiple factors influenced grasshopper sparrow survival. Results emphasize the importance of researchers using multiple covariates when examining
منابع مشابه
Supervivencia Posterior al Emplumamiento de Ammodramus savannarum en Pastizales Manejados con Fuego y Pastoreo POSTFLEDGING SURVIVAL OF GRASSHOPPER SPARROWS IN GRASSLANDS MANAGED WITH FIRE AND GRAZING
More accurate estimates of survival after nestlings fledge are needed for population models to be parameterized and population dynamics to be understood during this vulnerable life stage. The period after fledging is the time when chicks learn to fly, forage, and hide from predators. We monitored postfledging survival, causespecific mortality, and movements of Grasshopper Sparrows (Ammodramus s...
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Patch-burn grazing is a management framework designed to promote heterogeneity in grasslands, creating more diverse grassland structure to accommodate the habitat requirements of many grassland species, particularly grassland birds. Published studies on the effects of patch-burn grazing on passerines have been conducted on relatively large (430–980 ha pastures), contiguous grasslands, and only ...
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