Habitat Relations and Breeding Biology of Grassland Birds in Western New York: Management Implications

摘要: In 1994 we began a study of the habitat relations and breeding biology grassland birds in western New York. Most fields contained fewer than four species, with Bobolink (Dolichonyx oryzivorous) Savannah Sparrow (Passerculus sandwichensis) being two most common species. Species management concern Northeast, such as Henslow's (Ammodramus henslowii) Upland Sandpiper (Bartramia lonf?icauda), were absent from area. Birdhabitat models generated through Principal Components Analysis stepwise multiple regression indicated that field area, or variables correlated explained variation overall bird species richness (partial r2 = 0.43) abundance r 0.60) Bobolinks Sparrows. Grassland generally smaller 5 hectares. Areas few shrubs low horizontal heterogeneity supported more did high heterogeneity. shorter, less dense vegetation had individuals taller, vegetation. Few occurred planted switchgrass (Panicum virf?atum) monocultures. More 90 percent all known nesting pairs fledged young by end first week July. Nest success was high; proportion nests fledging one 0.76 for Sparrows, 0.54 Bobolinks, 0.67 Eastern Meadowlarks (Sturnella magna). populations this may benefit practices increase control shrub invasion, encourage growth grasses other switchgrass. The current levels grazing at Iroquois National Wildlife Refuge, cattle allowed pastures only after 15 July, do not appear to be harmful populations. LAS RELACIONES ENTRE LOS HABITATS Y LA BIOLOGIA REPRODUCTIVA DE AVES PASTIZAL EN NUEVA YORK Sinopsis. En iniciamos un estudio de las relaciones entre los habitats y Ia biologfa reproductiva aves pastizal en el oeste Nueva La mayorfa campos tenfan menos cuatro especies pastizal, con Tordo Arrocero Gorri6n Sabanero como dos mas comunes. Las importancia para manejo noreste, Henslow Zarapito Ganga longicauda) estaban ausentes del area estudio. Los modelos producidos por Analisis Componentes Principales regresiones multiples escala indicaron que campo (o correlacionadas area) daban cuenta mayor parte variaci6n riqueza total (parcial 0,43 ), abundancia elias 0,60) Tordos Arroceros Gorriones Henslow. generalmente hectareas. areas pocos arbustos una escasa heterogeneidad mantenfan abundante horizontal; vegetaci6n baja densa individuos alta densa. Habfa pocas sembrados monoculturas Panicum virgatum. Mas ciento todas parejas conocidas nidos produjeron pollos fin primera semana julio. El exito fue alto; proporci6n polio o 0,76 Sabaneros, 0,54 0,67 Praderos Orientales poblaciones pueden beneficiarse practicas aumenten campos, controlen invasion estimulen crecimiento hierbas no sean bajos niveles actuales apacentamiento Refugio Nacional Fauna Iroquois, ganado permitido praderas solamente despues julio, parecen ser dafiinos pastizal.