科研之友
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摘要
A decline in the amount of North America's early-successional habitats has triggered a concern for birds that nest in these environments. In West Virginia and throughout the Northeast, sharp drops have been detected in the populations of early-successional birds. We monitored the nest success of birds in Crataegus (hawthorn)-dominated areas of grasslands in the Canaan Valley National Wildlife Refuge (herein called The Refuge) during the summers of 1999 and 2000. We found 30 nests of six species, including Bombycilla cedrorum (Cedar Waxwing), Turdus migratorius (American Robin), Pooecetes gramineus (Vesper Sparrow), Tyrannus tyrannus (Eastern Kingbird), Spizella passerina (Chipping Sparrow), and Geothlypis trichas (Common Yellowthroat). Hawthorn trees were the dominant plants used for nest placement. Overall, a similar number of nests fledged young (n = 17, 56.7%) as failed (n = 13, 43.3%) (P = 0.31). We attributed most nest failures to avian or mammalian predation, which may reflect an edge effect. The clutch size of the Cedar Waxwing was greater than for other species (P = 0.03). We recommend that The Refuge's managers focus on reducing edge features, studying predator-edge relations, and monitoring avian use of early-successional habitats.
- 出版日期2015-10
