FIELD SPARROW REPRODUCTIVE SUCCESS AND NESTING ECOLOGY
FIELD SPARROW REPRODUCTIVE SUCCESS AND NESTING ECOLOGY
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作者：
BEST, LB
在美国伊利诺斯州中部的草地、灌丛草地和灌丛林地上，研究了小麻雀（Spizella pusilla）的繁殖成功率和营巢生态。卵和巢的成功率分别为11.2%和10.2%。巢失败的主要原因包括捕食，主要是由蛇[Coluber constrictor，Lampropeltis calligaster，Sistrurus catenatus，Thamnophis radix]（76%的所有活跃的巢），巢遗弃后，由brown-headed cowbird [Molothrus ater]（7%），巢遗弃原因不明（7%）。11%的巢穴被寄生，大多数（63%）因此被遗弃。有幼鸟的巢比有卵的巢受到更重的捕食。早期的巢主要放置在站在草凋落物，但随着繁殖季节的提前杂类草，树木和灌木成为最常用的筑巢基质。平均巢高随着季节的推进而增加。遗弃（原因不明），燕八哥寄生，蛇捕食和成功的羽翼未丰的频率没有显着差异放置在主要植被类型的巢穴，虽然哺乳动物捕食[Procyon lotor，Urocyon cinereoargenteus，狐狸fulva和Didelamphalesmarsupalis]确实有显着差异。巢高对筑巢结果无显著影响。巢脆弱性蛇捕食是独立的相对巢隐蔽。在整个研究区域的巢之间均匀分布的administration（nonparasitized巢）和蛇捕食，但巢捕食哺乳动物有点丛生，燕八哥寄生巢内或附近的灌木林地。蛇捕食的发生与巢穴的数量成正比。捕食强度不相关的育雏大小。随着季节的推进，筑巢成功率略有上升。蛇捕食的发生率与最大日相对湿度呈负相关，但与其他天气测量无关。
Field sparrow [Spizella pusilla] reproductive success and nesting ecology were studied in central Illinois [USA] on a tract composed of grassland, shrub-grassland and shrub-woodland. Egg and nest successes were 11.2% and 10.2%, respectively. Major causes of nest failure included predation, primarily by snakes [Coluber constrictor, Lampropeltis calligaster, Sistrurus catenatus, Thamnophis radix] (76% of all active nests), nest desertion following brood parasitism by the brown-headed cowbird [Molothrus ater] (7%), and nest desertion from unknown causes (7%). Eleven percent of the nests were parasitized and most (63%) were deserted as a result. Nests with young received heavier predation than nests with eggs. Early nests were placed predominantly in standing grass litter, but as the breeding season advanced forbs, trees and shrubs became the most frequently used nesting substrates. Mean nest height increased as the season advanced. The frequency of desertion (from unknown causes), cowbird parasitism, snake predation and successful fledging was not significantly different among nests placed in the major vegetation types, although mammalian predation [by Procyon lotor, Urocyon cinereoargenteus, Vulpes fulva and Didelphia marsupalis] did differ significantly. Nest height did not influence nesting outcome significantly. Nest vulnerability to snake predation was independent of relative nest concealment. Desertion (nonparasitized nests) and snake predation were distributed uniformly among nests throughout the study area, but nests preyed upon by mammals were somewhat clumped, and cowbirds parasitized nests within or near the shrub-woodland. The occurrence of snake predation was proportional to the number of nests. Predation intensity was not related to brood size. Nesting success increased slightly as the season advanced. The incidence of snake predation was negatively correlated with maximum daily relative humidity, but unrelated to other weather measurements.