摘要
We report that Western Sandpipers （Calidris mauri） on Alaska’s Yukon-Kuskokwim River Delta exhibited aggregated breeding behavior at a relatively small spatial scale. Prior to clutch initiation, males performing song flight displays on a 36 ha plot were aggregated as were subsequent initial nesting attempts on the plot. We tested three hypotheses commonly invoked to explain aggregated breeding in territorial species （social mate choice, predation, and material resources hypotheses）, and found support for the material resources hypothesis, as dispersed individuals were more often associated with tundra habitat patches, and aggregated individuals nested more often in undulating-tundra habitat patches compared to patch availability. The pattern of habitat occupancy conformed to an ideal despotic distribution with aggregated nesting birds in undulating-tundra patches experiencing lower reproductive success. On our study plot, older, more aggressive males solicited females more often, and defended larger, more dispersed sites in tundra habitat patches, compared to younger, less aggressive males that were aggregated in undulating-tundra habitat patches. Breeding aggregations are often concentrated on or near a critical resource. In contrast, Western Sandpiper breeding aggregations occur when dominant and/or older individuals exclude younger, subordinate individuals from preferred habitat. Although many taxa of non-colonial birds have been reported to aggregate breeding territories, this is the first quantitative report of aggregated breeding behavior in a non-colonial monogamous shorebird species prior to hatch.
该文报道了西滨鹬 (Calidris mauri) 在美国阿拉斯加州育空-卡斯科奎姆河三角洲相对较小的空间尺度上所表现的集群繁殖行为。在开始产卵之前, 西滨鹬雄鸟聚集在一处 36 hm2的区域鸣唱飞行, 进行求偶炫耀。随后在该区域营巢时, 西滨鹬也保持着集群状态。检验了三个常用于解释具领域行为的物种的集群繁殖的假说:社会成员选择假说、捕食假说和物质资源限制假说。结果表明, 与斑块可利用性相比, 分散的个体常栖息于地势平坦的苔原栖息地斑块, 而集群个体常筑巢于地势起伏的苔原栖息地斑块, 因此, 该研究支持物质资源限制假说。在地势起伏的苔原栖息地斑块集群营巢的西滨鹬繁殖成功率较低, 这表明西滨鹬的这种栖息地占有模式符合理想的等级分布。在研究样地中, 年长且更具攻击性的雄鸟向雌鸟求偶的次数更多, 并且保卫位于地势平坦的苔原栖息地斑块上更大的领域; 相比之下, 年幼且攻击性较弱的雄鸟则聚集在地势起伏的苔原栖息地斑块。通常情况下, 繁殖期的集群多集中于某种关键资源的分布区内或分布区附近, 但西滨鹬繁殖集群的出现是由于年长和处于优势地位的个体将年幼和处于从属地位的个体排斥出高质量的栖息地。虽然, 繁殖领域的集群现象在很多非群居的鸟类中都曾有报道, 但该文是首次对非群居的单配制鸻鹬类物种在孵卵之前的集群繁殖行为进行了定量研究。
