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首页> 外文期刊>Canadian Journal of Zoology >Foraging patterns of male and female Double-crested Cormorants nesting in the Columbia River estuary
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Foraging patterns of male and female Double-crested Cormorants nesting in the Columbia River estuary

机译：在哥伦比亚河河口筑巢的雌雄双冠Double的觅食模式

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摘要

The nesting colony of Double-crested Cormorants, Phalacrocorax auritus (Lesson, 1831), on East Sand Island in the Columbia River estuary is currently the largest for this species on the Pacific Coast of North America. We used radiotelemetry to investigate the spatial and temporal foraging patterns of nesting cormorants to better understand how this colony of piscivores meets its resource needs. We determined that nesting adults tended to forage >5 km from the colony and foraging distribution was distinctly different between the sexes. On average, males commuted nearly twice the distance to forage compared with females. Females typically foraged in the estuarine mixing zone, reportedly the region of the estuary with the greatest densities of schooling fishes, while males tended to commute more than 15 km to forage in the freshwater zone. Foraging intensity of both sexes varied by time of day, tide stage, and tide series; foraging generally intensified during ebb tides. These gender differences in foraging patterns, combined with the ability to forage at considerable distance from the colony on a wide variety of prey, may allow this large and growing colony to remain productive while potentially competing for food with many thousands of other piscivorous waterbirds that use East Sand Island.
机译：目前，在哥伦比亚河河口东沙岛上，双冠Ph（Phalacrocorax auritus）巢（Lesson，1831年）是该物种在北美太平洋海岸的最大集落。我们使用无线电遥测技术研究了cor筑巢的时空觅食模式，以更好地了解食蚁兽如何满足其资源需求。我们确定，筑巢成年的成年人倾向于在距该殖民地> 5 km的地方觅食，而两性之间的觅食分布明显不同。平均而言，雄性通勤的距离是雌性的两倍。雌鱼通常在河口混合区觅食，据报道，河口地区的养鱼密度最大，而雄鱼往往在淡水区通勤超过15公里。男女的觅食强度随一天中的时间，潮汐阶段和潮汐序列而变化;退潮期间通常会增加觅食。这些在觅食方式上的性别差异，再加上在各种各样的猎物上从该殖民地进行相当远的觅食的能力，可能使这个庞大且不断增长的殖民地保持生产力，同时有可能与成千上万的其他食鱼性水鸟争夺食物东沙岛。

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