ABSTRACT

Migratory shorebirds feed in intertidal wetlands during the winter non-breeding season, to meet their daily needs and accumulate reserves for the flight to their breeding grounds. However, these habitats may be impacted by development. Eastern Curlew (Numenius madagascariensis) populations are declining in Australia, where we assessed relationships among the curlews’ feeding behaviours, prey types, broad substrate types, feeding microhabitat preferences, and population density, across 11 tidal flats in Moreton Bay, South East Queensland, Australia. Most prey were crustaceans, of varied size. Within flats, the types and rates of feeding actions, and feeding success, varied with sex, microhabitat and tidal stage. Among different flats, the estimated rate of prey biomass intake was strongly correlated with curlew density, explaining 57 per cent of its variation (2–77 birds/100 ha); whereas neither feeding attempts nor successful feeding acts per unit time were good density predictors. Substrate resistance was negatively correlated with both biomass intake and curlew density, because curlews were able to use their long bills to extract larger prey from deep burrows in more penetrable flats. The curlews, therefore, chose feeding areas directly according to food supply, but the substrate penetrability provides a promising rapid indicator of regional-scale variation in habitat quality.

摘要

冬季非繁殖季节，候鸟在潮间带湿地觅食，以满足日常需求，并为飞往繁殖地的飞行积累储备。然而，这些栖息地可能会受到开发的影响。东鹬 ( Numenius madagascariensis) 澳大利亚的种群数量正在下降，我们在澳大利亚昆士兰东南部莫顿湾的 11 个潮滩上评估了麻鹬的摄食行为、猎物类型、广泛的基质类型、摄食微生境偏好和种群密度之间的关系。大多数猎物是大小不一的甲壳类动物。在平原内，摄食行为的类型和频率以及摄食成功率因性别、微生境和潮汐阶段而异。在不同的平地，估计的猎物生物量摄入率与麻鹬密度密切相关，解释了 57% 的变异（2-77 只鸟/100 公顷）；而每单位时间的进食尝试和成功的进食行为都不是很好的密度预测指标。底物抗性与生物量摄入量和麻鹬密度呈负相关，因为麻鹬能够用它们的长喙从更易穿透的平坦地带的深洞中猎取更大的猎物。因此，麻鹬直接根据食物供应选择觅食区，但底物渗透性提供了一个有希望的快速指示栖息地质量区域尺度变化的指标。