Survival and home ranges of woodland birds in restoration plantings

Woodland birds are a species assemblage of conservation concern, and their
persistence in fragmented agricultural landscapes is dependent on both the
preservation of existing woodland remnants and the implementation of
restoration plantings. However, little is known about the habitat-use and
persistence of birds in fragmented agricultural landscapes. We present a
detailed, population-oriented study of woodland birds in temperate
eucalypt woodland restoration plantings and remnant woodland patches in
the South-west Slopes bioregion of New South Wales, Australia. First, we
undertook a three-year mark-recapture project to assess annual survival
and site fidelity in restoration plantings and woodland remnants. We
supplemented our recapture efforts with resightings of colour-banded
individuals. Second, we tracked individual birds of two species – superb
fairywren (Malurus cyaneus) and willie wagtail (Rhipidura leucophrys) –
and documented snapshots of their home ranges and movement patterns during
the breeding season. Annual survival in the woodland bird assemblage was
lower than expected (51%). Home ranges of the superb fairywren were
positively correlated with patch size, and were constrained by patch edges
in linear sites. Superb fairywrens and willie wagtails were more likely to
travel longer distances between substrates while foraging in linear sites.
Willie wagtails engaged in significant gap-crossing (up to 400 m) between
adjacent habitat patches. Our findings indicate that 1) patch isolation
and certain patch configurations place resident birds at an energetic
disadvantage, and 2) in our study area, woodland bird populations are
continuing to decline. We recommend landscape-scale restoration programs
aim to address ongoing population declines. Studies such as ours conducted
over longer time periods would provide a deeper understanding of
habitat-use and population processes of woodland birds in fragmented
agricultural landscapes.

林地鸟类是一类受保育关注的物种组合，它们在破碎化农业景观中的存续，既依赖于现有林地遗留斑块的保护，也有赖于人工恢复造林举措的实施。然而，目前学界对破碎化农业景观中鸟类的栖息地利用与种群存续情况仍知之甚少。本研究针对澳大利亚新南威尔士州西南坡生物区的温带桉树林恢复造林地与遗留林地斑块中的林地鸟类，开展了一项以种群为导向的详细研究。其一，我们开展了为期三年的标记重捕项目，以评估恢复造林地与遗留林地斑块内鸟类的年存活率与生境位点保真度；同时通过对彩色环志个体的重观察来补充重捕数据。其二，我们对两种鸟类——华丽细尾鹩莺（superb fairywren，学名Malurus cyaneus）和白眉扇尾鹟（willie wagtail，学名Rhipidura leucophrys）——的个体进行了追踪，并记录了繁殖季内它们的家域范围与活动模式的快照式数据。林地鸟类组合的年存活率为51%，低于预期水平。华丽细尾鹩莺的家域范围与斑块面积呈正相关，且在线性生境斑块中会受到斑块边缘的限制。在这类线性生境斑块中觅食时，华丽细尾鹩莺与白眉扇尾鹟更倾向于在不同栖息基质间移动更长的距离。白眉扇尾鹟会在相邻生境斑块间进行长距离的生境间隙穿越（最远可达400米）。本研究结果表明：其一，斑块隔离度与特定的斑块构型会使留居鸟类面临能量上的劣势；其二，在本研究区域内，林地鸟类种群仍在持续下降。我们建议，景观尺度的恢复计划应将解决种群持续下降问题作为核心目标。开展更长时间跨度的同类研究，将有助于更深入地理解破碎化农业景观中林地鸟类的栖息地利用与种群动态过程。