Understanding how birds select breeding sites plays an important role in habitat protection, especially for the conservation of endangered species. With the increase in population size of the endangered Crested Ibis Nipponia nippon, its distribution range has expanded from mountain areas to plains located outside protected areas, representing a new challenge for conservation of the species. Identifying the current nesting habitat requirements is thus needed and can provide valuable information for the planning of new nature reserves. In this research, we surveyed a total of 117 nests across the whole distribution range from 2015 to 2019. We used generalized linear mixed-effects models to assess nesting preferences of the Crested Ibis in the wild. Results showed that in mountain areas, Masson pines Pinus massoniana were preferred (64.6%), whereas elms Ulmus pumila (44.9%) and aspens Populus davidiana (40.6%) were used more frequently lower down, probably because of their higher availability. In both mountain areas and plains the ibises selected tall nesting trees with larger diameter at breast height and preferred nesting rather high above ground, especially in plains where taller trees provided higher suitable nesting positions. The ibises also preferred nesting close to tree trunks, especially in mountain areas, probably for more safety from collapsing. Furthermore, in mountain areas, slope and distance to path had positive effects on nesting occurrence, and understorey coverage was avoided by nesting ibises, while these variables had little impact in plains. Our results indicate that, despite their range expansion, Crested Ibises rely on very specific habitat characteristics for nesting. We suggest relatively tall trees like elms and aspens should be preserved in plains. In addition, we highlight how selection patterns of Crested Ibises may vary, and that such variation should be addressed in conservation planning, especially in future reintroduction.

了解鸟类如何选择繁殖地在栖息地保护方面发挥着重要作用，特别是对于濒危物种的保护。随着濒临灭绝的朱鹮种群规模的扩大，其分布范围已从山区扩大到保护区外的平原，对物种保护提出了新的挑战。因此，需要确定当前的筑巢栖息地要求，并且可以为新自然保护区的规划提供有价值的信息。在这项研究中，我们调查了 2015 年至 2019 年整个分布范围内的总共 117 个巢穴。我们使用广义线性混合效应模型来评估野生朱鹮的筑巢偏好。结果表明，在山区，马尾松首选马尾松(64.6%)，而榆树( Ulmus pumila ) (44.9%) 和白杨 ( Populus davidiana )(40.6%) 使用频率较低，可能是因为它们的可用性更高。在山区和平原，朱鹮都选择胸高直径较大的高大筑巢树，并且更喜欢在地上较高的地方筑巢，尤其是在高树提供更高合适筑巢位置的平原上。朱鹭还喜欢在树干附近筑巢，尤其是在山区，可能是为了更安全地避免倒塌。此外，在山区，坡度和路径距离对筑巢发生有积极影响，筑巢朱鹮避免了林下覆盖，而这些变量在平原上影响不大。我们的研究结果表明，尽管它们的活动范围有所扩大，但朱鹮依赖于非常特定的栖息地特征进行筑巢。我们建议比较高大的树木如榆树和白杨应保留在平原上。此外，我们强调了朱鹮的选择模式可能会如何变化，并且这种变化应该在保护计划中得到解决，特别是在未来的重新引入中。