Tropical cities provide challenging conditions for resident wild species to undertake critical activities such as roosting and breeding. Tree-nesting waterbirds are widespread urban inhabitants but how they choose sites for these critical activities in urban areas, and whether requirements vary by species, are poorly understood. We assessed whether waterbirds chose roosting and nesting sites using similar cues in a rapidly urbanising small Indian city, Udaipur. Roost sites (N = 78, 17 species especially Ardeola grayii, Bubulcus ibis, Pseudibis papillosa) were located mostly beside roads and wetlands. Nest sites (N = 130, 12 species especially B. ibis, P. papillosa and Anastomus oscitans) were different from roost sites and were located mostly in built-up areas and wetlands. Waterbirds used 23 of 39 available tree species for roosting and nesting, strongly preferring snags and the largest trees of introduced (Azadirachta indica), native (Ficus spp., Vachellia nilotica) and exotic (Eucalyptus sp.) species. Site locations for both activities were associated negatively with built-up areas at the smallest spatial scale. At larger spatial scales they were associated positively with wetlands and built-up areas, with waterbirds entirely avoiding the Aravalli mountains. Individual waterbird species displayed idiosyncrasies in choice of tree species but used similar cues to locate roost and nest sites. Retaining large trees and wetlands across Udaipur city is essential to allow space for waterbirds’ critical activities. The scale and diversity of waterbirds roosting and nesting in Udaipur city is unprecedented suggesting that the ability of small tropical cities to aid urban biodiversity conservation has been overlooked.

热带城市为当地野生物种进行栖息和繁殖等关键活动提供了具有挑战性的条件。树巢水鸟是广泛存在的城市居民，但人们对它们如何在城市地区选择这些关键活动的地点以及要求是否因物种而异，人们知之甚少。我们评估了在快速城市化的印度小城市乌代浦，水鸟是否使用类似的线索选择栖息地和筑巢地。栖息地（N = 78，17种，尤其是Ardeola Grayii、Bubulcus ibis、Pseudibis papillosa）大多位于道路和湿地旁边。巢址（N=130，12种，尤其是朱鹮、乳头鹳和Anastomus oscitans）与栖息地不同，大多位于建筑区和湿地。水鸟使用 39 种可用树种中的 23 种来栖息和筑巢，特别喜欢引入的障碍物和最大的树木（Azadirachta indica）、本地树种（Ficus spp.、Vachellia nilotica）和外来树种（Eucalyptus sp.）。这两项活动的场地位置与最小空间尺度的建成区呈负相关。在更大的空间尺度上，它们与湿地和建筑区呈正相关，水鸟完全避开阿拉瓦利山脉。不同的水鸟物种在选择树种方面表现出不同的特质，但使用相似的线索来定位栖息地和筑巢地点。保留乌代浦市的大树和湿地对于为水鸟的关键活动提供空间至关重要。乌代布尔市栖息和筑巢的水鸟的规模和多样性是前所未有的，这表明热带小城市帮助城市生物多样性保护的能力被忽视了。