Nesting birds can act as thermal ecosystem engineers by providing warm habitats that may attract arthropods to colonise the nest structure. This cohabitation of birds and nest-dwelling invertebrates may foster symbiotic relationships between them, but evidence is lacking. We investigated whether ants are attracted to bird nests by the heat generated by the hosts, and/or the nests’ structural insulation properties, to raise their broods (larvae and/or pupae) in advantageous thermal conditions. We found that the endothermic activity of birds within their nests created ‘heat islands’, with thermal conditions potentially promoting the survival and development of ant larvae in cool environments. We experimentally confirmed that the presence of heat within bird nests, and not the structure itself, attracted the ants to colonise the nests. As ants might benefit from exploiting warm bird nests, this may be a previously overlooked commensal, mutualistic or parasitic relationship which may be ecologically significant and globally widespread among various nesting birds and reproducing ants. Similar interspecific interactions may exist with other arthropods that reproduce in avian and mammalian nests. Further research is needed to reveal the nature of these relationships between such taxa, and to understand the role of warm-blooded animals as thermal ecosystem engineers.

筑巢的鸟类可以充当热生态系统工程师，提供温暖的栖息地，吸引节肢动物在巢结构中定居。鸟类和巢居无脊椎动物的这种共居可能会促进它们之间的共生关系，但缺乏证据。我们研究了蚂蚁是否会被宿主产生的热量和/或巢穴的结构隔热特性吸引到鸟巢，以便在有利的热条件下养育它们的幼虫（幼虫和/或蛹）。我们发现鸟类在巢穴内的吸热活动产生了“热岛”，热条件可能促进蚂蚁幼虫在凉爽环境中的生存和发育。我们通过实验证实，鸟巢内存在热量，而不是结构本身，吸引了蚂蚁在巢穴中定居。由于蚂蚁可能会受益于利用温暖的鸟巢，这可能是一种以前被忽视的共生、互利或寄生关系，这种关系可能具有生态意义，并且在各种筑巢鸟类和繁殖蚂蚁中广泛存在于全球范围内。在鸟类和哺乳动物巢穴中繁殖的其他节肢动物也可能存在类似的种间相互作用。需要进一步的研究来揭示这些类群之间关系的本质，并了解温血动物作为热生态系统工程师的作用。