Abstract
Bird nests and bird-excavated cavities provide suitable environments for egg incubation and nestling development. However, bird-created structures are also exploited by a wide range of organisms, including taxa that are phylogenetically distant from the avian constructors. While birds, mammals, and invertebrates are well documented as secondary users of nests and cavities, the occurrence of ectothermic tetrapods, i.e. amphibians and reptiles, in bird-created structures has received little attention. Here, we review published records of amphibians and reptiles using bird nests, cavities excavated or modified by birds, nest boxes, and bird burrows. Our review shows that bird-created structures serve as shelters, hibernacula, breeding or foraging sites, and resource-rich microhabitats for a diverse range of amphibians and reptiles. Although records of ectothermic tetrapods occupying bird-created structures remain relatively scarce, we identified representatives of multiple families associated with structures created by a range of bird species across most biogeographic realms. The limited number of available records may reflect either the infrequent and short-term nature of these interactions or methodological challenges associated with detecting herpetofauna in active or abandoned nests, burrows, and cavities. We suggest that the use of bird-created structures by ectothermic vertebrates is more widespread than currently documented, but targeted surveys and appropriate detection methods are needed to investigate this phenomenon.