My home is your home: Nest boxes for birds and mammals provide habitats for diverse insect communities

Cavity-bearing trees are important nesting sites for many birds and mammals but have become rare due to anthropogenic modification of natural environments. Nest boxes are often used to compensate for the loss of these microhabitats. Nest boxes contain amounts of organic debris exploited by a variety of organisms, mainly insects. We studied the largely unexplored group of nest-dwelling insects by rearing them from plant detritus and animal remains accumulated in nest boxes of six bird and two mammal species, distributed in forest, farmland and urban environments in Poland. We recorded 119 species representing eight insect orders. Nest substrates composed of plant detritus and animal remains supported similar insect species richness but differed significantly in terms of the insect community composition. Nests of Falco tinnunculus and Tyto alba and also Parus spp. and Strix aluco had very similar insect communities. The structural compositions of insect communities were also similar in nests of Parus spp. and Sturnus vulgaris, and of F. tinnunculus and S. aluco. Flies and earwigs were associated with nests of Parus spp. and Sciurus vulgaris and were more abundant in forests and urban environments, whereas wasps preferred S. aluco nests in forests. Our study shows that nest boxes may serve as replacement habitats for a variety of nest-associated insects. Therefore, we suggest a more flexible approach to nest boxes maintenance and management, for example, less frequent cleaning or providing more than one nest box in a given place to enhance conservation of nest-associated insects.

Automated summary

Nest-bearing trees are declining due to human activities, making nest boxes an important replacement habitat for a variety of nest-associated insects across different environments. Different types of nests support different insect species, with similarities in insect community composition observed among certain bird and mammal species' nests.