Data for: Cavity-breeding birds create specific microhabitats for diverse arthropod communities in boreal forests

The nests of secondary cavity-nesters located in tree cavities may form
specific microhabitats of conservation importance due to their limited
accessibility and availability. Species-specific nesting materials in
nests of different secondary cavity-nesters may furthermore provide very
different microhabitats for arthropods. The potential differences in
arthropod communities inhabiting nests of different bird species in
excavated cavities or nest boxes have, however, rarely been studied
despite their relevance for conservation. Here we investigated the
diversity and composition of arthropod communities in these different
cavity types and bird species’ nests in managed boreal forests. We
identified morphologically and by DNA-metabarcoding arthropods in nest
materials that were collected in and compared between i) woodpecker-size
cavities from seven different combinations of cavity type (nest box or
excavated cavity), tree species (aspen or pine) and accumulation history
of nest materials (single-season cleaned or uncleaned nest boxes that
accumulated nests of passerines or an owl species); and ii) nests of two
different passerine species in small nest boxes. We identified 64
arthropod taxa in ten orders, from which Diptera, Coleoptera,
Siphonaptera, and Lepidoptera were the most abundant. Shannon diversity
index was similar among the cavity-nest-type combinations, but taxa
richness was the highest in the owl nests. The arthropod communities
(especially Histeridae beetles) deviated most from the other types of
nests in owl and aspen cavity nests with more advanced decomposition of
nest material (soil or wet environment-related taxa). The differences in
arthropod communities between the different nest types point out the
importance of the ecological chain “tree cavities – bird nests – arthropod
communities”.