Lack of specialist nidicoles as a characteristic of mite assemblages inhabiting nests of the ground-nesting wood warbler, Phylloscopus sibilatrix (Aves: Passeriformes)

Bird and mammal nests provide microhabitats that support a range of other species, including invertebrates. However, the variation between communities of nest-dwelling invertebrates in different nests is poorly understood. The major aim of this study was to analyze the assemblage structure of mites from the suborder Uropodina (Acari: Mesostigmata) and from superfamily Crotonioidea (Acari: Oribatida) inhabiting nests of the wood warbler, Phylloscopus sibilatrix (Aves: Passeriformes), located on a forest floor in Białowieża Forest, in eastern Poland. We also assessed the correlation between the nest material used by the birds with the assemblage structure of Uropodina mites, and compared the results with published studies of the nests of other birds and a mammal (common mole, Talpa europaea), and also with communities of mites inhabiting the soil. The field research was conducted in the strict nature reserve of the Białowieża National Park, a near-primeval European temperate forest. In 2019, immediately after the breeding period, 69 wood warbler nests and 439 soil samples were collected. Analyses revealed assemblages of Uropodina mites inhabiting the nests that consisted of 14 species, mostly common soil species. Only five species of oribatid mites from superfamily Crotonioidea were present in the nest material. Analyzed nests had a high percentage of tree leaves and grass blades, whereas moss was the least frequent component of the nest material. The Uropodina mites were more abundant in the nests that had greater amounts of grass blades, but similar relationships were insignificant for the nests with varying amounts of tree leaves or moss. The assemblages of Uropodina mites inhabiting wood warbler nests were very similar to those found in soil and nests of the common mole, but they lacked typical nest-dwelling species of Uropodina (i.e., specialized nidicoles).

Territory-level temperature influences settlement decisions, breeding phenology and productivity in three forest passerine birds

Temperature is a key determinant of breeding phenology in temperate zone birds, with increasing spring temperature across years or large geographic gradients known to advance timing of breeding. It is less well understood how localised, territory-scale temperature variations effect territory occupation, breeding phenology and productivity, primarily due to a lack of fine-scale temperature data.We examine the influence of temperature at the territory-scale, and its interaction with mean annual temperature, on territory selection and breeding outcomes of three co-occurring forest passerine bird species; two long-distance migrants (pied flycatcher Ficedula hypoleuca and wood warbler Phylloscopus sibilatrix) and one resident (blue tit Cyanistes caeruleus); all species dependent on seasonal invertebrate food for reproductive success.Spring temperature was recorded at intersections of a 150m2 grid encompassing 417 ha of forest in South-West England 2015-18, with temperature across the study area interpolated from this point data. Breeding phenology and productivity from 672 nests across the three species was quantified, and general linear models used to examine the influence of territory temperature on breeding phenology and productivity.All three species exhibited significant trends in reproductive traits associated with territory-scale temperature. Pied flycatchers settled in cooler territories first, where they raised more fledglings. Blue tits laid larger clutches in warmer territories in warm years and always laid earlier at warmer territories irrespective of annual mean temperature. Contrastingly, pied flycatcher and wood warbler breeding phenology was earlier at warmer territories in cool years and cooler territories in warm years, with wood warbler clutch size responding similarly to this interaction. Greater previous breeding experience and increased territory quality also predicted earlier breeding phenology and higher productivity for pied flycatchers.Our results show that local-scale spatial variation in temperature is associated with spatial variation in territory occupancy, breeding phenology and productivity in forest passerines. We suggest that the two migrant species may be best synchronised with their prey requirements in cooler years at a local population level while resident blue tits match local phenology at lower trophic levels across all years, potentially advantageous under warmer predicted climate change scenarios.