Looking at the forest through the eyes of birds: A radio-tracking study of microhabitat use in provisioning great tits

Detailed knowledge of habitat utilization by animals is integral in understanding their ability to adjust resource exploitation to the conditions of heterogeneous and constantly changing habitats. To identify the most important micro- and macrohabitat landscape characteristics that are important factors for birds when choosing foraging patches in their territory, we used a radio-telemetric approach with nestling-feeding great tit (Parus major) females in a heterogeneous habitat mosaic. We showed that birds preferred to forage in areas with low or high but not mid-range normalized difference vegetation index (NDVI) values, similarly in coniferous and deciduous forests. At the same time, foraging birds avoided areas with low or high but not mid-range canopy cover only in the dense deciduous forest, whereas in the more open coniferous forest, females used areas, which vary widely in the amount of canopy coverage. Females employing this foraging behaviour raised larger broods on average. Our results suggest that foraging microhabitat selection in forest passerines is a complicated process subject to diverse and interacting effects of habitat characteristics other than simply a habitat's position on a food-richness axis. Moreover, the study demonstrates how using a micro-scale approach can reveal subtle, but significant, habitat selection mechanisms that remain hidden at a macro-scale level.