Habitat partitioning and spatial segregation at multiple scales promotes year-round coexistence in a guild of forest songbirds

Abstract

Species of the same guild often show ecological, biological or genetic similarities, yet they should also show different micro-habitat requirements or local spatial distributions to coexist in the same area. These patterns may be fundamental in reducing interspecific competition and maintaining biodiversity across ecological and evolutionary timescales. We examined habitat differences and spatial segregation in a guild of five sympatric woodland songbirds (family Paridae) inhabiting mixed forests of south-central Europe. Specifically, we performed interspecific comparisons of habitat and space use across two phenological periods (breeding and non-breeding) and two spatial scales (home-range and foraging habitat). At the home-range scale, habitat preferences revealed two distinct and seasonally consistent subgroups within the guild, namely ‘broadleaf’ and ‘conifer’ species. During breeding, we showed that all species largely overlapped in their use of different foraging micro-habitats within the tree canopy, even within each subgroup. Yet, we detected significant spatial segregation of breeding territories among species. Conversely, during the non-breeding period, individuals of different species within mixed flocks foraged on different and complementary sectors of the canopy, potentially partitioning foraging habitats. This study suggests that the coexistence of species within the south-central European tit guild across different phenological periods is facilitated by differentiation of habitat use at the home-range and foraging habitat scales, as well as by spatial segregation of breeding territories. These findings highlight how long-term coexistence among sympatrically and ecologically similar species can be shaped by temporal shifts in space and habitat use, which differ across the annual cycle.