Coexistence of Mediterranean tits: A multidimensional approach

Abstract

Differential traits (e.g., feeding at different heights in trees) have evolved to allow the coexistence of putative competitors; such traits have been well studied in small passerines (e.g., Paridae), mainly during the winter. However, few studies have been carried out during the breeding season, when competition could be more intense. We applied here a multidimensional approach, examining ecological (prey type and size, and nesting habitat characteristics) and life history (timing of maximum nestling food demand) traits that might help to explain the coexistence of great (Parus major), crested (Lophophanes cristatus), and coal (Periparus ater) tits breeding in a Mediterranean pine forest. The diets of great and crested tit nestlings were equally diverse, and more diverse than that of coal tit nestlings. Prey size diversity was similar among species. Great and crested tits consumed longer caterpillars than coal tits. This last species preferred to build its nests in nest boxes surrounded by mature vegetation, while great tits preferred immature vegetation and crested tits preferred intermediate vegetation stages. Finally, the breeding cycles of both great and coal tits overlapped to a great extent, while crested tits bred earlier. In summary, each species has a unique combination of niche characteristics that might contribute to the coexistence of the 3 tit species.