Breeding Biology of Four Sympatric Tits In Northern Japan

In order to understand evolution in life history strategies, it is useful to compare breeding parameters among closely related species and/or different habitats within the same species. The Paridae family, known as tits and chickadees, are suitable for such studies since they are distributed worldwide and use a variety of habitats. However, previous studies are mostly limited to populations in Europe and North America. Few studies have compared breeding biology in sympatric Paridae species. In this study, we investigated the breeding biology of Japanese Tits (Parus minor), Coal Tits (Periparus ater), Marsh Tits (Poecile palustris), and Varied Tits (Sittiparus varius) in a cool temperate forest of northern Japan. A previous study has shown that Japanese Tits have higher annual production (i.e., clutch size, rate of multiple brooding) compared to a European sister species, the Great Tit (Parus major), possibly because of greater diversity and abundance of prey items. Therefore, we predicted that annual breeding productivity should also be high in the other sympatric species. Contrary to the expectation, annual productivities were not high for the other species with few or no second clutches, indicating the lack of a general rule of high food availability in this region. Some ecological or physiological constraints may exist for other species, such as trade-offs involving survival versus fecundity or resident versus migrant. This study provides basic but important information on breeding biology of Paridae in understudied Asian populations.