Extra-pair paternity (EPP) in birds is a widespread and highly variable reproductive phenomenon not only in species level but also among individuals and breeding attempts. A number of studies have been conducted to reveal the adaptive function of the behavior focusing on the physical and genetic characteristics. However, relatively few have studied on the spatial distribution of individuals.

In the present study, we considered spatial patterns of EPP in the Japanese great tit (Parus major minor) in Hokkaido Japan. The studied population had a high reproductive productivity with multiple brood rates (<60%) and breeding density (.48pair/ha.). Also, this species is highly territorial during the breeding season, and is an ideal subject to study the spatial distribution of extra-pairs. We used PCR-amplified microsatellites to assess the paternity of over 700 nestlings from 92 broods with 132 adult birds over two breeding seasons. Overall, 10.0% of nestlings were sired by EP males in this population. We further determined the genetic fathers of these nestlings using CERVUS and determined the spatial distribution of these individuals.

In this session, we will show the spatial distribution of EP males and their breeding status such as temporal breeding states and breeding success and discuss how spatial distribution of breeding individuals affects the patterns of EPP behavior.