We investigated the genetic relationship between parents and broods of the Japanese Tit Parus minor in a residential area in Saitama Prefecture from 2011 to 2014. We obtained blood samples, and extracted DNA, from nine adults and 36 nestlings in five nest boxes. We conducted microsatellite polymorphism analyses using 12 markers. The EPP ratio, estimated from genetic polymorphism of the nine valid markers, was 3.0 or 6.1% (one or two out of 33 nestlings). Some nestlings shared no genetic relationship with either of their parents, indicating that intraspecific brood parasitism or nest take-over had occurred.
