Breeding season, courtship behaviour, and territoriality of White and Japanese Wagtails Motacilla alba and M. grandis

The breeding ecology of White and Japanese Wagtails, Motacilla alba and M . grandis, was studied along a river in central Japan. The home ranges of the two species greatly overlapped along the river, but no interbreeding occurred. M. grandis spent more time on the river than M . alba and defended territories there. M . alba used the river as part of the entire home range, and did not defend the river areas as territories. Singing activity and breeding started earlier in M . grandis than in M . alba. The early breeding of M . grandis was related to the lack of moulting in spring, less necessity for pair formation due to the existence of pairs in the winter, and the greater dependency on larval than on adult insects. Songs were very different between the two species. The bowing display that preceded the pre-copulation display was found only in M . alba. During the pre-copulation display, male M . grandis lifted both wings above the horizontal while male M . alba drooped both wings. The pre-copulation display of M . grandis was similar to that of Large Pied Wagtails M . maderaspatensis in India, suggesting a closer relationship of the two species than to M . alba.