2005 Volume 1 Pages A25-A32
The distributions and habitats of the three species of wagtails, Japanese Wagtails Motacilla grandis, White Wagtails M. alba and Gray Wagtails M . cinerea were studied from April to July in 2004 in Utsunomiya City, central Japan, in order to reveal changes after 20 years. The species, number and breeding status of the wagtails were recorded in 500m quadrate units, each of which was classified as one of six types of habitats: city, residential, agricultural, river, industrial and hilly areas. The city and residential areas have expanded, whereas agricultural and hilly areas have decreased in the study area. Although the breeding distribution and habitats of M. grandis never changed, those of M alba and M. cinerea have changed significantly. M. alba have expanded their distribution into agricultural and river areas where they did not occur 20 years before. Coexistence of the two species may be enabled by lowered competition for nesting sites in the agricultural and river areas due to urbanization. On the other hand, M. cinerea, retaining their habitat preference, have lost a large number of quadrates in distribution. The factors affecting this change are not clarified.