Western House Martin

The western house martin, also called the common or northern house martin, is a migratory swallow-family bird 13cm long with a wingspan of 26–29cm and an average weight of 18.3g. It is steel-blue above with a white rump and pure white underparts, and is found in both open country and near human habitation. It has two accepted subspecies (Wikipedia, general species account).

It feeds on insects caught in flight and migrates to climates where flying insects are plentiful. Four or five white eggs are usually laid. The source does not describe its status in China (Wikipedia, general species account).