1964. Paperback in original brown wrapper. Top of spine has small tear. Writing on front cover. Papers on Game Research 24. This study is based on field data collected in the city area of Helsinki and its vicinity in 1953-1963. An attempt has been made to obtain, on the basis of representative data, a total idea of the social behaviour of the mallard, of the annual rhythm of behavior patterns in each sphere of activity, of their phenology and of the external, mainly those associated weather and partial factors governing these relationships.