A nesting study of Mallard in Berkeley New Decoy, Slimbridge

Abstract

Mallard nesting in the Decoy wood were studied in 1961-63. 224 nest-sites used are discussed in relation to available habitat. There is some evidence that individual females have traditional sites. The onset of laying was 3 weeks later in 1962 and 1963 than in 1961, when it began in mid-February. The average size of early clutches was 12.6 eggs and that of later ones 9.9 eggs. Though one egg was usually laid each day, there was often a gap of a day during the laying of the first seven eggs. The average incubation period of 51 clutches was 27.6 days, the range 24-32 days. 88.7% of 180 nests were successful and 82.4% of eggs hatched. The association of first laying with spring temperatures is examined and compared with Continental studies.