The Number of Broods Reared by Stonechats in Surrey

Abstract

A population of stonechats [Saxicola torquata] nesting on heathland in Surrey [England] was studied from March-Aug. in 1972 and 1973. The territories were very scattered and successive nesting attempts by particular pairs could be followed throughout the season. Of the 30 pairs found with 1st brood nests, 29 (97%) attempted a 2nd brood and 15 (50%) a 3rd brood. This compares with proportions of 32% and 10% for 2nd and 3rd broods, respectively, in the national Nest Record Card collection. By using the time interval required between the onset of successive nesting attempts by the same pair (usually aobut 44 days) one can determine, in many cases, the probable outcome of the earlier nest depending on whether the 2nd brood occurs at the correct time or not. As there were only 8 known failures in 78 attempts nesting success may possibly be as high as 90%. The number of broods reared in a season affects the determination of the breeding season, clutch size and overall productivity of young per pair. Using all nest record data the average number of broods per pair is 1.71 and productivity 2.82/pair per yr. From this Surrey study the average number of broods is raised to 2.47 and productivity to 4.07 young.