Distribution and Breeding of Red Kites in Relation to Land-Use in Wales

Abstract

(1) The breeding performance of Milvus milvus was examined in relation to habitat using data collected in mid-Wales in the period 1946-78. (2) Nests in beech trees more often produced young than nests in other tree-species, but no significant variation in breeding performance was noted among nests at different heights above ground, on slopes facing different directions, or in isolated trees and woods of different size. With increase in altitude above sea level, egg-laying became later and the proportion of nests which produced young seemed to decline. (3) Occupation of territories was relatively greater on land of lower agricultural potential and, within occupied territories, nests were built more often. Young were fledged more often from clutches on good land than from clutches on poor land. Overall, however, productivity was no better on good land than on poor. The lower success early in the season on good land may have been due to greater human disturbance and to less sheep carrion than on poor land. (4) Little variation in breeding performance was noted that could be associated with variations in the ratios of forest to open land around the nesting territories. The early stages of breeding seemed to be more successful in the more forested parts of the area, and the later stages of breeding in the less forested parts. Overall, there was no variation in production of young associated with extent of forest. (5) Tree-planting activities near occupied nests may have reduced egg-laying by territorial pairs in the year concerned. (6) No firm evidence was found that increasing afforestation of sheepwalk has influenced the distribution of territorial kites in Wales. (7) The increase in kite numbers in recent years may have been due to less human persecution, an incidental result of changes in land use and in human attitudes.