Nest sites in the KestrelFalco tinnunculus

Abstract

An analysis of 3803 records of nest sites used by Kestrels from 1937 to 1987 showed that cliffs, crags and quarries comprised 27% of the total, abandoned stick nests in trees 17%, tree cavities 20%, buildings 16% and nest boxes 15%. There were strong regional variations in the distribution of these sites. Frequency of use of different types may have been partly influenced by nest predation rates. Stick nests were mainly used in trees in forests, woods, copses, clumps or belts of trees, and 83% of such nests were those of Carrion Crows; 45% of the trees were pines. Height influenced the choice of stick nests used by Kestrels, lower nests generally being avoided. There was a continual decline in the proportion of stick nests used during the period, whilst the use of tree cavities increased. Tree cavities were mainly used in hedgerow, park and isolated trees, and their use was linked to the extent of tilled farmland in any area. This pattern was perhaps partly encouraged by modern cultivation techniques, but probably mainly resulted from changing human attitudes to farmland trees. The tree species used for cavity nesting by Kestrels differed markedly from those used by owls, and choice of cavity also showed some differences. There was a remarkable concentration of Kestrel nest sites in rural buildings in NW England, a pattern apparently increasing. This may have been linked to the types of farm buildings thrre. The sites used in buildings differed from those used by Barn Owls.