Turnover and dispersal in a Peregrine Falco peregrinus population

• Published in: Ibis
• Main Authors: Mearns, R., Newton, I.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1984
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Falco peregrinus
• Online Access: http://dx.doi.org/10.1111/j.1474-919x.1984.tb00255.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1984.tb00255.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1984.tb00255.x

In south Scotland, most Peregrines returned to the same territories to breed in successive years, though a few females changed territory from one year to the next. Annual mortality among breeding birds was at most 9% among females (or 11% in both sexes combined). There may have been considerable annual variation, however, and excluding one exceptional year out of five reduced the estimate for females to 7%. These estimates are maxima, but are still considerably lower than those obtained from ring recoveries of dead birds reported by members of the public. Among trapped birds, four males first bred at age two years, one at three and another at four or five; two females first bred at one year, 13 at two years old and one at three. Five other females which were seen to be in first‐year plumage but were not trapped, also laid eggs, and 12 other such paired females held territory but did not lay. Only one paired male held territory in first‐year plumage. In their movements between natal and breeding territories, some females moved further than males, with median distances of 83 and 58 km respectively. In addition, of birds trapped breeding in the study area, a greater proportion of the males than of the females had been born locally, despite an equal sex ratio among fledglings; this was also consistent with a greater dispersal of females. In general, Peregrines made much longer movements in their first year of life than subsequently. Movements were in any direction.