Individual study: Survival and breeding productivity of translocated red kites Milvus milvus reintroduced into northern Scotland
Evans I.M., Summers R.W., O'Toole L., Orr-Ewing D.C., Evans R., Snell N. & Smith J. (1999) Evaluating the success of translocating red kites Milvus milvus to the UK. Bird Study, 46, 129-144
The red kite Milvus milvus was formerly widespread in Great Britain, but was exterminated from England and Scotland in the 1870s, and, until recently, persisted only in central Wales. This study documented the survival and breeding productivity of translocated red kites following their reintroduction into an area of the species's historic range in northern Scotland.
In total, 93 juvenile kites (52 males, 40 females and one unsexed) were released in northern Scotland during July and August of 1989-1993. Birds had been obtained as nestlings from southern Sweden, with chicks reared in groups of two to four in quarantine aviaries until their release. All individuals were fitted with leg rings, patagial wing tags and radio-transmitters prior to release.
Minimum survival rates (up to July 1995) were estimated from radio-telemetry data and wing tag observations. Data on nesting attempts were collected from spring 1991 to August 1995.
First-year survival of released kites was 51.6%, but annual survival increased in the second and third years following release to 66.7–88.0%, and was 75.0–90.9% for the few fourth- and fifth-year birds for which data were available. Survival rates of males and females were not significantly different. Known causes of mortality for 15 released individuals recovered dead during 1989–1994 included poisoning and collisions with power lines and (in one case) a train!
Breeding was first attempted (successfully) in 1992, and the number of pairs subsequently increased annually, to 15 breeding (plus two territorial, but non-breeding) pairs in 1995. In total, 29 clutches were laid and 47 chicks fledged successfully during 1992–1995. First-year survival of wild-raised birds was 42.9%, which did not differ significantly from that of released birds during 1992–1994 (when both groups of birds were present).
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