Lesser Spotted Eagle (Aquila pomarina) Science Article 4
To date there are no definite conclusions as to the age at which the Lesser Spotted Eagle Aquila pomarina reaches sexual maturity. In the course of a long-term study we were able to trap 4- and 5-year-old ringed birds in Germany and Slovakia. A 4-year-old female and a 5-year-old male reproduced; another 4-year-old male had paired up and occupied a territory but did not breed (Tab. 1).The 4-year-old female and 5-year-old male were already in full adult plumage, whereas the 4 year old male still had a yellow nape patch as well as many fresh juvenile type feathers on various parts of the body, including typical juvenile plumage in the rump area. From this it appears that male Lesser Spotted Eagles attain full adult plumage and sexual maturity one year later than female birds.Both male birds had settled markedly closer (4.7 and 8 km) to their birthplace than two females (59 and 90 km) (Tab. 1). 18 adult birds reached an average age of 10.5 years (Tab. 2). Taking this and the average breeding success of the Lesser Spotted Eagle into account, it can be calculated that sexually mature females produce about 4.5 and males approx. 3.9 fledged young during their lifespan.Shooting was by far the commonest cause of mortality of Lesser Spotted Eagles at least 11 of 30 ringed individuals (Tab. 2, 3 and 4).Some 1 and 2-year-old ringed Lesser Spotted Eagles returned to the breeding area during the breeding season. On the other hand, a 2-year-old eagle caught in August had remained in the wintering area in Zambia (Tab. 4). The prevailing behaviour is still unclear.
Meyburg, B.-U., T. Belka, St. Danko, J. Wojciak, G. Heise, T. Blohm & H. Matthes (2005), Limicola 19: 153-179