<abstract xmlns="http://www.w3.org/1999/xhtml"><p>An unexpected expansion of the Eastern Imperial Eagle (Aquila heliaca) population was observed in East Hungary from mountainous habitat into lowlands from 1989 onwards. Here the population markedly increased from 2 to 59 breeding pairs by 2006, while the mountainous population remained more or less stable with 12-17 breeding pairs. At the beginning of the expansion process the nearest neighbour distances between breeding pairs was lower in the mountains than in the lowlands, but presently they are similar, indicating a saturation process in the lowland areas, but no density dependence was revealed on breeding success. During the study period a higher ratio of non-adult pairs was observed in the lowland territories (49%) than in the mountains (22%). We found that both age and habitat influenced breeding success. We also found that age-effect was significant on success rate (i.e. the ratio of pairs that produce at least one chick), while habitat-effect was more evident on fledging success (i.e. the number of fledglings per productive pair). The overall productivity (i.e. number of fledglings per breeding pair) was affected primarily by the age of the pairs, but the interaction term of age x habitat also was significant. We suppose that better feeding possibilities (closer foraging areas and larger prey density) could explain the higher fledging success in the lowlands. We also predicted that pairs inhabiting agricultural areas in the lowlands will have a reduced success rate due to higher human disturbance, together with an age effect of the breeding pairs. Therefore adult pairs probably can habituate to disturbance even if it happens in the close vicinity of their nesting sites.</p></abstract>

An unexpected expansion of the Eastern Imperial Eagle (Aquila heliaca) population was observed in East Hungary from mountainous habitat into lowlands from 1989 onwards. Here the population markedly increased from 2 to 59 breeding pairs by 2006, while the mountainous population remained more or less stable with 12-17 breeding pairs. At the beginning of the expansion process the nearest neighbour distances between breeding pairs was lower in the mountains than in the lowlands, but presently they are similar, indicating a saturation process in the lowland areas, but no density dependence was revealed on breeding success. During the study period a higher ratio of non-adult pairs was observed in the lowland territories (49%) than in the mountains (22%). We found that both age and habitat influenced breeding success. We also found that age-effect was significant on success rate (i.e. the ratio of pairs that produce at least one chick), while habitat-effect was more evident on fledging success (i.e. the number of fledglings per productive pair). The overall productivity (i.e. number of fledglings per breeding pair) was affected primarily by the age of the pairs, but the interaction term of age x habitat also was significant. We suppose that better feeding possibilities (closer foraging areas and larger prey density) could explain the higher fledging success in the lowlands. We also predicted that pairs inhabiting agricultural areas in the lowlands will have a reduced success rate due to higher human disturbance, together with an age effect of the breeding pairs. Therefore adult pairs probably can habituate to disturbance even if it happens in the close vicinity of their nesting sites.

Simultaneous Effect Of Habitat And Age On Reproductive Success Of Imperial Eagles (Aquila Heliaca) In Hungary

Magyar Madártani és Természetvédelmi Egyesület (MME BirdLife Hungary), 1121 Budapest, Költő utca 21., Hungary,

Magyar Madártani és Természetvédelmi Egyesület (MME BirdLife Hungary), 1121 Budapest, Költő utca 21., Hungary

MTA-ELTE-MTM Ecology Research Group, c/o Biological Institute, Eötvös Loránd University, 1117 Budapest, Pázmány Péter sétány 1/C., Hungary and Hungarian Natural History Museum, 1088 Budapest, Baross utca 13., Hungary

Ornis Hungarica

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

An unexpected expansion of the Eastern Imperial Eagle (Aquila heliaca) population was observed in East Hungary from mountainous habitat into lowlands from 1989...

Simultaneous Effect Of Habitat And Age On Reproductive Success Of Imperial Eagles (Aquila Heliaca) In Hungary

Published Online: Dec 04, 2014

Page range: 57 - 68

DOI: https://doi.org/10.2478/orhu-2014-0011

Keywords
population dynamics, breeding success, territory, raptor

© 2014

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Simultaneous Effect Of Habitat And Age On Reproductive Success Of Imperial Eagles (Aquila Heliaca) In Hungary

Published Online: Dec 04, 2014

Page range: 57 - 68

DOI: https://doi.org/10.2478/orhu-2014-0011

Keywordspopulation dynamics, breeding success, territory, raptor

© 2014

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
population dynamics, breeding success, territory, raptor