Imperial Eagle Workshop

The World Working Group on Birds of Prey and Owls

Imperial Eagle Workshop

 

William S. Clark (Oral)

Sequence of Plumages of the Eastern Imperial Eagle Aquila heliaca

Eastern Imperial Eagles, like other large eagles, attain adult plumage after four annual moults, resulting in four immature plumages. These are described and shown, beginning with juvenile and ending with adult plumage. Both of these are well known, described and depicted, but the plumages of the older three immatures are not. Moult is not completed during any annual cycle in this species, with fewer than half the body and covert feathers and not all of the flight feathers being replaced in any one year. Moult of the primaries (wave moult) and secondaries and the characters of new feathers are crucial in determining the sequence of plumages. I used museum specimens and photographs to determine each plumage. Second plumage eagles are much like juveniles, as their replacement feathers are nearly alike. New feathers of third plumage eagles are dark, adult-like, resulting in an overall mottled appearance. Fourth plumage eagles also appear mottled but are somewhat darker, differing from third plumage by having dark throats and legs, no white on the upper tail coverts, worn tips to secondaries that have dark tips, and new tail feathers adult-like. Fifth plumage is essentially adult; however, some individuals may show a few retained immature feathers.

2301 S, Whitehouse Circle, Harlingen, Texas 78550, USA.

Tel: + 1 956 364 0415  Email: raptours@tiagris.com

H. Mehmet Gursan1 and C. Can Bilgin2 (Oral)

Status of the Imperial Eagle Aquila heliaca in Turkey: Population Size, Threats and Conservation

The Eastern Imperial Eagle (Aquila heliaca) breeds locally but widely over most of northern Turkey. Recent records expand its known breeding range south into the Taurus ranges. Most pairs breed in highland (900-1500 m) habitats, usually near a water body and at the edge of a wooded patch with tall, mature Black Pine (Pinus nigra) trees. Nests may be close to human settlements and the birds are quite tolerant of human presence. A smaller population occupies lowlands (0-250 m) in northwestern Turkey and uses riverine habitats for nesting. For all of Turkey, a total breeding population of 42-180 pairs is estimated. This is several times above the latest figures (10-50 pairs: Heredia 1995; Kasparek & Bilgin 1996) and supports a downgrade of the species' national threat status from "Critically Endangered". Several Imperial Eagle nest sites coincide with IBAs, but large parts of the species' breeding range are unprotected. Direct persecution is rare, but scavenging habits and proximity to human settlements increase the chance of accidental poisoning. However, the main limiting factors seem to be a lack of suitable trees to nest in and a high mortality of immatures.

Department of Biology, Middle East Technical University, Ankara, 06531 Turkey

1. Tel: + 90-312-4427013  Fax: +90-312-4358645  Email: gursan@ada.net.tr

2. Tel: +90-312-2105017  Fax: +90-312-2101289  Email: cbilgin@metu.edu.tr

Todd Katzner, Evgeny Bragin, Steven Knick and Andrew Smith (Oral)

Dietary Response and Demography of Imperial Eagles (Aquila heliaca) in a Spatially Heterogeneous Environment in Pakistan

We evaluated determinants of diet in a large population of Imperial Eagles in Kazakhstan in the context of spatial and temporal variability in the prey environment, and assessed effects of this behavioral response on eagle demography. Eagle diet varied greatly within the population and tracked changes in prey populations in regions where nests were located. Thus, diet selection by eagles was not due to either ontogenetic imprinting on a specific prey type, or to competition between neighboring pairs for foraging resources. Instead, prey selection by eagles was best explained by a functional response, and diet of eagle pairs was closely linked to temporal and spatial availability of prey. Where eagles nested near a high-density prey resource they used that resource heavily; in other locations they used a broader prey base. There were demographic consequences of this predator-prey relationship. Specifically, spatial patterns in dietary specificity were positively associated with eagle nest density, breeding success and reproductive output. However, temporal patterns in dietary specificity were positively associated only with eagle reproductive output. These data show that functional responses by Imperial Eagles can develop due to spatial patterning in the environment, and that these responses can impact eagle reproduction.

Todd Katzner, Wildlife Conservation Society, Central Asia Program, 2300 Southern Boulevard, Bronx, NY 10460, USA.

Email: tkatzner@asu.edu

Evgeny Bragin, Science Department, Naurzum National Nature Reserve, Kustanay Oblast, Naurzumski Raijon, Dokuchaevka, 459730, KAZAKHSTAN

Steven Knick, USGS Forest and Rangeland Ecosystem Science Center, Snake River Field Station, 970 Lusk St., Boise, ID 83706, USA

Andrew Smith, Department of Biology, PO Box 871501, Arizona State University, Tempe, AZ 85287-1501, USA.

Simeon Angelov Marin, Ivelin Ivanov and Dilian Georgiev (Oral)

Food of the Imperial Eagle Aquila heliaca on Sakar Mountain and Dervent Heights, Bulgaria

This study was carried out by Green Balkans NGO team during the period 1999-2003. Observations of behaviour and collecting of bone, feather, skin and hair remains in the nests of four pairs of Imperial Eagles (one in Dervent Heights and four on Sakar Mountain) were made.

In the diet of the Imperial Eagle on Sakar Mountain, 10 species of mammals, 7 species of birds and 2 of reptiles were recorded. In Dervent Heights, 4 species of mammals, 3 of birds and 1 of reptiles were recorded. The main prey of the eagles in Sakar Mountain are Martin Erinaceus concolor and chicken Gallus g. domestica, but the main food source is animal carcasses. In Dervent Heights, the main prey and main food source is Lepuseuropaeus and Gallus g.domestica.

Capreolus capreolus, Canis familiaris, Capra hircus, Equus caballus, Oryctolagus cuniculus domesticus. Larus cachinans, Burchinus oedicnemus, Carduelis chloris, Falco tinnunculus, Cairina moschata, Ophisaurus apodus and Testudo graeca are reported for the first time in the food of the Imperial Eagle in Bulgaria.

Green Balkans, 160 Shesti Septemvri Str., Plovdiv, Bulgaria

Tel/Fax: +359 32 626 977  + 359 32 626 915  Email: greenbal@mbox.digsys.bg

Vojtech Mrlik (Poster)

Nest Site Selection in the Eastern Imperial Eagle (Aquila heliaca) in the North-west part of its Range

Observations were made in a forested mountain range at the north-west limit of the species' distribution during the years 1976-2002. Two breeding sites were controlled. At "A", five different pairs bred, occupying 11 different nest platforms (NP); at "B" two pairs occupied 18 NP. Selection of breeding habitat (BH) differed between both localities. At "A" the NP was situated in forest far from open places and settlements but close to the crest of the mountain at ca 450 m a.s.l.  At "B" it was also in forest, but closer to open spaces and settlements, and far from the mountain crest. ca  340 m a.s.l.

At "A" the NP was built in the forest wall in a marginal tree or max. 20 - 30  from the forest edge.  At "B" it was also often similar.  Only a few NPs were inside forest in a closed stand or in a solitary tree in a vast glade.

At "A", there is a slow trend in BH selection to move from higher to a lower altitudes a.s.l. and from the proximity of the crest to the periphery of the range and forest edge i.e. to the vicinity of open areas. The NP is now situated 2.7 km from fields. At "B" there is an evident shift from higher to lower altitudes and to the periphery of the forest edge, immediately near open areas. The type of NP placement has not changed at both localities.

These changes can be considered favourable since they indicate the ability of the eagles to adapt to human exploitation of the landscape. Under present conditions and provided the present trends last, the eagles could breed in future years at sites formerly avoided. Expansion of the breeding area further west or northwest could follow.

Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Kvetná 8, 603 65  Brno , Czech Republic

Email: mrlik@brno.nature.cz

Stoycho Stoychev, Ivelin Ivanov, Tzeno Petrov, Simeon Marin, (Oral)

Dimitar Demerdzhiev, Gradimir Gradev and Dobromir Domuschiev

Status of the Eastern Imperial Eagle (Aquila heliaca) in Bulgaria 1994 to 2002

In the period 1994-2002 research, monitoring and conservation activities on the Eastern Imperial eagle (Aquila heliaca) in Bulgaria were significantly increased. Fifteen nest sites were discovered. Most important breeding areas are located on the border with Turkey in the Sakar mountains (7 nests) and Strandja mountains - Dervent heights (5 nests). The majority of the nests (13) are located between 150 and 400 metres altitude. Most important nesting tree is the poplar -19 out of 25 nests discovered were in poplar ( Populs sp.) trees. During the 9 years of study 54 breeding attempts were surveyed out of which 35 were successful. The mean breeding success was 1 young per occupied nest and 1.54 chicks per successful nest. However, in the last 4 years (with increased number of monitored nests) the breeding success per occupied nest is between 0.83 and 0.9. The total Bulgarian population is estimated at 20-25 pairs. The adult birds were mainly sedentary spending the winter in the breeding territories. Three wintering and temporary settlement areas important for immature birds were identified. Main threats are: disturbance, cutting of poplar trees and abandonment of pastures.

Stoycho Stoychev, BSPB\BirdLife Bulgaria; Haskovo 6300, P.O.Box 130, BG

Tel/fax +359 38 62296  Email: sakarbg@mbox.digsys.bg   www.bspb.org

Tzeno Petrov, Dimitar Demerdzhiev BSPB\BirdLife Bulgaria; Sofia, 1111, P. O. Box, 50, BG

Tel/fax +359 2 722640  Email: bspb@bspb.org  www.bspb.org

Ivelin Ivanov, Simeon Marin, Gradimir Gradev

Green Balkans – Stara Zagora; 6000 Stara Zagora; ul. Car Ivan Shishman 76

Tel: +359 42 54071  email : greenbalsz@mbox.digsys.bg  www.greenbalkans.org

Dobromir Domuschiev Birds of Prey Protection Society; Sofia 1000, byl. Vasil Levski 40

Tel: +359 89 2135462  Email: dikata@mail.bg

 

 

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