THE BALD EAGLE OF NORTH AMERICA

USGS- Forest and Rangeland Ecosystem Science Center,

The bald eagle (Haliaeetus leucocephalus) is a large raptor, weighing up to 6 kg. It is found only in North America, mostly north of Mexico to the boreal forests of Canada and Alaska. For a large bird, it is comparatively widespread and common, but it has undergone some dramatic changes in population size, including reaching threatened or endangered status in much of its range. Bald eagles from many areas migrate between their breeding site and their winter area. Prey availability apparently is the major factor affecting their yearly movements. Fish is the most common food group, however, bald eagles also eat waterfowl, medium-sized mammals, and carrion. Nest sites, perches, and roosts usually are close to shallow lakes or streams, but in some areas bald eagles breed and winter along sea coasts. Large trees that rise above the adjacent treetops or are at the edges of the forest are commonly used to support the nest, and for perching and roosting. These trees provide a good vantage of the surrounding area and shelter from the sun and wind. In some areas bald eagles build their nests on cliffs or on the ground. Many bald eagles have been found to return to the same breeding and wintering areas year after year. The factors that caused population declines are human activities that alter the forest, reduce prey, disturb the birds' behavior, or cause their death. Environmental contamination from agricultural and industrial chemicals, lead poisoning, and other pollutants have been especially detrimental since the 1940's. The recovery of the bald eagle populations from endangered and threatened status is being accomplished largely by banning the use of some pesticides, protecting habitat, and making it unlawful to shoot or trap the birds.

STATUS OF BREEDING SSE AND WSE ON SAKHALIN AND AMUR.

Abstract not yet available

DISTRIBUTION OF THE STELLER'S SEA EAGLE IN THE MAGADAN AND NORTHERN KHABAROVSK DISTRICTS.

Steller's Sea Eagles numbers were recorded on the coastline of the northern part of the Sea of Okhotsk and along the rivers during surveys in the summers of 1991-1998. Every breeding and non-breeding territory was recorded and mapped. The breeding density in various regions is presented; location of areas with relatively high nesting density (hot-spots) is discussed. The eagle bred on the largest rivers, coastline and islands. The breeding range occupied a 100 km wide strip along the seacoast. Breeding of the eagles inland include large river valleys with high canopy forests. The inland border of the range coincide with the upper limits of the spawning grounds of the Pacific salmon. The upper-most nest on the Yama river is located in 89 km inland, whereas the most up-stream spawning ground is located 100 km inland. Areas of highest breeding density on the Chelomdja river cover 75% of spawning grounds of Pink salmon (Onkorhyncus gorbusha), 80% of Chum (O. keta) and about 100% of King salmon (O. kishuch). Of two known eagle territories located upstream from this densely populated area only one was occupied. It was located 211 km up-river, but only 91 km from the sea because the river paralleled the coastline for much of its length. There were some locations where the landscape appeared appropriate, but breeding was found to be absent. Several places have had high densities of the eagles. Total number of the eagles breeding in the surveyed territory is given. There is a negative trend in the overall numbers of breeding pairs in the last few years.

HABITAT PREFERENCES, FACTORS AFFECTING THE POPULATION DENSITY AND BREEDING SUCCESS OF THE STELLER'S SEA EAGLE (HALIAETUS PELAGICUS) ON THE NORTH-WEST OKHOTIA.

Distribution of the Steller's Sea Eagles was studied along the coastline of the northern part of the Sea of Okhotsk in surveys of 1991-1998. Every breeding territory was classified by a number of qualitative factors describing character of the coast, type of vegetation cover, various characteristics of the tidal zone and presence of human settlements. The PCA analysis revealed that the strongest environmental gradient in the breeding preferences of the Steller's Sea Eagle was associated with the type of vegetation (forest/creepy (might translate into 'creeping' pine) pine communities vs. no plant cover). The second axis was associated with the type of the coast (low coast vs. cliffs). Separate multiple regression analysis of the factors affecting breeding in the two types of the coastlines revealed that along low coast the eagles breed in higher densities at the coastal fragments with vast littoral zones, tolerate presence of human settlements and even ignored close neighborhood with humans. In contrast along cliffy coastline, the eagles preferred the places with proximity of sea-bird colonies, were not able to coexist with human settlements, including small occupied cabins for fishermen. This differences in habitat preferences and tolerance to humans was explained by a fundamental differences in hunting strategy at low coasts with vast littoral zones and at cliffy coasts with narrow littoral zone.

AIRSURVEYS OF BREEDING AND WINTERING STELLER'S SEA EAGLE AND WHITE -TAILED SEA EAGLE AT KAMCHATKA: SUCCESSES, FAILURES AND PERSPECTIVES

The systematic air-surveys of large birds of prey have begun on Kamchatka from the middle of 80th. For the surveys the various types of air crafts and various techniques and strategies were used, the disadvantages and advantages of which are discussed in the presentation. Now more than 350 SSE and more than 20 WSE nests are mapped, inspected more than 10 millions hectares, the data about preferred by raptors habitats are systematized. The most full inspected are the following areas: a valley of the river of Kamchatka, east coast of a peninsula from cape Lopatka up toUst-Kamchatsk, the river Elovka basin. If it is possible to recognize results of the surveys of the breeding birds as satisfactory and representative, almost it is not known about the status and distribution of wintering birds, that now is the most dangerous blank in our knowledge of raptors ecology. Therefore most urgent actions on monitoring a SSE population at Kamchatka is to organization of the global winter surveys.

DISTRIBUTION OF SSE AND WSE IN KURIL ISLAND

Abstract not yet available

STATUS OF WINTERING SSE AND WSE IN JAPAN

Abstract not yet available

ESTIMATION OF POPULATION TREND OF STELLER'S SEA EAGLES BY A COMPUTER SIMULATION

Mutsuyuki Ueta (Wild Bird Society of Japan)

Vladimir Masterov (Moscow University)

We estimated the population trend of Steller's Sea Eagles using a computer simulation. The simulation was conducted by an "individual based model". This model uses the mean probability of life history factors, such as breeding success and mortality rates, and a table of random numbers. The life expectancy of each individual was decided by the table and the probability. Based on the result of individuals, the trend of total population was constructed. This model is suitable to show the population trend for animals with a small population because the model includes the accidental fluctuations of probability, such as successive hatching of one of the sexes.The parameters used in this simulation model were; 1. the mean breeding success from the Amur River basin, and 2. mortality rate of each age that was estimated from the number of individual's age, surveyed in Hokkaido. The simulation showed that the population was stable or slowly decreasing. However, if the mortality rate increases only by 1 %, for instance, because of lead poisoning, the population will rapidly decline.

PROBLEM IN OIL POLLUTION FOR SSE POPULATION

Abstract not yet available

OIL SPILL EFFECT ON BALD EAGLE

Philip F. Schempf: Migratory Bird Management-Raptors U. S. Fish and Wildlife Service

Stratified random plot surveys and island censuses of adult bald eagles within PWS provided indices of population size. Indices of the adult population with a 90% confidence interval for 1982, 1989, 1990, 1991, and 1995 were 1662 ア 543, 2199 ア 405, 1935 ア 209, 2116 ア 243, and 2641 ア 376, respectively. There was no significant change in numbers from 1989 through 1991. However, because of the size of the confidence limits for the estimates during these years, we could not have detected the estimated magnitude of mortality caused by the spill. A deterministic life table model suggests that the PWS bald eagle population has an annual finite growth rate of 2%. We predicted that the bald eagle population returned to its pre-spill size by 1992.Survival of adults, sub-adults and first year eagles radio tagged in PWS 4-5 months after the spill was high, 88%, 95% and 71% respectively. We found no differences in survival between eagles exposed to oil and those we believed were not exposed to oil. Most mortality attributable to the spill likely occurred prior to the time we marked the eagles.

CONTAMINATION BY PERSISTENT ORGANOCHLORINES AND LEAD IN STELLER'S SEA EAGLE AND WHITE-TAILED SEA EAGLE FROM HOKKAIDO, JAPAN.

*Department of Environment Conservation, Ehime University, Tarumi 3-5-7, Matsuyama, Japan

$Shiretoko Museum, Honmachi 49, Shari, Hokkaido, Japan

Chronic exposure to man-made chemicals, particularly persistent organochlorines, in raptors has been associated with their reproductive impairment and population decrease. In addition, incidents of sub-lethal and lethal poisoning of lead in raptors through the ingestion of spent gunshot have also been reported. However, little information was available on the contaminant levels of steller's sea eagle (Haliaeetus pelagicus) and white-tailed sea eagle (Haliaeetus albicilla) from Hokkaido, Japan. Therefore, the objectives of this study were to determine the levels of toxic contaminants including polychlorinated biphenyls (PCBs), organochlorine pesticides and lead in these sea eagles, and to evaluate their ecotoxicological risk based on the concentration data. Steller's sea eagles and white-tailed sea eagles which were found dead or weakened and subsequently died in Hokkaido from 1986 to 1998 were used for the chemical analysis. All the eagles contained detectable amounts of PCBs,DDTs, hexachlorocyclohexane isomers, chlordane related compounds, and hexachlorobenzene. The highest concentrations of PCBs and DDTs in the breast muscles reached 18,000 and 17,000 ng/g on wet weight basis, respectively. Furthermore, non-ortho and mono-ortho substituted coplanar PCB congeners were also detected in the breast muscles, leading to 59.5 - 538 pg/g of 2,3,7,8-TCDD toxic equivalents (TEQs) derived from WHO toxic equivalence factors. Geographical distribution of PCB and DDT concentrations in the air and riverine/oceanic waters from the Far East showed that the contaminant levels in Khabarovsk and Magadan were much higher than those in Hokkaido and the North Pacific, suggesting a high potential of the east Siberian cities as the contamination source of these eagles. Residue levels of PCB and DDT in the breast muscles of steller's sea eagles were comparable to those of raptors collected after the 1980s from North America and Europe. The residue levels of PCBs and DDTs found in this study may elicit the induction of hepatic cytochrome P450 1A and eggshell thinning, respectively. More than 10,000 ng/g on dry weight basis of lead was found in the liver of some eagles. These residue levels exceeded the concentrations in other raptors previously diagnosed as lead-poisoned. Furthermore, one lead pellet was also found in the intestine of a steller's sea eagle which accumulated 140,000 ng/g on dry weight basis of lead in the liver. These results indicate that the eagles are subjected to secondary poisoning by lead when feeding on gunshot wildlife in Hokkaido.

LEAD POISONING OF STELLER'S AND WHITE-TAILED SEA EAGLES IN HOKKAIDO

In the winter 1997 to 1998, 15 Steller's and 3 White-tailed Sea Eagles were found dead in Hokkaido. Necropsies showed they had died from lead poisoning. In the mountain of Hokkaido, there are many dead deer killed by human hunting and eagles scavenge them. Eagles died from lead poisoning because they ingested bullets from deer.We analyzed how proportion of eagles that visited Hokkaido are using mountain area by using satellite-tracking data. Eighteen satellite-tracked eagles visited Hokkaido. Six of them used mountain area (75, 33, 26, 25, 9, and 5 days respectively). It suggests that a large proportion of the eagles wintering in Hokkaido are exposed to possible lead poisoning. Computer simulation results also suggest that lead poisoning will bring population decline. Recently, limiting of deer hunting got loose, and number of hunted deer is increasing. Number of exterminated deer is also increasing. There is possibility that the lead poisoning will increase, we are asking to change lead bullets to copper bullets.

CREATION OF ARTIFICIAL SSE POPULATION IN ZOO

Abstract not yet available

SSE mean Steller's Sea Eagle, and WSE mean White-tailed Sea Eagle