First Symposium on Steller’s and White-tailed Sea Eagles in East Asia pp. 59-70, 2000
UETA, M. & MCGRADY, M.J. (eds) Wild Bird Society of Japan, Tokyo Japan

Habitat preferences and factors affecting population density and breeding
rate of Steller’s Sea Eagle on Northern Okhotia
Eugene POTAPOV1*, Irina UTEKHINA2 & Michael J. MCGRADY3#
1. Institute of Biological Problems of the North, Russian Academy of Sciences, Magadan 685000, Russia.
E-mail: Eugene_Potapov@compuserve.com
2. Magadan State Reserve, Portovaya str. 9, Magadan 685000, Russia. E-mail: zapoved@online.magadan.su
3.Raptor Research Center, Boise State University, 1910 University Drive, Boise, Idaho 83725-1516, USA.

Abstract. Distribution of Steller’s Sea Eagles Haliaetus pelagicus was studied along the coastline of
the northern part of the Sea of Okhotsk in surveys of 1991-1998. Every breeding territory wasclassified by a number of qualitative factors describing the character of the coast, type of vegetation
cover, various characteristics of the tidal zone, presence of human settlements and distance to thenearest river with salmon spawning grounds. PCA analysis revealed that the strongest environmental
gradient in the territorial preferences of Steller’s Sea Eagle was associated with the type of the coast(low coast vs. cliffs). The second axis was associated with the type of littoral zone (stone littoral vs. nolittoral). The third factor was associated with the type of vegetation (forest/creepy pine cover vs. noplant cover). Separate multiple regression analyses were conducted of the densities of territorial
pairs in the portions of coastline classified by factors with the strongest environmental gradientrevealed by the PCA. These showed that along low coast eagles breed in higher densities in coastal
fragments with vast littoral zones and were to lerant of human presence including commercial fishingactivities. In contrast, along cliffy coastline eagles preferred places in close proximity to sea-birdcolonies, and were not able to coexist with human settlements including cabins occupied by small
groups of fishermen. These differences in habitat preferences and tolerance of humans were explainedby fundamental differences in hunting strategy at low coasts with vast littoral zones and at cliffy
coasts with narrow littoral zone.

INTRODUCTION
Due to its limited distribution (a narrow strip around the coasts of the Sea of Okhotsk)
Steller’s Sea Eagles Haliaetus pelagicus was listed in the Red Data Book of the RussianFederation (Eliseev 1985) and in Appendix 2 (threatened species) of CITES. Although it is thelargest sea eagle in the world and an endemic to Russia, it has attracted little attention by raptor* Present address: School of Biological Sciences, Bristol University, Woodland Rd, Bristol, BS8 1UG UK.
# Present address: Institute for Wildlife Studies, P.O.Box 1104, Arcata, CA 95521, USA.

e-mail: mikemcgrady@hotmail.com

60
researchers. The numbers and distribution of Steller’s Sea Eagle have been studied in the
Kamchatka Peninsula (Lobkov 1986, Lobkov & Neifeldt 1986) and also in the northern
Primorie (Babenko et al. 1988, Masterov 1992). Both studies dealt with river or lake-dwelling
eagles, whereas the majority of the Steller’s Sea Eagles in the Northern Okhotia breed notalong the rivers, but along the sea coast (Potapov et al. 1995). Except for a few observations ofbreeding birds (Leito et al. 1991), there is no information on the distribution and numbers of
the Steller’s Sea Eagle in the coastal zone, and in particular in the north-western part of the
Okhotsk Sea, which has been suspected of being the stronghold of the species (Lobkov 1988).
We have made an effort to survey Steller’s Sea Eagle throughout the whole breeding range in
the northern part of the Okhotsk Sea (Potapov et al. 1995, 2000). This survey has been given
some urgency with plans for oil exploitation and other large-scale developments (e.g. increased
timber harvest, and increased fishery exploitation).
In this study our aims were:
1. To determine and classify habitats around nest-sites of Steller’s Sea Eagle breeding along thenorthern coast of the Okhotsk Sea.
2. To determine important factors affecting the density, occupancy and breeding rate ofSteller’s Sea Eagle in various coastline habitats.

METHODS
Steller’s Sea Eagles were counted during coastal surveys undertaken by motorboat and on
foot. The surveys were conducted June-August between 1991 and 1998. During these surveys
Steller’s Sea Eagle territories were identified, and, if possible, occupancy and reproductive
success were determined.
The area surveyed is shown in Figure 1 and Table 1. A total of 145 nests were recorded
along 1852 km of coastline.
The data were analyzed in the following steps:
1. To determine the most favorable combination of factors at coastal breeding habitats.
2. To classify the entire coastline according to the dominant environmental factors revealed by
the first step.
3. By use of stepwise multiple regression, identify factors with the most predictive power forthe density of territorial pairs of Steller’s Sea Eagle in various segments of coastline.
4. To identify factors with the most predictive power for the breeding rate in various segmentsof the coastline.

61

Fig. 1. The coastline and the rivers within the study area.

62
Table 1. Dates and portions of coastline surveyed.
Year
Months1993 26-28 May
24 Jul. - 3 Aug.
1994 11 Jun.
27 Jun. - 3 Aug.

Place
Koni peninsula, Umara Island
Koni peninsulaStaritskogo Peninsula
Coastline from Tauy estuary to the Shestakova
peninsula, portions of coastline from Yama
estuary to Taygonos peninsula

Means of surveys
Motor-boat, boat
Motor-boat, boat, on footMotor-boat
Motor-boat

10 Aug.
1995 24-25 Jun.
30 Jul.
13-14 Aug.
1996 31 May
2-10 Jul.
15-26 Jul.
7-12 Aug.
1997 3 Jun.
20 Jun., 10 Jul.
14-17 Jul.
1-4 Jul.
18-27 Jul.

Gertnera Bay coastline, Staritskogo peninsula
Rechnoy Bay - Umara island coastline
Staritskogo peninsula
Koni peninsula, Odyan Bay
Staritskogo peninsula
Odyan Bay, Koni peninsula
coastline from Tauy estuary to point Enken
Motykley Bay
Staritskogo peninsula
Odyan bay and Koni peninsula
Odyan Bay
Coastline from Tauy Estuary to Gavantsa cape
Coastline from Sheltinga bay to Okhotsk sea
port, Umara and Spafariev islands, Motykley
Bay

Motor-boat, on footMotor-boat
Motor-boat
Motor-boat
Motor-boat, on footMotor-boat, boat
Motor-boat, boat
Motor-boat, on footMotor-boat
Motor-boat
Motor-boat
Motor-boat
Motor-boat, boat

31 Jul., 1 Aug.
9-15 Aug.
22-30 Sep.
1998 2 Apr. - 18 May
12-17 Jun.
13 Jul.
14-18 Jul.
30-31 Jul.
1 Aug.
5 Aug.
9 Aug.
10 Aug.
12 Aug.

Odyan BayYama river
Chelomdja and Tauy rivers
Talan island
Lisyanskiy peninsulaStaritskiy peninsula, Nedorasumenia Island
Lisyanskiy Peninsula, Spafariev island
Umara island, Odyan Bay
Onatsevicha peninsula - Shestakova capetliLisyanskiy
peninsula
Lisyanskiy peninsula - Izmailova Cape
Talan Island, Khmitievskiy peninsula
Motykley Bay

Motor-boat
Motor-boat, rafting
rafting
on foot
on foot, motor-boat, boat
motor-boat
Motor-boat
Motor-boat
Motor-boat
Motor-boat
Motor-boat
Motor-boat
Motor-boat

Nest site habitat analysis
Habitats surrounding nest locations on the seacoast were described by a number ofqualitative factors:
1. character of the coast at the nest site:• cliffs• mountain slope• low coast)
2. type of vegetation:• Siberian Larch Larix daurica cover ("forest" thereafter)• Creepy Pine Pinus pimula cover

63• no vegetation, which in this study means either tundra or steppe-like communities,
wide gravel terrace with no bushes, or vast bog with no trees
3. type of littoral zone:• no littoral zone
• vast mud-stone littoral zone (with many stones emerging at low tide)• vast sandy stone littoral zone (more than 0.5 km wide),
4. other factors:• presence of sea-bird colonies in the proximity of the nest
• turbidity of sea water at the nest-site (turbid or transparent)• presence of rivers and their estuaries at the distance less than 2 km.
In combination these environmental factors were features of the coastal landscape fromwhich the eagles were able to choose. Stochastic environmental factors which acted
simultaneous on all closely situated nests (e.g. weather) were not considered in this study. The
data were subjected to principal component analysis (PCA) as a way of summarizing intercorrelated variables and identifying dominant environmental gradients of the coastline at
nest-sites. Nest-sites were then grouped according to the results of the ordination.
Territorial density analysis
The entire coastline surveyed was classified into segments of variable length according to
the factors identified by the PCA as dominant environmental gradients. The length of thesecoastline segments varied from 10 to 103 km. The density of the eagles territories (i.e.
territorial pairs per 10 km of coastline) was measured for every segment of the classified
coastline on a computer map (GISWare 1997).
The coastline segments classified according to dominant environmental factors were
described by environmental factors used for nest habitat description (above). In addition,
density of active fisheries (fishermen’s cabins or camps occupied all summer) per 10 km ofcoast, minimum distance from the segment to the nearest settlement, minimum distance to ariver or river estuary, number of rivers per 10 km of coastline in the segment, and theabundance of large stones on the littoral zone (many or few) were included in the analysis.
The densities of Steller’s Sea Eagle territories in various segments of the coastline wereclassified by these factors, and analysed separately for the coast types classified by the factors
determined by the PCA using multiple regression. This analysis was carried out in order todetermine the factors with the most predictive power for Steller’s Sea Eagle territory density
within a particular portion of coastline. Similar analysis was performed for occupancy (ratio of
the number of breeding pairs to the total number of territorial pairs in particular segment) andbreeding rate (average number of fledglings seen per nest for a particular segment). In the caseof occupancy only nests observed for a period of not less than 3 years were included in theanalysis. The average occupancy per nest was then calculated for particular portions ofcoastline.
The statistical analysis was performed using Statistica and StatView packages.

64

1
Stone littoral
Slope

Factor 2

Creepy pine

0

Cliff

ForestSand-stone littoral
River
Colonies
Mud-stone littoral
No plants
Water
Low coast

No littoral

-1
-1

0

1

Factor 1
Fig. 2. Principal component analysis (PCA) of variables measured at Steller’s Sea Eagle nest sites along thecoastline in north Okhotia.

RESULTS
Environmental patterns at nest sites
The strongest environmental gradient (Factor 1) was associated with the type of coastline(cliffy coasts vs. low coast) and explained 32% of the total variance in environmental data (Fig.
2). The ordination indicated the following gradation of the factors: cliffy coast, no littoral zone,
bird colonies, no plants, sand-stone littoral, turbid water, river/river estuary, mud stone littoral,
low-coast. The second dominant environmental gradient (Factor 2) was somewhat
asymmetrical and covered types of littoral (stone littoral vs. no littoral) and explained 15% of
the total variance (Fig. 2). The third environmental gradient included vegetation categories“forest - creepy pine - no plants” and explained 12% of the variance (Fig. 3).
Territorial density of the Steller’s Sea Eagles in various coastline types
Because the strongest environmental gradient determined by the PCA was “Low coast
type - Cliffs” (Fig. 2), the territorial densities in the portions of coastline classified by these two
characteristics were subjected to multiple regression analysis separately.
The multiple regression procedure (Table 2) included the factors "presence of sea-birdcolonies" and number of fisheries per 10 km of the coastline in the model, but left out otherfactors including presence of slope, presence of low coast portions, lack of littoral, presence ofstones at the littoral, lot or little stones at the littoral, turbid water, mud-stony littoral, number

65

ForestStone littoral
No littoral

Low coast

Cliffs

Water

Colonies

Mud-stone littoral
River

Slope

Factor 2
No plants

Factor 3

Creepy pine

Factor 1

Fig. 3. First three axes revealed by the principal component analysis of Steller’s Sea Eagle nest sites on the
coastline in north Okhotia.

of rivers/river estuaries per 10 km of the coastline. This revealed that in cliff-dominatedsegments the numbers of territorial Steller’s Sea Eagle pairs were negatively correlated with thenumber of fisheries and positively correlated with the number of sea bird colonies.
The stepwise regression model for the "low coast" included only the presence of vast
mud-stony littoral as a significant and positive factor. In such places eagle density did not show
any significant association with density of fisheries, density of rivers/estuaries, presence ofother types of littoral (stony, sandy or insignificant littoral), proximity to settlements, or thepresence of fishermen’s camps.
Occupancy and breeding rate of the Steller’s Sea Eagles in various coastline types
Average occupancy of territories (aggregating both coastline types) showed significant
and negative association with turbid waters (Table 3). Other factors showed no influence on
occupancy. Occupancy of nests analysed separately for low coast and cliffy coastline showedthat no recorded factors had significant association with occupancy.
Average number of fledglings per nest along particular coastline segments showedsignificant negative association with water turbidity (Fig. 3). Other recorded factors such astype of coastline, littoral, presence or absence of forests, settlements, or fisheries proved to havenon-significant correlation. The average number of fledglings per nest showed negative
association with the presence of many stones in the littoral zone in the segments of cliffy

66
Table 2. Results of multiple regression of factors influencing breeding density of
Steller's Sea Eagles on the sea coast. Separate analyses were performed for'Low coast" and "Cliffs" types of coastline. Variables rejected by the procedure for"Cliff Coastline" are: presence of slope, low coast, absence of littoral zone,
absence of stones at the littoral, many stones at littoral, presence of sandy-stone or
muddy-stone littoral, water turbidity, density or rivers/estuaries per 10 km andproximity to settlements. Rejected variables for "Low coast" are: presence of slope,absence of littoral zone, many stones at littoral, presence of sandy-stone littoral andfisheries/fishermen's camps density, proximity of settlements, density of rivers/
estuaries per 10 km of coastline.
R
0.62

R2
0.383

Cliff Coastline
Adj. R 2
0.322

SourceREGRESSIONRESIDUAL
TOTAL

DF
2
20
22

Analysis of VarianceSS
8.42
13.52721.954

Variable:
INTERCEPT
Sea-bird colonies
Fisheries/km

Variables in Equation
Coefficient
Std. Err.
0.663
1.259
0.452
-0.528
0.251

R
0.764

R2
0.585

Low coast
Adj. R 2
0.589

SourceREGRESSIONRESIDUAL
TOTAL

DF
1
9
10

Analysis of Variance
SS
5.889
4.177
10.066

Variable:
INTERCEPT
Muddy-stone littoral

Variables in Equation
Coefficient
Std. Err.
0.101
1.521
0.427

Residual
0.822
MS
4.21
0.676

F -test6.229

Std. Coeff.

F to Remove

0.488-0.368

7.746
4.401

Residual
0.681
MS
5.889
0.464

F -test12.68

Std. Coeff.

F to Remove

0.765

12.689coasts, and positive association with presence of vast mud-stone littoral in the low coast
segments (Table 4). Other factors, like presence of settlements, fisheries, sand-stone littoral andtype of vegetation, were found not to be significant by the step-wise regression procedure.

DISCUSSION
Steller’s Sea Eagle breeding sites in this study were grouped by the results of the PCA
ordination along three main environmental gradients: the type of coast (cliffs vs. low coast
associated with vast mud-stony littoral zone and turbid waters), type of littoral (stone littoral vs.
no littoral) and type of vegetation gradient (forest-creepy pine - no plant cover). The strongest
environmental gradient explaining most of the variation was the type of coast. Indeed, thebreeding ecology of the Steller’s Sea Eagle in these two categories of coastline was

67
Table 3. Results of multiple regression of factors influencing breeding performanceof coastal Steller's Sea Eagles. Coast types were aggregated.
R2
0.147

Occupancy, all coast types
Adj. R 2
0.127

SourceREGRESSIONRESIDUAL
TOTAL

DF
1
42
43

Analysis of Variance
SS
0.064
0.374
0.0438

Variable
INTERCEPT
Water turbidity

Coefficient
1-0.111

R
0.38

R
0.576

Variables in Equation
Std. Err.
0.041

Breeding rate, all coasts
R2
Adj. R 2
0.332
0.309

SourceREGRESSIONRESIDUAL
TOTAL

DF
1
29
30

Variable
INTERCEPT
Water turbidity

Coefficient
0.633-0.521Analysis of Variance
SS
2.049
4.119
6.169
Variables in Equation
Std. Err.
0.137

Residual
0.094
MS40.0640.009

F -test7.254

Std. Coeff.

F to Remove-0.383

7.254

Residual
0.376
MS
2.049
0.142

F -test14.425

Std. Coeff.

F to Remove-0.57614.425

Table 4. Results of multiple regression of factors influencing breeding performanceof coastal Steller's Sea Eagles. The analysis was performed separately for "Low coast"and "Cliffs" types of coastline.
R
0.506

R2
0.256

Breeding rate, cliffs
Adj. R 2
0.215

SourceREGRESSIONRESIDUAL
TOTAL

DF
1
18
19

Analysis of Variance
SS
1.046
3.039
4.85

Variable:
INTERCEPT
Many stones

Coefficient
0.762-0.479R
0.752

Variables in Equation
Std. Err.
0.192

Breeding rate, low coasts
R2
Adj. R 2
0.566
0.519

SourceREGRESSIONRESIDUAL
TOTAL

DF
1
9
10

Variable:
INTERCEPT
Mud-stony littoral

Coefficient
00.242

Analysis of Variance
SS
0.149
0.115
0.264
Variables in Equation
Std. Err.
0.07

Residual
0.411
MS
1.046
0.168

F -test:6.194

Std. Coeff.

F to Remove-0.506

6.194

MS
0.113
MS
0.149
0.013

F -test:11.768Std. Coeff.

F to Remove

0.752

11.768

68
fundamentally different. Eagles nesting on cliffs obtained most of their food from sea-birdcolonies, from the sea surface or at the surf-line, whereas eagles living on low coast fed
primarily on the vast littoral during low tide, taking small-size prey from puddles. Lobkov &Neifeldt (1986) mention that Steller’s Sea Eagles on the coastline of Kamchatka breed on cliffs
without a vast littoral zone or on the forested low coast of western Kamchatka, which at least
locally has a large littoral zone. Although they provide no quantitative data, their description
indicates a situation similar to the one we observed.
Lobkov (1986) noted that coastal Steller’s Sea Eagles on Kamchatka are associatedwith river estuaries. Distribution of nesting eagles in North Okhotia showed a different
pattern. Nesting eagles were found on the coastline far away from the river estuaries. The
PCA did not reveal the proximity of estuaries as an important factor in determining the densityof eagle territories
Simple hierarchical separation of nesting habitat into ‘low coast’ and ‘cliffs’ followed bymore detailed separation on the basis of habitat preferences shown by eagles would give astraightforward method for habitat classification in GIS models.
Different factors influenced the population depending upon whether the coast was
predominantly cliffs or low coast. For the cliffy coasts the most important factor was thepresence of sea-bird colonies, while a limiting factor was the density of active fishing camps.
Major parts of such coastlines had no estuaries of large, salmon-spawning rivers, and few
estuaries of small salmon runs, and as a result eagles fed primarily on sea birds and sea fish. In
addition, a small littoral zone meant that eagles had limited access to small sea fish that aretrapped in small puddles left at low tides. Active fisheries (which were mostly located at river
estuaries) with a lot of boats and people, kept eagles away from these places which have anabundance of pre-spawning salmon.
In contrast, along low coast with a vast littoral zone Steller’s Sea Eagles seem to ignore
people and perch on large rocks that emerge at low tide. Walking on these mud-flats isdifficult for humans, but the abundance of small shallow puddles with land-locked fish (mainly
flounders Pleuronectus sp. and sticklebacks Gastrosteus sp.) makes this habitat perfect foreagles. Within such habitat eagles might breed in close proximity to settlements, in spite ofnumerous cases of nest robbery and constant disturbance caused by motorboats at high tide. In
addition, the results of this study show that in the low coast type of habitat the number offledglings per nest is relatively high at nests which have access to vast littorals, whereas small
littoral and sandy-gravel beach predetermine low breeding rate. Strictly speaking, vast mudflats
are habitats where Steller’s Sea Eagles could share the coastline with humans with little
conflict, provided that direct human access to the nests is limited.
Occupancy seemed not to be determined by any of the environmental factors wemeasured, when the two types of coast were analysed separately. However, analysis of thewhole data set revealed a negative association between occupancy and high water turbidity. In
places with turbid waters occupancy was low or less stable in the years in which we made

69
observations.
Breeding rate was generally lower in low coast segments. In such habitats the best
performance was demonstrated by eagles breeding in proximity to vast mud-stony littoral. In
cliff coast segments breeding rate was best in segments with narrow littoral zone without big
boulders, suggesting small boulder size made it difficult to hunt at the surf line. It appears thatthe optimal size of boulder should be of the size of the eagle itself, and that the best beaches foreagles were covered in medium to large ball-shaped rocks with some shoals close to theshore that become exposed at low tide.
The results of this study suggest that it is important to limit human activity of eagles atfishing camps during the eagle breeding season in close proximity to cliff coast with denseseabird colonies, because it is there that eagles are most susceptible to disturbance. In theseareas the protection of nest sites only is not sufficient to ensure successful breeding. In
contrast, the protection of nest sites of eagles breeding close to mud flats is crucial to themaintenance of the breeding rate in such habitats.

CONCLUSIONS
1. Steller’s Sea Eagles habitats on the coast can be classified into two general landscapefeatures “cliffs” and “low coast” according to the results of the PCA ordination.
2. Territory density of Steller’s Sea Eagles in “cliffy” coastline was negatively correlatedwith numbers of fishing camps and positively correlated with the presence of sea-birdcolonies. In “low coast” the presence of vast mud-stony littoral was positively correlatedwith territory density.
3. There were no factors that we examined that affected occupancy of territories in either low
coast or cliffs, but high water turbidity was negatively correlated with occupancy for bothcoast types combined.
4. The highest number of fledglings per nest was along segments of low coast with vast mudstony littoral, and in cliffy coasts segments with little or no littoral without big boulders.
Generally the breeding rate along cliffy coast was higher than along ‘low coast’.

ACKNOWLEDGEMENTS
The research was funded by Chugach National Forest, Institute for Wildlife Studies (California),
WWF Russian Program Grant (1996), Institute of Biological Problems of the North (Russian Academy of
Sciences), Magadan State Reserve, Olle & Signhild Engkvists Stiftelser and WWF/Sweden (grants to EP,
1995-6), U.S. Department of Defense, and personal contributions. We are grateful for help in the field by
G. Bukaria, V. Mandehall, A.Ya. Kondratiev, B. Benter, M. Thompson, R. Shrank, A. Sovkov, Yu.
Balulis, Matvienko and D. Garcelon. We thank the Osprey Foundation for the 1996 endorsement grant to
IU and Avon Inflatables, Ltd. for the fine, inflatable motor-boat (1994-), which was key to the success ofthe surveys.

70

LITERATURE CITED
Babenko, V.G., Mzhulis, D.V., Ostapenko, V.A., Pererva, V.I. & Poyarkov, N.D. 1988. Distribution, numbers
and breeding ecology of the Steller’s Sea Eagle in the Lower Amur. In: Litvinenko, N.M. (ed). Rare
Birds of the Far East and Their Conservation. pp. 132-137. Nauka Publishers, Vladivostok. In
Russian.
Eliseev N.V. (ed). 1985. The Red Data Book of the Russian Federation -Animals-. Lesnaya promyshlennost’,
Moscow.
GISWare. 1997. 1000 Maps of Russia. Ingit, St. Petersburg.
Leito, A., Mand, R., Oja, T. & Paal, J. 1991. Ecosystem studies on the Koni Peninsula (Magadan Nature
Reserve). Paal, J. (ed). Tallinn: 179.
Lobkov, E.G. 1986. The Breeding Birds of Kamchatka. Nauka Publishers, Vladivostok. In Russian.
Lobkov, E.G. & Neifeldt, I.A. 1986. Distribution and biology of the Steller’s Sea Eagle (Haliaeetus pelagicus
Pall.). Proc. Zoological Institute, Academy of Science 150: 107-146. In Russian.
Lobkov, E.G. 1988. Results of the first international winter survey of the Steller’s Sea Eagle in Kamchatka
1985/1986. In: Litvinenko, N.M. (ed). Rare Birds of the Far East and Their Conservation. pp 88-90.
Nauka Publishers, Vladivostok. In Russian.
Masterov, V.V. 1992. Ecological energetics and interspecific relationship of Haliaetus albicilla and H.
pelagicus in the Lower Amur and Sakhalin. PhD. thesis, Moscow University, Moscow. In Russian.
Potapov, E.R., Utekhina, I.G. & McGrady, M. 1995. The Steller’s Sea Eagle in Magadan District: an example
of international co-operation. Raptor-link 3(2): 1-4.
Potapov, E.R., Utekhina, I.G. & McGrady, M. 2000. Steller’s Sea Eagle in the Magadan District and in the
North of the Khabarovsk District. In: Ueta, M & McGrady, M.J. (eds). First Symposium on the
Steller’s and White-tailed Sea Eagles in East Asia. pp. 29-44. Wild Bird Society of Japan, Tokyo.