First Symposium on Steller’s and White-tailed Sea Eagles in East Asia pp. 29-44, 2000
UETA, M. & MCGRADY, M.J. (eds) ©Wild Bird Society of Japan, Tokyo Japan

Steller’s Sea Eagle in Magadan District and in the North of
Khabarovsk District
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. The numbers of Steller’s Sea Eagles Haliaeetus peragicus were recorded on the coastline
and rivers of the northern part of the Sea of Okhotsk during surveys in the summers of 1991-1998, andduring relatively small scale surveys in 1999. A total of 1852 km of coastline (165 nests) and 1148 kmof rivers (109 nests) were surveyed. The breeding range was within a 100 km wide strip along theseacoast. Inland eagle breeding areas include large river valleys with high canopy forests where tree
nests were constructed. On coasts eagles nested on both trees and cliffs. The inland border of thebreeding range coincided with the upper limits of the spawning grounds of Pacific salmon. There weresome locations where the landscape appeared appropriate, but breeding did not occur. The average
breeding density varied from 0.7 pairs / 10 km on rivers to 0.9 pairs / 10 km on the coast. Several
places had high densities of breeding eagles. Percentage of coastal breeding pairs, as well as thepercentage of breeding pairs in both coastal and river habitats combined showed a decline over the
study period. Thirty-nine percent of occupied nests on rivers produced chicks, as did 65% of thecoastal nests (overall mean 53%). Average brood size was stable over years at around 1.23 chicks /successful nest (1.4 on the coast and 1.1 on rivers). Sampled breeding success was 70% (N = 31) andwas not different between riverine and coastal habitats. The total number of chicks fledged per
territorial pair declined from 0.8 in 1993 to 0.5 in 1998.

INTRODUCTION
The Steller’s Sea Eagle Haliaeetus peragicus is a CITES Appendix II species (Eliseev
1985), but little detail is known of its distribution and numbers throughout most of its range.
Counts have been made in some parts of the breeding range including Kamchatka (Lobkov &Neifeldt 1986) and Lower Amur (Babenko et al. 1988), and the size of the population has been
estimated from winter surveys (Nakagawa et al. 1987). No accurate and up-to-date counts of* 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

30
Steller’s Sea Eagles in the Northern Okhotia have been made and little information on breedingstatistics has been published.
Notes on the history
The species was first found in the 1760s when the great Northern Expeditions reached thecoast of the Sea of Okhotsk with Georg Steller employed as a collector. The scientificdescription of the species was made by Pallas (1811-1814) and was based on a specimen
collected by Steller from “the islands between Kamchatka and American continent” (Stepanyan
1990). In 1789 the Tauy Bay was visited by C.H. Merck, a member of the Billings expedition.
He mentioned the Steller’s Sea Eagle as a common species around the Tauisk settlement(Stresemann 1948). In 1896-97 the environs around Okhotsk and the Gizhiga tundra werevisited by collector N.V. Slynin, whose collection, including some Steller’s Sea Eagles
specimens, was processed by Menzbier (Menzbier 1900). N. Buxton, who collected specimens
around the Gizhiga settlement, observed Steller’s Sea Eagles several times in summer and shot
one immature male in October (Allen 1905). The doctor of the hydrographical expedition
aboard the RS "Okhotsk" visited Eirineyskaya Bay of the Lisyanskiy peninsula, and mentionedthat there were many sea eagles building nests on top of larch trees and pinnacles (Buturlin1911). Kharitonov (1915) mentioned the Steller’s Sea Eagle as a common species in theareas close to Okhotsk. Dementiev (1940) noted that Steller’s Sea Eagles were breeding in theOla bay, where in 1939 three nestlings were taken and subsequently delivered to the Moscow
Zoo.
Kishinskiy (1968) encountered the species breeding in the Bulun, Takor and Topolevka
rivers (Shelikhova Bay). He also mentioned at least 3 pairs on the 30 km of coastline bordering
the Babushkina Bay. Lobkov & Neifeldt (1986) referred to personal communications with
A.V. Andreev, A.V. Krechmar, Zheleznov and Roslyakov that stated that the Steller’s Sea
Eagle is absent from the Taygonos peninsula, and defined the range of the eagle as a continuous
strip along the coast from the Gizhiga River west to Okhota and Kukhtuy Rivers and probably
up to the Uda river in the Shantar Bay. Some preliminary data were collected from the Kavaand Chelomdja Rivers by S.V. Tarkhov of the Magadan State Reserve (Pererva et al. 1992).
For details of occupancy and breeding success we present data from our own surveys, andinclude data from other sources (Pererva et al. 1992 (Kava and Chelomdja rivers); Leito et al.
1991 (Koni peninsula), Tarkov pers. comm. (Kava and Chelomdja rivers)) to provide acomplete picture.

MATERIALS, METHODS AND REGIONS SURVEYED
Steller’s Sea Eagles were counted during coastal and riverine surveys conducted by
motorboat, on foot, and by air (Utekhina 1995). Most of the riverine systems were surveyed byair; coastal surveys were made from a small inflatable motorboat accompanied by a seaworthy
ship that acted as a base. The surveys were conducted between June and August 1991 through31
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

Odyan BayYama river

Motor-boat
Motor-boat, rafting

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

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

1998 with a small-scale survey in 1999, mostly in the Magadan Reserve. All calculations on
the occupancy, breeding rate and reproductive success were made on the basis of 1991-1998
results. The dates and areas of surveys are given in Table 1 and Figure 1. The surveyed
regions were within the Magadan and Khabarovsk (Khabarovsk Kray) Administrative Districts.
During the surveys Steller’s Sea Eagle territories were identified, and, if possible,
occupancy and reproductive success were determined. Territories were identified by thepresence of nests. A territory was considered occupied if at least one non-juvenile eagle waspresent. Breeding pairs were those that produced at least one egg, and breeding success wasachieved when at least one chick was produced. The ratio of successful nests to the number ofbreeding attempts is defined as ‘breeding success’ in this study. We also recorded encounterswith immature eagles; these were often not associated with a particular territory.

32

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

33
The density of breeding eagles was calculated as the number of pairs / 10 km of coastline
or 10 km of the main stretch of the river. The density of immature eagles is the maximum
number of the immatures observed in a single run along a portion of the coastline or river inany year per 10 km of the coastline or river stretch.

RESULTS AND DISCUSSION
Overall distribution of the Steller’s Sea Eagle in the region
In the northern Sea of Okhotsk Steller’s Sea Eagles breed along the coastline (including
most of the larger islands) and along the lower reaches of large rivers (Fig. 2). Distribution ofbreeding eagles was uneven, with large gaps along some portions of coastline and rivers, anddense clusters of nests along others. In some places eagles nested close to human settlements,
but in other areas where the landscape appeared otherwise appropriate, breeding was absent
close to settlements and roads. Several areas of high breeding density displayed stablebreeding rates over years.
Distribution of the immature eagles was also uneven (Fig. 3). Densities of immatures insome areas was lower than densities of territorial pairs in the same areas. In fact, it appears thatimmatures may avoid areas with high breeding densities. In any given breeding season, thenumber of immatures we observed did not exceed 45 individuals.
Coastal nests
Topography along the coast appeared to be linked to local breeding density. Most areasof high density were on south-facing portions of coastline, portions of the coast where there
were cliffs and in low-lying areas on bays like Motykley and Siglan. Areas of high nesting
density nesting areas are located on the Lisyansky and Koni peninsulas and on the coastal cliffs
between the Tauy estuary and Uski Bay. Low coastal areas with wide beaches, such as isfound between the Arman’ and Tauy rivers, and between the Shilki , Urak, and Yama estuaries
had no breeding pairs.
We saw no indication of breeding nor did we observe solitary eagles on the Tayganos
peninsula during incomplete surveys of the area (Potapov et al. 1995). This is consistent with
reports by other observers (Lobkov & Neifeldt 1986, Matvienko pers. comm.). No eagles were
found on the Tainochin Cape. Fragmentary surveys along the coastline between the Gizhiga
estuary and Yama lagoon indicated only a few territorial pairs the Nayakhan river estuary andat the capes at Storozhevoy, Ostrovnoy, and Tavatum consistent with Matvienko (pers. comm).
No eagles breed from Shilki Bay to the Enken cape (see Fig. 2 and Table 2). In Shelikhova
Bay Steller’s Sea Eagle is scarce (Dementiev 1940, Matvienko pers. comm). The most
northerly territorial pair observed during our surveys was in Pestraya Dresva Bay (Potapov etal. 1995), however there is some reliable information that it breeds in the more northerly
locations in Nayakhan Bay (Matvienko pers. comm.).
Although some eagles fed mostly on sea birds (and these pairs usually reared more than

34

Fig. 2. Density of territorial Steller’s Sea Eagles pairs in surveyed areas (pairs per 10 km coastline or 10 km orriver stretch).

35

Fig. 3. Density of immature eagles (individuals per 10 km coastline or 10 km or river stretch).

36
Table 2. Inventory of the Steller's Sea Eagle in coastal areas of Northern Okhotia. L: length ofthe coastline surveyed, N: number of territorial pairs recorded, N / 10 km: number ofterritorial pairs per 10 km of the coastline.
Portion of the coastline
Taygonos peninsula (Zubchatiy Cape - Povorotnyi Cape)
Cape Tainochin - Cape Varkhalamsky
Cape Glinyaniy - Cape Granitniy (Topolovka estuary)
Cape Storozhevoy
Nayakhan Bay, Nayakhan estuary
Tavatum Cape
Pestraya Dresva Bay
Cape Ostrovnoy
Iret' Cape
Yama lagoon and coastline up to Yapon Cape
Cape Yapon - Cape Pyagina
Cape Sredniy - Cape Tolstiy
Kekurniy Bay
Babushkina Bay
Evreinova Cape

L N N / 10 km
Comments
110 0
0.00
45 0
0.00
30 0
0.00
20 1
0.50
Matvienko pers. comm.
20 1
0.50
Matvienko pers. comm.
30 2
0.60
Matvienko pers. comm.
20 1
0.50
30 1
0.30
18 1
0.55
110 0
0.00
37 1
0.27
30 1
0.33
36 0
0.00
57 5
0.84
20 2
1.00

Siglan Bay
Kiras Cape - Burgauli estuary
Berezovka estuary - Taran capeZavialova island
Taran Cape - Mekovodnaya Meteo stn
Mekovodnaya Meteo stn - Naidenaya bay
Beringa Cape - Rechnoy Cape
Rechnoy Cape - Ola lagoon
Uira spit - Dukcha estuary
Staritskogo peninsula
Nagaevo Bay
Ostrovnoy Cape - Arman Mts.
Nedorasumenia Isl.
Arman estuary - Tauy estuary
Shelikan Isl.
Tauy estuary - Amakhton capeAmakhton Bay - Motykley Cape
Motykley Bay
Talan island
Spafariev island
Stanukevicha Cape - Oira estuary
Bystrukha river - Ushki Bay

22
57
58
58
77
38
18
25
23
39
25
19
7
66
0.8
22
32
49
6
32
102
113

5
11
6
2
13
7
3
1
1
3
0
1
1
0
1
5
7
12
2
3
25
20

2.27
1.92
1.03
0.34
1.68
1.84
1.66
0.40
0.43
0.77
0.00
0.53
1.42
0.00
1.25
2.27
2.19
2.44
3.33
0.93
2.45
1.77

Ketlaski estuary - Kulku Bay
Kulky Bay - Kulku estuary
Kulku estuary - E. Duga capeW. Duga - E. Duga
W. Duga - Eirineiysky Cape
Eirineiysky cape - Kekurniy Cape
Kekurniy Cape - Shilki estuary
Shilki estuary - Urak estuary
Kynnerkan estuary - Ottynda estuary
Ottynda estuary - Enken Cape

14
19
13
1.5
22
45
24
146
22
113

1
2
0
0
9
8
3
0
1
0

0.71
1.05
0.00
0.00
4.09
1.78
1.25
0.00
0.45
0.00

First breeding in 1999
7 pairs in 1994
8 pairs in 1994
1 or 0 pairs in some years

19 in some years

7 in some years

37
one chick in most years), the presence of a seabird colony did not ensure the presence of eagles.
No eagles were found on the Tainochin cape, despite the presence of a massive colony of theThick- and Thin-billed Murres Uria aalge and lomvia. Nor did Steller’s Sea Eagle breed nearanother large seabird colony on the Yamskie Islands. However, the small island of Talan andits large colony of seabirds normally accommodates two pairs of the eagles. The relatively
large islands of Spafarieva and Zavialova have breeding eagles, but neither support massive sea
birds colonies.
The total number of territorial pairs on the seacoasts, including estimated pairs andthree pairs nesting on islands with sea-bird colonies is 165. Along the 1852 km of the coast
surveyed the average breeding density was 0.9 pairs per 10 km of coastline, but this varied
between 0 and 4.1 pairs / 10km of coast.
River nests
The Yama, Chelomdja, Kava, Tauy, Inya, Ulbeya, Kukhtuy, Okhota, and Ulbeya Rivers
supported the highest densities of nests on rivers (Fig. 2, Table 3). Steller’s Sea Eagle iscommon on the rivers that drain into Shelikhova Bay (Dementiev 1940, Matvienko pers.
comm). From Shilki Bay to the Enken Cape (see Fig. 2 and Table 2) eagles breed only along
the lower stretches of the larger rivers. Steller’s Sea Eagles were absent on the Ola,
Lankovaya, Arman’ and Khasyn Rivers. Tauy River estuary supports nesting pairs, whereas nonests were found on the estuaries of the Yama, Arman’, Yana, Inya, Ulbeya, Kukhtuy, orOkhota Rivers. Human disturbance is the likely cause of the absence of the Steller’s Sea
Eagles along the Ola and Arman’ Rivers and the lower reaches of the Yama and Okhota.
Inland breeding of eagles was observed in large-river valleys with high canopy forests.
Where the course of the river was, in general, perpendicular to the coast, the inland limit of thebreeding range coincided with the upper limits of the spawning grounds of the Pacific salmon.
The upper-most nest on the Yama River was located 89 km inland, whereas the most up-stream
spawning ground is located at the river confluence with the tributary Tob about 100 km
inland. Areas of highest breeding density on the Chelomdja River cover 75% of spawning
grounds of Pink Salmon Oncorhynchus gorbuscha, 80% of that of Chum O. keta and about
100% of that of King Salmon O. kishuch.
Eagles breeding on rivers that run parallel to the coast may live above the level of the
major spawning grounds. Two eagle territories are located upstream from the area of higheagle breeding density on of the Kava River. In the year this area was visited, only one
territory 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.
The total length of the rivers surveyed was 1148 km. The average density was 0.7
territorial pairs per 10 km of river, with variation between 0 and 2.72 pairs per 10 km. A totalof 109 territorial pairs have been recorded along the rivers surveyed.

38
Table 3. Steller's Sea Eagle breeding density along the rivers of Northern Okhotia.
L: Length of river surveyed(km); N: Number of territories; D: Distance between nests (km);DENS: Density (pairs / 10 km).
River
Gizhiga
Garmanda
NayakhanTavatum

L
0
0
0

N

D

4
0

DENS

0

Shirokaya

00

TumanyKalaloga
Topolovka
Bulun
Malkachan
Yama from sources to Alut
tributary
Yama from Alut tributary to
Khalanchiga
Khalanchiga
SivuchSiglanBurgauli
KhindyaKalkutyOla
Lankovaya
Arman'
KhasynOira
Yana
OmunkaTauy
Chelomdja (up to Khuren river)
Chelomdja (From Khuren to
Burgagylkan)
MoldotKava (From Ikrimun river to
Tauy)
Kava from sources to Ikrimun
river
ChukchaOmylenUsulu
Motykleyka
Ukluchan`
Kulku
Inya
UlbeyaB. Marekan
Kukhtuy
Okhota

0
0
0
0
35
80

1
1
1
4
0

1.14
0.00

0

67

10

1.49

6.4 (1.8-15.8)

20
20
25
15
14
12
45
25
80
35
20
90
10
74
84
59

1
2
5
1
1
1
0
0
0
0
1
3
1
6
17
1

0.50
1.00
2.00
0.67
0.71
0.83
0.00
0.00
0.00
0.00
0.50
0.33
0.81
2.02
0.17

16
92

0
9

0.00
0.98

120

5

0.41

14
16
22
30
10
12
35
33
12
35
28

1
1
1
1
1
1
5
9
0
4
3

0.71
0.63
0.45
0.33
1.00
0.83
1.42
2.72
0.00
1.14
1.07

10
22
16

1
4
2

1.00
1.81
1.25

Urak
Ul'ya
Kynnerkan

Comments
Probably breeding
Probably breeding
Matvienko, pers. comm.
Eagles have been noted, no breeding
recorded. Matvienko, pers. comm.
Eagles have been noted, no breeding
recorded. Matvienko, pers. comm.
1996, questionnaire
1997, questionnaire
1997, questionnaire
Possibly breeding, Kishinskiy 1968.

Data 1998
3.7 (1.5-6.0)

No breeding

Data 1996
Data 1986
questionnaire
7.8 (2.6-12.0) 4 territories in 1998
5.4 (2.5-13.0)

7.5 (3.8-17.3)
Questionnaire

Data 1994
One old nest

3.4 (1.5-6.5)
5.8 (4.5-7.0)
Not complete information due tocomplexity of river system
3 (2.0-4.6)

3960

1 Chick
2 Chicks
40

3 Chicks

20

0

River

Coast
Fig. 4. Steller’s Sea Eagle brood sizes in coastal and riverine nests.
1.8

River

1.6

Coast
Average

1.4
1.2
1
0.8
1992

1993

1994

1995

1996

1997

1998

Year
Fig. 5. Steller’s Sea Eagle breeding success (number of chicks per breeding pair).

Breeding rate
Brood size
Average brood size for coastal nesting eagles was 1.4 ± 0.31 (SD), and 1.1 ± 0.15 forriver nesting eagles. The distribution of the number of chicks in the broods was also different
between the coastal and river nests (Fig. 4). Coastal broods more often had broods of two andthree . Three chicks broods were observed only along the coast. The difference between riverand coastal brood sizes was statistically significant (T-test assuming unequal variances, T=-3.23, P = 0.001, Nriver = 62, Ncoast = 87).
Brood size was relatively stable (see Fig. 5) over the years and fluctuated between 0.9 and1.2 chicks/nest along the rivers (average 1.1) and between 1.3 and 1.6 in coastal nests (average
1.4). The mean annual brood size for all nests fluctuated between 1.2 and 1.3 chicks / nest,
with the average in all years of 1.23 chicks/nest. There was no significant trend over the years
in the fluctuation of brood size in the river nests (R2 = 0.36, F = 2.90, P = 0.15), coastal nests(R2 = 0.36, F = 1.74, P = 0.27), or in the two habitats combined (R2 = 0.22, F = 1.45, P = 0.28).

40
100

River
Coast

80

Average

60
40
20
0
1991

1992

1993

1994

1995

1996

1997

1998

Year
Fig. 6. Ratio of breeding pairs to the total number of territorial pairs of Steller’s Sea Eagles (Occupancy).

Occupancy
The proportion of occupied territories in which breeding occurred was lowest in riverine
territories (average 39%), and highest in the territories along the coasts (65%). The overall
average was 53%.
There was a highly significant negative trend across years (Fig. 6) in the percentage of thepairs taking part in breeding in coastal areas (regression coefficient -9.98, R2 = 0.84, F =27.2, P = 0.006). There was no significant regression trend found in the occupancy of the rivernests, but the trend of occupancy across both habitats was negative and significant (regression
coefficient -6.68, R2 = 0.83, F = 20.4, P = 0.01). The overall percentage of pairs participatingin breeding declined from 70 to 35% in all monitored territories, and from 83 to 44% forcoastal territories. The occupancy of the river territories fluctuated between 12.5 (1997) and
66.7% (1993).
Breeding success and overall breeding rate
The average breeding success was difficult to estimate since many nests were too remote
to be visited several times per season. Nevertheless, the breeding success at a proportion ofnests could be determined and used to estimate overall success. Breeding success was 80 ±25 % (N = 35) in the coast nests and 70 ± 37% (N = 22) in the river nests. The overall
reproductive success was 70 ± 31% (N = 57) for both coastal and river nests combined.
Breeding success fluctuated from 62 to 88% (Fig. 7). There was no statistical difference in
breeding success between years (Friedman χ2 = 1.33, P = 0.93). Breeding success in the
coastal nests did not show significant correlation with the fluctuations of the success in the rivernests (R2 = 0.36, F = 1.74, P = 0.27).
The total number of chicks fledged per territorial pair fluctuated between 0.1 and 0.8(average 0.4) in river nests and between 0.5 and 1.2 (average 0.7) for coastal nests. The
average fluctuation for all nests was between 0.3 and 0.8 in different years, with the average for

41
100

11
10

75

4

11

1996

1997

16

4

50
25
0
1993

1994

1995

1998

Year
Fig. 7. Steller’s Sea Eagle breeding success. Numbers indicate sample size.

River

1

Coast
Average

0.5

0
1992

1993

1994

1995

1996

1997

1998

Year
Fig. 8. Number of Steller’s Sea Eagle chicks fledged per territorial pair.

all nests in all years being 0.55 fledglings per territorial pair (Fig. 8).
During the study period there was a significant decline in the breeding rate of eagles
living on the coastline (Regression coefficient = -3.7, R2 = 0.77, F = 10.1, P = 0.05), but there
was no significant change observed on rivers (Regression coefficient = -5.4, R2 = 0.31, F =2.27, P = 0.19). The overall number of chicks fledged per territorial pair for both river andcoastal nests combined showed a significant decline over the years of the study (Regression
coefficient = -9.42, R2 = 0.89, F = 32.20, P = 0.005).
Total number of Steller’s Sea Eagle in North Okhotia and estimation of the breeding
performance of the population
Over the years we surveyed the whole of the coast between Enken Cape (57°43’54”N
140°18’04”E) and Povorotniy Cape, Taigonos Penisula (60°43’11”N 160°47’46”E). We also
visited all large rivers in the area up to a point where they became unnavigable by our small
craft or up to the upper-most salmon spawning grounds. We estimate that we covered 50% of
small creeks and 100% or large rivers (See Table 2). We covered 85% of the coastline, theother 15% was visited by local rangers and fish inspectors who can reliably identify Steller’s

42
Sea Eagles and their nests. Because we had no detailed habitat information upon which to base
extrapolation, our estimations of population size and breeding performance represent ‘best
guesses’, rather than statistically reliable estimates. Our estimations were made by dividing thesurveyed area into three habitat types: coastal cliff, coastal non-cliff, and riverine. We usedmean densities of nesting territories, mean percentage of occupied territories, and mean values
for reproductive success from these habitats in surveyed areas to crudely estimate likely
values for areas we did not survey.
The number of recorded pairs of Steller’s Sea Eagles in all years of the study in the North
Okhotia was165 on the seacoast and 109 on rivers or a total of 274 pairs. Simple extrapolationfrom data on occupancy and breeding where surveys have been extensive suggests a total of
370 (± 2%) territorial pairs, or 200 breeding pairs for North Okhotia. On average theseproduce 1.24 chicks per brood, or a total of 248 chicks per year, of which 174 fledge (average
reproductive success 70%). In addition, some 50 (extrapolated from 45 observed immatures)
immature eagles are within the study area during the breeding season. Therefore, the total, premigratory local population of the Steller’s Sea Eagles of all ages is estimated to be 934
individuals in North Okhotia.

DISCUSSION
Lobkov & Neifeldt (1986) hypothesized that Steller’s Sea Eagles do not occupy low areas
along the seacoast without forests, or areas along rivers without forested valleys and Pacificsalmon spawning grounds. Generally, this study supports this statement, although eagles
were not found breeding in the low coasts between the Arman’ and Tauy Rivers or between the
Shilki Fay and Urak Lagoons despite the occurrence of forested portions of coast.
The absence of eagles between the Arman’ and Tauy Rivers is probably due to constanthuman disturbance caused by a busy road. Human disturbance is likely for the absence off theeagles at the estuaries of Arman’, Ola, Inya, Urak, Kukhtuy and Okhota, as there aresettlements at these locations. Absence of eagles from the Khasyn and Lankovaya Rivers ismore difficult to explain, as there are no roads or areas of high levels of human activity. The
paucity of eagles along the Ola River away from the estuary might be attributable toagricultural activities along the lower part of the river and the continuous presence of people.
Cases of Steller’s Sea Eagles deserting areas have been recorded in Kamchatka (Lobkov &Neifeldt 1986) at the Avacha River, lower Paratunka, Tigil and around the human activity
centers of Petropavlovsk-na-Kamchatke and Kluchi. Nevertheless, around Magadan itself andnear the village of Balagannoe Steller’s Sea Eagles showed a capacity to coexist with humans.
In one instance eagles successfully bred only 300 m from a busy coastal resort center despite
the year-round presence of humans. A similar example of the coexistence of Steller’s Sea
Eagle and humans was described at Kizi Lake (Babenko et al. 1988), where eagles shared thelake with inhabitants of several settlements in the 1930s.
Extrapolation from our data may not give an absolutely precise estimate of the population

43
in North Okhotia. We were unable to visit nests several times during the breeding season, so
we probably underestimated occupancy and breeding. On the other hand, we rarely saw adulteagles that we could not associate with a territory. Because our surveys were, for the most part,late in the breeding season, it is likely that our estimate of fledging success was better, but wealso know that large eagle chicks sometimes do not fledge or that they die soon after fledging(McGrady et al. 2000). The estimate by Lobkov & Neifeldt (1986) for the Magadan District
was of at least 200 breeding pairs and about 500 pairs on the coasts of the Khabarovsk district(out of which 200 live in the Lower Amur and Shantar Islands), or a total of 500 breeding pairs
in the area covered by this study. This is somewhat higher than the 370 territorial pairs, and200 breeding pairs we estimate. Since no exact data are available for the Lobkov & Neifeldt(1986) estimate, and it is not clear whether the estimate refers to breeding pairs or territorial
pairs, there is no solid basis on which to conclude that there has been 40% decline in thebreeding population over the last 12 years. However, the decline in occupancy and the total
number of chicks produced per unit area during the period of this study causes concern that the
population as a whole may be in decline. Nevertheless, as there are no precise data on
survival rate of immatures (or other ages) and there is no knowledge of recruitment rates andage of first breeding, we are unable to confirm the stability of the population.
Because of the large area covered by our survey, it is likely to provide data that can beused to test predictions made by statistically based extrapolation in the future, and to provide
context. It is important that when the resources become available, that a more comprehensive
estimation of the population and breeding success in North Okhotia is made.

ACKNOWLEDGMENTS
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,
1996), US 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 of1996 to IU and Avon Inflatables, Ltd. (Dyfed, Wales, UK) for the supply of the fine inflatable motor-boat(1994), which was a key tool in the surveys.

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