8lM/AK/OF-83/04 BlM-Alaska Open File Report 4 

June 1983 

Results of the 1981 .Bald Eagle 

Nest Survey in the Gulkana River 

and Delta River Wildlife Habitat 

Areas 

by	 Laurence C. Byrne 

David W. Daum 

Michael W. Small 

Julie S. Henderson 

Bureau of Land Management 

Alaska 
OPEN FILE REPORTS 

The category of "Open File Report" is used by BU!-Alaska to identify 

the results of inventories or other investigations that are made 

available to the public outside the formal BL~-Alaska technical 

publication series. These reports include preliminary or incomplete 

data that are not published and distributed in quantity but that are 

available for public inspection at BL~ offices in Alaska, the USDI 

Resources Library in Anchorage, and the various libraries of the 

University of Alaska. 

Copies of open file reports are also available for inspection at the 

USDI Natural Resources Library in Washington, D.C. and the BUr Denver 

Service Center library. 

At the time this report was prepared, Laurence C. Byrne, David W. Daum, 

and Julie S. Henderson were seasonal wildlife biologists with the 

Glennallen Resource Area. Michael W. Small is a natural resource 

specialist with the Glennallen Resource Area of the Bureau of Land 

Management's Anchorage District. 
StudY Area 

The study area encompassed the Gulkana River Wildlife Habitat 

Area (WHA) (1,132,300 acres) and the Delta River WHA (approximately 

72,000 acres). This inventory was conducted in accordance with two 

BL~ Habitat Management Plans (HMPs) which direct protection of bald 

eagle populations in these two drainages. 

Gulkana River WHA 

The Gulkana River IfHA (Figure 1) is located approximately 35 road 

miles north of Glennallen, Alaska. It includes land in the Gulkana 

River drainage north and west of Sourdough. The area is virtually 

roadless although numerous Off-Road Vehicle (ORV) trails exist within 

it. Road access is limited to the eastern perimeter. The Gulkana 

River is composed of a Mainstem, a Middle Fork, and a West Fork. The 

West Fork has two branches. 

Because of underlying permafrost and low relief, the southern 

third of the area (south of the West Fork) is poorly drained. Extensive 

boggy areas, numerous small lakes and interconnecting streams are the 

dominat features. Elevations generally range from 1800 to 2600 feet 

above sea level (a.s.l.) with occasional hills reaching over 3000 

feet. Vegetation is characterized by bog species, such as black 

spruce (Picea mariana), shrub birch (Betula glandulosa, 1. ~),

willows (Salix sp.), and lowericaceous shrubs (Vaccinium uliginosum, 

V. vitis-idaea, Ledum groelandicum). 

North of the West Fork, elevations range from 1900 to 5400 feet. 

a.s.l. Hills and valleys are predominantly gently rolling except at 

the higher elevations, which can be quite steep. The vegetation above 

3000 feet is dominated by dwarf birch, willow, and alder (Alnus ~.).

Moist alpine tundra occurs at the higher elevations. 

The upper reaches of the Middle Fork and Mainstem flow through a 

rich tundra community of low shrubs and cotton grass. Below 2600 feet 

elevation the vegetation grades into an upland spruce-hardwood forest 

of white spruce (Picea glauca), poplar (Pooulus balsamnifera), and 

cottonwood (P. trichocarpa). The vegetation type along the West Fork 

and lower re;ches of the Mainstem is a lowland spruce-hardwood forest 

of black spruce, paper birch (Betula Eapvrifera) and cottonwood. 

Delta River WHA 

The Delta River WHA (Figure 2) is located about 90 road miles 

north of Glennallen. Road access is possible from the Denali Highway 

at Tangle Lakes (mile 20) and by the Richardson Highway between mileposts 

212 and 226 (from Phelan Creek to the Black Rapids Glacier). The area 

includes Tangle Lakes, the Delta River from the Tangle Lakes to the 

1
 
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Black Rapids Glacier, and a corridor of land averaging two miles in 

width. 

The Tangle Lakes are the headwaters of the Delta River. From 

these lakes the river flows north through the Amphitheater Mountains 

and the Alaska Range to the Tanana River. Topography is rugged with 

peaks reaching 6000 to 9000 feet in adjacent areas. The river is 

clear from Tangle Lakes toEureka Creek, where cold, glacial, siltladen water enters the river and changes the water quality for the 

rest of its course. 

Shrub tundra is the dominant vegetation type for the entire tfHA. 

This consists of dwarf birch, willow, and alder along with low ericaceous 

shrubs. Spruce-hardwood forest occurs where the drainage patterns are 

favorable, especially along the lower stretches of the river. 

Methods 

Aerial surveys were flown over both ~s between 6/4/81 and 

7/20/81. The majority of flights were in June during the eagle's 

incubation and early hatching periods. Flights totaling 24.5 hours of 

air time were required to complete the survey (21 hours in the Gulkana 

tiaA and 3~5 hours in the Delta WHA). A Cessna 180 was used for most 

of the surveying. tlhen the 180 was not'available, a Cessna 185 or 

Piper Super Cub was utilized. The 180 seemed to be the best aircraft 

of the three for the job because it was slightly slower than a 185, a 

bit faster than a Super Cub, and extra observers could be used. An 

extra observer was a definite advantage. 

~ests were numbered and pertinent information was recorded on 

Eagle Nest Tree Parameter Forms (Figure 3). Initially, a 1:250,000 

map was used to plot nest and eagle locations. Because of the need to 

plot accurate locations, 1:63,360 series USGS maps were later utilized. 

Flight lines were traced on survey maps during the flights. Grid 

patterns were not used. Flights were chosen along wooded rivers, 

creeks, and lakes. Extensive, forested areas distant from water, and 

boggy areas without trees, i.e., the lake region, consisting of the 

southern third of the Gulkana WHA were not intensively surveyed. 

Approximately 90% (200,000 acres) of the WHAs estimated "eagle habitat" 

was inventori~d. Because of the unusually rainy weather this season, 

the survey took over one month to complete. Clear, sunny days were 

utilized whenever possible. 

When a nest was spotted, the pilot would circle the nest while 

information was recorded. Photos of nest and habitat were taken. 

Potential problems, such as nearby cabins or ORV trails, '..ere noted. 

If a perched eagle was sighted, several passes would be flown in the 

4 
o 

1. ID NUMBER:
 

2. DATE: 

3. OESERVERS:
 

4. LOCATION: TOi.'NSHIP • RANGE , SEC._, MER.	 _ 

5. ELEVATION: - • 6. DRAINAGE: 

7. CIRCLE KIND Or: EAGLE: BALD, GOLDEN. OR UNKNO\JN 

{ 

8. SPECIES OF TREE CONTAINING NEST: _ 

9 • HE! GRT OF NEST 'I'Rtt: 

10. DEH OF TREE:
 

11. DISTANCE OF TREE TO NEAREST ~ATER BODY:	 _ 

12. AGE.	 SHAPE. s VIGOR OF TREE: -:--~~- ~~:__~__:_~--

13. IS 'TREE DEAL ABOVE NEST (Y OR N); BELO~ NEST (1 OR N)? 

14. TREE'S ANGLE WITH GROUND: CIRCLE ONE--O-IOo, 10°-30°, 30°-----: 

15. DIRECTION (S) OF FLIGHT APPROACH: 

16. NEST	 TREE'S RELATIONSHIP !J ST~~D:

17. AGE,	 SPECIES, DENSITY. SIZE OF STAh~:

18. HEIGHT OF NEST ABOVE GROUND: '	 _ 

19. EST.	 DIA.~TER OF TREE AT NEST: _ 

20. EXPOSURE (S) OF NESX: 

21. ACTIVE NEST OR NOT: 

22. HOW MANY EAGLES SEEN: 

23. EST. rnSTANCE OF NEST =T~O-::HtJ}:::-=-1!~AN~A-::C~T~I~V~ITY:::-=-:---------

24. OTHER: 

25. Visibility: 

26.	 Accessibility:

By foot 

By climbing 

27. Habitat description: 

28. Substrate and description of nest: 

29. General observations: 

Figure 3. Eagle nest parameter form. 

5
 
vicinity to look for a nest. 

In addition, three ground surveys were conducted using raft or 

canoe. This was done along the West Fork and Mainstem of the Gulkana 

River, and in the Delta River-Tangle Lakes area. Two nests were 

walked to from the highway system, and Paxson Lake nest liS was reached 

by canoe. Nest trees were measured for diameter at breast height 

(dbh), distance from water, habitat description, ease of climbing and 

accessibility. Observations at active nests were also recorded. iJhen 

weather was cold and wet, disturbance was kept to an absolute minimum. 

If nestlings were large and easily excitable the nest tree was not 

approached for fear of a bird jumping out of the nest. 

It is felt that more reliable nest tree statistics could be 

gathered from the ground than from the air. Ground' survey dates were 

as follows: 

July 2-6 Mainstem Gulkana River (Byrne, Daum, Recreation Crew) 

July 23-24 Delta River/Tangle Lakes (Byrne, Daum, Recreation 

Crew) 

August 3-13 West Fork Gulkana River (Tindall, Fish, Dapkus, 

Kajdan) 

July 15, Paxson Lake nests #1, #2, and #5. (Byrne, Daum) 

Results 

1. Percentage of Active Nests 

Forty-nine nests were found in the total study area during the 

1981 BL~ Bald Eagle Survey (43 nests in the Gulkana WHA, and six in 

the Delta w1iA). Additionally, six nests were found outside the study 

area, ~NO active and four inactive. These six are not included in any 

calculations or tables presented here. 

The percentage of active nests was 49% for the total study area, 

53% for the Gulkana WHA and 17% for the Delta WHA (Table 1). Only one 

active bald eagle nest was found in the Delta WHA. Nesting activity 

does not indicate reproductive success, however. 

Active nests were determined by aerially observing the presence 

of adult birds on the nest, or the presence of eggs or young in the 

nest; or by ground observations of adult behavior. Bald eagles sometimes 

defend nests that are not active (Robards and Hodges, 1976). Thus, 

some nests recorded as active may not actually have been so. 

6 
Table 1. Nt:m1ber and Percent Active Nests 

area 4/:nests lI:a.ctive nests reactive nests
 

Gulkana. W.H.A. 43 23 53
 

Delta W.H.A. 6 1 17
 

Total 49 24 49
 

7
 
Ospreys (Pandion haliaetus) also occur in the study area, although 

only one adult was observed during the 1981 field season. The sighting 

was on Pork Chop Lake (Vermillion Lake) in the Alphabet Hills region. 

It is possible that one or more nests classified as a bald eagle nests 

may be an osprey nest. 

2. Distribution of Nests 

Bald eagle nest locations were plotted to determine the distribution 

patterns. Interestingly, the Delta River area has no recorded nests 

down river (north) from the nest located near Ann Creek (Figure 2), 

despite the many large spruce stands on both sides of the river for 15 

miles north of this site. The Delta River is very silty and braided 

over this section. The resultant low availablility of prey might 

explain the absence of nests. 

The distribution pattern of eagle nests in the Gulkana t~ varies 

by area. The are~ north of the Alphabet Hills and west of the Middle 

Fork of the Gulkana River was not surveyed. Because this area contains 

few large trees, and no salmon, it would likely support a sparse 

population of eagles. The Middle Fork area had four nests recorded, 

only one of which was active, although nests were found up to Dickey 

Lake where the survey ended. 

Nests were scattered throughout the West Fork-drainage on both 

branches with the exception of one 25 mile middle section. The Paxson 

Lake/Gulkana River Mainstem also exhibits a scattered nest distribution. 

A high concentration of inactive nests was located on the Mainstem 

below its confluence with the West Fork. 

The lake area south of the West Fork consists of approximately 

468 square miles. In this area eight active eagle nests were recorded 

out of 13 total nests. Seven nests were sighted in the Fish Lake/deep 

Lake region; the other six nests were scattered over the remainder of 

the lake area. 

King and red salmon (Onchorynchus tschawytscha, Q. ~) occur 

in the whole Gulkana River system with the exception of the south 

branch of the West Fork. Reds also occur through a portion of the 

lake region from Fish Lake to Crosswind Lake. Grayling (Thvmallus 

archticus), whitefish (Coregonus autumnalis), and burbot (Lata ~)

occur in waters throughout the whole Gulkana WHA. Rainbow trout and 

steelhead (Salma gairdneri occur on the Mainstem and to Dickey Lake on 

the Middle Fork. Lake trout (Salvelinus namaycush) inhabit many of 

the lake region waters. Correlations between eagle nest and fish 

distribution patterns would be valuable, as fish seem to be the primary 

food source for bald eagles in this area. Waterfowl nesting habitat 

may also be a factor influencing nest tree selection. 

8 
30 Nest Density 

Nest density r~gures were calculated for the different areas
 

(Table 2). Nest density in the riparian areas was calculated in nests
 

per linear mile. In the lake area, nests per square mile calculations
 

were used. Closest and farthest distances between active nests are
 

presented by area.
 

For the density calculations, the Mainstem Gulkana River does not 

.include Paxson Lake. Even so, the Mainstem Gulkana River had the 

highest density of total nests (.24 nests/mile), active nests (.13 

active nests/mile) and closest distance between active nests (2 miles, 

a value shared with one location on the West Fork). The West Fork 

(both branches) had the lowest density of nests with .11 nest/mile. 

The Delta WHA had lowest density of active nests with .02 active 

nests/mile as only one active nest was found. 

White spruce was the 40minant nest tree species (86%) in the
 

study area (Table 3). tVhite spruce occurs most frequently along the
 

water systems. There were substantial numbers of large cottonwoods,
 

probably Ponulus balsamnifera, but few contained bald eagle nests.
 

There are very few stands of trees in the Tangle Lakes region.
 

Only one nest, an inactive ground nest, was found in 1981 in this
 

section. Observation of two adult eagles perched approximately 1/2
 

mile up river on the lakeshore suggest that an active ground nest may
 

occur in this relatively treeless area. An active ground nest was
 

discovered and photographed by BLM personnel in 1979 in this area.
 

Forty-four percent of all nest trees were between 41' and 50'
 

high, 48' being the average (Table 4). Of the nests in this height
 

class. 76% were active. No active nests were in trees less than 30'
 

tall, but six percent of the total nest trees were under 30' tall.
 

(The one ground nest is included in this calculation.) Figure 4
 

depicts the percentages of active nests within a nest tree height
 

class.
 

4. Location of Nests 

The average distance from a nest tree to a water body was 127'. 

Sixty-one percent of the trees were located within 100' of water. 

Nest trees either 11'-50' or 401+' from water had the highest percentage 

of active nests. (Table 5). 

The elevation of nests was also determined and the average nest 

elevation over the entire study area was 2350'. Gulkana WHA eagle 

nests had an average elevation above sea level of 2292', compared to 

the higher 2758' average elevation for the Delta WHA nests. Table 6 

shows that active nests are found at a slightly lower average elevation 

9
 
Table 2. Nest Density for Different Areas 

River Miles Nests Active Nests Maximun Dist. Closest Dist. 

Area 

Gulkana R. 

Miles 

45 Surveyed 45 

per mJle 

.24 per mile .13 

BtVJn Act. 

13 miles 

Nests Btwn Act. 

2 miles 

Nests 

Mainst6U G-2 to G-7 WF-l to G-13 

Gulkana West 95 95 .11 .05 25 miles 2 miles 

Fork (Both Br.) 

Gulkana Middle 

Fork 

Tangle/Delta 

River 

30 

56 

30 

L.9 

Miles 2 

.13 

.12 

Nests 

.03 

.02 

Active Nests 

WF-5 to Wli'-8 

17 miles 

MF-2 to c-i 

only one 

(1) nest 

MaXimuu Dist 

Wli'-l to G-13 

only one 

(1) nest 

only one 

(1) !lest 

Closest Dist 

Miles 2 Surveyed per mile 2 per mile 2 BtWl.Act.Nests Btwn. Act. Nests 

10 miles 2.5 miles 

Lake Region 468 351 .04 .02 SSL-l to 20SL-l PrL-l to DvL-l 

Table 3. Species of Nest Tree 

IJNests in l!Nests in Ground % 

Area White Spruce % %Active Cotton~ % %Active Nests % Active 

Gulkana W.Il.A. 37 86 57 6 14 33 0 0 0 

Delta W.II.A. 5 83 20 0 0 0 1 17 0 

Total Study Area 42 86 52 6 12 33 1 2 0 

) 
0 

ercent 

Tree Height Total Delta Total Gulk. Delta Total Delta 

1 1 2 17 0 0 

1-10
 

11-20
 

21-30 2 2 4 5 0 0 

31-40 11 9 2 22 21 33 21 33 0 

41-50k 21 18 3 44 43 50 76 83 33 

51-60 9 9 19 21 33 33 

61-70 4 4 8 10 50 50 

*tbte: WF-10 not included. Nest has fallen out of tree. x'=48 1 

)
 
Figure 4. Percent Active Nests in Trees of a Certain Heig.r"t Class 

100­

fo> 

76% 

fo> (n=16) 

0­

50'% 

(n=2) 

33% 

27% (r.=3) 

(n=3) 

" . a 1-10 11-20 21-30 31-40 41-50 51-60 61-70 

Nest Tree Height
 

(Feet)
 

12 

..... 
Table 5. Distance of Nest Tree from Body of Water 

Distance Number Percent Percent Active 

Fran Water (Ft) Total Gulkana Delta Total Gu1kana Delta Total Gull«:ma Delta 

0-10 1 1 2 2 0 0 

11-25 11 10 1 23 24 17 64 70 0 

26-50 8 7 1 17 17 17 75 86 0 

51-100 10 9 1 21 21 17 40 33 100 

101-200* 6 5 1 12 12 17 33 40 0 

201-300 11 9 2 23 21 33 36 Lt4 0 

301-400 

400t 1 1 2 2 100 100 

*Note: one nest located 125' from water fell out of the tree during 

the study and is not included in this data. 
Table 6. Elevation of Nest Locations 

Area 

Total Nests 

Avg. Elevation (Ft) 

Active Nests 

Avg. Elevation (Ft) 

Gulkana W.H.A. 2292 2272 

Delta W.H.A. 2758 2700 

Total Study Area 2350 2290 

Table 7. Percent Active Nests in Areas of Human Activity and Undisturbed Area~

if Active if Inactive % 

Area Nests Nests Active Nests 

Areas of Human Activity 

Gulkana R. (Mainstem) 9 7 56 

and Paxson Lake 

tJndis'turbed Areas 

Middle and West Forks 6 8 43 

Gulkana River 

Lake Region 8 5 62 

Total Undisturbed 14 13 52 

14
 
than are inactive nests. No bald eagle nests were located above 2900' 

in elevation. 

5. Human Caused Disturbance 

In the Gulkana WHA "areas of human activityll were compared with 

relatively "undisturbed areas" for percentages of active nests (Table 

7). Disturbed areas were defined as the Mainstem of the Gulkana River 

and the Paxson Lake area. Over 3,614 recreationists (both persons 

floating and using motorized boats) used the river between P~xson Lake 

and Sourdough in 1981 (pers. comm., Bill Ziegler, BL~). A BL~ campground 

is located on Paxson Lake which is widely used by fishermen. The 

Middle, West Fork, and lake region were categorized as relatively 

undisturbed areas. Some activities such as hunting. fishing and cabin 

use are scattered throughout these areas, but the human disturbance 

factors appear to be of a lesser impact than along the mainstem of the 

Gulkana River. In a 2 x 2 contingency table there was no significant 

difference between the number of active nests in the disturbed areas 

versus the undisturbed areas (Disturbed vs. West Fork and Middle Fork 

X2 .001(1) = .2679; disturbed vs. lake region X2 .001(1) = .2679; 

disturbed vs. undisturbed combined X2 .001(1) = .1250). 

On the Mainstem of the Gulkana River. powered river boat use is 

mainly confined to the area from Sourdough to approximately four miles 

above the confluence of the West Fork. The maximum use 'period is during 

the king salmon run from mid-June to mid-July. In 1981 over 1200 people 

in motorized craft used this 12 mile stretch. The 30 miles UP river 

from this section are almost exclusively used by non-motorized 

watercraft. 

These ~NO sections of river were compared for the occurrence of 

active nests (Table 8). The motor use area had substantially lower 

percentage of active nests (20%) than the non-motor section with 83%. 

However, it should be pointed out that most non-motorized use in 

the WHA originates at Paxson Lake and terminates downriver at Sourdough 

or Gulkana Village. Thus the floaters also use the lower 12 mile 

stretch, giving that section of the river the most use. 

Nest densities along the two distinct use areas of the Gulkana 

River are presented in Table 9. The 12 mile section with motorized use 

had a very high density of nests, but a low density of active nests 

compared to the non-motorized 30 mile section. 

Discussion 

Forty-nine percent of the bald eagle nests were active. This 

figure is very similar to the 43% (Robards, King 1966) and 49% (Robards, 

Hodges. 1976) active nest results found for southeastern Alaska. 

15 
Table 8. Active Nests Along the Motor Use and Non-o:otor Use 

Section of the l-f.ainstem Gulkana River 

4F Total % 

Use Area Active Nests Nests Active Nests 

Motor 1 5 20
 

5 6 83
 

Table 9. Nest Density Along the Mainstem of the Gulkana River 

Motor 12 .42 .08 

Non-lIXJtor 30 .2 .17
 

16
 
The nest density figures from this study differ from densities 

along the coastline of southeastern Alaska. Our study area had nest 

densities ranging from .11 to .24 nest/river mile and from .02 to .13 

active nests/river mile. In southeastern Alaska. Robard and Hodges 

(1976) determined nest density to be between .20 and 1.04 nest/mile 

while Robards and King (1966) estimated between .20 and .70 active 

nests/mile. Factors such as food supply, available nest sites, human 

disturbance, and climate may have an influence on nest densities. The 

bald eagle populations in the Gulkana and Delta drainages appear to be 

healthy, but low density figures indicate the need for intelligent 

management and further study to insure a viable and productive eagle 

population. 

White spruce was found to be the dominant nesting tree (86%) in the 

study area. Other studies have documented other nest sites, for 

example, Sitka spruce (Picea sitchencis) (72.8%) in southeast Alaska 

(Carr 1974); ground nests on sea stacks and ridges (81.5%) on Amchitka 

Island, Alaska (Sherrod et. al., 1976); quaking aspen (Populus 

tremuloides) almost exclusively in northwestern Ontario (Orten et. al., 

1981); and white pine and red pine (Pinus strobus, ~. resinosa) (80%) in 

northern Minnesota (Mathison 1968). The almost exclusive use of 

specific nesting sites indicates a strong nest selection preference in 

different geographic locations of the bald eagle range. No doubt this 

is based somewhat upon availabili~y of the specific tree species in a 

given location. 

The overall effects of human disturbance on bald eagle populations 

are unclear. Stalmaster (1968), Carr (1974), and Juenemann et. al., 

(1972), found that human actiVities had a direct or indirect 

relationship with nesting behavior and wintering bald eagle populations. 

Mathisen (1968) reported no apparent difference in nesting success 

between disturbed and undisturbed areas. Many factors come into play 

when trying to assess the impact of human disturbance on nesting bald 

eagles. Timing of the disturbance during the eagle reproductive cycle 

seems important, as does the type of disturbance. Incubation and early 

nestling periods (mid-April through mid-July) are the most sensitive 

times. The majority of human contact is from mid-June to mid-July on 

the Gulkana River. From field observations, the bald eagles during this 

time of human activities are in the late incubation to the mid-nestling 

period. 

Recreational use on the Gulkana has increased a great deal in 

recent years. In 1970, fewer than 300 people boated the river, and in 

1980 over 3,000 did--a tenfold increase in ten years. An overall view 

of the study area suggests that little impact occurred on the Gulkana 

River during the 1981 nesting season. The percentage of active nests in 

disturbed and undisturbed zones are similar. These figures may be 

misleading since "active nests" do not necessarily denote reproductive 

success. Also, the classification of.disturbed areas is somewhat 

17
 
subjective. Since past bald eagle nest data is very limited in the 

study area, long-term impacts would be difficult to assess at this time. 

Motor boat use may affect the percentages of active nests along the 

Gulkana River. The 83% figure for the non-motorized section is 

substantially higher than the 20% calculation for the motorized area. 

the low number of active nests and relatively high density of inactive 

nests in the motorized section suggests nest dispacement may have taken 

place. 

Recommendations 

The Gulkana River and Delta River Wildlife Habitat Areas are 

heavily used by recreationists, especially along the river systems. 

Also, oil and gas leasing may occur in the Gulkana Basin in the near 

future. Because of these pressures on the wildlife resource a wise 

management program should be adopted to protect and ensure that wildlife 

species maintain productive populations. The bald eagle is protected by 

both federal and state laws; therefore, these raptors should be given 

special attention. 

Bald eagle populations along the Gulkana and Delta Rivers are in 

direct contact with ever-increasing numbers of river enthusiasts. Over 

2000 people floated the Mainstem of the Gulkana during the summer of 

1981. Some areas along the river are very popular camping sites. Also 

in 1981, over 1300 fishermen using outboards, jet units, and air boats, 

established fish camps during salmon season along the Gulkana from 

Sourdough up river to beyond the confluence of the West Fork. These 

activities are at a peak from mid-June through mid-July. Bald eagles 

during this period are at a sensitive state reproductively, in that the 

eggs are either being incubated or the young have just hatched. 

Therefore, the bald eagle populations should be strictly monitored to 

see if these disturbances are affecting the maintenance of a viable 

population. 

Two aerial surveys should be flown each year over the Gulkana and 

Delta WHAs. A Cessna 180 has proven effective during this type of suvey 

work because of room for an additional observer and the relatively slow 

flight speed. Data should be recorded on 1:63,360 USGS maps. One 

flight should be flown in late May to identify active and inactive 

nests. The whole survey should be flown in a one-week period, weather 

permitting. A second aerial survey should be flown in late July to 

obtain any nest displacement and/or loss information, and nestling 

numbers when possible. Total flight time for both surveys would be 

approximately 25 hours. Both surveys should include all the nests in 

both WHAs so a reliable data base can be established bet"'N'een "disturbed" 

and undisturbed" areas. These surveys would be an efficient aid to 

18
 
, , 

measuring how the bald eagle population is faring from year to year, 

Also a project should be initiated on the Gulkana River to 

determine what effects human disturbances have on bald eagles. Two 

active nests should have a wooden sign up river and down river from 

the nest restricting camping and disturbance. This would be a test to 

see if signs are an effective means of protection. One sign location 

should be in the lower portion of the Gulkana where riverboat activity 

is heavy and the other sign location up the Gulkana where floating 

activity is exclusive (no power boats). A float trip should be done 

in early June (after aerial survye) for strategic placement of signs, 

BL.'1 should monitor both a "posted" active nest and "unposted" active 

nest in the exclusive float craft section of the Gulkana. Also 

undisturbed areas (lake or river with salmon) shouid be monitored 

between mid-June and Mid-July for comparison purposes. Approximately 

5 hours flight time will be needed for this part of the study, 

A color banding program should also be undertaken to accurately 

identify birds in the field. This would help in monitoring displaced 

birds and nest fidelity. Equipment for banding and the markers would 

be an added cost. The marking effort should be coordinated with the 

USFWS. A banding license must be ob'cadned from the bird banding 

laboratory, Office of Migratory Bird Management. U.S. Fish and Wildlife 

Service 1 Laurel. Maryland 20810. before color-marking the birds. 

19
 
Bibliography 

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