146 
at each den site. Fresh fecal pellets were collect- 
ed for later analysis of prey species content. 
Behavioral data were collected during three 
6-hour observation periods from tent or truck 
blinds located several hundred meters from the 
den sites. 
Results 
A total of eight arctic fox dens have been 
located in the Prudhoe Bay area. Six of these 
dens are within 2.5 km (four are within 100-200 
m) of the road system that was constructed in 
the area in 1968-70. The two dens located near 
Point McIntyre are in an area of low level human 
activity. 
Four of the dens are associated with pingos 
(geomorphic structures resembling small hills) 
ranging in height from approximately 2m to 
9m in the Prudhoe Bay area. These structures, 
which are formed from the refreezing of lake 
bottoms following drainage, have a core of 
segregated ice. Dens near the tops of these 
structures have a commanding view of the sur- 
rounding tundra. 
The remaining dens are also located in rela- 
tively high, dry ground. Two of them are in 
ridge banks which are probably the banks of 
ancient, drained lakes. The vegetation at all den 
sites was considerably more robust than that of 
the surrounding territory and ‘‘greened up” 
noticeably earlier, indicating a richer soil and 
more favorable growing conditions for plants. 
Following the age classification system of Chese- 
more (1967), it was determined that all of the 
dens located ranged from young to mature. Den 
site DH4, located in a large pingo nearly 9m 
high, has two den systems. Although both were 
utilized by the pups, the one near the top with 
10 entrances seemed to be used preferentially. 
In the 1971 summer season, five dens were 
examined, two of which supported young. At 
den site DH3, at least two young were heard, 
but apparently the litter was moved during the 
night following discovery, before an accurate 
count of the pups could be made. In 1972 eight 
den sites were examined, and four contained 
pups. It is likely that two of these dens contain- 
ed pups from the same litter. After several days 
of observation at site DH3, the litter of three 
apparently disappeared. The following day a 
new den containing three pups was discovered 
(den site DH6) in a riverbank not far from a 
well-traveled road. Although the den faced away 
from the road and could not be seen easily the 
pups were quite obvious when active. It is 
doubtful that the den could have existed all 
summer without being noticed. 
For the four litters observed during the 
2-year period in which accurate counts could be 
made, the average litter size was 5.5. This is 
somewhat smaller than the average number of 
seven reported by MacPherson (1969) for arctic 
foxes in the Lake Baker region of Canada. 
Table 1 
Densities in the Prudhoe Bay area 
Code Facing Approximate No. of No. of pups 
number! Location direction dimensions entrances 71 72 
DH 1 Teg. NW. 7.5x 4.5m 15 none none 
DH 2 1.9 N 15.3x 9.9 50 5 10 
DH 3 8.7 Ss 18.0x14.1 18 2(?) 33 
DH 4 20.4 E 9.0x 9.0 10 4 
E 4.5x 3.0 7 
DH 5 21.4 n/a? n/a 25 none 
DH6 10.3 n/a n/a 10 33 
MI 1 23.5 E 14.0x 4.0 56 none none 
MI 2 21.4 SE 8.0x 5.0 8 none none 
1. DH refers to Deadhorse area; MI refers to Point McIntyre area. 
2. Distance in kilometers from Deadhorse air terminal. 
3. Probably same litter. See text. 
4. n/a indicates data not available. 
