Analyses of predator scats and pellets 
To help determine what species of microtine 
rodents inhabit the Prudhoe Bay area, owl pel- 
lets, jaeger pellets, and fox scats were collected 
during the summer of 1971. About 80% of the 
224 fox scats came from outside a den about 
200 m NW of live trap grid O. The remainder of 
scats and the 11 pellets were from other loca 
tions away from the live trap grids. The scats 
and pellets were teased apart, and the skeletal 
remains of prey were identified by species when 
possible (Bee and Hall 1956; Burt and Grossen- 
heider 1964). 
Results 
Numbers, biomass, density 
As shown in Table 1, only two lemmings 
were captured during the entire summer of 
1971. During the first trapping period in June, 
two collared lemmings were captured, marked, 
and recaptured on grid Q. Although fresh fecal 
droppings were found around and in some of the 
traps in June and July, no other lemmings or 
other microtines weré captured during the re- 
mainder of the summer on either grid. In late 
August, two arctic ground squirrels were cap- 
tured on grid P. No animals were captured on 
any of the temporary live trapping or snap 
trapping sites during the summer of 1971. 
In June 1972 an increased activity of micro- 
tine rodents over the previous summer was 
apparent from the fresh signs of burrows and 
fecal pellets. Observations over a wide area of 
Prudhoe Bay road system suggested a low to 
moderate level of activity and a very patchy 
distribution. Live trapping revealed a definite 
increase in numbers of collared lemmings in 
June 1972 [5-8(0.25 ha)! grid area] over the 
level in June 1971 [0-2(0.25 ha)! grid area] 
(Table 1). The presence of three juveniles of 
12-14g on grid P indicated that breeding had 
begun before the snowmelt. Although subadults 
and adults of both sexes remained in breeding 
condition with adult females pregnant through 
late July, the numbers captured declined from 
5-7(0.25 ha)! grid area in early July (Table 1) 
to 0-1(0.25 ha)! grid area by late August. 
Biomass of live lemmings captured on each grid 
is shown in Table 2 and simply follows the trend 
in numbers captured through the summer of 
1972. 
139 
Density estimates of collared lemmings 
based on the number captured and the assumed 
range of movements (Brooks and Banks 1971) 
are shown in Table 3. Densities were generally 
higher on grids P and O and reached maximums 
of 10.2 and 6.6 lemmings ha’! respectively, in 
July. 
Lemming species in predator scats and pellets 
Although there were many pieces of uniden- 
tifiable microtine remains in the predator scats 
and pellets (about 50%), of the total 16% were 
identified as collared lemming, 13% as brown 
lemming [Lemmus sibericus (=trimucronatus)] 
and 25% unidentified bird remains. M/crotus 
oeconomus (tundra vole) could not be positively 
identified in these samples, although it had been 
previously found by MacLean (pers. comm.) in 
raptor pellets. 
Discussion 
Species composition and numbers 
The results suggest that at Prudhoe Bay, in 
contrast to Barrow, the collared lemming may 
be more abundant than the brown lemming and 
that the lemming populations at Prudhoe Bay 
may never reach the magnitude seen at Barrow. 
Examination of the tundra for fresh signs of 
microtine rodent activity by S. MacLean in July 
1970 (pers. comm.) and P. Whitney (pers. 
comm.) in September 1970, revealed little evi- 
dence of small mammal activity. In early Sep- 
tember 1970, Whitney (pers. comm.) established 
two live trapping grids near the sites of grids P 
and QO in the present study, but captured no 
microtines during 2 days of trapping. Thus, it 
appears that the lemming populations were quite 
low in 1970, remained low in 1971, and reached 
trappable numbers as high as 8 collared lem- 
mings (0.25 ha)' grid area, or a maximum 
density of about 7-10 lemmings ha’! during the 
summer of 1972. 
One or two isolated instances of hand cap- 
turing of brown lemmings were reported in bird 
censusing areas in 1971 (I. Ailes, pers. comm.) 
and 1972 (J. Curatolo, pers. comm.). In addi- 
tion, brown lemmings were identified as a prey 
item in the diet of the arctic fox in 1971-72. 
However, the amount of lemming prey sign was 
considered sparse at Prudhoe Bay fox den sites 
compared to sign at den sites in other areas of 
the Alaskan North Slope (Underwood 1974). In 
spite of evidence for the presence of brown 
