Herd 
Table 1 
Comparison of estimates of herd proportions (% of total number of 
animals) of Prudhoe Bay with estimates for the large arctic herds. 
Year Female 
Male 
Approximate 
157 
Shee eee a —a——[————— 
Prudhoe Bay 1972 34(100) 35(101) 
1973 52(100) 19(37) 
Arctic 1970 40(100) 26(65) 
Porcupine 1972 - _ 
Porcupine 1972 
July 52(100) 12(23) 
October 49(100) 28(57) 
Calves Yearlings no. classified Reference 
23(67) 8(24) 2,632 This study 
16(31) 13(25) 248 This study 
19(47) 15(37) 242,000 Pegau and 
Hemming (1972) 
24 = 50,000 LeResche 
(1973) 
26(50) 9(17) 17241 Calef and 
15(31) 9(18) 2,997 Lortie (1973) 
Values in parentheses are ratios expressed per 100 adult females. 
Group activity patterns of caribou 
In the 1972 season the number of individu- 
als in a group or herd variously involved in the 
activities of eating, lying, standing, walking, trot- 
ting, or running was recorded at 456 separate 
15 min intervals. Activity of adults (female, 
yearling, and male) over the whole observed 
period averaged 48% eating, 28% lying, 4% 
standing, 14% walking, 5% trotting, and 1% 
running. The disproportionately few observa- 
tions on male activity, except under insect ha- 
rassment, make an accurate comparison with 
female activity times difficult. However, the 
contrast between adult and calf activity times 
was quantified after recording the activity with- 
in 15 groups (containing females, yearlings, and 
calves) over 4 insect-free days in late June 1972. 
The result is summarized in Table 2a; analysis of 
variance on the full data (Thomson 1974) indi- 
cates that females plus yearlings spend signifi- 
cantly more time eating than do calves, while 
the calves spend significantly more time lying, 
standing, trotting, and running. Only walking 
time is not significantly different between the 
calves and older animals. 
Calves at this age (approximately 2-4 wk by 
end of June) graze considerably more and lie 
less than do calves at 1-10 days of age (wild 
Table 2a 
Summary of activity patterns of female yearlings and calves during insect free periods 
(values are % of study period). 
Sex/age class Eating Lying 
Female-yearling 52.8 S2H7, 
(4.8) (4.5) 
Calf 2325 54.6 
(5.9) (6.9) 
Comparison of classes X Xx 
Standing Walking Trotting Running 
1.2 le 1.8 0.1 
(0.9) (3.0) (1.3) (0.2) 
4.7 10.9 4.5 1.5 
(3.2) (4.4) (2.8) (123) 
X NS X X 
Value in parentheses is the standard deviation. A total of 15 groups were observed: three groups were observed for 
more than 6 hr duration; the remainder were observed for less than 6 hr and were combined into five groups according to 
date. Calves were 3-7 wk of age. 
NS, not significant; x, P<0.05. 
