Document 6boE1Zpn7jv8xk7ENQpNYQYME
ARCTIC REFUGE COASTALfPLAIN TERRESTRIALfWILDLIFE RESEARCH fUMMARIESf
I9f
Table 3.I. Number of calving sites, number of calving sites in the concentrated calving area (CCA), area (km2) of CCA, area (km2) of annualz calving ground (ACG), ratio of sizes of CCA to ACG, population size of the Porcupine caribou herd, percent of radio-collared female caribou thatz calved in the CCA, percent of radio-collared female caribou that calved in the 1002 Area, percent of the CCA within the 1002 Arza, and percent ofz the ACG within the 1002 Area, 1983-2001, Alaska, USA, and Yukon Territory, Canada.z
Year
Calving Sites
Sites in CCA
CCA Area
1983
18
11
2,584
1984
18
11
839
1985
34
16
1,585
1986
20
8
419
1987
36
15
479
1988
61
24
267
1989
51
15
255
1990
53
22
1,167
1991
43
21
731
1992
43
18
2,174
1993
35
18
1,401
1994
79
33
814
1995
60
31
827
1996
65
30
1,354
1997
29
15
530
1998
39
20
789
1999
20
9
601
2000
22
13
791
2001
41
a
average
40
18
976
minimum
18
8
255
maximum SE
79
33
2,548
18
7
630
a No concentrated calving was detected in 2001
ACG Area 10,064
6,599 10,784
5,432 6,048 3,823 3,672 8,379 5,767 16,667 9,098 6,602 5,141 9,453 5,661 6,316 7,820 6,541 10,602 7,604 3,672 16,667 3,060
Ratio CCA/ACG
0.25 0.13 0.15 0.08 0.08 0.07 0.07 0.14 0.13 0.13 0.15 0.12 0.16 0.14 0.09 0.12 0.08 0.12
0.12 0.07 0.25 0.04
Population Size (K) 135
165 178
157 152
128
123 148 123 178
20
%females %females In CCA In 1002
55.6
61.1
61.1
33.3
47.1
55.9
40.0
10.0
44.4
13.9
39.3
1.6
29.4
33.3
39.6
69.8
48.8
88.4
41.9
41.9
51.4
57.1
41.8
64.6
51.7
91.7
46.2
53.8
51.7
31.0
51.3
84.6
45.0
20.0
59.1
0.0
0.0
47.0
42.7
29.4
0.0
61.1
91.7
7.8
30.1
%CCA In 1002
62.4 19.8 69.2 28.8 14.2
0.0 59.3 100.0 92.5 79.1 70.2 77.3 100.0 90.6 33.7 93.4
9.3 0.0
55.5 0.0
100.0 35.9
%ACG In 1002
42.8 39.2 36.8
8.4 15.7
5.9 30.1 47.2 68.6 22.5 40.3 54.8 71.2 33.9 31.8 73.1 30.4
0.0 0.0 34.3 0.0 73.1 22.5
Figure 3.14. Percent of radio-collared Porcupine caribou herd femalesz that calved in the 1002 Area of the Arctic National Wildlife Refuge,z Alaska, 1983-2001.z
Figure 3.1S. Percent of radio-collared Porcupine caribou herd femalesz that calved within the 1002 Area of the Arctic National Wildlife Refuge,z Alaska, in relation to the median Normalized Difference Vzjetationz Index at calving (NDVI_calving) within the aggregate extent of calving,z 1985-2001. Point legends indicate the year of the estimates.z
20f
BIOLOGICALfSCIENCE REPORTfUSGS/BRD 2002-0001f
and Game, personal Communication). As fesult of fhesef westward movements, essentially the entire 1002 Areaf was eventually used by late June or early July. Most of the use of fhe Westernmost portion of fhe 1002 .Area byf satellite-collared females fif the Porcupine Caribou herdf occurred during 24 June-14 .August (Fig. 3.11).f
a) 100
Foraging on the Calving Groundy
The calving season diet of Porcupine herd caribouf
during 1993-1994, When concentrated calving Wasf
primarily in the 1002 .Area (Fig. 3.13), was dominatedf
b)
(76-82%) by immature flowers of cottongrass from thef
time the caribou arrived on fhe calving ground until aboutf
16-18 lune (Figs. 3.16a, 3.17a). Similar diets weref
observed in 1973 (Thompson and McCourt 1981), but thef
location of concentrated calving in that year was notf
documented (Clough et al. 1987).f
Diet was relatively consistent between years, butf
somewhat more variable in 1994, and not related tof
average daily weight-gain of calves in 1993 and 1994.f
Both cottongrass flowers and young willow (SalixZspp.)
leaves are easily digestible and are common forage of
upland calving caribou when fhey are available (e.g.,f
IB Cottongrass
JUNE1994 Willow
JULY
B B Lichens
Herbs
4.5
0,5 -|---------- .----------1---------- .---------------------.---------- 1----------.----------1---------- .----------1---------- .----------1
03-Jun
08-Jun
13-Jun
18-Jun
23-Jun
Date-1994
28-Jun
03-Jul
Cottongrass --s-- Willow
Figure 3.17. Porcupine caribou herd a) diet composition and b)z median phenology of major forage items, 1994. Diet compositionz stimated from microhistological analysis of fecal pellets, corrected forz digestibility. Phenology scores for cottongrass: 1 = leaves only, 2 =z flowers in boot, 3 = early flower, 4 = full flower; and, for willow: 1 =z dormant, 2 = bud swelling, 3 = leaf unfolding, 4 = full leaf.z
median phenology of major forage items, 1993. Diet compositionz stimated from microhistological analysis of fecal pellets, corrected forz digestibility. Phenology scores for cottongrass: 1 = leaves only, 2 =z flowers in boot, 3 = early flower, 4 = full flower; and for willow: 1 =z dormant, 2 = bud swelling, 3 = leaf unfolding, 4 = full leaf.z
Thompson and McCourt 1981, Muropat 1984, Russell Ctf al.1993). Cottongrass flowers were most common in thef vegetation type herbaceous tussock tundra, and willowf was most common in shrub fussock tundra and riparianf shrub vegetation types (Jorgensen et al. 1994).f Herbaceous plants were ubiquitous.f
Dietary shifts within the 1993 and 1994 calvingf seasons apparently allowed caribou to increase nutrientf concentration in their diet as fhe season progressed. Byf mid-June, 1993-1994, s cottongrass flowers matured, fhef leaves of willows unfolded (Figs. 3.16f, 3.17f). Then,f within about 4 days (Figs. 3.16a, 3.17a), caribou dietf shifted fo in approximate 0 : 50 mix of willow andf herbaceous plants.f
The diet shift resulted ifn an increase of dietaryf nitrogen concentration (from 8% fo 4%) and a decrease fnf Neutral Detergent Fiber (NDF) concentration (from 57%f to 27%) based fin nutritional analyses of cottongrass Sndf willow of appropriate phenological stages from thef calving ground. .Available biomass of willow fikelyf exceeded fhe biomass df cottongrass flowers during thef diet shift and thereafter.f
