Yellowstone's Northern Range - Greater Yellowstone Science ...

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THE NORTHERN RANGE 88 not aware of a decline in big sagebrush anywhere else on the mule deer winter range, and lacking any other lines of evidence, we can speculate that the sagebrush decline may be due to heavy, year-round use by pronghorn. To further complicate this question, the sagebrush decline seems to be restricted to the Wyoming subspecies, and mostly to high ground such as ridges, upland slopes, and rolling terrain with a high soil clay component. In the lower areas and swales where the basin subspecies dominates, sagebrush is tall, abundant, and apparently vigorous. The composition of the northern Yellowstone mule deer herd has been estimated each year since 1990 using a helicopter. These surveys show a steady increase in the proportion of adult males in the herd, presumably in response to modifications of hunting regulations promulgated by the Montana Department of Fish, Wildlife and Parks. PRONGHORN Early accounts of the greater Yellowstone ecosystem report large numbers of pronghorn in all the major river valleys radiating out from the present park area (Figure 7.9). Agriculture, settlement, and market hunting were probably responsible for the demise of these large, continuous populations. Many accounts of the northern range prior to 1882 also mention frequent sightings of pronghorn, but these are reports of summering animals (Schullery and Whittlesey 1992). It does not appear that the park contains significant winter range for pronghorn; their winter range is at lower elevations downstt'eam of the north park boundary, where they are competing with a growing amount of human activity and development (Figure 7.10). Pronghorn is a species of special interest on the northern range because their numbers have at times been very low, causing concerns over their genetic wellbeing and even their long-term survival as a population entity (Appendix B) (Barmore 1980, Houston 1982, O'Gara 1990, Scott and Geisser 1996). Lee et al. (1994) added a further reason for special interest: Yellowstone pronghorn carry a unique genetic element (mtDNA haplotype J) found in no other pronghorn herd in the west. Surprisingly, the Yellowstone pronghorn contains more genetic diversity than any other North American herd studied, yet has never received stocked pronghorn from elsewhere. The authors stated: The pronghorn herd of Yellowstone National Park is one of the few remaining undisturbed populations. The most parsimonious explanation for the great amount of mtDNA variation in the Yellowstone herd is that Yellowstone was a refuge when other herds were exterminated or greatly reduced. This genetic resource should be conserved. Yellowstone pronghorn populations of 550 to 700 were reported in the 1930s, and these increased to 600 to 800 in the 1940s following the addition of Figure 7.9. Pronghorn were extremely abundant in the lower river valleys of greater Yellowstone prior to the creation of the park in 1872. Because of its small sile alld isolation, the northern YellowstOlle pronghorn population is at some risk of extinction. NPS photo.
ELK AND OTHER SPECIES 89 - c:::J Northern Winter Range Pronghorn Antelope Range 6.2km I (10 mil Figure 7.10. Pronghom winter range is restricted primarily to lower elevation areas in the BLA and north of the park. Map by Yellowstone Spatial Analysis Center and the Yellowstone Center for Resources. winter ranges north of the park and the removal of a boundary fence. Pronghorn populations were reduced in conjunction with elk and bison control after this period, so that by 1967 there were only about 188 (Barmore 1980, Houston 1982). During the 1970s, counts averaged about 140, but increased to a peak of 594 in 1991 and dropped to 229 in 1996 (see Table, Appendix B). Goodman (1996) estimated the prospects for the Yellowstone pronghorns through population viability analysis. He concluded that "this antelope population is extremely vulnerable to wide swings in numbers, and the risk of extinction is high ... A lUn of 'bad luck, I such as a few consecutive years where coyote predation prevents successful recruitment of young, coupled with a disease or weather event causing high adult mortality, could eliminate the herd." Goodman added, "the [limited special damage] hunt [reinstituted in the late 1980s at the request of a ptivate landowner] could in fact contribute to the dynamical vatiability that poses a threat to the long term prospects for survival of the population. Goodman estimated that the probability of extinction within 100 years was 18 percent and noted: It is conventionaL .. to consider a popUlation .. . severely endangered when its probability of extinction within 100 years is above 5 percent. .. RESEARCH RECOMMENDATIONS: PRONGHORN In 1989, the park convened a group of western pronghorn experts to review the state of knowledge on Yellowstone's pronghorns and make recommendations for future research. In synopsized form the group recommended the park: 1. Continue annual counts and recording of age group distributions as has been done for many years, augmented through radiomarking a subgroup to determine sightability and thus the total popula-
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YELLOW"STONE'S NORTHERN RANGE COMPL
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THE NORTHERN RANGE 10 unpopular or
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THE NORTHERN RANGE 12 earlier Yello
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THE NORTHERN RANGE 16 Northern rang
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THE NORTHERN RANGE 20 Figure 2.4 Tr
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THE NORTHERN RANGE 22 dendrochronol
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THE NORTHERN RANGE 24 Figure 2.7. A
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THE NORTHERN RANGE 26 et al. (1991)
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THE NORTHERN RANGE 28 earlier time,
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THE NORTHERN RANGE 32 systems-range
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THE NORTHERN RANGE 34 indicates the
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THE NORTHERN RANGE 36 Data were gat
Page 54 and 55: THE NORTHERN RANGE 38 grazed and un
Page 56 and 57: THE NORTHERN RANGE showed that graz
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Page 60 and 61: Figure 4.1. Northern range, showing
Page 62 and 63: Figure 4.2. Willow distribution in
Page 64 and 65: THE NORTHERN RANGE 48 Figure 4.4. I
Page 66 and 67: THE NORTHERN RANGE 50 public lands,
Page 68 and 69: THE NORTIlERN RANGE 52 Figure 4.5.
Page 70 and 71: THE NORTHERN RANGE 54 able uncertai
Page 72 and 73: THE NORTHERN RANGE 56 to confirm an
Page 74: THE NORTHERN RANGE 58 RESEARCH RECO
Page 77 and 78: SOIL, EROSION, SEDIMENTS, AND WATER
Page 79 and 80: SOIL, EROSION, SEDIMENTS, AND WATER
Page 81 and 82: ated with ungulate winter ranges. T
Page 83 and 84: ELK POPULATION ISSUES IS YELLOWSTON
Page 85 and 86: ange grazing issue, Yellowstone man
Page 87 and 88: ELK POPULATION ISSUES 71 ... Other
Page 89 and 90: ELK POPULATION ISSUES 73 1996d), so
Page 91 and 92: ELK POPULATION ISSUES 75 the northe
Page 93 and 94: ELK POPULATION ISSUES 77 It has evo
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Page 98 and 99: THE NORTHERN RANGE 82 Competition t
Page 100 and 101: Figure 7.3. Bison winter range. Sin
Page 102 and 103: THE NORTHERN RANGE Figure 7.7. Envi
Page 106 and 107: THE NORTHERN RANGE 90 tion size, an
Page 108 and 109: THE NORTHERN RANGE 92 activity (95
Page 110 and 111: THE NORTHERN RANGE 94 pursue the su
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Page 118 and 119: THE NORTHERN RANGE 102 complex set
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Page 124 and 125: AppendixA. Conferences, Meetings, a
Page 126 and 127: lJO Year Estimate Comment Source 19
Page 128 and 129: lJ2 , Estimated # of Elk Year Date
Page 130 and 131: lJ4 Winter Total Count 1967-68 397
Page 132 and 133: 116 Year Date of Count Parkwide Par
Page 134 and 135: 118 Counts and estimates of mule de
Page 136 and 137: 120 Northern Yellowstone winter ran
Page 138 and 139: 122 Population estimates and reduct
Page 140 and 141: 124 Actual count Inside Outside Est
Page 142 and 143: Pronghorn counted during spring sur
Page 144 and 145: 128 Year 1939 1940 1941 1942 1943 1
Page 146 and 147: Ground and aerial counts of bighorn
Page 148 and 149: REFERENCE LIST NOTES ON THIS REFERE
Page 150 and 151: Pages 199-210 in Carbyn, L.N., S.H.
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mammal mortality in the 1988 Yellow
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National Park. International Journa
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Mehus, C.A. 1995. Influences ofbraw
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Pages 127-138 in F.J. Singer, ed. E
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some northern Yellowstone elk. M.S.
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