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

More documents

Recommendations

Info

THE NORTHERN RANGE 82 Competition theory suggests that diet and habitat overlaps between species should decline, that is, the usable niche of each species should diverge and be more restricted, if they are competing. This is the opposite of what was observed on the northern range (Singer and Norland 1994, 1996). Two lines of evidence for direct competition between elk and the less abundant ungulates were investigated: 1) if they were in serious competition, elk numbers should depress the population growth rates of other ungulate populations, and 2) if they were competing for a food item or habitat, the diet and/or habitat overlaps between pairs of ungulate species should decline. Neither Barmore's (1980) study from 1962 to 1970 nor Houston's (1982) study from 1970 to ' 1979 suggested direct competition between elk and mule deer, pronghorn, or moose. However, Houston (1982) found significant association between elk and bison numbers, and both Houston and Barmore considered elk-bighorn sheep competition at least a possibility. Houston pointed out that Keating (1982) found competition between elk and bighorn sheep. Total ungulate numbers on the northern range nearly tripled between 1969 and 1988, so the differences in ungulate population growth rates, diet overlaps, and habitat overlaps were compared between the 1960s data and the period between 1986 and 1988 for possible evidence of increasing competition between ungulate species (Singer and Norland 1994, 1996). Singer and Norland found no evidence that the population size of elk had a major depressing influence either upon popUlation growth rates or on productivity rates of other ungulates. These are important findings, but it must be stated that the possibility that elk numbers slowed the population growth rates of the other species can not completely be ruled out, particularly with bighorn sheep, mule deer in the Boundary Line Area, and moose throughout the northern range, because no control situations existed for the studies. Singer and Norland (1994, 1996) found that elk and pronghorn diets did not change significantly between the 1960s and the 1980s. Bison, mule deer, and bighorn sheep diets did change. Bison ate 19 percent more grasses and 24 percent less sedges, while mule deer ate 14 percent less grasses and 7 percent more shrubs. Bighorn sheep diet changes were more subtle. They ate 7 percent more grasses, 3 percent more shrubs, and 10 percent less forbs. Apparently, bison changed their diets due to range expansion to include winter range areas with more rolling terrain, more grasses, and fewer sedges. Non.e of the diet changes suggested any decline in the number of forage species. None of the diet changes were consistent among the ungulate species. For example, two ungulate species ate more grasses, but three species ate fewer grasses; three ungulates ate more shrubs, but two ate less; and three ungulates ate more conifers, but two species ate less. None of the diet changes were interpreted as evidence that forages were limited, or that the northern range was overgrazed. Only 3 of 10 possible diet overlaps between species of ungUlates, and only 2 of 30 possible habitat overlaps, changed between the 1960s and the 1980s. All the diet and habitat overlaps increased. These changes do not suggest that ungulates were competing for resources in short supply. BISON The bison of Yellowstone National Park were almost extirpated from the park by market hunters prior to 1900 (Appendix B) (Meagher 1973). A few dozen animals survived in the wild in 1902, when additional animals from domesticated herds elsewhere in the country were introduced to Yellowstone. For almost a half century, a small wild herd roamed Yellowstone and a larger, intensively managed semi-domesticated herd was established on the northern range, where it was subjected to a variety of ranching and husbandry practices until the 1950s (Figure 7.1) (Meagher 1973). Roughly concurrent with elk reductions, the park bison popUlation was reduced from 1,477 in 1954 to 397 in 1967 (Figure 7.2). When reductions ceased, the entire park population grew steadily to more than 3,900 the mid-1990s (Meagher, U.S. Geo!. Surv., unpub!. data). For centuries bison have survived winters in the Yellowstone area by
ELK AND OTHER SPECIES 83 Figure 7.1. At its most extensive period, prior to the 1950s, the "Buffalo Ranch" operation ill the Lamar Valley iI/valved not only the ranch facilities, but introduction of exotic feed grasses ill the valley, manipulation of animal movements in the valley (note the felice reaching clear across the valley), Gnd other husbandry of the valley's plGllts Gild a1limals. NPS photo. migrating to low-snowpack geothermal areas inside the park, and to lower elevation ranges found within and outside present park boundaries (Figure 7.3). Bison have wandered outside park boundaries periodically for the past century but disease concerns by state and other federal agencies in the late 1960s and early 1970s forced the park into signing "bound31y control agreements" with each of the adjacent three states. These agreements began the "official" policy of excluding bison outside park boundaries, even when they roamed on publicly-owned wildlands such as the national forests. By the winter of 1988-1989, the northern bison herd numbered about 900, most of whom migrated to or beyond the northern boundruy that winter, resulting in the killing of 569 by sport hunters and state management agencies. In the winter of 1996-1997, unprecedented snowfall and icing conditions forced an even greater number of bison to seek lower elevation ranges outside park boundaries and over 1,000 were killed in Montana by state and federal officers. The presence of brucellosis in Yellowstone bison has been controversial for many years (Meagher 1989a, 1989b; Price and Schullery 1993), and has greatly complicated bison conservation in Yellowstone, originally seen as one of the great early successes of the conservation movement (Haines 1977). The increase in numbers of bison leaving the park, especially to the north and west, in the late 1980s and early 1990s has also caused concerns related to overpopulation. These migrations are seen by SOme people as somehow Figure 7.2. Elk and bison ill holdillg corrals, 1961. Bison as well as elk were ,·educed to l'ely low numbers during the 1960s. NPS photo.
Page 1:
YELLOW"STONE'S NORTHERN RANGE COMPL
Page 4 and 5:
.. •.
Page 6 and 7:
Suggested citation: Yellowstone Nat
Page 8 and 9:
c=J Northern Winter Range _ Boundar
Page 10 and 11:
Aspen, willows, and biodiversity ..
Page 12 and 13:
vii
Page 14 and 15:
THE NORTHERN RANGE xii range criter
Page 16 and 17:
L ~I , }! \,.'1. J 4 f ; " IF , , 1
Page 18 and 19:
THE NORTHERN RANGE 2 Figure 1.1. Ph
Page 20 and 21:
THE NORTHERN RANGE tion. There was
Page 22 and 23:
THE NORTHERN RANGE 6 Figure 1.6. Gr
Page 24 and 25:
THE NORTHERN RANGE 8 Figure 1.8. El
Page 26 and 27:
THE NORTHERN RANGE 10 unpopular or
Page 28 and 29:
THE NORTHERN RANGE 12 earlier Yello
Page 30 and 31:
, ! ~ , I~ " 1 \, • .' '-, , \, ,
Page 32 and 33:
THE NORTHERN RANGE 16 Northern rang
Page 34 and 35:
Figure 2.3. Sum ot rotal annual riv
Page 36 and 37:
THE NORTHERN RANGE 20 Figure 2.4 Tr
Page 38 and 39:
THE NORTHERN RANGE 22 dendrochronol
Page 40 and 41:
THE NORTHERN RANGE 24 Figure 2.7. A
Page 42 and 43:
THE NORTHERN RANGE 26 et al. (1991)
Page 44 and 45:
THE NORTHERN RANGE 28 earlier time,
Page 46 and 47:
.', P (/ i0~ , • 9 ~ § , , ~ , i
Page 48 and 49: THE NORTHERN RANGE 32 systems-range
Page 50 and 51: THE NORTHERN RANGE 34 indicates the
Page 52 and 53: 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
Page 58 and 59: , ~ , • V , '. ~ ;' t ~ " ~ .' .~
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
Page 96 and 97: 4 , ~ 1 v " 'It , \ J~ ~""~ .:,~ ",
Page 100 and 101: Figure 7.3. Bison winter range. Sin
Page 102 and 103: THE NORTHERN RANGE Figure 7.7. Envi
Page 104 and 105: THE NORTHERN RANGE 88 not aware of
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
Page 112 and 113: THE NORTHERN RANGE 96 factors were
Page 114 and 115: THE NORTHERN RANGE Figure 7.13. Num
Page 116 and 117: , .. , , " , ! I ." ~, ~ " ,.\ ,•
Page 118 and 119: THE NORTHERN RANGE 102 complex set
Page 120 and 121: THE NORTHERN RANGE 104 practically
Page 122 and 123: THE NORTHERN RANGE 106 appear suppr
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.
Page 152 and 153:
Yellowstone National Park. Technica
Page 154 and 155:
mammal mortality in the 1988 Yellow
Page 156 and 157:
National Park. International Journa
Page 158 and 159:
Mehus, C.A. 1995. Influences ofbraw
Page 160 and 161:
__ , and __ . 1996a. Preburn root b
Page 162 and 163:
Pages 127-138 in F.J. Singer, ed. E
Page 164 and 165:
some northern Yellowstone elk. M.S.
Page 166:
I I I I I
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?