PLEASE RETURN POPULATION ECOLOGY OF MULE DEER WITH EMPHASIS ON POTENTIAL IMPACTS OF GAS AND OIL DEVELOPMENT ALONG THE EAST SLOPE OF THE ROCKY MOUNTAINS, NORTHCENTRAL MONTANA MONTANA STATE LIBRARY S 599.7357 F2pe 19827 c.2 Ihsle T 111 j"on ecol°9» °< m"le deer with emp MAK 221989 3 0864 00038975 2 STATEMENT OF PERMISSION TO COPY In presenting this thesis in partial fulfillment of the require- ments for an advanced degree at Montana State University, I agree that the Library shall make it freely available for inspection. I further agree that permission for extensive copying of this thesis for schol- arly purposes may be granted by my major professor, or, in his absence, by the Director of Libraries. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission. Signature Date Digitized by the Internet Archive in 2014 http://archive.org/details/populationecolo1982pach_0 ii VITA Helga Beate Ihsle was born July 24, 1955 in Berlin, Germany to Gertrude and Wolfgang Ihsle. She graduated from Van Nuys High School, Van Nuys, California in June 1973. In June 1979 she received a Bachelor of Science degree in Fish and Wildlife Management from Montana State University, Bozeman. In January 1980 she began studies toward a Master of Science degree in Fish and Wildlife Management. iii ACKNOWLEDGMENTS I wish to express my sincere appreciation to the following peopl for their vital contribution to this study: Dr. Lynn Irby, Montana State University, for direction of the study, assistance, and guidanc in preparation of the manuscript; Dr. Richard Mackie and Dr. Robert Eng, Montana State University, and Dr. John Weigand, Montana Fish, Wildlife and Parks Department, for critically editing the manuscript; Dr. William Gould and Dr. Jack Taylor, Montana State University, for reviewing the manuscript; Mr. Steve Rumley for drawing the cover, Mrs Dorothy Levens for typing the manuscript; Mr. Gary Olson, Mr. John McCarthy, Mr. Dan Hook, and Ms. Gayle Joslin, Montana Fish, Wildlife and Parks Department, for technical and field assistance; Mr. Wayne Kasworm, for invaluable assistance in every phase of the study; Mr. Jack Jones and Mr. Wayne Elliot for project planning and field assis- tance; Mr. James Mitchell, Mr. Terry Lonner, Mr. Bert Goodman, Mr. Bill Hill, Dr. Henry Jorgensen, and Mr. Kenneth Greer, Montana Fish, Wildlife and Parks Department, for providing equipment and assistance Dr. John Rumely, for aid in identification of plant specimens; Mr. Doug Getz, Mr. Cliff Higgins, Mr. Jim Heppner, Mr. Mark Duffy, and Mr Gene Sherman, whose flying skills aided immensely; Mr. Lloyd Swanger, Mr. Lewis Young, and employees of the Lewis and Clark National Forest for assistance and use of facilities and equipment; and all those who who assisted in drive-netting. I would also like to thank local iv landowners for their cooperation, friendship, and help, especially Mr. and Mrs. Bud Olson, Mr. and Mrs. Larry Dellwo, Mr. Tom Salansky, Mr. and Mrs. Mark Priewert, Mrs. Mary Knowlton, Mr. and Mrs. Dean States, Mr. and Mrs. George DenBoer, Mr. and Mrs. Albert DenBoer, Mr. and Mrs. Otis Bryan, Mr. and Mrs. Al Haas, Mr. and Mrs. Ken Gleason, Mr. and Mrs. Wayne Gollehon, Mr. and Mrs. Chuck Blixrud, Mr. Dave Barrett, Mr. and Mrs. Kenny Duncan, Mr. and Mrs. Ted Crawford, Mr. Evan Campbell and family, Mr. and Mrs. Dick Klick, Mr. and Mrs. Jim Boadle, Mr. Parocai, Mr. Don Anderson, Mr. Bill Rappold, Mr. Karl Rappold, Mr. and Mrs. Faye Lear, Ms. Maureen Lear, Ms. Madeline Rands, Mr. Bob Kiesling and the Nature Conservancy and Mr. and Mrs. Mark Talaferro. I also wish to express special thanks to Mr. Dave Pac for encouragement, inspiration, and friendship; and to my family and many unnamed friends for encouragement and friendship. The East Slope Rocky Mountain Front Mule Deer Study and Investigation was supported by the Bureau of Land Management through a contract (YA- 512-CT9-33) to the Montana Department of Fish, Wildlife and Parks. TABLE OF CONTENTS Page VITA ii ACKNOWLEDGMENT iii TABLE OF CONTENTS v LIST OF TABLES vii LIST OF FIGURES x ABSTRACT ..... xi INTRODUCTION 1 STUDY AREA 3 Geology 3 Climate . . . 5 Land Use 7 Winter Range 7 Summer Range 7 Vegetation 8 METHODS 9 Seasonal Distribution and Population Dynamics 9 Habitat Characteristics and Use 10 Gas and Oil Impacts 11 RESULTS 12 Seasonal Distribution, Movements, and Home Ranges .... 12 Seasonal Distribution and Movements 12 Home Ranges 16 Fidelity 20 Population Dynamics 21 Habitat Characteristics and Use 30 Habitat Characteristics 30 Mule Deer Habitat Use 35 Gas and Oil Impacts 42 vi TABLE OF CONTENTS (CONTINUED) Page DISCUSSION AND CONCLUSIONS 47 Seasonal Distribution , Movements, and Home Ranges 47 Population Dynamics 53 Habitat Characteristics and Use 54 Hydrocarbon Exploration Impacts 56 MANAGEMENT IMPLICATIONS 59 APPENDIX 66 LITERATURE CITED 79 LIST OF TABLES Table Page 1. Average temperature (°C), total precipitation (cm), total snowfall (cm) , and deviation from the long term average for 3 weather stations along the East Front from October 1980 through September 1981 (U.S. Dept. of Commerce 1980-1981) 6 2 2. Areas (km ) of population units, total and primary winter ranges, and associated transition ranges of mule deer on the East Front during 1979-1981 15 2 3. Summer and winter home range sizes (km ), number of relocations (N) , and seasonal home range means (km^) for mule deer on the East Front during 1979-1981 19 4. Total, numbers and proportions of marked animals observed and Lincoln index estimates during March and April for helicopter surveys of mule deer between Birch Creek and Sun River, 1980-1981 22 5. Number and classification of deer in the early winter helicopter survey on the East Front on January 12-13, 1981 on 5 winter ranges 23 6. Number and percent composition of adult and fawn mule deer on 5 winter ranges on the East Front, January through April, 1981 24 7. Early and late winter fawn: adult ratios for mule deer and Chi-square test values with associated signifi- cance levels (p) on the East Front in 1980 and 1981 .... 25 8. Fawns :100 adult mule deer for 1979-1980, 1980- 1981, long term means, and standard deviations for populations on the East Front in 2 MDFWP management units from 1961-1979 26 9. Numbers and percentages of sex and age classes for mule deer captured during drive-netting on the East Front in 1981 28 yiii LIST OF TABLES (CONTINUED) Table Page 10. Numbers and percentages (by sex and age classes) of mule deer checked during 9 days at the Teton Check Station in autumn 1980 28 11. Data on deer hunters and deer harvest from check stations on the East Front study area during autumn 1980 29 12. Origin of hunters (%) checked during 9 days by county and hunting districts in autumn 1980 on the study area : 29 13. Number of male and female radioed and neckbanded deer marked, accounted for, and unaccounted for from 1973-1980 on the East Front from Birch Creek to Sun River 30 14. Area (km ) and percentages of vegetation cover types for 3 low deer use areas, 2 transition ranges and 5 winter ranges3 on the East Front during 1980- 1981. Variations in proportions of cover types among areas are expressed as coefficients of variation (C.V.) 31 15. Chi-square analysis of availability of vegetative cover types among: low use zones and winter ranges; transition ranges and low use zones; and transition ranges and winter ranges3 = 34 2 a 16. Summary of Chi-square (x ) analysis of observed deer use vs. availability for 3 environmental variables 38 17. Average elevations at 3 low use zones, 2 transition ranges, and 6 winter ranges. Average elevations (m) of deer observations on 5 winter ranges during 1980-1981 41 18. Contents of 5 mule deer rumens (by percent volume) collected in the study area during 1980-1981 43 ix LIST OF TABLES (CONTINUED) Table Page 19. Amounts and percentages of vegetation cover types found on individual winter ranges (Kasworm 1981) , transition ranges, and low deer use zones on the East Front from 1980-1981 67 20. Descriptions of cover types not previously described by Kasworm (1981) 68 21. Key to 4-letter plant species abbreviations 69 22. Plants collected during 1980 and 1981 on the East Front study area 70 LIST OF FIGURES Figure Page 1. Map of the East Front study area showing major features . . 4 2. Map of the East Front study area (Kasworm 1981) showing total and primary winter ranges, and transitional ranges as observed during 1979-1980, and 1980-1981. .... 13 3. Map of the East Front study area showing tentative population units associated with winter ranges observed during 1979-1981 17 4 . Locations of summer and winter home ranges for collared mule deer on the East Front during 1978-1981. ....... 18 5. Age class distribution (%) for mule deer captured during drive-netting on the East Front in 1980 and 1981 27 6. Map of the East Front showing 3 low use zones, 2 transition areas, and Swanson Ridges that were vegeta- tively and topographically sampled during 1981 33 7. Aspect distribution (%) on 3 low use zones, 2 transition ranges and 6 winter ranges for mule deer on the East Front during 1979-1981 36 8. Percentages of 4 slope categories found on 3 low deer use zones, 2 transition areas, and 6 winter ranges for mule deer on the East Front during 1979-1981 . . 37 9. Observed deer use (%) of 4 slope categories relative to availability on 5 winter ranges on the East Front during 1980-1981 39 10. Percentages and average aspects that deer were observed occupying on 5 winter ranges during 1980-1981. . . 40 11. Gas well locations, proposed well locations, and seismic lines run on the East Front 1980-1981 44 12. Home ranges of 4 radio-collared mule deer in winter 1979-1980 (prior to gas and oil activity at the Blackleaf- Teton winter range) and in winter 1980-1981 (during activity at the Blackleaf-Teton winter range) 46 xi ABSTRACT A study was conducted on the East Front of the Rocky Mountains in northcentral Montana from June 1980 to September 1981, It was the second phase of a 2-part investigation designed to collect quantita- tive baseline information on mule deer seasonal distribution, move- ments, population characteristics, and habitat use on a representative portion of the East Front subject to gas and oil exploration and development. Six, and possibly 7, population units were delineated by winter range origin. A total of 6,000 to 7,000 mule deer were included in these units. Monitored deer showed a high degree of fidelity to seasonal ranges. Three out of 78 marked deer were known to have dispersed from one winter range to another. Mean winter home range size for females was larger in 1980-1981 (6.0 km2) than 1979- 1980 (4.6 km2). Three summer range segments were confirmed from previous work. Of 22 radio-collared deer, 14% were residents, 59% summered east of the Continental Divide, and 27% summered west of the Continental Divide. Mean summer home range was 6.4 km2 in 1979, 3.5 2 ? km in 1980, and 1.4 km in 1981 for female deer. Population estimates indicated that the population wintering on the study area increased by 6% from 1980 to 1981. Ratios of fawns per 100 adults were lower (49.8 in early winter, 49.8 in late winter) in 1981 than in 1980 (69.3 in early winter, 61.7 in late winter). This decrease was attributed to a higher proportion of non-productive yearlings in the population. The age structure and high proportion of males (19 antlered per 100 non- antlered) indicated a healthy population that could withstand greater harvest than occurred during the study. At least 90% of deer summering north of the Sun River and west to the South Fork of the Flathead River winter on the study area. Winter ranges were separated by low deer use zones. Low deer use zones had a lower percentage of moderate to steep slope categories and a lower proportion of southerly aspects than core winter ranges. Mule deer apparently preferred moderate slopes, higher elevations, south and east aspects, and limber pine timber types within core winter ranges. Impacts of gas and oil exploration were difficult to assess due to the low intensity of activity, the mild winter condi- tions, and low density of deer in the vicinity of the only active well sites during this study. Implications of more intense development were discussed. INTRODUCTION The east slope of the Rocky Mountains in northcentral Montana provides winter habitat for a large mule deer (Odoaoileus hemtonus) population. This area has a high potential for gas and oil production, and commercial quantities of gas have already been discovered. By October, 1981, 4 producing gas wells had been drilled between the Muddy and Dupuyer Creek drainages. At least 3 additional wells will be completed in 1982 on this area, and seismic lines are continually being surveyed by several companies. Knowledge of mule deer wintering along the East Front is essential if impacts of gas and oil exploration on this species are to be ascertained. This study, conducted from June 1980 through September 1981, represents the second phase of a 2-part investigation. The first phase was conducted from June 1979 through September 1980 (Kasworm 1981). These studies were designed to collect baseline information on mule deer, including seasonal distribution, movements, population dynamics, and habitat use, to evaluate potential conflicts between hydrocarbon exploration and deer, and to develop management guidelines. Previous studies and management surveys on deer in this area by Montana Department of Fish, Wildlife and Parks (MDFWP) personnel have provided some information on range use, food habits, reproduction and population trends (Schallenberger 1966, McCarthy et al.1978, 1979, 2 1980). Background information on the area is available from studies on grizzly bear (Jrsus arotos) (Sumner and Craighead 1973, Hamlin and Frisina 1973, Schallenberger 1974, 1976, Jonkel 1976, 1977, Schallen- berger and Jonkel 1978, 1979, 1980, and Aune 1981), Rocky Mountain bighorn sheep {Ovis canadensis) (Schallenberger 1966, Erickson 1972, Frisina 1974), Rocky Mountain elk (Cervus elaphus) (Picton 1960, Knight 1970, Picton and Picton 1975), and Rocky Mountain goats (Oreamnos amevicanus) (Thompson 1981). STUDY AREA 2 The 2,725 square kilometer (km ) study area (Fig. 1) was located in and adjacent to the Sawtooth Range along the east slope of the Rocky Mountains in western Teton, Pondera, and Flathead Counties, Montana. It was bordered on the north by the Blackfoot Indian Reservation and on the south by the Sun River. Important drainages on the study area included Birch Creek, Muddy Creek, the Teton River, Deep Creek, the Middle Fork of the Flathead River, and the Sun River. The center of the area was approximately 40 km west of Choteau. Most (85%) of the area consisted of public lands administered by the Lewis and Clark and Flathead National Forests. Remaining lands were administered by the Bureau of Land Management (BLM) or owned by private organizations, private individuals, and the State of Montana. The BLM administered 95% of the mineral rights on the study area. Geology Geological characteristics of the study area have been described by Gieseker (1937), Deiss (1943) and Johns (1970). The East Rocky Mountain Front is composed of a combination of parallel north-south extending ridges, characterized by abruptly sloped east faces and moderate west facing slopes, separated by precipitous drainage val- leys. During the early Cenozoic era, the Lewis overthrust pushed late Precambrian and Paleozoic limestone and shales over more recent Mesozoic sediments, creating a situation conducive to petroleum 4 Figure 1. Map of the East Front study area showing major features. 5 deposition and accumulation. Glaciation and erosion have created the buttes, ridges, and foothills dissected by small drainages that char- acterize mule deer winter ranges along the mountain front. Elevations range from 1,311 meters (m) to 1,798 m on winter ranges and from 1,707 m to 2,863 m on summer ranges. Climate Climatological data for 3 weather stations along the East Front are presented in Table 1. Gibson Dam (GD) was located at the southern end of the study area. The Choteau (CH) and Blackleaf (BL) stations represent midway points. Blackleaf was closer to the Front, but data were incomplete for some months; therefore, Choteau was included to show trends. Average annual precipitation at these stations ranged from 35 to 56 centimeters (cm). Winter precipitation was higher than average in 1978-1979 and 1979-1980 (Kasworm 1981) and lower than average in 1980-1981. Average annual temperature in the area is about 5°C. The 3 winters covered during this study were climatically very different. Temperatures in 1978-1979 were much lower than average, in 1979-1980 they were approximately average (Kasworm 1981) , and in 1980-1981 they were slightly above average. Very strong southwesterly chinook winds characterize this area and can influence deer behavior and distribu- tion on the winter ranges. 6 T— * C 1 4J o CO CO CO Oh w I— i U 0) o v — ' X3 o 4J u iH CU i— t bO co C! •4— < O 0 r-l o CO c m ns 4-1 O iH o 4J cd •H a u 4J - rH OO i-i r*+ JS CO CO c£ 4J D O S O 4-1 u u JS 4-t 4-1 — - oo o o c CO o CTi rH i — 1 a> CD u D JS cu 4-1 u & CO 0 s-l a 4-1 0) o u M o ? 14-4 e 4-1 c o o u o > CU rJ X! [4- m o> cn n h CN m \D CN CN m nD CTi rH rH CN + + rH <■ r- r- co CO H 7 Land Use Winter Range The Ear Mountain Game Range and the Blackleaf Game Range, adminis- tered by MDFWP, were located on the study area. Livestock grazing was prohibited on both areas. Most (90%) mule deer winter range, however, is located on private and public land used for livestock grazing dur- ing spring, summer, and fall. A small subdivision is located on a portion of the Ear Mountain winter range. A few guest ranches are located in this area and in the Sun River drainage . White-tailed deer (Odocoileus virginianus) , elk, bighorn sheep, mountain lion (Felis ooncolor) , black bear (Ursus americanus) , and coyotes (Canis Zatvans) commonly occur on mule deer winter range. This area also provides important habitat for a grizzly bear popula- tion. Hydrocarbon exploration activity on the study area commenced in the 1950' s but was followed by 20 years of no activity. Recent activ- ity began in 1979, and the first new well was drilled in 1980. The renewed interest in oil and gas development has led to marked increases in road building, seismic line blasting, drilling, heli- copter traffic, and human disturbance. Summer Range Most of the summer range lies within the Lewis and Clark and 8 Flathead National Forests. This area includes portions of the Bob Marshall and Great Bear Wildernesses. Some livestock grazing allotments exist on BLM and Forest Service land. A small ski resort is located on the Teton road in the Lewis and Clark National Forest. Timber harvest occurs in small amounts. This area has important recreational values for backcountry use as well as supplying habitat for elk, white-tailed deer, mountain goats, bighorn sheep, black bears, and grizzly bears. Vegetation Vegetation on the study area was discussed in detail by Kasworm (1981). Lower elevations were characterized by short grass prairie and shrublands interspersed with buttes and ridges covered by limber pine (Pinus flexilis) savannahs and forests. Aspen (Populus tvemu- loides) and cottonwood (Populus tvichooavpa) stands were scattered along drainages and foothills. At higher elevations, Douglas fir (Pseudotsuga menziesii) , lodgepole pine (Pinus oontorta) , and sub- alpine fir (Abies lasiocavpd) dominated the forests. Sagebrush (Artemisia tvidentata) or shrubby cinque-foil (Potentilla fvutioosa) and grassland habitat types were also common at higher elevations. Extensive areas of serai grass/shrublands were found on burned sites. METHODS Seasonal Distribution and Population Dynamics Deer were captured using a helicopter drive net (Beasom et al . 1980) or baited panel traps (Lightfoot and Maw 1963) and were marked with radio transmitting collars or 10-cm-wide Armor-tite neckbands (Mackie et al . 1978) . A total of 149 deer were marked during 1978- 1981. Twenty-five were equipped with radio-transmitting collars, and 122 were outfitted with individually recognizable neckbands. Two fawns, captured by hand, were marked with orange ear tags in 1980. Radio relocation flights for my segment of the study were made twice a month, weather permitting. A total of 60 flights were con- ducted from March 1979 through October 1981 using either a Piper Super Cub equipped with a 3-element Yagi antenna or a rotational antenna or a Cessna 180 outfitted with twin whip antennas. Radio relocations from both segments of the study (1979-1980 and 1980-1981) were analyzed using the TELDAY computer program (Lonner 1981) for calculation of seasonal home range sizes and activity cen- ters used by radio-equipped deer. Chi-square and analysis of variance techniques (Snedecor and Cochran 1980) were used to test differences in home range size and consistency between population segments, indi- vidual deer, and years. Analyses were run on a Honeywell Level 66 computer . Winter distributions, sex ratios, and population estimates were determined by helicopter (Bell 47G 3B-2) surveys conducted in January, 10 March, and April of 1981. Population estimates were derived as Lincoln indexes from observations of marked and unmarked deer as described by Overton and Davis (1969). These surveys were compared with results from surveys in 1980 (Kasworm 1981). Ground observations were conducted on each of 5 winter ranges at least twice a month from January through March 1981. Deer were classi- fied as bucks (males >1 year), does (females >1 year), or fawns (<1 year) through January and later as adults (>1 year) or fawns (<1 year). Observations were plotted on 1:24,000 topographic maps. Slope, aspect, and habitat type at each sighting were noted. Hunters were checked on 9 days during the 1980 hunting season to determine hunting pressure, hunter distribution, and the location, sex, and age of deer shot. Hunter-killed deer were aged by tooth replacement and wear (Robinette et al. 1957). Collar returns from marked deer were used to determine location and timing of mortality. Habitat Characteristics and Use Vegetation cover-type maps and measurements made for most winter range sites were presented by Kasworm (1981). I described, typed, and mapped 1 additional winter range, fall and spring transition areas, low-use areas, and drill sites using techniques and habitat descrip- tions similar to those described by Pfister et al . (1977) and Mueggler and Stewart (1980) . Plant taxa were verified in the Montana State 11 University Herbarium. Nomenclature followed Hitchcock and Cronquist (1973). Availability of vegetation types, slope, aspect, and elevation within seasonal range units was determined using a random sampling technique (Marcum and Loftsgaarden 1980) in conjunction with vegeta- tion-type and topographic maps. Range units and observed deer use of habitat within units were compared using Chi-square analyses (Snedecor and Cochran 1980) . Five rumens were collected on the study area and analyzed using macro-histological methods developed by Wilkins (1957). Gas and Oil Impacts Type, location, and duration of hydrocarbon- related activity on the study area was noted, mapped, and monitored when possible. Several approaches were used in attempts to measure direct mule deer responses to activity. Efforts to conduct track surveys were hampered by the absence of adequate snow cover. When possible, aerial transects were flown near active well locations to count and record the distribution of deer in relation to drill sites. An observation of behavioral responses to seismic activity was made on 1 occasion. Distributions of radio-marked mule deer prior to and after hydrocarbon activity were compared. RESULTS Seasonal Distribution, Movements, and Home Ranges Seasonal Distribution and Movements Kasworm (1981) delineated 6 winter ranges on the study area. I delineated 1 additional winter range, Swanson Ridges, located adjacent to the Dupuyer Creek winter range (Fig. 2). It may represent an extension of the latter or a secondary range used in mild winters and/or at high mule deer population densities. The total and core area sizes for each winter range based on 1980-1981 and earlier (Kasworm 1981) deer distributions are given in Table 2. Transition areas (Table 2) were delineated from observations during spring and fall, 1979-1981. Some radio-collared deer from summer ranges west of the Continental Divide (WOD segment) used the transitional range extensively for 2-3 months in the fall before mov- ing onto the winter range. Migratory deer summering east of the Divide (EOD segment) and resident deer (RES segment) either stayed on their individual summer ranges as long as possible before moving directly to the winter range or moved onto transitional range up to 8 weeks after WOD deer. WOD deer moved onto transitional areas with the first severe snow storms in late October-early November of 1980 and 1981. Migratory deer moved back onto transitional range enroute to summer ranges in late May-early June of 1981, about the same time as in 1979 and 1980 (Kasworm 1981). Figure 2. Map of the East Front study area (Kasworm 1981) showing total and primary winter ranges, and transitional ranges as observed during 1979-1980, and 1980-1981. Figure 2. Continued. 15 Table 2. Areas (km ) of population units, total and primary winter ranges, and associated transition ranges of mule deer on the East Front during 1979-1981. Winter Range Location of Population Unit Total Population Unit Total Winter Range Primary Winter Range Associated Transition Range Scoffin Butte 339 26.6 10, .2* DnniivpT PtppW 31 . 6 13, .4* 24.9 Swanson Ridges 29.2 10, ,6 Blackleaf-Teton 328 80.8 20. ,9* 53.5 Ear Mountain 375 44.0* 16. .6* 47.1 Long Ridge 37.6* 23. , 9* 12.3 Castle Reef 1056 38.9* 18. ,1* Total 288.7 Kasworm (1981) Overall, 6 (27%) of the deer with functional radio collars sum- mered west of the Continental Divide, 13 (59%) summered east of the Divide but off the winter range, and 3 (14%) were yearlong residents on or in proximity to the winter range. Approximately 63% of the deer radioed on the Blackleaf-Teton winter range summered west of the Divide, the highest proportion for any winter range. Tentative yearlong herd ranges or population units (Mackie et al. 1980) of mule deer associated with the 5 major winter ranges on which 16 radio-collared deer occurred are shown in Figure 3. These ranges were estimated from the summer distribution of radio-collared and neck- banded deer relocated during the summers of 1979, 1980, and 1981 (Fig. 4). Collared deer from the Blackleaf-Teton winter range were relo- cated as far west as the Spotted Bear Ranger Station (57 air km) in summer. One doe, marked on the Scoff in Butte winter range, was sighted in the summer of 1977 and subsequently killed in the winter of 1978 near Glacier National Park, approximately 64 airline kilome- ters northwest of its winter range. A doe from the Castle Reef winter range was relocated 37 airline kilometers to the west, near White River Pass. Home Ranges Home range sizes, based on all relocations during 1979-1981, are given in Table 3. Total summer range used by 7 deer for which 3 years 2 2 of data were available averaged 8.9 km in 1979, 3.5 km in 1980, and 2 1.4 km in 1981. The decrease between years was significant (ANOVA, p<.05). Deer summering west of the Continental Divide individually 2 used significantly larger total summer home ranges (x = 13.8 km ) _ 2 than EOD deer (x = 8.5 km ) for the 3 years. WOD deer also used larger annual summer home ranges than EOD deer (ANOVA, p<.05). Summer 2 home ranges of EOD deer were significantly larger in 1979 (6.0 km ) 2. 2 than in 1980 (2.9 km ) and 1981 (1.4 km ). Annual summer home ranges Figure 4. Locations of summer and winter home ranges for collared mule deer on the East Front during 1978-1981. 19 2S KS22 r 1S.0 7.0 o *\ 5.5 19.7 12.8 8.6 5.0 1.6 7.2 23.5 3.5 9.8 34.8 !: a 12.5 10.7 10.5 26.7 9. 4 9.2 12.6 42.2 3.5 16.0 8.5 10.8 14.0 11.7 13.0 5.6 6.9 20.9 23 SI "Sa"^ 2^ °^2' s " * * s ~ * ~ •-■ ' 3 S |J| r-c-or-.eN iOOmHK)| mo S " ;232 2' u-i u-i .05) between 2 2 2 years but averaged 7.5 km in 1979, 3.3 km in 1980, and 2.2 km in 1981. Total winter home range used by individual radio-collared deer 2 over the 3 years averaged 14.2 km . Winter home range size for indi- 2 2 2 vidual years averaged 3.4 km in 1979, 4.6 km in 1980, and 6.0 km in 1981. There were no statistical differences in the average size of winter home ranges between years or between winter ranges for the same year. Fidelity Fidelity of radio-collared animals to summer range was strong. Only 1 of 16 females for which 2 or more years of data were available changed its summer range between years. That doe switched ranges between 1979 and 1980. All radio-collared deer returned to the same winter range on which they were trapped, and only 1, a doe, significantly changed its activity center within a winter range between years. Three neck-banded males were known to have changed winter ranges between 1980 and 1981. One, a yearling trapped at Antelope Butte in 1980, wintered west of the Continental Divide near the Spotted Bear Ranger Station in 1981. The others, a yearling and a 3-1/2-year-old, were trapped 21 at Ear Mountain in 1980 and relocated the following winter at Castle Reef. Population Dynamics Fewer animals were seen during helicopter surveys of winter ranges in 1981 than in 1980 (Table 4). The March survey provided the best 1981 winter population estimate since the reduced proportion of marked animals observed in April indicated some prior movement of deer to transition ranges. A non-stratified Lincoln index estimate from the March survey data indicated a population of 6,014 on the study area in late winter 1981, an increase of about 6% over March 1980. The highest proportions of bucks were recorded on the Scoffin Butte and Castle Reef winter ranges. The January 1981 helicopter survey indicated the sex ratio was 19 antlered bucks: 100 antlerless deer (Table 5) for the winter ranges surveyed. Ground observations on 5 winter ranges (Table 6) showed no sta- tistical differences in sex (antlered: antlerless) and age (fawn: adult) ratios between areas. Fawn: adult ratios were lower in 1981 than in 1980 during both early (January-February) and late (March- April) winter classifications (Table 7). Chi-square analysis of ratios for individual winter ranges indicated that Dupuyer Creek and Castle Reef contributed most to the decrease between years. 22 a H 3 a E cfl in O CO > u to u O CO CO >-4 i — i 01 id •U G P. -rH o a CJ A •H i-( T3 01 JS u u ra o iH E m 00 a- i-H rH o •H 1 M O CO a oo a < CJ> 0 ■H 13 4J C td o a> 0. £} > o O M a S3 c c oo co CO e o m CO CM 00 in X ■a 00 at at c ■o .14 a •H c \D V© m 00 T-i T> M u gd ro B c o n X JO 4J o ■H JO 00 O a C 3 0 u 0) cn c H 0 a 00 H a a 0 u u CJ cu 23 CD j3 4J c o Q) 3 W H CD o CJ "r~ H _§ }-t CD 4J 0) c 00 c ►> ►> frt w >> ■> s iH 4-1 a) 14-1 3 a 4-) O cu O P. cd M CO H n CJ 3 rH cd cd < C/3 Q W 0 24 co c sr m CO CO CO CO CO N \D MA vO CO ON iH CN m ON O in -*d" on CN o CO CO I— I CN r— 1 i — I O H cu o o co on o r» O CO t-4. O i-H \o rv \o oo in oo a\ nO 00 nO NO CM N CM s H S iH M-4 H s i-H M-l p>» H g i-H 14-1 >> H B i-H CO H-l 3 1 4J H-4 3 1 4-1 <4-4 3 1 4-1 <4-l 3 1 4-1 CJ o Cu ^ l-i CO O a u CO O P-. ^ CO o Cu ^ u n O o 3 i-H to CO O 3 i-l CO O 3 iH CO CO o 3 iH to to C/j — eQ w o CO a m w O CO a ea w u CO Q M w CJ >N 1-1 CO 3 G CO >-) >s U CO 3 u -O CU F*4 -G U CO V4 Cu < 25 CO o 00 X I 2 00 o 00 I •-5 rH rH CO rH CI T— 1 r-H VO o CI ON CO o CO r-. LO LO VD CM St CN CN i—l o> cr> >* 00 LO LO CM cr> CM i-~ rl 0) LO LO CO LO LO st o [-» LO CN i — i vO 00 CO H vO LO CN i-t .05). The drive-net samples, however, indicated some changes in the age structure of deer on the study area between 1980 and 1981 (Fig. 5). Yearlings comprised 54% of mule deer examined at a checking sta- tion maintained for 9 days during the 1980 hunting season (Table 10). Thirty-nine percent of the mule deer checked were females killed during 27 •5 1-5 2.5 33 4.5 5.5 6.5 + AGE CLASS Figure 5. Age class distribution (%) for mule deer captured during drive-netting on the East Front in 1980 and 1981. 28 Table 9. Numbers and percentages of sex and age classes for mule deer captured during drive-netting on the East Front in 1981. Age Class 0.5 1.5 2.5 3.5 4.5 5.5 6.5+ % Males 5 2 1 3 3 1 1 38 Females 6 5 1 7 2 1 4 62 % 26 17 5 24 12 5 12 N = 42 Table 10. Numbers and percentages (by sex and age classes) of mule deer checked during 9 days at the Teton Check Station in autumn 1980. Age Class 0.5 1.5 2.5 3.5 4.5 5.5 6.5+ Unk % Males 4 13 0 2 0 2 1 3 61 Females 2 7 0 3 2 1 0 1 39 % 16 54 0 14 5 8 3 N = 41 the first week when either sex harvest was permitted. Forty-one percent of checked animals were white-tailed deer (Table 11). Hunter success during the check (approximately 10%) was similar to the statewide average (John Cada pers. comm.). Eighty-four percent of the hunters were from counties near the study area. Most (93%) in this sample hunted in hunting districts 441, 442, and 450 (Table 12). Of the total mule deer marked on winter ranges within the study area from 1973 to 1980, 75% were females (Table 13). As of April 1981, 29 Table 11. Data on deer hunters and deer harvest from check stations on the East Front study area during autumn 1980. Check No. of No. of No. of Animals Date Station Parties "Hunters Whitetail Mule Deer 10-26-80 Blackleaf 15 37 1 0 10-26-80 Teton 56 133 8 14 10-29-80 Teton 20 50 1 8 11-1-80 Teton 26 62 4 2 11-2-80 Teton 49 119 1 7 11-8-80 Teton 23 52 5 0 11-9-80 Teton 39 98 6 2 11-11-80 Teton 18 32 0 0 11-29-80 Teton 24 57 1 5 11-30-80 Teton 34 78 0 3 11-30-80 Dupuyer 2 7 _2 0 Total 306 725 29 Table 12. Origin of hunters (%) checked during 9 days by county and hunting districts in autumn 1980 on the study area. County Distribution Hunting District Distribution Counties % of Hunters Hunting District % of Hunters Teton 49 441 32.0 Pondera 21 442 23.0 Cascade 14 450 38.0 Others in 11 406 3.0 Montana 404 0.2 Out of 1 State 421 0.4 Unknown 4 444 0.5 Unknown 3.0 30 Table 13. Number of male and female radioed and neckbanded deer marked, accounted for, and unaccounted for from 1973-1980 on the East Front from Birch Creek to Sun River. Number Accounted for Unaccounted Sex Marked Alive Dead for Male 31 14 7 10 Female _91 45 9 37 Total 122 59 16 47 the status of 61% of these deer were unknown. Thirteen percent of the total deer marked were known to be dead. The status of 32% of the col- lared males and 41% of the collared females was unknown. Fawns and year- lings comprised 80% of the unknown males and 19% of the unknown females. Habitat Characteristics and Use Habitat Characteristics Kasworm (1981) described 20 vegetation types on the East Front win- ter range (Appendix Table 19). I described three additional types, Pseudotsuga menziesii/Symphoricarpos oaaidentalis, Pioea engelmaniil Smilioina stellata, and Abies lasiooavpa / Clematis pseudoalpina (Appendix Tables 19, 20). The amount and percentage of area covered and coeffi- cients of variation in the occurrence of each of 17 types that occurred on 3 zones of low deer use, 2 transitional ranges, and 5 major winter ranges on the study area are presented in Table 14. Low deer use zones 31 Table 14. Area (km ) and percentages of vegetation cover types for 3 low deer use areas, 2 transition ranges and 5 winter ranges on the East Front during 1980-1981. Variations in propor- tions of cover types among areas are expressed as coeffi- cients of variation (C.V.)C. Low Use Winter Range Transition Total Mean C.V. Total Mean C.V. Total Mean C.V, Cover Types" km2 % % km2 % X kn)2 % Pofr-Fesc 11 .36 32 .3 105 10 .97 14 .0 38 2.80 19 74 Pifl-FescI 1 .42 3 .0 88 8 .51 9 .4 205 ' .10 1 141 Pifl-FescII 13 .87 29 .7 82 9 .90 12 .5 49 2.23 16 57 Pifl-FescIII 1 .66 3 .7 87 .25 .5 284 .20 2 141 Pif 1-Aspen .61 1. 7 170 .10 .1 22 .05 .5 141 Aspen 1. .52 3, .0 115 1. .77 2, ,1 68 .61 4 106 Shrub Riparian 3. 26 6, .3 108 3, .93 4. 9 40 .05 ,5 141 Tree Riparian 2. 31 7. 0 94 1, ,00 1. 5 224 .05 5 141 Psme-Spbe 1. 18 3. ,3 126 .10 .1 148 2.88 24. 5 61 Psme-Syal 69 2. 3 175 .49 3. 0 141 Pien-Smst .37 2. 5 85 Hay Meadow 25 7 165 1. .94 2. 3 82 Swamp 86 2. 3 176 1. 02 1. 0 197 Pifl-Beoc 12 3 192 Abla-Clps 73 2. 0 173 .70 7. 0 141 Pif 1-Junip 2. 38 2. 4 138 2.14 17. 0 25 Fesc-Agsp 30. 05 38. 1 30 .08 5 141 Total 39. 84 71. 92 12.75 aKasworm (1981) ^See Appendix Table 21 for key to 4-letter plant species abbreviations. cCoefficient of Variation = (SD) 100/mean. 32 were areas between major winter ranges where few or no deer were observed. They included Volcano Reef, Upper Dupuyer Creek, and Upper Muddy Creek. Cover types varied greatly in distribution and occurrence among low use zones, as well as between transition areas (Table 14). Those with coefficients of variation less than 100% on low use zones were Pinus flexilis /Festuca scabvella and riparian tree. For transition areas, types with relatively low variability included Potentilla fruticosa/Festuca scabvella, Pinus flexilis /Juniperus spp., Pinus flexilis IF estuca scabvella, Pseudotsuga menziesii I Spivea betulifolia, and Piaea engelmaniil Smilacina stellata. The locations of sampled low deer use zones, transition ranges, and the 1 winter range (Swanson Ridges) not previously described by Kasworm (1981) are shown in Figure 6. Amounts and percentages of vegeta- tion types occurring on individual areas are given in Appendix Table 20. A summary of Chi-square analyses of differences in the avail- ability of cover types between major winter ranges and low deer use zones, between winter ranges and transition ranges, and between low use zones and transition areas is presented in Table 15. Winter ranges differed significantly from low-use zones in the occurrence of all types except aspen, riparian shrub, and Pinus flexilis /Betula occidentalism Low-use zones had significantly more of the dense timber types than did winter ranges. Transition ranges differed from 33 1- Swanson Ridges 3-Volcano Reef 5-Upper Antelope Butte 2- Upper Dupuyer Creek 4-Upper Muddy Creek 6-Upper Chicken Coulee Figure 6. Map of the East Front showing 3 low use zones, 2 transition areas, and Swanson Ridges that were vegetatively and topo- graphically sampled during 1981. 34 Table 15. Chl-square analysis of availability of vegetative cover types among: low use zones and winter ranges; transition ranges and low use zones; and transition ranges and winter ranges3. Cover Low Use Winter Transition Low Use Transition Winter lype Zone Range Range Zone Range Range Pof r-Fesc + - - + + - Pifl-FescI - + - + - + Pifl-FescII + - - + NS Pifl-FescIII + - NS + - Pif 1-Aspen + - NS NS Aspen NS NS NS Shrub Rip. NS - + - + Tree Rip. + - - + NS Psme-Spbe + + Psme-Syal + NS Hay + Swamp + Pifl-Beoc NS Abla-Clps + Pif 1-Junip + Fesc-Agsp + ^S = No significant difference. - = Significant lower occurrence than the other unit in the test. + = Significant higher occurrence than the other unit in the test. ^See Appendix Table 21 for key to 4-letter plant species abbrevi- ations . 35 both low-use zones and winter ranges by having higher percentages of Pseudotsuga menziesii I 'Spirea betulifolia, Abies lasiocarpa I Clematis sp., Pinus / flexilis Juniperus sp. and low density Pinus flexilis/ Festuca scabvella types, and lower percentages of the riparian shrub and Festuca soabvellal Agvopyvon spioatum types. Aspen was the only type that occurred in similar proportions on all areas. Winter ranges also differed from low-use zones in topographic characteristics. Winter ranges were consistently lower in elevation. They also had wider availability of aspect classes (Fig. 7) and greater percentages of area in moderate and steep slope categories (Fig. 8) than did low-use zones. Transition ranges differed from win- ter ranges and low-use zones in having the steepest slopes and the highest average elevations. Mule Deer Habitat Use Mule deer use of vegetation cover types (Table 16), slope (Fig. 9, Table 16), aspect (Fig. 10, Table 16), and elevation (Table 17) on the 5 major winter ranges during 1980-1981 was compared with avail- ability of those components as determined by Kasworm (1981). Although use data doubtless were biased toward more open habitat configurations and diurnal periods, some selection for specific habitat attributes or configurations was evident. The Pinus flexilis (F estuca scabvella type was heavily used on all areas (Table 16). Snowdrift shrub type (Kasworm 1981), when 36 SCOFFIN BUTTE WINTER RANGES DUPUYER CREEK BLACKLEAF-TETON EAR MOUNTAIN LOW USE ZONES UPPER MUDDY CK VOLCANO REEF UPPER DUPUYER CK TRANSITION RANGES UPPMe,cken UPPER ANTELOPE BUTTE Figure 7. Aspect distribution (%) on 3 low use zones, 2 transition ranges, and 6 winter ranges for mule deer on the East Front during 1979-1981. 37 H 1 1 1 1 1 1 1 1 Z- n. a U D (A H o a Hi 2 a u Eh H Z H Q u. 08 p o as 8 3 8 rr 38 Table 16. Summary of Chi-square (x ) analysis of observed deer use vs. availability for 3 environmental variables. Areas Environmental variable Scoff in Dupuyer Blk-Teton Ear Castle Slope Asp Level 0-1° + NS Gentle 1-7° Moderate 7-16° + + + + + Steep 16+° + NS + >ect NE NS NS E + NS + + SE NS + NS + S + + + + SW NS NS W NS NS NS NW N + NS NS Vegetation typesD Fesc-Agsp Pofr-Phpr + Pofr-Fesc Pifl-FescI Pifl-FescII Pifl-FescIII + Riparian Hay meadow Snowdrift shrub Aspen Pifl-Beoc Pif 1-Aspen Artr-Fesc - = Significant negative occurrence. + = Significant positive occurrence. NS = No significant difference from expected. See Appendix Table 21 for key to 4-letter plant species abbrevi- ations. + + NS + + + NS NS NS NS NS + NS NS NS NS + NS NS NS 39 oooooooooo X o CO k « fl < n « - H 1 I I 1 1 ► I 1 r- O-K 2 5 < "Jo* - Q ■J ~ Hi Q> < Ul U^fi" > IS) >£o£ < = H 1 1 1 1 £ — ± — ' > *•* OOOOOOOOOO O 5> oo N -O "> v n — « jit < t u z o - 2 *5 iii 00 i n OS 1*1 J£ >-w 3U « OS on ^ - (A u 9) ■u C •H |3 m c o ■u •H cfl iH •H > td O ■u •H 0) U CO U QJ 00 CO 3 £1 Cfl QJ U 3 00 Figure 10. Percentages and average aspects that deer were observed occupying on 5 winter ranges during 1980-1981. 41 Table 17. Average elevations at 3 low use zones, 2 transition ranges, and 6 winter ranges. Average elevations (m) of deer observations on 5 winter ranges during 1980-1981. Average Elevations Average elevations of Range Unit of observed deer use Low use zones Volcano Reef 1,515 Upper Dupuyer Creek 1,545 Upper Muddy Creek 1,545 Transition ranges Upper Antelope Butte 1,758 Upper Chicken Coulee 1,818 Winter ranges Swanson Ridges 1,515 Blackleaf-Teton 1,515 1,545 Dupuyer Creek 1,455 1,515 Scoffin Butte 1,424 1,455 Castle Reef 1,424 1,485 Ear Mountain 1,545 1,576 available, also received greater than expected observed deer use. Fewer deer than expected were seen on the Agvopyron spicatum/F estuoa scabveZZa and riparian shrub types. The greater than expected numbers of deer observed on moderate slopes on all winter ranges indicated that type of terrain form was important to deer. Selection for aspect was less apparent, but deer generally were observed in less than expected numbers on northeast and northwest exposures and more frequently than expected, relative 42 to availability, on east and south exposures- In all cases, deer appeared to select higher-than-average elevations. Rumen Analysis Contents of 5 rumens collected on the study area in winter from 1980-1981 indicated that Juniperus horizontalis was heavily utilized (Table 18). Rumen contents consisted of 68% shrubs, 25% forbs, and 7% grasses. Gas and Oil Impacts Gas and oil drilling activity occurred exclusively in low deer use portions of the Blackleaf-Teton winter range during the winter of 1980- 1981. As a result, too few deer were present for adequately testing the influence of the drill site on deer distribution. Efforts to con- duct track counts were abandoned due to inadequate snow cover. Sight- ings of deer were limited to aerial transects and ground observations in the vicinity of the Blackleaf drill site. Three aerial transects were flown on January 2, January 23, and March 24, 1981 with 0, 7, and 2 6 mule deer counted, respectively, within 3 km of the drilling opera- tion. Figure 11 presents drill site locations, proposed drill sites, and seismic lines on the study area. Surveillance of deer behavior in close proximity to seismic blasting was not possible because of problems encountered in learning where and when lines were to be run. 43 Table 18. Contents of 5 mule deer rumens (by percent volume) col- lected in the study area during ; 1980-1981. Rumens3 Contents 1 2 3 4 5 Juho 7 61 17 60 71 Pifl 4 Grass 12 9 Trace 9 4 Unid. Forb 71 20 35 Unid. Shrub 5 8 Artr 10 11 Shea 5 10 Juco 14 Aruv 9 18 4 Pico 9 5 8 Sedum sp. 1 Pogr Trace Bosa sp. Trace Mushroom Trace Antenn. sp. Trace Douglasia sp. Trace Psme Trace Rumen : # Date Location Age Case of death 1- -2/80 Castle Reef Fawn Eagle kill 2- -1/80 Castle Reef Fawn Eagle kill 3- -2/80 Ear Mountain Fawn Coyote kill 4- -2/80 Dupuyer Adult Unknown cause of death 5- -1/81 Ear Mountain Adult Road kill However, observations on deer that were approximately 3 km away from the activity were made on one occasion. These deer looked up after blasts, assumed an alert posture, and then either ran a short distance or resumed feeding. Five radioed deer did not exhibit any noticeable long term changes in home range locations following seismic activity within their home ranges. 44 45 Winter home ranges of 4 radio-collared deer during 1979-1980 (prior to drilling activity) and 1980-1981 (during drilling activity) on the Blackleaf-Teton winter range are shown in Figure 12. Geographic activity centers were 1.8-4.1 km farther northeast or southwest in 1980-1981 than in 1979-1980. Geographic activity centers of 4 radio-collared deer on the Ear Mountain winter range, where no hydro- carbon exploration occurred, shifted 1.2-2.8 km in a northwesterly direction during the same time period. 46 ^ DRILL SITE Figure 12. Home ranges of 4 radio-collared mule deer in winter 1979- 1980 (prior to gas and oil activity at the Blackleaf- Teton winter range) and in winter 1980-1981 (during activity at the Blackleaf-Teton winter range). DISCUSSION AND CONCLUSIONS Seasonal Distribution , Movements, and Home Ranges Although a great deal of emphasis in this study was placed on winter ranges, the status of a mule deer population is only partially determined by winter range conditions. Other seasonal ranges have been shown to be equally important (Wallmo et al . 1977, Mautz 1978, Julander et al. 1961, Edwards and Ritcey 1958). Mackie et al. (1980) found that mule deer associated with a specific winter range could be characterized as a population unit associated with a definable yearlong herd range. Four of the 6 (possi- bly 7) winter ranges I recognized along the east slope of the Rocky Mountains between Birch Creek and the Sun River were represented by sufficient numbers of marked animals to tentatively delineate total 2 herd ranges. Those 4 varied from 328 to 1056 km . They had lower 2 densities (2-3 deer/km ) than herd ranges in the Bridger Mountains 2 (6-25 deer/km ) (Rosgaard 1981) . Very few deer (<100) winter west of the Continental Divide directly west of the study area (Jim Cross pers. comm.). This would indicate that 90% or more of all mule deer that summer in the portion of the Bob Marshall Wilderness north of the Sun River may winter on the East Front ranges. The East Front winter ranges were concentrated into at least 2 6, and possibly 7, discrete units ranging in size from 10 to 81 km . Winter densities of deer in 1979-1980 and 1980-1981 varied from 5 to 48 2 80 deer/km among these units. Other studies from mountain areas in Montana have reported densities on winter range of 10 to 150 deer/kmz (Mackie et al. 1980) . Deer density was inversely related to the size of individual winter range units. Winter ranges with the highest densities (22 to 2 2 80 deer/km ) were 10-39 km in size. Units with the lowest densities 2 2 (5 to 10 deer/km ) varied from 44-80 km . A similar relationship has been reported by Mackie et al. (1978) for the Bridger Mountains of southwestern Montana. The actual area occupied by East Front populations during winter, and consequently deer density, varied from year to year with differ- ences in snow and weather conditions. Average winter conditions pre- vailed in 1979-1980, and mild conditions occurred in 1980-1981. Total 2 winter range used by all populations units increased from 242 km in 1979-1980 (Kasworm 1981) to 289 km2 in 1980-1981. Information on deer distribution during a severe winter was limited to one helicopter survey in 1978-1979. Winter distribution within primary use areas was evidently similar in all 3 of the winters, but secondary range was used much more extensively in the 2 milder years. Winter ranges on the study area were separated by areas of little or no deer use. These low use zones may support greater deer numbers as the population increases, or they may provide usable winter range only during abnormally mild winters as 1980-1981. Although I could not 49 determine which of these two situations applied to the study area, because winter severity decreased and population size increased during the 2-year study, a helicopter survey by Olson (pers. comm.) in January 1982 indicated that the Volcano Reef low use zone was not occu- pied by deer despite an apparent increase in deer numbers on the Blackleaf-Teton winter range. Average individual winter home ranges of adult females increased 2 2 in size from 4.6 km in 1979-1980, to 6.0 km in 1980-1981. This indicated an inverse relationship between size and winter severity. Youmans (1979) documented larger winter ranges for mule deer during a mild year in the Bridger Mountains. East Front home ranges were smaller than those reported for the east side of the Bridger Mountain Range (Nyberg 1980) but larger than those found on the west slope of that range (Youmans 1979, Steerey 1979). Transition or holding areas were heavily used by deer in spring and fall. Transition range was characteristically located in the foot- hills adjacent to and west of winter ranges. The importance of transi- tion ranges as staging or holding areas along mule deer migration routes has been noted in Utah (Robinette 1966) and California (Bertram and Remple 1977). Pac (1976) and Steerey (1979) delineated holding areas for mule deer in the Bridger Mountains. Loveless (1967) felt that migratory movements were correlated with temperature and that snow accumulation forced deer to concentrate 50 on winter ranges. Along the Front, snow accumulation apparently influenced movements from transition and summer range during the 1978- 1979 and 1979-1980 winters, but tradition evidently played a role in timing of movements from transition to winter range in 1980-1981. Snow depths were so low during this winter that deer had access to transition ranges throughout most of the winter, yet most deer moved onto the East Front winter ranges in December and January as they did the previous winter. The moderate to heavily forested transition ranges along the East Front probably provide secure habitat for deer during the hunting season. I could not determine if hunting pressure forced deer into forested transition range or if security from hunters was a secondary outcome of autumn habitat preferences. Spring movement to summer ranges was direct, rapid, and apparently influenced both by snow melt in higher passes and plant phenology. Migration routes were described by Kasworm (1981). The same major drainages were used as migration routes during spring and fall. One additional migration route through the Blackfoot Indian Reservation was documented. Timing of spring (May to early June) and fall migra- tion was similar during 1979-1980 and 1980-1981. Fall movements of deer that summered west of the divide onto transition ranges occurred in middle October to early November of both years. 51 Three summer range segments were described by Kasworm (1981) and confirmed by my study. These included deer summering within or very close to the wintering area (RES) , deer summering east of the Conti- nental Divide (EOD) , and deer summering west of the divide (WOD) . Similar distributional patterns have been described by Harestad (1979) for black-tailed deer and Rosgaard (1981) for mule deer in other areas. The 22 radio-collared deer in the East Front population included 14% residents, 59% short-distance migrants (EOD), and 27% long-distance migrants (WOD) . If this distribution approximated the actual summer dispersal pattern, the East Front population had fewer long-distance migrants than the Brackett Creek winter range in the Bridger Mountains where residents, short-distance migrants and long-distance migrants made up 5, 20, and 75% of the population, respectively (Rosgaard 1981). Animals that summered near their winter ranges were more flexible in their movement patterns. They tended to make less use of transition range in fall than long distance migrants (WOD) , remained on summer ranges later in fall, and returned to summer range earlier in spring. Individuals that crossed a major divide were inclined to move with the first severe snow storms of the fall season. These differences in movement patterns among summer range segments have also been documented in the Bridger Mountains (Steerey 1979, Nyberg 1980, Rosgaard 1981). Average summer home range sizes for radio-collared females on 2 2 2 the study area were 6.4 km in 1979, 3.5 km in 1980, and 1.4 km in 52 2 1981. These compared to means of 3.7 km in 1979 (Nyberg 1980), and 2 3.1 km in 1980 (Rosgaard 1981) for mule deer ranging pn the east 2 side of the Bridger Mountains and a mean of 1.7 km for those on the west side of that range (Mackie et al. 1980) . Fidelity to summer home ranges (21 of 22 radio-collared deer) was high in 1980 and 1981. Other studies have also documented high fidelity of mule deer to both summer and winter ranges (Leopold et al. 1951, Gruell and Papez 1963, Zalunardo 1965, Robinette 1966, Pac 1976, Steerey 1979, Rosgaard 1981, Mackie et al.1979, 1980). Individual seasonal home range used in 1 year indicates only a portion of the total seasonal home range needed and used over a mule deer's lifetime. Data are not available for lifetime seasonal home ranges, but data from this study indicated that radioed deer relocated 2 for 3 summers had total seasonal home range that averaged 11.1 km , a much greater area than was used in a single year. Average summer home ranges for EOD deer were smaller than those for WOD deer in all 3 years for which radio-telemetry data were available. Three out of 78 marked animals were known to have dispersed (from one winter range to another) within the study area. All 3 deer that were known to change winter ranges were males; 2 of those were year- lings. Male mule deer are more likely to disperse than females (Pac 1976, Mackie et al.1979, 1980), and yearlings have a higher affinity 53 for dispersal than do other classes (Robinette 1966). If the observed sample of aged deer were representative of the population, dispersal rates for the total and yearling segments were 4 and 9%, respectively. Rosgaard (1981) documented dispersal of similar magnitude along the east side of the Bridger Mountains during a period of higher than average deer density. Population Dynamics Helicopter surveys conducted in 1978-1980 (Kasworm 1981) indi- cated that the mule deer population wintering along the East Front was increasing. An additional increase of approximately 6% occurred between 1980 and 1981. Actual numbers observed in March 1981 were lower than in March 1980; however, the proportion of collared animals observed during the 1981 helicopter survey was lower due to milder winter conditions and a wider distribution of deer. During 1981, numbers of deer on national forest lands that serve as secondary winter range were greater than in 1980. The low percentage of marked deer observed during the April 1981 survey indicated that deer were begin- ning to move off the winter range onto forested transition ranges and precluded the use of that survey for a population estimate. Fawn: adult ratios for mule deer on the Front were relatively high when compared to other mountain foothill areas (Mackie et al.1980). Ratios observed on the study area were greater in the 1979-1980 winter 54 than in 1980-1981. This probably was due to an increased proportion of yearlings in the "adult" category rather than to decreased produc- tivity. High yearling numbers will dilute fawn:adult ratios since yearlings generally are nonproductive in mule deer populations (Nellis 1968, Hamlin 1977). Mild conditions in 1979-1980 apparently resulted in abnormally low fawn mortality which led to high yearling recruitment for 1980-1981. A similar situation may occur during the 1981-1982 winter . Limited data indicated a relatively young age structure for popu- lation units on the study area. A similarly young age distribution was reported by Nyberg (1980) and Rosgaard (1981) for mule deer on the east side of the Bridger Mountains; whereas on the west slope, an older age structure has been reported (Mackie et al. 1980) . The proportion of antlered to non-antlered (does and fawns) deer (19:100 in January 1981) on the study area was higher than in some other southwestern Montana mule deer populations (Pac et al. 1981, Rosgaard 1981). High proportions of males may be attributed to low har- vest or to the general nature of the Front habitat characteristics. Habitat Characteristics and Use Deer wintering along the East Front were not uniformly distrib- uted. Even in a mild winter, some sites held very few or no deer, others had low to moderate densities, and 4 areas (Scoffin Butte, 55 Dupuyer Creek, Long Ridge, and Castle Reef) had high densities. Kasworm (1981) noted an inverse correlation between deer densities on winter ranges in the study area and elevation, but he did not inves- tigate differences between areas used by deer along the East Front and low deer use zones. I found that low deer use zones had significantly lower percentages of moderate to steep slope categories and a lower proportion of southerly aspects than core winter ranges. Observations of deer within core winter ranges indicated that- these slope and aspect categories received greater use than expected if deer were selecting for aspect and slope steepness in proportion to availability. Loveless (1967) noted that southern aspects receive 9 times as much direct sunlight as northern aspects. He found that east and south slopes received greater use by mule deer on winter ranges in Colorado during periods of low temperature and that snow depths were lower on east and south than on north and west slopes. Greater deer use was observed at elevations higher than average for the winter range. Loveless (1967) found that higher portions of slopes on the winter range were warmer than lower portions of slopes on the winter range. The vegetation on winter ranges was very different than that on low use zones, but a high degree of variability in occurrence of individual cover types among winter ranges and the low use zones made interpretation difficult. Deer favored the Pinus ftexilis IF estuoa 56 soabrella type on winter ranges, presumably because it represented a mixture of open slopes and patchy timber. Timber types have been reported to provide increased security, thermal cover, reduced snow depths, and protection from wind (Loveless 1967, Moen 1968, 1976, and Ozoga and Gysel 1972). Analysis of 5 rumens and studies of winter food habits of mule deer on the study area (McCarthy et al . 1978, Kasworm 1982 unpubl. report to BLM, Butte) have indicated that plant species abundant on open, exposed slopes comprised the bulk of mule deer diets. On the East Front, timber patches, moderate to steep slopes, and windward aspects at elevations low enough to be blown clear by chinook winds evidently are essential components in the environmental mosaic that enables mule deer to survive winter condi- tions. Transition or holding areas along the Front were characterized by a high percentage of cover, higher elevations than winter ranges, eastern exposures, moderate slopes, and proximity to winter ranges. Transition ranges provided security during the hunting season and, presumably, preferable feeding conditions until snow accumulationed or tradition forced deer onto winter ranges. Hydrocarbon Exploration Impacts Impacts of hydrocarbon exploration were difficult to assess due to the low intensity of activity during the study, the mild winter 57 conditions, and the low density of deer in the vicinity of the only active well sites on the area during the 1980-1981 field seasons. The limited data collected showed no obvious avoidance by deer of the well sites in the Blackleaf-Teton unit. The changes in geo- graphic activity centers between 1980 and 1981 for 4 radio-collared mule deer in the vicinity of those drill sites were more likely due to differences in weather conditions between the 2 years than to gas exploration. However, as activity intensifies and a gas field is developed, the potential for impacts will increase. Knight (1980) found that activity at the site of an oil well did not statistically influence elk movements or distribution. He attrib- uted the lack of response to the adaptability of elk to predictable and stationary disturbances. Geist (1971) described this phenomena in other ungulate species. Since mule deer can be easily habituated to human activities (Geist 1981) and are difficult to force from their home ranges (Robinette 1966), the direct effects of gas/oil drilling at scattered sites for short periods of time may be negligible. Dense fields, however, may lead to physical habitat loss and increased access which could increase the risk of mortality to mule deer due to habitat deterioration, accidents, or poaching. Seismic activity on the study area was extensive. The Lewis and Clark National Forest has sustained greater seismic activity than any other National Forest in western Montana during the past 2 years; 288 58 km of seismic lines were completed in 1981 al one (Great Falls Tribune Jan. 23, 1982). Radio-collared mule deer did not show any apparent long-term changes in seasonal home ranges as a result of seismic activ- ity. I was unable to test short-term changes because of the reticence of seismic companies in divulging the exact timing of seismic opera- tions and financial limitations on flight time. Limited ground obser- vations indicated that deer 3 km away from seismic activity did run short distances and/or assumed alert postures. Seismic operations on the East Front apparently influenced elk distribution (G. Olson pers. comm.) and led to short-term movements in mountain goats (G. Joslin pers. comm.). Seismic activity affected elk movements but not distribution in Michigan (Knight 1980) . Knight felt that seismic activity had a greater potential for negatively impacting animals, through decreasing feeding efficiency, decreasing reproduction, and increasing energy expenditure, than did well drill- ing. Geist (1971) noted that disturbances are potentially more detri- mental if unpredictable and frequent. Seismic activity along the Front in 1982 will reportedly be 4 times as great as in 1981 (L. Irby pers. comm. ) . MANAGEMENT IMPLICATIONS AND RECOMMENDATIONS General Management Implications Effective management or assessment of the potential influences of environmental factors on mule deer populations requires understanding of the spatial distribution and patterns of deer use in all seasonal habitats. Although individual seasonal ranges may be viewed separately for some management purposes, complete units are critical for the survival of viable populations. The three seasonally used segments identified within individual population-habitat units include: (1) winter range on which mule deer depend for survival from November- December through April-May, (2) summer range on which those animals are produced, and (3) transition range, which provides security during the hunting season and may also be important in determing the condition of deer as they move onto winter range. The high percentages of successful does (i.e., does with fawns) and high fawn: doe ratios observed in early winter indicated that summer ranges were reasonably adequate. Because of this, management efforts relative to harvest and the influences of gas and oil development will most likely concern winter and transition ranges. Greatest opportunity for conflict occurs on winter ranges, large portions of which are pri- vately owned and/or have privately-owned mineral rights. Deer popula- tions on privately-owned surface areas are maintained primarly because landowners continue to tolerate the presence of deer and/or have 60 maintained land-use practices compatible with deer use. Regulation of the timing, type, and intensity of mineral development, extent of grazing, farming, hunting access, and housing developments on private land is beyond the control of state and federal wildlife and land management agencies. The population apparently increased during the last few years, indicating a potential for greater harvest. The summer range segments, however, differ in their vulnerability to overharvest. The long dis- tance migrants (WOD) seemed most vulnerable to hunting since they were hunted both on their summer ranges during early season hunts (mid- September through October) and on their transition or winter ranges during regular hunts (late October through November) . Recovery by this segment following a serious reduction could take a long time because of the long distances to summer ranges and behavioral charac- teristics related to distribution. Similarly, loss of East Front winter ranges used by these deer would seriously impair their ability to occupy vast areas of wilderness summer ranges west of the Continen- tal Divide. More access might be desirable at current high population levels in order to increase harvest and to spread hunting pressure more widely and uniformly across transition range, but control of access is essential. Uncontrolled access, as a result of extensive road development, could be dangerous to the entire population, especially 61 the WOD segment. Restriction of access to the few drainages easily reached through public lands could concentrate hunting pressure to the extent that specific population units (the Blackleaf-Teton and Ear Mountain units under current land ownership patterns) could be jeop- ardized. Cooperation of private landowners is essential in gaining and controlling access. Winter range sizes delineated in this study are tentative and could change with increasing population size. Similarly the 7 individ- ual winter ranges varied widely in basic environmental features and the manner of deer use. Summer range characteristics are important in determining the size and quality of populations on winter ranges, but current data are insufficient to fully assess the influence of variation in summer range characteristics for mule deer along the East Front. Because of the changing status of the East Front population, the limited available data, and the unique characteristics associated with each winter-transition-summer range complex, each population unit should be considered individually. No single, rigid set of regulations governing development can be expected to apply to the entire East Front. Priorities for protection of winter ranges should be determined relative to the potential value of the range for development, live- stock grazing, recreation, and wildlife habitat for mule deer and other species, but the regulation of impacts should be undertaken on a site by site basis. 62 Population units should be monitored closely to detect changes in population size, productivity, mortality, and distribution associ- ated with changes in land use. Monitoring will be crucial in detect- ing, or possibly predicting, future deterioration in populations and in judging the success of management practices. Possible innovative management options could include deer easements on private winter range, trades of livestock grazing on noncritical range on public lands for wildlife grazing reservations on private critical range, road closures, year to year shifts in numbers of doe permits, alterna- tive opening and closing of land access, and manipulation of timing and/or spacing of development on public land to compensate for activi- ties on adjacent private land. Gas and Oil Impacts and Management Recommendations Seismic activity- Seismic activity can potentially disrupt fawn rear- ing, rut activity, and winter resting. Deer can evidently tolerate low to moderate frequencies of seismic activity, but the potentially unlimited and loosely controlled activity permitted under present laws could surpass the tolerance range of deer rather easily. Roads built during seismic operations could potentially lead to a greater harvest of deer (legal and illegal), more road kills, and more harassment. Drilling and production- The potential for deer to adapt to distur- bances is much greater if the disturbance is predictable and 63 stationary. Therefore, short-term effects of drilling may be minimal, especially in low deer use areas. However, placement of drill sites on core winter ranges can have detrimental effects. The potential for damage will vary at each drill site depending on distribution of deer, condition of deer, condition of range, amount of new access created, permanence of the disturbance, and spatial or temporal relationships to disturbances on adjacent areas. Conflicts due to pipelines and sweetening plants will also vary between sites. ' Timing and access- Timing of activity and regulation of access can minimize potential conflicts. Primary and secondary winter range should be avoided from December 15 to May 15, migration routes from May 15 to June 15, and transition areas from October 15 to December 31. Road locations, permanence, and extent of traffic should be care- fully planned prior to construction. Helicopter travel during seismic operations should be limited to specific corridors. Regulations- Compatability of hydrocarbon development and mule deer would be enhanced if certain precautions, regulations, and coopera- tive agreements were formulated and enforced. Restriction of firearm, motorbike, and snowmobile use by personnel of gas and oil operations would minimize harassment. Modifications of laws to allow limits on frequency of exploration or sharing of information (i.e. pooled oil company exploration, or exploration financed by the Forest Service and 64 sold to interested parties) would greatly reduce stress placed on wildlife. Consideration of cumulative impacts- When gas and oil development occurs in conjunction with other impacts, such as livestock grazing, presence of other wildlife species, housing development, recreation, and severe winters, the detrimental effects of hydrocarbon-related activity on mule deer may be accentuated. Consideration of these additional impacts when planning development is critical. Placement of pipelines, industrial plants, drill sites, and seismic lines on lands subject to public control should be carefully examined on a site by site basis to minimize conflicts with deer populations. Coordination- Communication and cooperation between resource managers, private land owners, and the petroleum industry are critical to suc- cessful coexistence of mule deer populations and hydrocarbon develop- ment along the East Front. Communication and cooperation are also necessary among federal and state agencies assigned to manage resources. Specific suggestions that would facilitate cooperation include : 1. One person should be assigned responsibility for coordination, communication, and gaining cooperation between resource agencies, the gas and oil industry, and the public. 2. Advance notice of seismic proposals should be given to field biologists so that the effects can be monitored. 65 3. The detrimental effects of unplanned development should be communi- cated to land owners and resource users. 4. Development plans that are compatable with mule deer should be disseminated to land owners and resource users. 5. A system of shared responsibility and financial support should be developed for monitoring mule deer. The management of wildlife and their habitat is directly related to the management of human impacts. The public must decide the balance between shorter term economic gains from gas and oil development and the much longer term economic and aesthetic benefits of large, healthy, and productive mule deer populations. APPENDIX 67 . 1 cfl T3 O c U o •H 4J 00 o •H o> 1-1 CO 1 ■I-l C 1 CO CO o 4J u 00 cu 4-» 00 cu > £ rH Q <4-4 00 u o <^ iH 4-1 CO 4J cu E c bo S-i o cfl o i-l jj & Bh a CO CU CO 4J u CO u cfl CD td D. CO cu cu T3 00 XI C c 4J CO CO iH CU "§ H C cu o. < S S J S I o o o 00 CO o o O O m