The management of free-roaming, feral horse (Equus caballus) populations in the western United St... more The management of free-roaming, feral horse (Equus caballus) populations in the western United States is a contentious and challenging issue. Between 2008 and 2014, 1,873 individual horses from a closed population in the northern Great Basin, USA were captured, uniquely marked, and were either removed for private adoption or had permanent fertility control treatments (i.e., vasectomy or ovariectomy) applied prior to release. We derived the annual population size, growth rate, and the number of horses by sex and age by using the horse's estimated age at first capture to infer its age during each year it was part of the population. Estimates of population size from 2 aerial survey techniques averaged within 5.3%–9.6% of derived population estimates. The overall survival (i.e., recapture) rate for individual horses was 88% for individuals released back into the population between 2009 and 2012. Treated horses maintained group associations and there were no differences between survival rates for released females or males that received fertility control treatment, compared to animals released without treatment. The application of combined fertility control efforts resulted in a decline in the population-level annual foaling rate from >20% to <4% within 4 years. Maintaining a proportion of a population as permanently non-reproducing has the potential to safely maintain free-roaming horse herds at desired management levels.
Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2015
Free-roaming horse ( Equus caballus ) management is a complex issue incorporating social, economi... more Free-roaming horse ( Equus caballus ) management is a complex issue incorporating social, economic, emotional, political, and environmental factors. Currently, few proven field techniques exist for managing free-roaming horse population growth, which can reach 20-25% annually. Although there are several strategies available for sterilizing mares when managing free-roaming horse populations, surgical vasectomy is the only method used in the field for stallions. Some managers believe that surgically vasectomizing dominant stallions would have significant effects on reducing horse populations. However, sterilizing only dominant harem stallions results in a relatively modest reduction in population growth as substantial reproduction may occur even when 100% of the dominant harem stallions are sterilized if other males perform as little as 10% of the breeding. The overall goal of the current project was to evaluate the efficacy of a novel nonsurgical method for sterilizing free-roaming h...
American black bear (Ursus americanus) feeding damage to conifer stands can result in substantial... more American black bear (Ursus americanus) feeding damage to conifer stands can result in substantial economic losses in the Pacific Northwest. However, little is known about which sex and age classes of bears cause the most damage and the effectiveness of current control methods. We examined the frequency, intensity, and total conifer damage by radio-monitoring 13 male and 9 female black bears from 1998 to 1999 to determine which sex and age classes caused the most damage. We also examined which sex and age classes were affected by control measures (hunting) to determine the efficacy of management actions. Females were associated with greater frequency (P = 0.078), intensity (P = 0.037), and total conifer damage (P = 0.015) than males. Adult females damaged more trees than other sex and age classes combined (P = 0.092). Adult males comprised the majority of bears removed by hunting (66%) but caused only 11% of total damage. Current damage control measures do not seem to be as effective...
Brown bear (Ursus arctos) population size correlates with density of high-quality food resources.... more Brown bear (Ursus arctos) population size correlates with density of high-quality food resources. We report on a ten-year study (1993 - 2003) of brown bear nutritional ecology in southwestern Alaska during which changes in resource availability and density occurred. The diets of 21 female bears captured multiple years were characterized by stable isotope analysis (delta13C, delta15N, and delta34S) of guard hairs and putative diet items, followed by application of a Bayesian mixing model to derive assimilated diet estimates. Diet estimates were subsequently used to characterize individual-level resource specialization. Over the entire study period, salmon accounted for the highest proportion of bear diets (42.1%), followed by berries (24.5%), mammals (13.5%), freshwater fish (11.2%), and other plant matter (8.7%). The average salmon contribution to bear diets declined significantly from 48% to 34% following a precipitous reduction in salmon escapement mid-way through the study, after...
Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also... more Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also a relatively unmanaged, non-native grazer in North America, South America, and Australia. Information about their influence on vegetation and soil characteristics in semi-arid rangelands has been limited by confounding effects of cattle (Bos taurus) grazing and a lack of empirical manipulative studies. We compared vegetation and soil surface characteristics in feral horse grazed areas and ungrazed exclosures at five sagebrush (Artemisia) steppe sites in northern Nevada. Horse grazed areas had lower sagebrush density and plant diversity, greater soil penetration resistance, and lower soil aggregate stability than ungrazed areas. Herbaceous cover and density generally did not differ between grazed and ungrazed treatments, with the exception of heavily grazed sites in which perennial grass cover was reduced. The cumulative effect of feral horses on soil characteristics suggests that they may affect the ecological function of semi-arid rangelands by increasing the risk of soil erosion and potentially decreasing availability of water for plant growth. The two-fold increase in sagebrush density with horse exclusion suggests that feral horses may limit sagebrush recruitment and thereby negatively impact Greater Sage-grouse (Centrocercus urophasianus) and other sagebrush associated wildlife. The effects of feral horses on sagebrush and other semi-arid ecosystems should be considered when developing conservation plans for these ecosystems and associated wildlife.
Barren ground caribou (Rangifer tarandus) were reintroduced to the Nushagak Peninsula, Alaska in ... more Barren ground caribou (Rangifer tarandus) were reintroduced to the Nushagak Peninsula, Alaska in February of 1988 after an absence of more than 100 years. Since reintroduction, herd growth and population dynamics have been monitored closely. At this time, there has been no significant dispersal from the herds' core range. The Nushagak Peninsula Caribou Herd (NPCH) grew rapidly from 146 reintroduced individuals to over 1000 in 13 years. Dramatic mean annual growth during the first 6 years (1988)(1989)(1990)(1991)(1992)(1993)(1994) of 38% (r = 0.32) can be attributed to the high percentage of females in the initial reintroduction, high calf production and survival, exceptional range conditions, few predators, and no hunting. However, the populations' exceptional growth (peak counts of 1400) slowed and stabilized between 1996¬ 1998 and then decreased between 1998 and 2000. Size, body condition and weights of calves captured in 2000 were significantly lower than those captured in 1995 and 1997. Although calf production also decreased from close to 100% (1990-1995) to about 91% (1996-2000), overall calf survival continued to be high. Legal harvest began in 1995, and harvest reports have accounted for approximately 3% of population mortality annually. Although brown bears (Ursus arctos) and wolves (Canis lupus) are present, the extent of predation is unknown. Mean home range of the NPCH was 674 km 2 and group sizes were greatest during post-calving aggregation in July (x = 127). Caribou population density on the Nushagak Peninsula reached approximately 1.2 caribou/km 2 in 1997 before declining to about 1.0 caribou/km 2 . A range survey in 1994 noted only trace utilization of lichens on the Nushagak Peninsula by caribou. A subsequent survey in 1999 found moderate to severe utilization in 46% of plots, suggesting the reintroduced herd was beginning to alter range condition. Between 1997 and 2000, both calf production and condition of 10-month-old calves declined. Calving has also been delayed in recent years. However, we suspect the reduced herd growth can be attributed to increasing hunting pressure and some dispersal of caribou from the Peninsula, not reduced range condition.
Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roam... more Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roaming horse behavior and habitat use and to aid in making informed management decisions. Global positioning system (GPS) and very high frequency (VHF) radio collars can be used to provide high spatial and temporal resolution information for detecting free-roaming horse movement. GPS and VHF collars are a common tool used in wildlife management, but have rarely been used for freeroaming horse research and monitoring in the United States. The purpose of this study was to evaluate the design, safety, and detachment device on GPS/VHF collars used to collect free-roaming horse location and movement data. Between 2009 and 2010, 28 domestic and feral horses were marked with commercial and custom designed VHF/GPS collars. Individual horses were evaluated for damage caused by the collar placement, and following initial observations, collar design was modified to reduce the potential for injury. After collar modifications, which included the addition of collar length adjustments to both sides of the collar allowing for better alignment of collar and neck shapes, adding foam padding to the custom collars to replicate the commercial collar foam padding, and repositioning the detachment device to reduce wear along the jowl, we observed little to no evidence of collar wear on horses. Neither custom-built nor commercial collars caused injury to study horses, however, most of the custom-built collars failed to collect data. During the evaluation of collar detachment devices, we had an 89% success rate of collar devices detaching correctly. This study showed that free-roaming horses can be safely marked with GPS and/or VHF collars with minimal risk of injury, and that these collars can be a useful tool for monitoring horses without creating a risk to horse health and wellness.
From June 1993 to June 2003, 40 adult female brown bears (Ursus arctos) were captured, radiocolla... more From June 1993 to June 2003, 40 adult female brown bears (Ursus arctos) were captured, radiocollared, and tracked for 1 to 10 years in a previously unstudied population in southwest Alaska. Mean litter size upon emergence from dens was 2.0, decreasing to 1.5 at weaning. Mean age of offspring at weaning was 2.9. Mean age of primiparity was 7.2 years while first weaning was estimated at 9.5 years. Mean maximum age of a female weaning a litter was 27.3 years. Mean annual survival estimates were 90.1-97.2% for radiocollared females !5 years old, 48.2-61.7% for cubs of the year, and 73.3-83.8% for 1 and 2-year-old offspring combined. Of 129 offspring followed beginning with their first summer, 38 (29.5%) survived to be weaned. Hunters harvested at least 12 marked or radiocollared bears (9 males and 3 females). No defense of life and property (DLP) killings were reported within or near the study area, but illegal harvests of brown bears were known to have occurred in the general region. Harvests within or near the study area averaged 7.3-12.1 males/year and 4.8-5.2 females/year. This population's rate of increase (k) was estimated as 1.035-1.047 for the first half of the study, 0.963-0.997 for the second half, and was found to be most sensitive to survival of females 5-14 years old.
Between 1993 and 2003, 40 adult female brown bears (Ursus arctos) were radiocollared and monitore... more Between 1993 and 2003, 40 adult female brown bears (Ursus arctos) were radiocollared and monitored in the southwest Kuskokwim Mountains of Alaska. The 95% kernel home range size for individuals with >50 relocations (n = 20) ranged from 93-623 km2 (x = 356 km2). Bears occupied lower elevations during July and August (x = 454 m) when salmon (Oncorhynchus spp.) were available and higher elevations in September (x = 520 m), presumably to feed on berries, ground squirrels (Spermophilus parryii), and caribou (Rangifer tarandus). During the denning period, bears moved to higher average elevations (x = 632 m), generally remaining through June (x = 570 m). Radiomarked females entered the den in mid October and exited in mid May. There was fidelity to denning areas, with an average distance between consecutive dens of 4.5 km (SD = 3.1). Females with cubs were found at higher average elevations than females without young or with yearlings. Radiomarked females were found closer to anadromous streams from 16 July-15 August, coinciding with chinook (0. tschawytscha), chum (0. keta), and sockeye salmon (0. nerka) availability. Beginning in 1998, chinook and chum salmon escapement was low in the Kuskokwim drainage. There was an inverse relationship between measures of salmon availability and bear distances to anadromous streams. This indicates that although the study area was at the fringe of salmon range, salmon abundance influenced bear seasonal movements and distribution. With reduced salmon availability, this area may support a lower bear density, and brown bear population management should be considered in salmon escapement goals. Ursus 16(2):181-189 (2005) Brown bears (Ursus arctos) have historically been an important source of food and hides for Native residents of southwest Alaska (Van Daele et al. 2001). In 1991 and 1992, state and federal regulatory boards liberalized brown bear hunting regulations for subsistence users in southwest Alaska. The bear population affected by this liberalization had never been investigated, and little was known about its size, distribution, or behavioral characteristics. Home range estimates can indicate the ecological requirements of animals because home ranges include all resources used by a resident (Seaman and Powell 3Present address: US Fish and Wildlife Service, Tetlin National Wildlife Refuge, PO Box 779, Tok, Alaska 99780, USA; Gail_Collins@fws.gov 4Present address: US Fish and Wildlife Service, Innoko National Wildlife Refuge, PO Box 69, McGrath, Alaska 99627, USA; Steve_Kovach@fws.gov 5Michael_Hinkes@ fws.gov 1990). Home ranges and the movements within them are behavioral manifestations of basic biological requirements, such as food, shelter, and mates. Brown bear home range size is a function of habitat quality and population density (Nagy and Haroldson 1990). Several studies documented habitat use and movement patterns of coastal (Bers et al. 1980, Glenn and Miller 1980, Schoen et al. 1986, Hamilton and Bunnell 1987, Bares 1990, Ballard et al. 1993) and interior (Ballard et al. 1982) brown bears. These studies demonstrated how use of salmon (Oncorhynchus spp.) streams varied among bear populations. Brown bears in British Columbia ranged widely during the berry season, then restricted movement while feeding on salmon (Hamilton and Bunnell 1987). On the Alaska Peninsula (Glenn and Miller 1980), bears moved greater distances in spring than in summer and fall. Schoen et al. (1986) demonstrated that a portion of the Admiralty Island population did not feed on salmon, instead foraging in interior alpine and subalpine habitats. and black bear density estimation in Alaska using radiotelemetry and replicated mark-resight techniques. Wildlife Monograph 133. NAGY, J.A., AND M.A. HAROLDSON. 1990. Comparisons of some home range and population parameters among four grizzly bear populations in Canada. International Conference on Bear Research and Management 8:227-235. PEARSON, A.M. 1975. The northern interior grizzly bear (Ursus arctos L.). Canadian Wildlife Service Report Series 34. . 2001. Grizzlies, eskimos, and biologists: Cross-cultural bear management in southwest Alaska. Ursus 12:141-152. WORTON, B.J. 1995. Using Monte Carlo simulation to evaluate kernel-based home range estimators. Journal of Wildlife Management 59:794-800.
Brown bear (Ursus arctos) population density was estimated for a 21,178 km 2 study area in southw... more Brown bear (Ursus arctos) population density was estimated for a 21,178 km 2 study area in southwest Alaska. Estimates were obtained using an aerial line transect method that allows for peak detection to be both off the transect line and< 100%. Data collection required five small aircraft with two-person crews. Surveys were flown in 10-day windows to capture the period after den emergence but prior to full green-up. Surveys were flown in two consecutive years in order to detect sufficient bear groups to support the ...
SAMPLING 25 km Transects: (see .) randomly selected mid-points flat terrain -straight transects r... more SAMPLING 25 km Transects: (see .) randomly selected mid-points flat terrain -straight transects randomly hinged at mid-point mountainous terrain -transects followed elevation contours. Survey Timing, Duration, and Sequencing (see ) Transects were flown on 10 consecutive days after den emergence and prior to full leaf out. Transects were randomly assigned an id # then all transects with ids 1 -100 were completed prior to beginning transects 101 -200, etc.
The management of free-roaming, feral horse (Equus caballus) populations in the western United St... more The management of free-roaming, feral horse (Equus caballus) populations in the western United States is a contentious and challenging issue. Between 2008 and 2014, 1,873 individual horses from a closed population in the northern Great Basin, USA were captured, uniquely marked, and were either removed for private adoption or had permanent fertility control treatments (i.e., vasectomy or ovariectomy) applied prior to release. We derived the annual population size, growth rate, and the number of horses by sex and age by using the horse's estimated age at first capture to infer its age during each year it was part of the population. Estimates of population size from 2 aerial survey techniques averaged within 5.3%–9.6% of derived population estimates. The overall survival (i.e., recapture) rate for individual horses was 88% for individuals released back into the population between 2009 and 2012. Treated horses maintained group associations and there were no differences between survival rates for released females or males that received fertility control treatment, compared to animals released without treatment. The application of combined fertility control efforts resulted in a decline in the population-level annual foaling rate from >20% to <4% within 4 years. Maintaining a proportion of a population as permanently non-reproducing has the potential to safely maintain free-roaming horse herds at desired management levels.
Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2015
Free-roaming horse ( Equus caballus ) management is a complex issue incorporating social, economi... more Free-roaming horse ( Equus caballus ) management is a complex issue incorporating social, economic, emotional, political, and environmental factors. Currently, few proven field techniques exist for managing free-roaming horse population growth, which can reach 20-25% annually. Although there are several strategies available for sterilizing mares when managing free-roaming horse populations, surgical vasectomy is the only method used in the field for stallions. Some managers believe that surgically vasectomizing dominant stallions would have significant effects on reducing horse populations. However, sterilizing only dominant harem stallions results in a relatively modest reduction in population growth as substantial reproduction may occur even when 100% of the dominant harem stallions are sterilized if other males perform as little as 10% of the breeding. The overall goal of the current project was to evaluate the efficacy of a novel nonsurgical method for sterilizing free-roaming h...
American black bear (Ursus americanus) feeding damage to conifer stands can result in substantial... more American black bear (Ursus americanus) feeding damage to conifer stands can result in substantial economic losses in the Pacific Northwest. However, little is known about which sex and age classes of bears cause the most damage and the effectiveness of current control methods. We examined the frequency, intensity, and total conifer damage by radio-monitoring 13 male and 9 female black bears from 1998 to 1999 to determine which sex and age classes caused the most damage. We also examined which sex and age classes were affected by control measures (hunting) to determine the efficacy of management actions. Females were associated with greater frequency (P = 0.078), intensity (P = 0.037), and total conifer damage (P = 0.015) than males. Adult females damaged more trees than other sex and age classes combined (P = 0.092). Adult males comprised the majority of bears removed by hunting (66%) but caused only 11% of total damage. Current damage control measures do not seem to be as effective...
Brown bear (Ursus arctos) population size correlates with density of high-quality food resources.... more Brown bear (Ursus arctos) population size correlates with density of high-quality food resources. We report on a ten-year study (1993 - 2003) of brown bear nutritional ecology in southwestern Alaska during which changes in resource availability and density occurred. The diets of 21 female bears captured multiple years were characterized by stable isotope analysis (delta13C, delta15N, and delta34S) of guard hairs and putative diet items, followed by application of a Bayesian mixing model to derive assimilated diet estimates. Diet estimates were subsequently used to characterize individual-level resource specialization. Over the entire study period, salmon accounted for the highest proportion of bear diets (42.1%), followed by berries (24.5%), mammals (13.5%), freshwater fish (11.2%), and other plant matter (8.7%). The average salmon contribution to bear diets declined significantly from 48% to 34% following a precipitous reduction in salmon escapement mid-way through the study, after...
Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also... more Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also a relatively unmanaged, non-native grazer in North America, South America, and Australia. Information about their influence on vegetation and soil characteristics in semi-arid rangelands has been limited by confounding effects of cattle (Bos taurus) grazing and a lack of empirical manipulative studies. We compared vegetation and soil surface characteristics in feral horse grazed areas and ungrazed exclosures at five sagebrush (Artemisia) steppe sites in northern Nevada. Horse grazed areas had lower sagebrush density and plant diversity, greater soil penetration resistance, and lower soil aggregate stability than ungrazed areas. Herbaceous cover and density generally did not differ between grazed and ungrazed treatments, with the exception of heavily grazed sites in which perennial grass cover was reduced. The cumulative effect of feral horses on soil characteristics suggests that they may affect the ecological function of semi-arid rangelands by increasing the risk of soil erosion and potentially decreasing availability of water for plant growth. The two-fold increase in sagebrush density with horse exclusion suggests that feral horses may limit sagebrush recruitment and thereby negatively impact Greater Sage-grouse (Centrocercus urophasianus) and other sagebrush associated wildlife. The effects of feral horses on sagebrush and other semi-arid ecosystems should be considered when developing conservation plans for these ecosystems and associated wildlife.
Barren ground caribou (Rangifer tarandus) were reintroduced to the Nushagak Peninsula, Alaska in ... more Barren ground caribou (Rangifer tarandus) were reintroduced to the Nushagak Peninsula, Alaska in February of 1988 after an absence of more than 100 years. Since reintroduction, herd growth and population dynamics have been monitored closely. At this time, there has been no significant dispersal from the herds' core range. The Nushagak Peninsula Caribou Herd (NPCH) grew rapidly from 146 reintroduced individuals to over 1000 in 13 years. Dramatic mean annual growth during the first 6 years (1988)(1989)(1990)(1991)(1992)(1993)(1994) of 38% (r = 0.32) can be attributed to the high percentage of females in the initial reintroduction, high calf production and survival, exceptional range conditions, few predators, and no hunting. However, the populations' exceptional growth (peak counts of 1400) slowed and stabilized between 1996¬ 1998 and then decreased between 1998 and 2000. Size, body condition and weights of calves captured in 2000 were significantly lower than those captured in 1995 and 1997. Although calf production also decreased from close to 100% (1990-1995) to about 91% (1996-2000), overall calf survival continued to be high. Legal harvest began in 1995, and harvest reports have accounted for approximately 3% of population mortality annually. Although brown bears (Ursus arctos) and wolves (Canis lupus) are present, the extent of predation is unknown. Mean home range of the NPCH was 674 km 2 and group sizes were greatest during post-calving aggregation in July (x = 127). Caribou population density on the Nushagak Peninsula reached approximately 1.2 caribou/km 2 in 1997 before declining to about 1.0 caribou/km 2 . A range survey in 1994 noted only trace utilization of lichens on the Nushagak Peninsula by caribou. A subsequent survey in 1999 found moderate to severe utilization in 46% of plots, suggesting the reintroduced herd was beginning to alter range condition. Between 1997 and 2000, both calf production and condition of 10-month-old calves declined. Calving has also been delayed in recent years. However, we suspect the reduced herd growth can be attributed to increasing hunting pressure and some dispersal of caribou from the Peninsula, not reduced range condition.
Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roam... more Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roaming horse behavior and habitat use and to aid in making informed management decisions. Global positioning system (GPS) and very high frequency (VHF) radio collars can be used to provide high spatial and temporal resolution information for detecting free-roaming horse movement. GPS and VHF collars are a common tool used in wildlife management, but have rarely been used for freeroaming horse research and monitoring in the United States. The purpose of this study was to evaluate the design, safety, and detachment device on GPS/VHF collars used to collect free-roaming horse location and movement data. Between 2009 and 2010, 28 domestic and feral horses were marked with commercial and custom designed VHF/GPS collars. Individual horses were evaluated for damage caused by the collar placement, and following initial observations, collar design was modified to reduce the potential for injury. After collar modifications, which included the addition of collar length adjustments to both sides of the collar allowing for better alignment of collar and neck shapes, adding foam padding to the custom collars to replicate the commercial collar foam padding, and repositioning the detachment device to reduce wear along the jowl, we observed little to no evidence of collar wear on horses. Neither custom-built nor commercial collars caused injury to study horses, however, most of the custom-built collars failed to collect data. During the evaluation of collar detachment devices, we had an 89% success rate of collar devices detaching correctly. This study showed that free-roaming horses can be safely marked with GPS and/or VHF collars with minimal risk of injury, and that these collars can be a useful tool for monitoring horses without creating a risk to horse health and wellness.
From June 1993 to June 2003, 40 adult female brown bears (Ursus arctos) were captured, radiocolla... more From June 1993 to June 2003, 40 adult female brown bears (Ursus arctos) were captured, radiocollared, and tracked for 1 to 10 years in a previously unstudied population in southwest Alaska. Mean litter size upon emergence from dens was 2.0, decreasing to 1.5 at weaning. Mean age of offspring at weaning was 2.9. Mean age of primiparity was 7.2 years while first weaning was estimated at 9.5 years. Mean maximum age of a female weaning a litter was 27.3 years. Mean annual survival estimates were 90.1-97.2% for radiocollared females !5 years old, 48.2-61.7% for cubs of the year, and 73.3-83.8% for 1 and 2-year-old offspring combined. Of 129 offspring followed beginning with their first summer, 38 (29.5%) survived to be weaned. Hunters harvested at least 12 marked or radiocollared bears (9 males and 3 females). No defense of life and property (DLP) killings were reported within or near the study area, but illegal harvests of brown bears were known to have occurred in the general region. Harvests within or near the study area averaged 7.3-12.1 males/year and 4.8-5.2 females/year. This population's rate of increase (k) was estimated as 1.035-1.047 for the first half of the study, 0.963-0.997 for the second half, and was found to be most sensitive to survival of females 5-14 years old.
Between 1993 and 2003, 40 adult female brown bears (Ursus arctos) were radiocollared and monitore... more Between 1993 and 2003, 40 adult female brown bears (Ursus arctos) were radiocollared and monitored in the southwest Kuskokwim Mountains of Alaska. The 95% kernel home range size for individuals with >50 relocations (n = 20) ranged from 93-623 km2 (x = 356 km2). Bears occupied lower elevations during July and August (x = 454 m) when salmon (Oncorhynchus spp.) were available and higher elevations in September (x = 520 m), presumably to feed on berries, ground squirrels (Spermophilus parryii), and caribou (Rangifer tarandus). During the denning period, bears moved to higher average elevations (x = 632 m), generally remaining through June (x = 570 m). Radiomarked females entered the den in mid October and exited in mid May. There was fidelity to denning areas, with an average distance between consecutive dens of 4.5 km (SD = 3.1). Females with cubs were found at higher average elevations than females without young or with yearlings. Radiomarked females were found closer to anadromous streams from 16 July-15 August, coinciding with chinook (0. tschawytscha), chum (0. keta), and sockeye salmon (0. nerka) availability. Beginning in 1998, chinook and chum salmon escapement was low in the Kuskokwim drainage. There was an inverse relationship between measures of salmon availability and bear distances to anadromous streams. This indicates that although the study area was at the fringe of salmon range, salmon abundance influenced bear seasonal movements and distribution. With reduced salmon availability, this area may support a lower bear density, and brown bear population management should be considered in salmon escapement goals. Ursus 16(2):181-189 (2005) Brown bears (Ursus arctos) have historically been an important source of food and hides for Native residents of southwest Alaska (Van Daele et al. 2001). In 1991 and 1992, state and federal regulatory boards liberalized brown bear hunting regulations for subsistence users in southwest Alaska. The bear population affected by this liberalization had never been investigated, and little was known about its size, distribution, or behavioral characteristics. Home range estimates can indicate the ecological requirements of animals because home ranges include all resources used by a resident (Seaman and Powell 3Present address: US Fish and Wildlife Service, Tetlin National Wildlife Refuge, PO Box 779, Tok, Alaska 99780, USA; Gail_Collins@fws.gov 4Present address: US Fish and Wildlife Service, Innoko National Wildlife Refuge, PO Box 69, McGrath, Alaska 99627, USA; Steve_Kovach@fws.gov 5Michael_Hinkes@ fws.gov 1990). Home ranges and the movements within them are behavioral manifestations of basic biological requirements, such as food, shelter, and mates. Brown bear home range size is a function of habitat quality and population density (Nagy and Haroldson 1990). Several studies documented habitat use and movement patterns of coastal (Bers et al. 1980, Glenn and Miller 1980, Schoen et al. 1986, Hamilton and Bunnell 1987, Bares 1990, Ballard et al. 1993) and interior (Ballard et al. 1982) brown bears. These studies demonstrated how use of salmon (Oncorhynchus spp.) streams varied among bear populations. Brown bears in British Columbia ranged widely during the berry season, then restricted movement while feeding on salmon (Hamilton and Bunnell 1987). On the Alaska Peninsula (Glenn and Miller 1980), bears moved greater distances in spring than in summer and fall. Schoen et al. (1986) demonstrated that a portion of the Admiralty Island population did not feed on salmon, instead foraging in interior alpine and subalpine habitats. and black bear density estimation in Alaska using radiotelemetry and replicated mark-resight techniques. Wildlife Monograph 133. NAGY, J.A., AND M.A. HAROLDSON. 1990. Comparisons of some home range and population parameters among four grizzly bear populations in Canada. International Conference on Bear Research and Management 8:227-235. PEARSON, A.M. 1975. The northern interior grizzly bear (Ursus arctos L.). Canadian Wildlife Service Report Series 34. . 2001. Grizzlies, eskimos, and biologists: Cross-cultural bear management in southwest Alaska. Ursus 12:141-152. WORTON, B.J. 1995. Using Monte Carlo simulation to evaluate kernel-based home range estimators. Journal of Wildlife Management 59:794-800.
Brown bear (Ursus arctos) population density was estimated for a 21,178 km 2 study area in southw... more Brown bear (Ursus arctos) population density was estimated for a 21,178 km 2 study area in southwest Alaska. Estimates were obtained using an aerial line transect method that allows for peak detection to be both off the transect line and< 100%. Data collection required five small aircraft with two-person crews. Surveys were flown in 10-day windows to capture the period after den emergence but prior to full green-up. Surveys were flown in two consecutive years in order to detect sufficient bear groups to support the ...
SAMPLING 25 km Transects: (see .) randomly selected mid-points flat terrain -straight transects r... more SAMPLING 25 km Transects: (see .) randomly selected mid-points flat terrain -straight transects randomly hinged at mid-point mountainous terrain -transects followed elevation contours. Survey Timing, Duration, and Sequencing (see ) Transects were flown on 10 consecutive days after den emergence and prior to full leaf out. Transects were randomly assigned an id # then all transects with ids 1 -100 were completed prior to beginning transects 101 -200, etc.
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Papers by Gail H Collins