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Showing papers in "Journal of Wildlife Management in 1995"


Journal ArticleDOI
TL;DR: This book presents a meta-modelling framework for estimating the probability of detection on the line or point in the context of tuna vessel observer data to assess trends in abundance of dolphins in the North Atlantic.
Abstract: 1 Introductory concepts.- 1.1 Introduction.- 1.2 Range of applications.- 1.3 Types of data.- 1.4 Known constants and parameters.- 1.5 Assumptions.- 1.6 Fundamental concept.- 1.7 Detection.- 1.8 History of methods.- 1.9 Program DISTANCE.- 2 Assumptions and modelling philosophy.- 2.1 Assumptions.- 2.2 Fundamental models.- 2.3 Philosophy and strategy.- 2.4 Robust models.- 2.5 Some analysis guidelines.- 3 Statistical theory.- 3.1 General formula.- 3.2 Hazard-rate modelling of the detection process.- 3.3 The key function formulation for distance data.- 3.4 Maximum likelihood methods.- 3.5 Choice of model.- 3.6 Estimation for clustered populations.- 3.7 Density, variance and interval estimation.- 3.8 Stratification and covariates.- 4 Line transects.- 4.1 Introduction.- 4.2 Example data.- 4.3 Truncation.- 4.4 Estimating the variance in sample size.- 4.5 Analysis of grouped or ungrouped data.- 4.6 Model selection.- 4.7 Estimation of density and measures of precision.- 4.8 Estimation when the objects are in clusters.- 4.9 Assumptions.- 4.10 Summary.- 5 Point transects.- 5.1 Introduction.- 5.2 Example data.- 5.3 Truncation.- 5.4 Estimating the variance in sample size.- 5.5 Analysis of grouped or ungrouped data.- 5.6 Model selection.- 5.7 Estimation of density and measures of precision.- 5.8 Estimation when the objects are in clusters.- 5.9 Assumptions.- 5.10 Summary.- 6 Extensions and related work.- 6.1 Introduction.- 6.2 Other models.- 6.3 Modelling variation in encounter rate and cluster size.- 6.4 Estimation of the probability of detection on the line or point.- 6.5 On the concept of detection search effort.- 6.6 Fixed versus random sample size.- 6.7 Efficient simulation of distance data.- 6.8 Thoughts about a full likelihood approach.- 6.9 Distance sampling in three dimensions.- 6.10 Cue counting.- 6.11 Trapping webs.- 6.12 Migration counts.- 6.13 Point-to-object and nearest neighbour methods.- 7 Study design and field methods.- 7.1 Introduction.- 7.2 Survey design.- 7.3 Searching behaviour.- 7.4 Measurements.- 7.5 Training observers.- 7.6 Field methods for mobile objects.- 7.7 Field methods when detection on the centerline is not certain.- 7.8 Field comparisons between line transects, point transects and mapping censuses.- 7.9 Summary.- 8 Illustrative examples.- 8.1 Introduction.- 8.2 Lake Huron brick data.- 8.3 Wooden stake data.- 8.4 Studies of nest density.- 8.5 Fin whale abundance in the North Atlantic.- 8.6 Use of tuna vessel observer data to assess trends in abundance of dolphins.- 8.7 House wren densities in South Platte River bottomland.- 8.8 Songbird surveys in Arapaho National Wildlife Refuge.- 8.9 Assessing the effects of habitat on density.- Appendix A List of common and scientific names cited.- Appendix B Notation and abbreviations, and their definitions.

1,629 citations


Journal ArticleDOI
TL;DR: In this article, the authors define conservation biology as "the value of biodiversity" and "the threat of biodiversity extinction", and present a vision of sustainable development at local and national levels.
Abstract: PART I: DEFINING CONSERVATION BIOLOGY 1. What is Conservation Biology? 2. What is Biodiversity? 3. Where is the World's Biodiversity Found? PART II: THE VALUE OF BIODIVERSITY 4. The Value of Biodiversity 5. Indirect Economic Values 6. Environmental Ethics PART III: THREATS TO BIODIVERSITY 7. Extinction is Forever 8. Vulnerability to Extinction 9. Habitat Destruction, Fragmentation, Degradation, and Global Climate Change 10. Overexploitation, Invasive Species, and Disease PART IV: CONSERVATION AT THE POPULATION AND SPECIES LEVELS 11. Problems of Small Populations 12. Applied Population Biology 13. Establishing New Populations 14. Ex Situ Conservation Strategies PART V: PRACTICAL APPLICATIONS 15. Establishing Protected Areas 16. Designing Protected Areas 17. Managing Protected Areas 18. Conservation Outside Protected Areas 19. Restoration of Damaged Ecosystems PART VI: THE CHALLENGE OF SUSTAINABLE DEVELOPMENT 20. Sustainable Development at Local and National Levels 21. International Approaches to Sustainable Development 22. An Agenda for the Future

1,168 citations


Journal ArticleDOI
TL;DR: Kernel density estimators have been used to estimate home range size but little is known of their statistical properties, so four hypothetical models of home range suggested by Boulanger and White (1990) were used to evaluate bias and precision of these estimators.
Abstract: Kernel density estimators have been used to estimate home range size but little is known of their statistical properties. I applied kernel-based estimators of home range size, calculated from 95% probability contours of nonparametric density estimators, to computer-simulated radiolocation data. Four hypothetical models of home range suggested by Boulanger and White (1990) were used to evaluate bias and precision of these estimators in estimating known home range sizes. Kernel methods compared well with the best methods that are available for home range size estimation provided the appropriate level of smoothing was selected. I used brush rabbit (Sylvilagus bachmani) telemetry data to illustrate how Monte Carlo methods may also be used to assess estimator performance from field radiolocation data. A kernel estimator is preferred to a harmonic mean estimator in this example because it is less biased (i.e., the harmonic mean method has an inherent problem).

675 citations


Journal ArticleDOI
TL;DR: Investigation of dispersal of radio-tagged juvenile cougars in a California landscape containing 3 corridors found them to use corridors that are located along natural travel routes, have ample windy cover, include an underpass integrated with roadside fencing at high-speed road crossings, and lack artificial outdoor lighting.
Abstract: There is little information on the spatiotemporal pattern of dispersal of juvenile cougars (Felis concolor) and no data on disperser use of habitat corridors. I investigated dispersal of radio-tagged juvenile cougars (8 M, 1 F) in a California landscape containing 3 corridors (1.5, 4.0, and 6.0 km long) and several habitat peninsulas created by urban growth. Dispersal was usually initiated by the mother abandoning the cub near an edge of her home range. The cub stayed within 300 m of that site for 13-19 days and then dispersed in the direction opposite that taken by the mother. Mean age at dispersal was 18 months (range 13-21 months). Each disperser traveled from its natal range to the farthest part of the urban-wildland edge, Dispersing males occupied a series of small (<30% the area used by ad M in the same time span), temporary (10-298 days) home ranges, usually near the urban-wildland interface, and often with its longest border along that edge. Each of the 3 corridors was used by 1-3 dispersers, 5 of the 9 dispersers found and successfully used corridors, and 2 dispersers entered but failed to traverse corridors. Dispersing cougars will use corridors that are located along natural travel routes, have ample windy cover, include an underpass integrated with roadside fencing at high-speed road crossings, lack artificial outdoor lighting, and have <1 dwelling unit/ 16 ha

370 citations


Journal ArticleDOI
TL;DR: Mammals birds reptiles fish invertebrates wildlife management pollution hibernation terrestrial animals marine animals freshwater animals estuaries wetlands environmental physiology territories social behaviour home ranges foraging predation orientation and navigation homing statistical analysis satellite tracking VHF radio UHF and microwaves radar underwater acoustics infra-red lasers.
Abstract: Mammals birds reptiles fish invertebrates wildlife management pollution hibernation terrestrial animals marine animals freshwater animals estuaries wetlands environmental physiology territories social behaviour home ranges foraging predation orientation and navigation homing statistical analysis satellite tracking VHF radio UHF and microwaves radar underwater acoustics infra-red lasers.

222 citations


Journal ArticleDOI
TL;DR: Evaluated performance of nondifferentially corrected GPS collars in an experimental forest with mature, evenly spaced trees and on wild free-ranging moose to determine the influence of canopy on positional accuracy and observation rate.
Abstract: An automated animal location system, based on Global Positioning System (GPS) technology, is being used for wildlife research. The GPS is a divergent technology, and positional accuracies vary between millimeters and tens of meters, depending on the system used and operating conditions. Before GPS-based tracking data can be used for habitat analyses, the influence of habitat on GPS-collar performance must be evaluated under various canopy conditions, including the optimal condition of no canopy. We evaluated performance of nondifferentially corrected GPS collars in an experimental forest with mature, evenly spaced trees and on wild free-ranging moose (Alces alces) to determine the influence of canopy on positional accuracy and observation rate. In an experimental forest with mature, evenly spaced trees (henceforth called spacing trial), canopy characteristics of tree species, spacing, height, basal diameter, and canopy closure had no influence on positional accuracy (P > 0.05), but had an influence on GPS observation rate (P < 0.001). Location error was greater if positions were based on 2-dimensional rather than 3-dimensional mode of operation (P < 0.001), with location errors of 65.5 and 45.5 m, respectively. Location error in 3-dimensional mode did not differ from the expected error of 40 m (P = 0.43). As tree density increased, observation rate decreased and the probability of the GPS receiver operating in 2-dimensional mode increased (P < 0.001), resulting in increased location error. With future development of differentially corrected GPS collars, location errors of <10 m are expected. J. WILDL. MANAGE. 59(3):543-551

210 citations


Journal ArticleDOI
TL;DR: Gri Grizzly bear and wolf predation on neonates during the calving season was a limiting factor for the Denali Caribou Herd.
Abstract: Calf mortality is a major component of caribou (Rangifer tarandus) population dynamics, but little is known about the timing or causes of calf losses, or of characteristics that predispose calves to mortality. During 1984-87, we radiocollared 226 calves (≤3 days old) in the Denali Caribou Herd (DCH), an unhunted population utilized by a natural complement of predators, to determine the extent, timing, and causes of calf mortality and to evaluate influences of year, sex, birthdate, and birth mass on those losses. Overall, 39% of radio-collared calves died as neonates (≤ 15 days old), and 98% of those deaths were attributed to predation. Most neonatal deaths (85%) occurred within 8 days of birth. Few deaths occurred after the neonatal period (5, 10, and 0% of calves instrumented died during 16-30, 31-150, and >150 days of age, respectively). Survival of neonates was lower (P = 0.038) in 1985, following a severe winter, than during the other 3 years. In years other than 1985, calves born during the peak of calving (approx 50% of the total, born 5-8 days after calving onset) experienced higher (P 10 days old. Wolf predation was not related (P > 0.05) to calf age and peaked 10 days after onset of calving. Grizzly bear and wolf predation on neonates during the calving season was a limiting factor for the Denali Caribou Herd.

196 citations


Journal ArticleDOI
TL;DR: Bird populations may continue to decline in strips before regeneration of adjacent clear-cuts provides suitable habitat for forest-dwelling species, and there was evidence that 60-m-wide strips are required for Forest-Dwelling birds.
Abstract: Riparian forest strips are usually protected from logging for their buffer effect on aquatic habitats. However, their value to terrestrial wildlife is unknown. From 1989 to 1992, we compared bird abundance and species composition in 5 experimental riparian forest strips (20-m, 40-m, 60-m, and control [>300 m wide], intact strips, and 20-m-wide thinned strips), in boreal balsam fir (Abies balsamea) stands, for 3 years following clear-cutting. Bird densities increased 30-70% (P 0.05) thereafter to approximately pretreatment levels. The 20- and 40-m-wide riparian strips had highest mean bird densities, but also the fastest (P < 0.05) decreases thereafter. By the third year after clear-cutting, forest-dwelling species were less (P = 0.01) abundant than ubiquitous species in the 20-m strips. The golden-crowned kinglet (Regulus satrapa), Swainson's thrush (Catharus ustulatus), blackpoll warbler (Dendroica striata), and black-throated green warbler (D. virens) became nearly absent in 20-m strips. The removal of 33% of the trees in some 20-m strips resulted in a <20% decline of bird densities, a moderate effect that combined with the greater effect of strip narrowness. There was evidence that 60-m-wide strips are required for forest-dwelling birds. Bird populations may continue to decline in strips before regeneration of adjacent clear-cuts provides suitable habitat for forest-dwelling species

167 citations


Journal ArticleDOI
TL;DR: Management of coyotes may be an effective method for increasing duck nest success in uplands of 36 areas managed for nesting ducks in North Dakota and South Dakota.
Abstract: Low recruitment rates prevail among ducks in the Prairie Pothole Region of North America, primarily because of high nest depredation rates. The red fox (Vulpes vulpes) is a major predator of duck eggs, but fox abundance is depressed by coyotes (Canis latrans). We tested the hypothesis that nest success of upland-nesting ducks is higher in areas with coyotes than in areas with red foxes. We conducted the study during 1990-92 in uplands of 36 areas managed for nesting ducks in North Dakota and South Dakota. Overall nest succes averaged 32% (95% CI = 25-40) on 17 study areas where coyotes were the principal canid and 17% (CI = 11-25) on 13 study areas where red foxes were the principal canid (P = 0.01). Both canids were common on 6 other areas, where nest success averaged 25% (CI = 13-47). Habitat composition, predator communities with the exception of canids, and species composition of duck nests in coyote and red fox areas were similar overall. Upon examining only nests with ≥6 eggs on the last visit prior to hatch or depredation, we determined nests with evidence characteristic of fox predation accounted for 4% of depredated nests in coyote areas and 27% in fox areas (P = 0.001). An expanding coyote population is contributing to higher overall nest success. Management of coyotes may be an effective method for increasing duck nest success

165 citations


Journal ArticleDOI
TL;DR: Restoration efforts may be beneficial to neotropical migrant species such as eastern woodpewee and prairie warbler, in addition to declining species of regional interest such as red-cockaded woodpecker, Bachman's sparrow, and northern bobwhite that depend upon pine-grassland habitats.
Abstract: Plans exist to restore the fire-dependent pine (Pinus spp.)-grassland community in Ouachita National Forest and potentially throughout the southeastern United States to benefit the endangered red-cockaded woodpecker (Picoides borealis). Restoration and management techniques include wildlife stand improvement (WSI; thinning of midstory and codominant trees) and prescribed fire. We evaluated how habitat improvement for the red-cockaded woodpecker affected other breeding bird species. We compared avian species frequency of occurrence and abundance during 2 breeding seasons in untreated pine-hardwood stands with that in treated stands after WSI and in 3 growing seasons following WSI and prescribed fire. Total bird densities were highest (P = 0.037) in the second growing season following WSI and fire and lowest in the control, whereas species richness did not differ (P = 0.399) among treatments. Densities of ground/ shrub-foraging and shrub-nesting species increased (P = 0.002 and 0.002, respectively) the most following WSI and fire. Only ground-nesting species were more abundant (P < 0.001) in untreated stands than in treated stands. Restoration efforts may be beneficial to neotropical migrant species such as eastern woodpewee (Contopus virens) and prairie warbler (Dendroica discolor), in addition to declining species of regional interest such as red-cockaded woodpecker, Bachman's sparrow (Aimophila aestivalis), and northern bobwhite (Colinus virginianus) that depend upon pine-grassland habitats

150 citations


Journal ArticleDOI
TL;DR: P piping plover chicks moved from ocean beach nest sites to the bay beach and island interior along ephemeral, vegetation-free paths created during winter storms by waves surging across the island, and should be maintained to enable them to move to the island interior and bay habitats where chick survival is greatest.
Abstract: The decline of piping plover (Charadrius melodus) populations and subsequent listing as a threatened species has been attributed, in part, to low chick survival. During 1988-90, we observed piping plover chicks daily to evaluate hypotheses of differential food resources, predation, and disturbance explaining differences in chick survival in 3 habitats on Assateague Island National Seashore (AINS), Maryland. Chicks reared on the bay beach and island interior had higher daily survival rates (0.97, 0.99 vs. 0.87; P < 0.001), higher foraging rates (13.3, 10.8 vs. 5.9 attempts/min; P < 0.001), and spent more time foraging (76, 80 vs. 37%, P < 0.004) than chicks reared on the ocean beach. Terrestrial arthropod abundance on the bay beach and island interior was greater than on the ocean beach in 5 of 6 cases (P < 0.01). Amphipods, however, were more abundant on ocean beaches than in bay and island interior habitats each year (P ≤ 0.03). Chicks 4-5 days old that were reared on the bay beach or island interior habitats were heavier than those reared on the ocean beach (8.5, 7.8 vs. 6.5 g; P < 0.01). Overall disturbance rates did not differ among habitats (behavioral observations; P = 0.29). The number of predator trails did not differ among the 3 habitats (P = 0.2). Red fox (Vulpes vulpes) trails were more numerous in the island interior and ocean beach (P < 0.001), ghost crab (Ocypode quadrata) burrows were more numerous on ocean beach (P < 0.001), and gull (Larus spp.) and raccoon (Procyon lotor) trails were more numerous on bay beach (P < 0.001 and P = 0.001, respectively). Piping plover chicks moved from ocean beach nest sites to the bay beach and island interior along ephemeral, vegetation-free paths created during winter storms by waves surging across the island. These paths should be maintained to enable piping plover chicks to move to the island interior and bay habitats where chick survival is greatest. Preserving access to high quality brood-rearing habitat will ensure reproductive rates that will sustain the local population and contribute to the species' recovery.

Journal ArticleDOI
TL;DR: Seasonal survival, annual survival, and cause-specific mortality of 1,001 radio-marked bobwhite in northern Missouri were estimated and greater vulnerability of males to avian predators may represent a cost of displaying.
Abstract: Efforts to understand fluctuations in northern bobwhite (Colinus virginianus) abundance illustrate inadequate knowledge of demographic processes. Therefore, we estimated seasonal survival, annual survival, and cause-specific mortality of 1,001 radio-marked bobwhite in northern Missouri. Annual survival was 5.3 ± O.5% and did not differ between ages (P = 0.33) or sexes (P = 0.48). Fall-spring survival (15.9 ± 0.8%) was less than spring-fall survival (33.2 ± 2.7%, P < 0.001). Females had lower fall-spring survival (13.7 ± 1.1%) than males (17.6 ± 1.1%, P = 0.02). Male-biased sex ratios likely result from differential fall and winter survival. Avian (28.7%) and mammalian (25.7%) predators were primary natural mortality agents. Hunter-retrieved (22.9%) and -unretrieved (5.3%) kill resulted in 28.2% harvest-related mortality. During springfall, males experienced higher avian mortality (26.5%) than females (20.0%) (P = 0.09). Greater vulnerability of males to avian predators may represent a cost of displaying. Each incubation and brood-rearing attempt reduced survival by 16% when compared with nonreproductively active birds during a similar period. Bobwhites must be highly productive to replace annual population losses

Journal ArticleDOI
TL;DR: The reproductive system of northern bobwhite enables recovery from low annual survival or periodic catastrophic declines and may be an adaptation to fluctuating resources in ephemeral, dynamic habitats.
Abstract: To better understand the reproductive mechanisms that enable northern bobwhite (Colinus virginianus) to recover from high annual mortality, we studied the reproductive strategies, success, and mating systems of 321 radio-marked bobwhite in northern Missouri during 1990-92. Seventy-four female and 43 male bobwhite incubated 159 nests. Females exhibited apparent monogamy during 60% of nesting attempts and apparent polyandry during 40%. Over the entire nesting season, 71% of females were polyandrous. Of those birds alive 15 April (n = 112 F, n = 148 M), 40.2% of females and 13.5% of males successfully hatched ≥1 nest. Seventy-four percent of females (n = 42) and 26% of males (n = 50) surviving until 1 September successfully hatched ≥1 nest. Nesting females that survived the nesting period incubated a mean of 1.8 nests (SE = 0.13), and males incubated 1.0 nests (SE = 0.04). Of those birds that failed on an initial nesting attempt, 57.9% of females (n = 38) and 2 of 23 males incubated ≥1 renest. Of those females that were successful on their initial nesting attempt, 25.7% attempted second nests. Female first nests represented 45.9%, female renests 20.1%, female double-clutch attempts 5.7%, and male-incubated nests 28.3% of all nests located. Nest survival was 43.7% (SE = 3.9). The reproductive system of northern bobwhite enables recovery from low annual survival or periodic catastrophic declines and may be an adaptation to fluctuating resources in ephemeral, dynamic habitats.

Journal ArticleDOI
TL;DR: Study of grizzly bear populations in Kananaskis and Selkirk Mountains of Idaho finds results are inconsistent with the no avoidance and food hypotheses but consistent with the sex hypothesis of sexual segregation.
Abstract: We studied 2 grizzly bear (Ursus arctos) populations to test 3 hypotheses of sexual segregation. The no avoidance hypothesis predicts that females do not avoid males and male-occupied habitats but simply have different habitats available to them within their home ranges. The food hypothesis predicts that subadult and adult females avoid males because of competition or cannibalism by males for food. The sex hypothesis predicts that only sexually mature adult females avoid males because of sexually motivated infanticide by nonsire males. Sexually mature females avoided (P < 0.05) food-rich, male-occupied habitats in Kananaskis, Alberta, but selected (P < 0.05) such habitats in the Selkirk Mountains of Idaho. Sexually immature females selected (P < 0.05) food-rich, male-occupied habitats in both areas. Unequal availability of habitat did not explain the pattern of segregation because food-rich habitats were available to all age-sex classes. Competition or cannibalism by males did not explain segregation because only sexually mature females avoided male-occupied habitats in Kananaskis and no females avoided males in the Selkirks. Adult female avoidance of potentially infanticidal, nonsire, immigrant males in Kananaskis appeared to explain the pattern of segregation. High mortality of older males in Kananaskis coincided with an influx of younger, potentially infanticidal, immigrant males, and adult females avoided those males and their favored habitats. No such segregation was observed in the Selkirks where mortality of older males was low and where there were few or no immigrant males. Results are inconsistent with the no avoidance and food hypotheses but consistent with the sex hypothesis of sexual segregation.

Journal ArticleDOI
TL;DR: Flying squirrels were not old-growth specialists; however, low densities in shelterwood stands suggest that heavy logging and intensive site preparation negatively affected flying squirrel populations.
Abstract: The northern flying squirrel (Glaucomys sabrinus) is the primary prey of northern spotted owls (Strix occidentalis caurina) and California spotted owls (S. o. occidentalis) throughout much of the owls' ranges. Flying squirrel abundance patterns, however, are poorly documented. Using capture-recapture techniques to estimate density, we compared flying squirrel densities among 3 types of fir (Abies spp.) forests in Lassen National Forest, northeastern California. We compared densities between 3 each of old and shelterwood-logged fir stands in 1990 and among 4 each of old, shelterwood, and young fir stands in 1991-92. Shelterwood stands had been logged and had undergone site preparation 5 years prior to our study. In 1990 flying squirrel density was greater in old (? = 2.76 squirrels/ha, SE = 0.55) than in shelterwood (? = 0.31 squirrels/ha, SE = 0.11) stands (P = 0.005). In 1991-92 density varied (P = 0.001) among the 3 stand types, averaging 3.29 squirrels/ha (SE = 0.63) in old, 2.28 squirrels/ha (SE = 0.18) in young, and 0.37 squirrels/ ha (SE = 0.17) in shelterwood stands. Body mass of adult males and females and recapture rate did not differ (M, P = 0.438; F, P = 0.983; P = 0.218, respectively) between old and young stands, and percent juveniles captured was greater (P = 0.052) in old than in young stands. Diet analyses were consistent with other studies and indicated that sporocarps of hypogeous fungi were a common food source. Frequency of hypogeous sporocarps was correlated (r s = 0.860, P < 0.001) with flying squirrel density, but cavity density and understory cover were not (P = 0.344 and 0.217, respectively). Flying squirrels were not old-growth specialists; however, low densities in shelterwood stands suggest that heavy logging and intensive site preparation negatively affected flying squirrel populations.

Journal ArticleDOI
TL;DR: This study supports the hypothesis that greater amounts of tall grass and medium-height shrub cover at nest sites lower risk of nest predation for sage grouse.
Abstract: Because of high nest predation and long-term declines in sage grouse (Centrocercus urophasianus) productivity in Oregon, we assessed the effects of vegetational cover and height on predation of artificial sage grouse nests (n = 330). Artificial nest fate was positively associated with tall grass cover and medium-height shrub cover collectively (P = 0.01). No other vegetation, predator, temporal, or spatial variables explained any additional variation in the probability of predation. This study supports the hypothesis that greater amounts of tall grass and medium-height shrub cover at nest sites lower risk of nest predation for sage grouse. Management practices that increase cover and height of native grasses in sagebrush communities with medium-height shrubs are recommended to enhance sage grouse productivity

Journal ArticleDOI
TL;DR: In this paper, the authors present components of situations that may affect the outcome of a relocation of a grizzly bear from human/bear conflict situations using data from Yellowstone National Park.
Abstract: Relocating grizzly bears (Ursus arctos) from human/bear conflict situations has been a standard management procedure. Using data from Yellowstone National Park, we present components of situations that may affect the outcome of a relocation. Survival rates of transported bears were lower (l x = 0.83) (P = 0.001) than those not transported (l x = 0.89). Survival was largely affected by whether the bear returned to the capture site (P = 0.029). Return rate was most affected by distance transported (P = 0.012) and age-sex group (P = 0.014). Return rates decreased at distances ≥75 km, and subadult females returned least (P = 0.050) often. Because of low survival and high return rates, transporting grizzly bears should be considered a final action to eliminate a conflict situation. However, transporting females must be considered a viable management technique because transports of some individuals have resulted in contributions to the population through successful reproduction.

Journal ArticleDOI
TL;DR: In this article, a new procedure for constructing confidence interval estimates of population size in mark-sight experiments is presented, where the method of selecting animals for marking must be equivalent to a simple random sample without replacement and the number of times animals are sighted must be independent of their mark status.
Abstract: A new procedure for constructing confidence interval estimates of population size in mark-sight experiments is presented. The method of selecting animals for marking must be equivalent to a simple random sample without replacement. Marked animals are required to be individually identifiable. The number of times animals are sighted must be independent of their mark status. The sighting process does not need to be composed of independent sighting trials or even decomposable into separate trials. Sighting probabilities can vary among individuals and can depend on such factors as group size and vegetational cover. Other methods of constructing confidence intervals in mark-sight experiments given these latter conditions have failed to achieve their stated nominal confidence level. Our confidence interval procedures are shown by simulation to have actual confidence levels close to nominal under conditions encountered in an application to a Colorado moose (Alces alces shirasi) population. For this population with 29 radio-collared moose and 5 helicopter sighting flights, the 90% confidence interval for the moose population size on the 1,400-km 2 area was 382-505.

Journal ArticleDOI
TL;DR: Movements of males to summer ranges could not be explained by food sources and may be related to predator avoidance, therefore, maintaining leks and habitat within 3-4 km of the lek center should be emphasized in capercaillie conservation.
Abstract: The capercaillie (Tetrao urogallus) is endangered in Central Europe; knowledge of its spatial requirements is vague but important for conservation. I radiotracked 40 capercaillie during 1988-92 in the Bavarian Alps, Germany, to study annual range use patterns and to identify habitat needs for capercaillie conservation. Annual home ranges of females (n = 7) and males (n = 19) were not different in size (P = 0.56), diameter (P = 0.41), or vegetation (P > 0.15). Home range size varied between 132 and 1,207 ha, and averaged 550 ha (SE = 52 ha). Home range size was inversely related to availability of bilberry (Vaccinium myrtillus) (P 5-year-old males were the last to leave. Movements of males to summer ranges could not be explained by food sources and may be related to predator avoidance. In the course of a year, birds of 1 lek may use a 30-50 km 2 area. Therefore, maintaining leks and habitat within 3-4 km of the lek center should be emphasized in capercaillie conservation

Journal ArticleDOI
TL;DR: It is proposed that digging for termites (sloth bears' primary food) was difficult in alluvium when the ground was saturated, prompting large males to move to better drained uplands and alluvial dry season ranges were smaller than wet season ranges, suggesting thatalluvium offered a plentiful food supply during the dry season.
Abstract: Sloth bears (Melursus ursinus) are the only myrmecophagous ursid. Ursids generally have large home ranges, often with widely separated seasonal ranges, whereas myrmecophagous mammals tend to have relatively small ranges for their body size. During 1990-93, we captured and radiocollared 18 sloth bears in Royal Chitwan National Park, Nepal, and tracked their movements for ≤3 years to assess whether sloth bears have large ranges like other bears, or if, as a result of their myrmecophagous foraging habits, their home ranges are smaller. Six of 8 males tracked ≥1 year exhibited seasonal home range shifts from grasslands and riverine forests of the alluvial floodplain to upland sal (Shorea robusta)-dominated forest during the onset of the monsoon (median movement date = 1 Jun); however, the 2 smallest males and most females did not make seasonal range shifts to sal forest. After the wet season (May-Nov), males returned to the alluvium (median return date = 14 Nov). Alluvial dry season ranges were smaller (P < 0.05) than wet season ranges, for bears that had moved to the sal and for those that did not, suggesting that alluvium offered a plentiful food supply during the dry season. We propose that digging for termites (sloth bears' primary food) was difficult in alluvium when the ground was saturated, prompting large males to move to better drained uplands. Home ranges of sloth bears in Chitwan were small compared with those of other ursids, and unlike typical ursids, sloth bears were not attracted to croplands outside the park, where they would have been subjected to risks of human-related mortality. Sloth bear populations may subsist in sanctuaries smaller than would be expected for an ursid, given sufficient alluvial habitat

Journal ArticleDOI
TL;DR: The reduction in native ungulate use of leafy spurge-infested sites may be attributed to lower forage production in infested sites as well as simple avoidance.
Abstract: Leafy spurge (Euphorbia esula), smooth brome (Bromus inermis), Japanese brome (B. japonicus), and downy brome (B. tectorum) are exotic plant species that dominate and displace native forage species throughout much of central North America. However, information on how exotic plant infestations affect native ungulate use of habitat is limited. We used pellet-group densities to estimate use of habitat by bison (Bos bison), elk (Cervus elaphus), and deer (Odocoileus spp.) during 1992-93 growing seasons within 4 exotic plant-infested and 4 comparable noninfested grassland habitats in Theodore Roosevelt National Park, North Dakota. We used twig count and twig measurement methods to estimate use of browse during summer (1992) and winter (1992-93), respectively, for both leafy spurge-infested and noninfested woodland habitats. Bison use of 2 leafy spurge-infested grassland habitats averaged 83% less than that for noninfested sites (P 0.05). Use of browse in green ash (Fraxinus pennsylvanica)- chokecherry (Prunus virginiana) habitat during summer and winter was reduced an average of 32% by infestations of leafy spurge (P < 0.05). The reduction in native ungulate use of leafy spurge-infested sites may be attributed to lower forage production in infested sites as well as simple avoidance.

Journal ArticleDOI
TL;DR: A model for estimating survival of young waterfowl from hatch to fledging is developed that enables interchange of individuals among broods and relaxes the assumption that individuals within broods have independent survival probabilities.
Abstract: Estimates of juvenile survival from hatch to fledging provide important information on waterfowl productivity. We develop a model for estimating survival of young waterfowl from hatch to fledging. Our model enables interchange of individuals among broods and relaxes the assumption that individuals within broods have independent survival probabilities. The model requires repeated observations of individually identifiable adults and their offspring that are not individually identifiable. A modified Kaplan-Meier procedure (Pollock et al. 1989a,b) and a modified Mayfield procedure (Mayfield 1961, 1975; Johnson 1979) can be used under this general modeling framework, and survival rates and corresponding variances of the point estimators can be determined.

Journal ArticleDOI
TL;DR: It is suggested that northern populations subjected to infrequent severe winters in mixed agricultural and forested environments likely would benefit more from enhancement of nesting and brood-rearing habitat and may result from variability of annual nest success and poult survival.
Abstract: Annual fluctuations of northern wild turkey (Meleagris gallopavo silvestris) populations often are attributed to high winter mortality. However, studies conducted in agricultural environments have demonstrated that seasonal survival can be highest during winter, suggesting other factors are more important to annual population change. We examined survival and reproduction of female eastern wild turkeys in south-central New York during 1990-93 and conducted a sensitivity analysis to determine the relative importance of demographic parameters to annual population change. Seasonal survival rates (n = 238) were 0.800 for spring, 0.855 for summer, 0.834 for fall, and 0.873 for winter. Fall survival rates varied by years (P < 0.01) and were higher during years of above average hen success. Annual survival rates averaged 0.498, and crude annual mortality rates (M) averaged 0.321 for predation and 0.117 for poaching, hunting, and wounding combined. Subadult females had lower nesting rates (P = 0.002, n = 201), lower renesting rates (P = 0.001, n = 115), and lower hen success rates (P = 0.02, n = 196) than adult females. Nest success averaged 37.9% (n = 232) and was highest (P = 0.005) during years with average to below average May rainfall. We observed annual variation in nest success (P = 0.001), hen success (P = 0.003), and hatching rates (P = 0.04). Poult survival averaged 40.0% (n = 605) and did not vary among years (P = 0.73). Nest success was the primary factor contributing to annual population change. We suggest that annual fluctuations of northern populations in mixed agricultural and forested environments rarely result from variability of annual survival and may result from variability of annual nest success and poult survival. Northern populations subjected to infrequent severe winters in mixed agricultural and forested environments likely would benefit more from enhancement of nesting and brood-rearing habitat.


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TL;DR: The potential of remote-sensing/GIS technologies to address the needs of those involved with the management of forest ecosystems is explored and the need for landscape-scale analysis to support forest ecosystem research and management is explored.
Abstract: Recent advances in remote-sensing technology and the processing of remote-sensing data through geographic information systems (GIS) present ecologists and resource managers with a tremendously valuable tool -- but only if they are able to understand its capabilities and capture its potential."Remote Sensing and GIS in Ecosystem Management" identifies and articulates current and emerging information needs of those involved with the management of forest ecosystems. It explores the potential of remote-sensing/GIS technologies to address those needs, examining: the need for landscape-scale analysis to support forest ecosystem research and management current challenges in the development of remote-sensing/GIS applications case studies of different forest regions in the United States the potential for further development or declassification of military and aerospace remote-sensing/GIS technologies As well as providing important information for ecologists and resource managers, the book will serve as a valuable resource for legislative and judicial policymakers who do not have a technical background in either remote sensing or resource management but who are nonetheless called upon to make decisions regarding the protection and management of forest ecosystems.

Journal ArticleDOI
TL;DR: A sightability model was developed to estimate bighorn population and composition parameters from data collected during helicopter surveys and found that activity and habitat were the most important factors affecting visibility.
Abstract: Visibility bias (failure to observe all animals) encountered during aerial surveys produces biased estimates of population parameters. Factors affecting visibility during helicopter surveys of bighorn sheep (Ovis canadensis) have not been quantified. We measured visibility bias for helicopter surveys of bighorn sheep in southwestern Idaho. Visibility was influenced (P < 0.05) by activity, habitat, sex composition of groups, light condition, position of sheep relative to the helicopter, and topographic position but not by group size (P = 0.781). Multivariate regression indicated that activity (P < 0.001) and habitat (P < 0.002) variables were the most important factors affecting visibility. A sightability model was developed to estimate bighorn population and composition parameters from data collected during helicopter surveys. We conducted 12 surveys in southwestern Idaho. The estimated population observed during helicopter surveys ranged from 51.7 to 78.1% and averaged 67.1% (CV = 10.6%). Confidence intervals for population estimates ranged from 16.4 to 22.9% and averaged 18.5% (CV = 16.0%) of the population estimate. We recommend correcting survey data for visibility bias to estimate bighorn sheep population parameters.

Journal ArticleDOI
TL;DR: A reward band study on mallards found evidence of geographic variation in reporting rates, but not of smooth latitudinal or longitudinal gradients, and evidence of lower reporting rates for females than males, especially in prairie Canada and the Central Flyway.
Abstract: We conducted a reward band study on mallards (Anas platyrhynchos) to estimate and test hypotheses about sources of variation in band reporting rate. We banded 25,398 mallards with standard and $100 reward bands (3 mallards banded with standard bands for every reward-banded mallard) during preseason (Jul-Sep), 1988. We used a series of multinomial models to model the resulting 2,776 band recoveries from 1988 to 1991. Estimates of reporting rate for males shot in 10 harvest areas ranged from 0.29 to 0.46 and averaged 0.38 (SE = 0.020). We found evidence (P < 0.01) of geographic variation in reporting rates, but not of smooth latitudinal or longitudinal gradients. There was evidence (P = 0.07) of lower reporting rates for females than males, especially in prairie Canada and the Central Flyway. Except for young males in the northern Atlantic Flyway, estimated harvest rates were lower than historical estimates, as expected from recent restrictive hunting regulations. Patterns of geographic and age-sex variation in harvest rates were similar to those obtained using historical band-recovery data.


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TL;DR: Although mowing reduces populations of gray-tailed voles and disrupts social organization, the high reproductive potential of the species enables populations to recover rapidly to premowing levels.
Abstract: Voles (Microtus spp.) commonly inhabit forage crops and may cause excessive damage to these crops. However, cover removal by mowing or haying may cause vole populations to decline. To determine if gray-tailed voles (M. canicaudus) responded to mowing of alfalfa in a density-dependent manner, we livetrapped 4 populations in each of low- ( 90) 0.2-ha enclosures before and after mowing in 1992. Survival rates of both sexes, population size and growth rates, and proportion of total captures that were recruits declined (P 0.22). Greater than 50% of dispersing adult females were pregnant, and we suggest that mowing disrupted social organization of voles causing some animals to abandon home ranges or territories. Although mowing reduces populations of gray-tailed voles and disrupts social organization, the high reproductive potential of the species enables populations to recover rapidly to premowing levels

Journal ArticleDOI
TL;DR: It is concluded that any effect of the spill on survival occurred before eagles were radiotagged and that the PWS bald eagle population has an annual finite growth rate of 2%.
Abstract: We investigated age-specific annual survival rates for 159 bald eagles (Haliaeetus Leucocephalus) radiotagged from 1989 to 1992 in Prince William Sound (PWS), Alaska. We monitored radio-tagged eagles for {le}3 years beginning 4 months after the Exxon Valdez oil spill. There was no difference (P > 0.10) in survival rates between eagles radiotagged in oiled areas and eagles radiotagged in unoiled areas of PWS. Pooled annual survival rates were 71% for first-year eagles, 95% for subadults, and 88% for adult bald eagles. Most deaths occurred from March to May. We found no indication that survival of bald eagles radiotagged >4 months after the oil spill in PWS was directly influenced by the spill and concluded that any effect of the spill on survival occurred before eagles were radiotagged. A deterministic life table model suggests that the PWS bald eagle population has an annual finite growth rate of 2%. Given the cumulative effects of direct mortality and reduced productivity caused by the oil spill, we predicted that the bald eagle population would return to its pre-spill size by 1992. 27 refs., 2 figs., 2 tabs.