Showing papers in "Journal of Wildlife Management in 1997"

Barriers and bridges to the renewal of ecosystems and institutions

Abstract: This volume uses a series of case studies to test an emerging theory of complex adaptive systems that forms the basis for explaining the interrelated dynamics of ecosystems, institutions and society. It deals equally with institutional organization and ecosystem structure.

Relative Effects of Habitat Loss and Fragmentation on Population Extinction

Abstract: In their review of the recent explosion of spatially explicit theory in ecology, Kareiva and Wennergren (1995) suggest a number of emerging principles for species conservation. One of these principles is that how habitats are arranged in space can mitigate the risks of species extinctions from habitat loss. I tested this by estimating the relative importance of habitat loss and habitat spatial pattern (fragmentation) on population extinction, using a simple, spatially explicit simulation model. Results indicate that the effects of habitat loss far outweigh the effects of habitat fragmentation. I therefore suggest that, in fact, details of how habitats are arranged cannot usually mitigate the risks of habitat loss. Conservation efforts should be aimed foremost at stopping habitat loss and at habitat restoration.

Environmental Contaminants in Wildlife: Interpreting Tissue Concentrations

Abstract: Residue Analyses: How They Were Used to Assess the Hazards of Contaminants to Wildlife, J.O. Keith DDT, DDD, and DDE in Birds, L.J. Blus Dieldrin and Other Cyclodiene Pesticides in Wildlife, D.B. Peakall Other Organochlorine Pesticides in Birds, S.N. Wiemeyer PCBs in Aquatic Organisms, A.J. Niimi Toxicological Implications of PCB Residues in Mammals, M.A. Kamrin and R.K. Ringer PCBs and Dioxins in Birds, D.J. Hoffman, C.P. Rice, and T.J. Kubiak Dioxins: An Environmental Risk for Fish? D. Sijm and A. Opperhuizen Polycyclic Aromatic Hydrocarbons in Marine Mammals, Finfish, and Molluscs, J. Hellou Lead in Waterfowl, D.J. Pain Interpretation of Tissue Lead Residues in Birds Other Than Waterfowl, J.C. Franson Lead in Mammals, W.-C. Ma Toxicological Significance of Mercury in Freshwater Fish, J.G. Wiener and D.J. Spry Mercury in Birds and Terrestrial Mammals, D.R. Thompson Metals in Marine Mammals, R.J. Law Cadmium in Small Mammals, J.A. Cooke and M.S. Johnson Cadmium in Birds, R.W. Furness Heavy Metals in Aquatic Invertebrates, P.S. Rainbow Selenium in Aquatic Organisms, A.D. Lemly Selenium in Birds, G.H. Heinz Fluoride in Birds, W.J. Fleming Fluoride in Small Mammals, J.A. Cooke, I.C. Boulton, and M.S. Johnson

Statistical power analysis in wildlife research

Abstract: Statistical power analysis can be used to increase the efficiency of research efforts and to clarify research results. Power analysis is most valuable in the design or planning phases of research efforts. Such prospective (a priori) power analyses can be used to guide research design and to estimate the number of samples necessary to achieve a high probability of detecting biologically significant effects. Retrospective (a posteriori) power analysis has been advocated as a method to increase information about hypothesis tests that were not rejected. However, estimating power for tests of null hypotheses that were not rejected with the effect size observed in the study is incorrect; these power estimates will always be ≤0.50 when bias adjusted and have no relation to true power. Therefore, retrospective power estimates based on the observed effect size for hypothesis tests that were not rejected are misleading; retrospective power estimates are only meaningful when based on effect sizes other than the observed effect size, such as those effect sizes hypothesized to be biologically significant. Retrospective power analysis can be used effectively to estimate the number of samples or effect size that would have been necessary for a completed study to have rejected a specific null hypothesis. Simply presenting confidence intervals can provide additional information about null hypotheses that were not rejected, including information about the size of the true effect and whether or not there is adequate evidence to accept a null hypothesis as true. We suggest that (1) statistical power analyses be routinely incorporated into research planning efforts to increase their efficiency, (2) confidence intervals be used in lieu of retrospective power analyses for null hypotheses that were not rejected to assess the likely size of the true effect, (3) minimum biologically significant effect sizes be used for all power analyses, and (4) if retrospective power estimates are to be reported, then the α-level, effect sizes, and sample sizes used in calculations must also be reported.

A pragmatic approach to modeling for wildlife management

Abstract: I contrast 2 views of modeling: the model as a representation of truth and the model as a problem-solving tool. Examples are given of how, in the latter case, the objective drives the design of small, simple models that focus relentlessly on the problem to be solved. A number of applications for small, focused models are offered. I stress the need for wildlife professionals to develop the skills for constructing and using such models on a regular basis; I end with ideas about how to create a modeling culture in conservation and resource management organizations.

Density dependence, compensation, and environmental effects on elk calf mortality in Yellowstone National Park

Abstract: We studied survival of radiocollared elk (Cervus elaphus) calves in Yellowstone National Park from 1987 to 1990, and survival of calves computed from population estimates from 1968 to 1992. We hypothesized that summer and winter survival of elk calves and mass of neonates were inversely related to population size, measures of environmental severity, and timing of births. Herd-wide survival estimates based on winter counts, reported harvests, and herd classifications, suggested that winter survival of elk calves was related inversely to estimated size of the elk population during winter (P = 0.0002), but we found no correlation with an index of winter severity (P = 0.51). Summer survival of elk calves also was correlated inversely with the estimated size of the elk population the previous winter (P = 0.03). Summer survival of radiocollared calves averaged 0.65 (n = 127 marked calves) from 1987 to 1990, the losses mostly due to predation (22%). Winter survival of calves averaged 0.72 (n = 88 marked calves entered the winter period), with losses due mostly to malnutrition (58%). Summer survival of radiocollared calves was positively correlated with estimated birth weight (P = 0.001). Survival of radiocollared calves during winters 1987-90 was correlated positively with early calving and mildness of the winter (in contrast to herd-wide survival estimates), and was inversely correlated with estimated elk population size that winter (P = 0.006). Winter survival of radiocollared calves was lower during 1988-89 following the drought and large fires than the other 3 winters (P < 0.001). Predation on elk calves during summer doubled after the drought and fires of 1988 (13% calf losses to predation before the fires vs. 29% after the fires). Potential compensation existed between components of calf mortality: predators killed more light (P = 0.041) and more late born calves (P = 0.146); calves were born later and lighter (P = 0.048) following severe weather conditions; and heavier born calves survived at a higher rate (P = 0.006). Our results are consistent with the hypothesis that density-dependent mortality of calves during winter due to malnutrition, and summer mortality of calves due to predation were partially compensatory but severe environmental conditions produced largely additive components to both summer (increased predation) and winter (increased malnutrition) mortality.

Forest bird response to regeneration practices in central hardwood forests.

Abstract: We studied breeding songbird populations in a managed, predominantly forested landscape, in southeastern Missouri. We determined differences in the relative abundance of breeding birds in forest stands that had been harvested by the clearcut (n = 12), shelterwood (n = 12), group selection (n = 12), and singletree selection (n = 10) forest regeneration methods, and mature even-aged stands (n = 12). Five migrant songbirds, the blue-winged warbler (Vermivora pinus), prairie warbler (Dendroica discolor), rufous-sided towhee (Pipilo erythrophthalmus), white-eyed vireo (Vireo griseus), and yellow-breasted chat (Icteria virens), were more abundant in clearcut treatments than other treatments (P 0.30). Nest success of species nesting in clearcut and shelterwood treatments was 18-50%. The percent of the site in gaps, shrub stem density, and tree-diameter distribution differed among forest regeneration methods (P < 0.001). We believe habitat requirements of birds in managed forests can be best met by a mixture of evenand uneven-aged forest management that creates a range of disturbance sizes. J. WILDL. MANAGE. 61(1):159-171

A philosophy of habitat management for northern bobwhites

Abstract: Northern bobwhites (Colinus virginianus) have received considerable research attention since the 1920s. I evaluated published results for patterns that might be meaningful in developing a general philoso- phy of habitat management for this species. Bobwhite populations show similar mean demographics (sur- vival, productivity) as climates, landscapes, and predator populations vary about them; this suggests some operational constancy in habitat quality wherever populations persist. Neither food abundance nor habitat type interspersion are satisfactory general predictors of population density on a management area, although interspersion provides a limiting condition (after min. interspersion requirements are met, further intersper- sion has, at best, neutral effects on density). Long-term, mean density on an area may vary in proportion to the quantity of space (amt permanent cover) that fits the physical, behavioral, and physiological adaptations of bobwhites through time. The goal of habitat management on an area should be to provide bobwhites the opportunity for unconstrained use of space through time (space-time saturation). This common sense out- look seems to have been obscured by unjustified concerns over food and interspersion and lack of a general understanding of successional affiliation. J. WILDL. MANAGE. 61(2):291-301

Sensitivity analysis to guide population recovery : Prairie-chickens as an example

Abstract: Calculation of elasticities in matrix population models is a formal type of sensitivity analysis that is used increasingly to guide recovery of declining populations. Results presumably allow recovery efforts to focus on the life stage most responsible for change in population growth, as indexed by the highest elasticity. Specifically, the highest elasticity denotes the vital rate whose proportionate change exerts the largest proportionate effect on the finite rate of increase (λ). We examined the utility of this analysis given uncertainty in parameter estimates and random variation in vital rates. We modeled these conditions to test the hypothesis that nest success and brood survival exert the greatest effect on population growth of greater prairie-chickens (Tympanuchus cupido pinnatus). We calculated elasticity associated with each age-specific vital rate contained in 1,000 randomly-generated replicates of a Leslie matrix model, and regressed λ on each randomly-varying rate. Age 0 survival (S o ) was associated with highest elasticity for 100% of the replicates and accounted for most of the variation in λ (r 2 = 0.95). Within S o , nest success and brood survival accounted for more variation in λ than other life stage combinations. These results demonstrate the utility of sensitivity analysis, but additional results point to its limitations. For example, the vital rate consistently associated with the second highest elasticity (S 1 ) accounted for minuscule variation in λ (r 2 = 0.0009), implying that rank of elasticities can fail to index the magnitude of a vital rate's effect on λ when vital rates vary simultaneously and disproportionately. To ensure that results are reliable, we recommend that sensitivity analysis be performed across the range of plausible vital rates, that simulations involve randomization of values within these ranges, and that elasticities be calculated in tandem with regression analysis to fully illuminate potential relations of vital rates with λ. A critical assumption is that variance of vital rates is estimated accurately.

Probability of Detecting Harbor Porpoise from Aerial Surveys: Estimating g(0)

Abstract: Harbor porpoise (Phocoena phocoena), and most other cetaceans, spend a significant proportion of time submerged, and are undetectable from the air. Abundance estimates based on line transect sampling may be severely biased by assuming that all porpoise near the line are detected [g(0) = 1]. By tracking groups of harbor porpoise from land, we estimated the proportion of time harbor porpoise spent at the surface and the probability that aerial observers detected groups within 200 m of the transect line. Two teams on land, equipped with electronic theodolites, tracked harbor porpoise while surveys were conducted from an aircraft equipped with side-bubble windows and a belly window. During 7 days, 33 hours of observation were made in a high-density area for harbor porpoise near Orcas Island, Washington. We monitored 7 different harbor porpoise groups from 15 to 66 minutes each. The average proportion of time at or near the surface was 0.231 (SE = 0.032). From a selected sample of 164 land-based sightings of harbor porpoise groups, 50 (30.5%) were observed from the aircraft. For our aerial line transect surveys of harbor porpoise conducted by experienced observers, g(0) = 0.292 (SE = 0.107). However, for the inexperienced observers, g(0) was 0.079 (SE = 0.046), which demonstrates the importance of experience and training.

Woodland caribou relative to landscape patterns in northeastern Alberta

Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radiocollared and monitored across 20,000 km 2 of northeastem Alberta. Adult survival averaged 0.88 ± 0.03, and did not differ among years. Calf survival was 18 calves/100 cows in March of both years it was measured, with calves composing a mean of 9.0% of the March populations. Highest calf mortality occurred during the first month of life. The population rate-of-increase, r, was -0.08 (A = 0.92), suggesting the population was declining. Caribou locations were restricted to peatlands, with 98.7% of locations falling within the 5 fen complexes in the study area. There was little permanent movement (5% of individuals over 4 yr) among fen complexes. Multi-year home ranges (100% minimum convex polygon; MCP) averaged 711 km 2 , with the size of individual home ranges (HR) correlated with the area of fen complexes. Summer HRs were smaller than winter HRs, and smaller for females than males in summer, but not winter. Locations were further from fen/upland boundaries in winter than in summer, and further from fen/upland boundaries than random points within fens in both seasons. Movement rates were highest in winter and lowest in summer, and did not differ between sexes. There was a negative correlation between movement rate and snow depth at month-end. Monthly trends in group size paralleled those in movement rates, while group composition was relatively stable throughout most of the year. Trends in group size, movement, and spatial distribution suggest caribou increased spacing among themselves during summer, and were more concentrated during winter. The study area consisted of 2 different landscapes, varying in the amount and configuration of fen patches. When we compared caribou biology between the 2 areas, we found lower calf survival and smaller home ranges in the landscape with smaller fen patches and a higher proportion of upland.

Behavior and Ecology of the Northern Fur Seal

Abstract: Preface Acknowledgments List of Contributors Pt. 1. Behavior at the Population Level Ch. 1. Introduction Ch. 2. Population Changes, 1974 to 1986 Ch. 3. Temporal Factors in Behavior Pt. 2. The Mating System Ch. 4. Behavior of Adult Males Ch. 5. Male-Female Associations Ch. 6. Behavior of Adult Females Pt. 3. Processes Fundamental to the Mating System Ch. 7. Site Fidelity and Philopatry Ch. 8. Estrus and Estrous Behavior By Roger L. Gentry, John R. Holt, Carolyn B. Heath Ch. 9. Ontogeny of Male Territorial Behavior Pt. 4. The Maternal Strategy Ch. 10. Female Attendance Behavior Ch. 11. Neonatal Growth and Behavior By Roger L. Gentry, Michael E. Goebel, John Calambokidis Ch. 12. Female Foraging Behavior: Inter- and Intra-Annual Variation in Individuals By Roger L. Gentry, Michael E. Goebel Ch. 13. Female Foraging Behavior: Effects of Continental Shelf Width By Roger L. Gentry, Mark O. Pierson, Valery A. Vladimirov Pt. 5. Summary, Comparisons, and Conclusions Ch. 14. Synthesis Ch. 15. Implications for Otariid Studies Appendix. Scientific and Common Names of Species Referred to in This Work Notes Literature Cited Author Index Subject Index

Accuracy of GPS telemetry collar locations with differential correction

Abstract: Global Positioning System (GPS) units in telemetry collars provide an unbiased and precise estimate of animal locations. Under ideal conditions at least 50% of locations are expected to be within 40 m in uncorrected mode GPS, and within 5 m in differential mode GPS. When the collar was placed under open sky, most locations were 3-dimensional locations that could be differentially corrected. Under hardwood canopies with leaves on, the frequency of 3-dimensional locations decreased, the frequencies of failed location attempts and 2-dimensional locations increased, and the precision of GPS locations decreased. We compared the precision of each GPS mode by calculating uncorrected mode and differential mode locations from the same pseudo-range and ephemeris data. We varied the number of satellites used in the location solution to simulate the effect of decreased satellite acquisition due to canopy cover on precision of locations. Precision of locations increased if signals from >4 satellites were used to calculate the location in uncorrected mode and in differential mode. We found that 2-dimensional locations were almost as precise as 3-dimensional positions if the altitude of the GPS unit was known. If the altitude used to calculate a 2-dimensional location was within 50 m of the actual collar altitude, the precision of 2-dimensional differential mode locations was better than 3-dimensional uncorrected mode locations. If the error in altitude was 100 or 150 m, then 50% of 2-dimensional differential mode locations were within 70 m and 95% were within 185 m of the true location. We used GPS locations from collars placed in different cover types and on free-ranging moose (Alces alces) to determine the effect of season, time of day, rainfall, and cover type on GPS performance. On free-ranging moose the collar GPS unit found ≥4 satellites on 52% of location attempts, >50% of locations were 3-dimensional, and >24% of locations were 2-dimensional. Precise tracking of individual animals in all weather throughout the year is possible with GPS telemetry.

Uncertainty and the management of mallard harvests

Abstract: Those charged with regulating waterfowl harvests must cope with random environmental variations, incomplete control over harvest rates, and uncertainty about biological mechanisms operative in the population. Stochastic dynamic programming can be used effectively to account for these uncertainties if the probabilities associated with uncertain outcomes can be estimated. To use this approach managers must have clearly-stated objectives, a set of regulatory options, and a mathematical description of the managed system. We used dynamic programming to derive optimal harvest strategies for mallards (Anas platyrhynchos) in which we balanced the competing objectives of maximizing long-term cumulative harvest and achieving a specified population goal. Model-specific harvest strategies, which account for random variation in wetland conditions on the breeding grounds and for uncertainty about the relation between hunting regulations and harvest rates, are provided and compared. We also account for uncertainty in population dynamics with model probabilities, which express the relative confidence that alternative models adequately describe population responses to harvest and environmental conditions. Finally, we demonstrate how the harvest strategy thus derived can "evolve" as model probabilities are updated periodically using comparisons of model predictions and estimates of population size. J. WILDL. MANAGE. 61(1):202-216

Avian use and vegetation characteristics of Conservation Reserve Program fields.

Abstract: We compared avian use of Conservation Reserve Program (CRP) fields enrolled in the CP1 (cool-season grasses and legumes) and CP2 (warm-season native grasses) options in southeastern Nebraska from 1991 to 1995. In winter and in the breeding season CP2 fields had taller, denser vegetation than CP1 fields. However, total bird abundance did not differ between CP1 and CP2 fields (P = 0.47). Dickcissels (Spiza americana) and grasshopper sparrows (Ammodramus savannarum) were the most abundant species during the breeding season although population numbers varied among years (P < 0.001). Dickcissels and grasshopper sparrows showed no differences in abundance between CPs, but dickcissels were associated with tall, dense vegetation and grasshopper sparrows with sparser vegetation and a shallow litter layer. Bobolinks (Dolichonyx oryzivorus) were more abundant on CP1 fields (P = 0.001), and common yellowthroats (Geothlypis trichas) and sedge wrens (Cistothorus platensis) were more abundant on CP2 fields (P = 0.001 and P = 0.05). Average winter abundances did not change over years (P = 0.90). American tree sparrows (Spizella arborea) and ring-necked pheasants (Phasianus colchicus) were the most abundant species during winter and were more abundant on CP2 fields (P < 0.05). Meadowlarks (Sturnella spp.) were more abundant on CP1 fields in winter (P < 0.05).

Raccoon habitat use at 2 spatial scales

Abstract: Among the numerous studies of raccoon (Procyon lotor) habitat use, none have explicitly considered habitat use at multiple spatial scales. Fifty-seven sites were selected in the vicinity of Ottawa, Ontario, Canada. An index of raccoon abundance was obtained from 2 tracking stations at each site. Macrohabitat features were measured in a 1-km radius circle (314 ha) around each site. Microhabitat woody vegetation features were characterized in a 10-m radius around each tracking station. Using stepwise Poisson regression analyses, we found that raccoons frequented: (1) woody vegetation features that are associated with fencerows, den trees, and deciduous stands, (2) macrohabitats with extensive agricultural edge, and (3) wooded remnants in areas with extensive corn cover. This information on raccoon habitat use in rural areas will aid in rabies control programs and identifies localities where heavy raccoon depredation is likely to occur.

Timber-management and natural-disturbance effects on moose habitat:landscape evaluation.

Abstract: We used 16 years of survey data for a moose population, and 3 Landsat satellite scenes, spanning 19 years, to evaluate the hypotheses that Ontario's Moose Habitat Guidelines for timber harvest: (1) mitigate the effects of unmodified clearcuts on moose populations, and (2) create enhanced habitat with greater interspersion of forage with cover and higher habitat suitability indices than areas dominated by unmodified clearcuts. The 5 study landscapes compared were 16,000-91,000 ha, and included landscape disturbance from timber-management and wildfire-burn, and landscapes with and without hunter access. Moose density differed among landscapes, but while neither main effects of hunter access (P = 0.083), nor landscape disturbance (P = 0.31) were significant, their interactions were (P = 0.003), with density increasing if disturbance occurs without hunter access. The habitat suitability index in the wildfire burn was similar (0.80) to both the modified and unmodified clearcut (0.85 and 0.83), and population rate of increase was positive in both the burn (B = 0.153, P < 0.0001) and the unmodified clearcut (B = 0.127, P < 0.0001). The population did not increase in the modified clearcut (B = -0.016, P = 0.9907) because hunter access increased as a consequence of high road density.

Effects of differential correction on accuracy of a GPS animal location system

Abstract: The location error of uncorrected data from Global Positioning System (GPS) collars range from ca. 45.5 to 65.5 m (Rempel et al. 1995). Improvements that potentially could reduce locational error to <10 m include correcting systematic bias by reference to GPS data collected at a known position (differential correction), increase in the proportion of positions based on ranging 4 rather than 3 satellites (3-dimensional node), and increase in the proportion of positions based on a well-spaced satellite configuration (low dilution of precision). Design changes meant to achieve these results were implemented in the second generation GPS collars we evaluated (Lotek Eng. Inc. 1996). We tested the performance of these collars under the controlled canopy conditions of the Thunder Bay experimental forest. Differential correction caused location error to decrease from 80 to 4 m (P < 0.0001), and the range of 25-75th percentile location error to decrease from 74.3 to 5.0 m. Location error among sample sites was greatest under tall red pines (Pinus resinosa; 15.7 m), possibly because the tall trunks interfered with signal reception, resulting in the acceptance of either 2-dimensional mode positions or positions based on poor satellite configuration (high dilution of precision), or because of multipathing effects caused by signal bounce off the tree trunks. Implementation of differential correction may involve substantial costs to maintain a GPS basestation and data handling, so effectiveness of this enhanced technology must be judged against study objectives and data requirements of the hypotheses being tested.

Effects of spatiotemporal scale on autocorrelation and home range estimators

Abstract: We compared 3 home range estimators (kernel estimator [Kernel], multiple polygons by clustering [Cluster], and minimum convex polygon [MCP]) and evaluated a measure of autocorrelation (Schoener's ratio), with respect to the effects of sampling frequency, spatial resolution of the sampling reference grid, and sample size. We also used Schoener's ratio as a descriptor of within home range movements. An extensive dataset from radiotracking of root voles (Microtus oeconomus) formed the basis for these comparisons. The degree of autocorrelation was sex specific. In particular, locations of reproductive females were significantly autocorrelated for a sampling interval equal to the period of the population's ultradian activity rhythm, indicating territory patrolling behavior in this sex. We assessed the effect of spatial resolution of animal location data on home range descriptors by manipulating the cell size of the sampling reference grids. The Kernel estimator was robust to changes in spatial resolution of the data. In contrast, the polygon estimates were severely biased upwards with decreasing spatial resolution (increasing grid cell size). Therefore, comparative studies based on polygon methods must use the same spatial resolution. The sampling frequency affected all estimators, but qualitative differences were found among the specific estimators. Numerical resampling methods indicated that home range sizes were underestimated, and that the precision of the estimators was generally low.

Are avian hematocrits indicative of condition ? American kestrels as a model

Abstract: Diseased animals or those in poor condition are known to have reduced hematocrits. Many investigators have assumed that hematocrit levels thus reflect condition and disease status of an animal. This study tested these assumptions by examining the relation between hematocrits of American kestrels (Falco sparverius) during several stages of the breeding season, and condition, prey abundance, and blood parasite load. We also examined the potential effects of a number of intrinsic and extrinsic influences on hematocrit. Hematocrits did not differ between the sexes, or between the pre-laying and incubation periods. Among females, hematocrit did not vary with the date of sampling, breeding chronology, prey abundance, condition, age, or molt, although hematocrit increased with ambient temperature during incubation. Hematocrit of males was not related to breeding chronology, prey abundance, condition, age, or molt. During incubation, male hematocrit increased with the date of sampling and ambient temperature. Hematocrits of both sexes declined with the time of day that the sample was taken, and increased with the level of infection of the blood parasite Haemoproteus. The use of hematocrits to assess the health and condition of clinically normal kestrels is therefore questionable, and given the positive association with parasite loads, may even lead to erroneous conclusions.

Satellite-monitored movements of the northern right whale

Abstract: The northern right whale, Eubalaena glacialis, remains the most critically endangered of the large cetaceans despite international protection since 1936. We used satellite-monitored radiotags to identify the late-summer and fall habitat use patterns of right whales in the western North Atlantic. We tagged 9 whales in the Bay of Fundy (BOF) and successfully tracked them for a total of 13,910 km (x = 1,546 km) in 195 whale-tracking days (range 7-42 days each, x = 21.7 days). Individuals tracked for more than 12 consecutive days (N = 6 whales) left the BOF at least once and had higher average speeds (x = 3.5 km/hr) than those that stayed within the bay (x = 1.1 km/hr). Three of the tagged whales not only left the BOF, but traveled more than 2,000 km each before returning to the general tagging area. One adult female with a calf went to New Jersey and back to the BOF (3,761 km) in 42 days. Most locations were along bank edges, in basins or along the continental shelf. Eighty percent of locations were in water <182 m (100 fathoms [F]) deep. All of the tagged whales were located in or near shipping lanes. Right whale distribution coincided with areas intensively used by humans for fishing, shipping, and recreation. Individuals moved rapidly among areas previously identified as right whale habitat. Whale locations plotted on sea surface temperature (satellite infrared) images suggest that one whale spent time at the edge of a warm core ring and others spent extended periods in upwellings. Observations of whales surfacing with mud on their heads suggest that these whales fed near the BOF seafloor. Satellite telemetry is a useful means of tracking cetacean species that are difficult to view, move long distances, and might be too expensive to monitor by other means.

Diversity and abundance of landbirds in a Northeastern industrial forest.

Abstract: We studied abundance and diversity of landbirds in all successional stages of habitat in an industrial forest landscape in northern Maine. Of 9 broad habitat categories, clearcuts and mature hardwood forests had the lowest avian diversity, but these 2 habitats each contained many individual species that showed their maximum abundance in those habitats. Greatest avian diversity was found in 2 young forest types (6-20 yr following harvesting). Young, even-aged regeneration had the greatest abundance of individual birds per unit area, whereas mature hardwood had the lowest total abundance. Ten of 37 Neotropical migrant species had their highest abundance in the 2 youngest stages of forest (clearcuts and regeneration) whereas 13 of 37 species had their highest abundance in the 3 mature forest types. Short-distance migrants had highest abundances in early-successional habitats, and mature softwood stands contained the greatest number of resident species. The presence or absence at a point count station of 10 late-successional species (of 37) and 13 early-successional species (of 35) was related to the amount of similar habitat within 1 km of the point count center (homogeneous landscapes). Few species showed highest abundances in heterogeneous landscapes. Spatially consolidating harvesting might enhance both early- and late-successional species simultaneously. Based on species-habitat associations identified in this study, estimated population trends in a 1,270 km 2 section of our study area did not correlate well with Breeding Bird Survey results for the state of Maine (1981-1992). This discrepancy probably, resulted because few Breeding Bird Survey routes occur in the industrial forest of northern Maine, and because of different trends in habitat abundances inside and outside of the study area. This result indicates there might be important subregional differences in landbird population trends. Current timber harvest rates likely will result in a decrease in abundance of mature forest in Maine's industrial forest. Many early-successional species, including some of conservation concern, will benefit from this trend. Abundances of mature-forest species probably will decrease. The challenge industry and conservation biologists face is how to construct dynamic landscapes that balance the age-class distribution of the forest and maintain mature forest species.

Dens of northern flying squirrels in the Pacific Northwest.

Abstract: Silvicultural prescriptions to enhance northern flying squirrel (Glaucomys sabrinus) habitat have been suggested as an aid for recovery of the threatened northern spotted owl (Strix occidentalis caurina). Flying squirrels are hypothesized to be limited by den sites (cavities in trees) and by food (truffles). However, no quantitative information exists on den sites of flying squirrels. Therefore, during 1986-94, we used radiotelemetry to locate 604 different den sites in the southern Coast Range of Oregon, the southern Olympic Peninsula, and the Puget Trough of Washington. Den sites included cavities in live and dead old-growth trees; cavities, stick nests, and moss nests in small (10-50 cm dbh) second-growth trees; dens in cavities in branches of fallen trees; and dens in decayed stumps of old-growth trees and suppressed young trees. Two-thirds of all dens located were in live trees. Most dens were located during a study of second-growth forests in the Puget Trough. Females selected cavities for maternal dens. Squirrels used multiple dens; denning partners varied with den. Dens of males were 211 ± 7 m apart; dens of females were 108 ± 4 m apart. Males used 2.2 ± 0.1 dens per month; females 2.3 ± 0.1 dens per month. Dens, except maternal dens, were often occupied simultaneously by several adult squirrels. Many fragile den sites were used by females. Secure cavities are scarce and may limit reproductive success. Management for cavity trees and dens could prove fruitful in owl recovery and habitat restoration efforts.

The role of protected areas as ecological baselines

Abstract: Learning to manage wildlife communities and ecosystems for stability, dynamic change or yield is an endeavor of general value, but we are not yet proficient at meeting these objectives. We argue for managing a representative number of protected areas as ecological baseline controls to help in understanding the effects of humans worldwide, and thus to enhance our ability to manage natural resources for a wide range of goals. The decision to manage protected areas as ecological baseline controls has several practical consequences, including that: (1) no effort is made to maintain an ecological status quo; (2) human interference that confounds natural ecological processes is kept to a minimum; (3) monitoring of natural and human-induced changes inside and adjacent to baseline controls is essential; and (4) if subjective opinion perceives that human effects are, nevertheless, altering the system, then management intervention should be carried out on part of the system only, leaving the rest as its own control. J. WILDL. MANAGE. 61(3):587-602

The effect of immunocontraception on the behavior and reproduction of white-tailed deer

Abstract: Behavioral and reproductive consequences of porcine zona pellucida (PZP) immunocontraception were examined in a herd of white-tailed deer (Odocoileus virginianus; n = 30) from September 1992 to September 1994. Does were captured from a wild population and placed within either of 2 large (32-ha total) wooded enclosures. Does were administered either: (1) a single injection containing PZP-emulsified in Freund's complete adjuvent (FCA) and microsphere-encapsulated PZP; (2) 2 injections of PZP-emulsified in FCA and Freund's incomplete adjuvant (FIA), 4 weeks apart; or (3) no treatment. Mature, spermic bucks (n = 5) were added to each pasture 4 weeks after the final PZP treatment, and reproductive behaviors and fawn production were observed for 2 years. Immunocontracepted females exhibited increased activity compared to non-treated females, presumably reflecting an increased number of estrus intervals. Similarly, enclosure bucks exhibited an extended breeding season compared to males in the surrounding wild population. The 2-injection PZP regimen provided effective contraception during both years of the study. The 1-injection PZP regime provided effective contraception only during the second year, following administration of a PZP booster. Histological evaluations of ovaries failed to reveal among-group differences in ovarian architecture. Contracepted-nonpregnant does gained significantly more weight than control females during the study.

A critical analysis on the use of indicator species in management

Abstract: We examined the habitat distributions of management indicator and sensitive species (MIS), as defined by the U.S. Forest Service within the Chequamegon National Forest (CNF) of northern Wisconsin and whether other bird species were positively associated with these MIS. We addressed these associations with 2 relatively large databases, annual breeding bird counts of 92 line transect segments gathered from 1986 to 1992 and counts of 122 Forest Stands gathered in 1992-1993. Of 25 MIS identified by the CNF, only 7 species were abundant enough for analyses. The other species were either too rare within the CNF or the censusing methods were not compatible with their life history. Only 2 of the MIS had nonrandom distributions associated with specific habitat types and warranted consideration as indicators. The yellow-bellied flycatcher (Empidonax flaviventris) was found primarily in lowland coniferous habitats, while the pine warbler (Dendroica pinus) was found primarily in upland coniferous habitats, especially pine. Although many positive species associations were found for most of the MIS, many inconsistencies among the 2 datasets also were identified. Most species responded to habitat attributes that satisfy their needs for survival and these autecological responses likely led to inconsistent patterns of species associations for most of the MIS. The lack of consistent patterns among most MIS casts doubt on the ability to use a few species as indicators for the well-being of many other species, especially for those that are uncommon and difficult to monitor. Developing more comprehensive techniques that improve habitat classifications and combine monitoring of trends in habitat and birds within those habitats likely will prove more fruitful than focusing on a few representative species.

Distribution of black-tailed jackrabbit habitat determined by GIS in southwestern Idaho

Abstract: We developed a multivariate description of black-tailed jackrabbit (Lepus californicus) habitat associations from Geographical Information Systems (GIS) signatures surrounding known jackrabbit locations in the Snake River Birds of Prey National Conservation Area (NCA), in southwestern Idaho. Habitat associations were determined for characteristics within a 1-km radius (approx home range size) of jackrabbits sighted on night spotlight surveys conducted from 1987 through 1995. Predictive habitat variables were number of shrub, agriculture, and hydrography cells, mean and standard deviation of shrub patch size, habitat richness, and a measure of spatial heterogeneity. In winter, jackrabbits used smaller and less variable sizes of shrub patches and areas of higher spatial heterogeneity when compared to summer observations (P 0.05), differed significantly between high and low population phase. We used the Mahalanobis distance statistic to rank all 50-m cells in a 440,000-ha region relative to the multivariate mean habitat vector. On verification surveys to test predicted models, we sighted jackrabbits in areas ranked close to the mean habitat vector. Areas burned by large-scale fires between 1980 and 1992 or in an area repeatedly burned by military training activities had greater Mahalanobis distances from the mean habitat vector than unburned areas and were less likely to contain habitats used by jackrabbits.