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Successful lobbying against certain hunting practices by animal-welfare and animal-rights groups and a steady decline in hunter recruitment, retention, and numbers raise legitimate concerns regarding the future of hunting and its relationship to wildlife management. The nonhunting, non-animal-rights-advocate majority will determine the fate of hunting. Thus, a successful hunting ethic must be logically consistent and intuitively appealing to this moderate majority. This shared ethic could encourage cultural, political, and economic support for wildlife management from both hunters and nonhunters alike. In light of this goal, I argue that 3 dominant hunting ethics—the naturalness hypothesis, the land ethic, and the sporting ethic—fail to justify hunting or place it in a shared context with modern society, and I suggest an alternative ethic that combines Aldo Leopold's vision of an expanding community with traditional utilitarian and rights-based evaluations of ethical criteria within an n-dimensional moral framework. This conceptualization of an ethical system would allow the use of tools applicable to systems analysis in analyzing moral issues and would foster communicative practices capable of creating a more inclusive community. Further, it can both create and elucidate the ethical space shared by the moderate majority and hunters.
The Theory of Reasoned Action can be used to predict the types of information that will influence attitudes toward and support for novel suburban deer (Odocoileus spp.) management techniques such as contraception. Information that is relevant to individuals' “behavioral beliefs” about the important outcomes of contraception is most likely to be influential, but these priority outcomes will vary from person to person. Different individuals' attitudes, therefore, may be influenced by different types of information. We tested the effects of tailoring information to the concerns of stakeholders. We conducted 2 mail surveys of the same residents of Irondequoit, New York, 19 months apart. The first survey provided a pretreatment measure of attitudes toward contraception and identified respondents' concerns about contraception. The second survey provided a post-treatment measure of attitudes and was distributed in 3 versions—2 containing different types of information about contraception and 1 (without information) to a control group. We confirmed that information addressing stakeholder concerns was most likely to influence attitudes. Agency communication, therefore, is most likely to influence public attitudes if it is tailored so that it addresses the particular concerns of each important stakeholder group.
Penguin populations are potentially sensitive indicators of ecological change in Antarctic and sub-Antarctic marine ecosystems. Aerial photographic surveys provide the most robust method for estimating breeding population size, particularly for large colonies. Obtaining population estimates from aerial photographs is laborious and usually carried out by manually counting individual birds on highly magnified prints. I derived population estimates using computer-based image analysis of digitally scanned color aerial photographs of macaroni penguin (Eudyptes chrysolophus) colonies at Bird Island, South Georgia. I compared automated image analysis with manual counts from the photographic prints and conventional ground counts, highlighting assumptions that contributed to differences in population estimates. The automated image-analysis routines produced estimates that were highly correlated with ground counts, indicating that the technique could be reliably used for large-scale macaroni penguin population surveys.
Adverse effects of radiotransmitters and handling are major concerns during radiotracking studies, especially in avian species. Fourteen out of 46 (30.4%) juvenile red-legged partridge (Alectoris rufa) trapped using hand-held nets and marked with necklace radiotags during a study in southern Spain died within a few hours after capture. We studied the affected birds and compared data from postmortem examination, blood chemistry, biometry, and meteorology on capture days to identify risk factors related to the deaths. The affected partridge had high creatine kinase plasma levels. Postmortem examination confirmed that the deaths had been due to self-injury, capture myopathy (CM), or both. Distribution of lesions indicated that struggling with the transmitter could have exacerbated CM caused by trapping and handling. There was no effect due to bird size or weight, but deaths were related to capture days with lower mean temperatures and higher humidity. The consideration of combined risk factors such as climate, capture method, and radiotag type may deserve more attention regarding capture and radiotagging techniques, especially in juvenile partridge.
Raccoons (Procyon lotor) are captured frequently for research purposes using wire cage and various restraining traps, and gender biases exist in the animals' response to traps. Previous studies have demonstrated the effectiveness and humaneness of the EGG™ (EGG Trap Company, Springfield, S.D.) trap compared to foothold traps, but researchers primarily use wire cage traps to capture raccoons. In this paper we compare performance of wire cage traps and EGG traps for capturing male and female raccoons and discuss cost-effectiveness of using both trap types during a 3-year field study in Mississippi. EGG traps were more likely to capture raccoons than cage traps; both genders also were more likely to be captured in EGG traps. EGG traps were particularly more effective at capturing male raccoons than cage traps. Events in which traps were sprung but no raccoons were captured were greater when using cage traps. Purchase costs were considerably lower for EGG traps. Our findings suggest that EGG traps perform better at capturing raccoons than wire cage traps. Given our findings, and earlier studies demonstrating reductions in injuries with EGG traps relative to foothold traps, we recommend that researchers consider using EGG traps to capture raccoons in field studies.
We evaluated the abilities of 6 infrared-triggered camera systems (TrailMaster 1500, TrailMaster 500, Buckshot RTV, Buckshot Scout, CamTrakker, and DeerCam) to detect 3 sizes of animal models at 2 heights above ground and from 3 distances. We also determined the size of the infrared detection zone and the relative sensitivity of different passive camera systems. All camera systems tested had a detection zone that was narrow in the vertical dimension (3–7°). Except for the TrailMaster 500, all systems also had a detection zone that was narrow in the horizontal dimension (<10°). Sensitivity varied among camera systems. Most performed well at default or high sensitivities; the CamTrakker and the Buckshots set at highest sensitivity produced the most detections. All systems except the Buckshot RTV performed better at lower ambient temperatures. We review technical aspects of infrared-triggered photography and recommend how researchers can improve their success in detecting animals by selecting the appropriate system for their study area and target species and by careful placement and precise alignment of camera units in the field.
Estimates of population density and diets of predators are often based on detection and examination of feces (scats). Decomposition rates and manipulation or consumption of scats by animals could bias studies that use scat to investigate life-history parameters. We investigated the longevity (persistence), nutritional content, and fates of coyote (Canis latrans) and bobcat (Lynx rufus) scats near Tucson, Arizona from April 2000–July 2001. We established 42 stations containing scats along roads in the Sonoran Desert. We placed half of the scats in protective cages to estimate degradation rates apart from disturbance by other animals. Unprotected scats disappeared sooner than expected based on decomposition rate. When pooled over spring, summer, autumn, and winter, median survival of unprotected wild canid scats was 11 days, but decreased to 4 days in June–July 2001. Some scats were moved to white-throated woodrat (Neotoma albigula) dens. A 1-m increase in distance of scats to woodrat dens resulted in a 2.2% (Wald 95% CI: 0.9–3.4%) increase in persistence (days) of unprotected scats of all types over all seasons. In June and July 2001 a 1-m increase in distance of scats to woodrat dens resulted in a 4% (Wald 95% CI: 2.7–5.4%) increase in persistence (days) of unprotected scats of wild canids. Studies based on detection, counts, or collection of predator scats may be biased by scat persistence. Investigators can minimize bias through frequent sampling and by accounting for local scat-degradation rates.
Video recording of prey deliveries to nests is a new technique for collecting data on raptor diet, but no thorough comparison of results from traditional methods based on collections of prey remains and pellets has been undertaken. We compared data from these 3 methods to determine relative merits of different methods for assessing raptor diet as part of a study of the breeding-season diet of northern goshawks (Accipiter gentilis) in Southeast Alaska. We applied these methods to 5 nests during each of the northern goshawk breeding seasons of 1998 and 1999 and identified 1,540 prey from deliveries, 209 prey from remains, and 209 prey from pellets. The proportions of birds and mammals varied among techniques, as did relative proportions of prey groups and age groups. Prey remains and pellets gave the least-similar diet descriptions. Over 2-day intervals during which data were collected using all 3 methods, prey-delivery data gave more individual prey and prey categories than the 2 other sources of information. We found that prey were not directly tracked in either prey remains or pellets compared with prey delivery videography. Analysis of prey-delivery videography provided the most complete description of diet, and we recommend that studies attempting to describe diet use this technique, at least as part of their methodology.
Snowshoe hare (Lepus americanus) pellet surveys are an efficient tool for monitoring population trends, but there is no standard methodology used to conduct surveys. To assist researchers in developing protocols, we evaluated pellet-decay rates and aging in 3 snowshoe hare habitat types in Alaska during the peak and decline of the hare population from 1999–2002. We found significant differences in decay rates among habitat types and recommend measuring decay rates if pellet counts are to be compared among habitats or regions. Our experiments with known-age pellets indicated that pellets could not be aged reliably, but results from side-by-side comparisons of survey methods provided contrary evidence. Counts from uncleared plots, in which observers subjectively decided whether pellets were “new” (<1 year old), were not statistically different from counts on annually cleared plots. We evaluated 4 methods for conducting pellet surveys: 1) cleared plots with counts of “new” pellets; 2) cleared plots with counts of all pellets; 3) uncleared plots with counts of “new” pellets; 4) uncleared plots with counts of all pellets. Annual trends in pellet counts were similar using the first 3 methods, but counts from method 4 were inflated in 2002 due to a high prevalence of “old” pellets. We conclude that cleared plots are preferable to uncleared plots, and we suggest that using subjective criteria to age pellets may be useful if tallies are kept of both “new” and “old” pellets for each plot.
Radiotelemetry is commonly used in northern bobwhite (Colinus virginianus) research. An underlying assumption is that radiomarked individuals provide unbiased estimates of population parameters. Our objectives were to evaluate the effects of radiotransmitters on body mass and feed consumption of radiomarked and banded-only pen-raised bobwhites in a controlled environment and to compare daily energy expenditure (kJ/g/day) between treatments in a simulated field setting. We randomly assigned a treatment (i.e., radiomarked or banded-only) to 40 pen-raised bobwhites and placed them in individual cages (51- × 27- × 28-cm) within an environmental chamber. We conducted 2 separate 21-day experiments to simulate summer (35°C daytime high, 23.9°C nighttime low, 15-hour photoperiod) and winter conditions (18.3°C daytime high, 4.4°C nighttime low, 10-hour photoperiod) typical for south Texas. For the field experiment, we evaluated energy expenditure via doubly labeled water for radiomarked (n=5) and banded-only pen-raised bobwhites (n=5) in a flight pen (50- × 30- × 4-m). We documented no difference in change in body mass or feed consumption between radiomarked and banded-only bobwhites during either experiment (P>0.05). We also found no difference in daily energy expenditure between radiomarked (0.839 ± 0.056 kJ/g/day) and banded-only pen-raised bobwhites (0.804 ± 0.014 kJ/g/day; P=0.77).
An increasingly common practice in southern Texas is baiting roads with grains such as milo (Sorghum spp.) and corn (Zea mays) to facilitate northern bobwhite (Colinus virginianus) harvest. However, baiting roads might have a negative impact on bobwhite survival by increasing predation or harvest rates. The objective of this project was to determine the effects of road baiting on bobwhite survival, home-range size, and predator abundance. The project involved 2 study sites (baited = treatment and nonbaited = control) that were monitored over 3 periods, pre-baiting (September–October), baiting (November–December), and post-baiting (January–February), during 2001–2002 and 2002–2003. We captured, radiomarked, and monitored bobwhites (n = 60 [treatment site]; n= 58 [control site]) in Jim Hogg County, Texas. We assessed relative abundance and activity of avian and mammalian predators using scent-station and road surveys, respectively. The effects of baiting roads varied between years. During 2001–2002, a relatively dry period, bobwhite survival (Ŝ = 1.00±0.00 [control site]; Ŝ = 0.68±0.10 [treatment site], P=0.01), covey home-range size (15.6±1.43 ha [control site]; 12.7±2.22 ha [treatment site], P=0.046), and covey distance to roads (193±24.6 m [control site]; 95±41.57 m [treatment site], P≤0.001) were lower on the treatment site during the feeding period in contrast to the control site. A nonsignificant trend was noted for higher avian predator abundance on the treatment site during the feeding period. During 2002–2003, a relatively wet period, no difference in bobwhite survival, covey home-range size, and covey distance to roads was found between sites and time periods due to baiting, and no trend in predator abundance was found between pastures and time periods. The practice of baiting ranch roads does not appear to benefit bobwhites in southern Texas, and during dry conditions the practice might be detrimental to bobwhite numbers by lowering survival. Baiting or other methods of dietary supplementation are more likely to benefit bobwhites in more northern climates with colder winters.
We analyzed long-term population data for bighorn sheep (Ovis canadensis nelsoni) occupying the San Gabriel Mountains in southern California. From 1967–1972 an estimated 500 bighorn sheep occupied that range. During 1968–1975 wildfires burned over half the occupied winter–spring ranges. Wildfires increased carrying capacity, and the population grew to 665 animals in 1976. During 1976–1982 adult mortality was low and recruitment was dependent on annual forage production and weather conditions during lambing. Rate of change indicated the population would double every 44 years, and it was considered to be stable. As vegetation matured and carrying capacity declined, mortality of adults and lambs increased and the population halved approximately every 8 years to 501±30 bighorn sheep in 1989. During 1989–1995 adult mortality increased and rate of change indicated the population would halve approximately every 2.8 years. From 1995–2002 the population was stable at 90 animals. Increased recruitment and an inverse relationship between number of adult ewes and recruitment rates between 1985 and 2001 suggested that neither habitat suitability nor disease was causing the dramatic population decline observed after 1989. We hypothesize that because of a declining mule deer (Odocoileus hemionus californicus) population, mountain lions (Puma concolor cougar) began to prey more frequently on bighorn sheep, which led to a dramatic decline in the sheep population after 1989.
The United States Fish and Wildlife Service's (USFWS) designation of critical habitat for the endangered Nelson's bighorn sheep (Ovis canadensis nelsoni) in the Peninsular Ranges of southern California has been controversial because of an absence of a quantitative, repeatable scientific approach to the designation of critical habitat. We used 12,411 locations of Nelson's bighorn sheep collected from 1984–1998 to evaluate habitat use within 398 km2 of the USFWS-designated critical habitat in the northern Santa Rosa Mountains, Riverside County, California. We developed a multiple logistic regression model to evaluate and predict the probability of bighorn use versus non-use of native landscapes. Habitat predictor variables included elevation, slope, ruggedness, slope aspect, proximity to water, and distance from minimum expanses of escape habitat. We used Earth Resources Data Analysis System Geographic Information System (ERDAS-GIS) software to view, retrieve, and format predictor values for input to the Statistical Analysis Systems (SAS) software. To adequately account for habitat landscape diversity, we carried out an unsupervised classification at the outset of data inquiry using a maximum-likelihood clustering scheme implemented in ERDAS. We used the strata resulting from the unsupervised classification in a stratified random sampling scheme to minimize data loads required for model development. Based on 5 predictor variables, the habitat model correctly classified >96% of observed bighorn sheep locations. Proximity to perennial water was the best predictor variable. Ninety-seven percent of the observations were within 3 km of perennial water. Exercising the model over the northern Santa Rosa Mountain study area provided probabilities of bighorn use at a 30 × 30-m2 pixel level. Within the 398 km2 of USFWS-designated critical habitat, only 34% had a graded probability of bighorn use to non-use ranging from ≥1:1 to 6,044:1. The remaining 66% of the study area had odds of having bighorn use <1:1 or it was more likely not to be used by bighorn sheep. The USFWS designation of critical habitat included areas (45 km2) of importance (2.5 to ≥40 observations per km2 per year) to Nelson's bighorn sheep and large landscapes (353 km2) that do not appear to be used (<1 observation per km2 per year).
The effects of 3 levels of mowing and cattle (Bos taurus) grazing were examined on rough fescue (Festuca scabrella) range on the Blackfoot Clearwater Wildlife Management Area in west-central Montana. Treatments were implemented in enclosures during the fall of 1997 and 1998 at 50%, 70%, and 90% removal of herbaceous standing crop. Elk (Cervus elaphus) and mule deer (Odocoileus hemionus) forage measurements were obtained in spring and summer on standing dead vegetation, green grass and forb biomass, total biomass, and percent live vegetation, and compared between mowing and prescribed cattle grazing at the same removal level. At the 50% mowing level, there was increased (P<0.05) availability of grass and biomass in the spring, with increased standing dead and decreased percent live vegetation in the summer. At the 70% mowing level, there was increased standing dead and grass and decreased percent live vegetation available to elk and mule deer in the spring when compared with the same level of grazing (P<0.05). At the 90% mowing level, there was decreased availability of grass and total biomass during spring and summer (P<0.05). Results indicated that at moderate (50%) levels of vegetation removal, fall mowing might be adequate to increase grass and total biomass availability in the spring, but fall grazing by cattle might remove more standing dead material, leaving more nutritious plants available to wildlife in the summer. Fall mowing at 70% removal might provide more grass for wildlife in the spring, but reduces percent live vegetation and leaves more standing dead when compared to fall cattle grazing. This would make it more difficult for wildlife to select preferred forage in the spring, when nutrition is needed for calf and fawn production. Fall cattle grazing might be a better tool to use at the 90% level, since mowing removes more grass and total biomass, leaving reduced vegetation for elk and mule deer.
The western population of the gopher tortoise (Gopherus polyphemus) was listed as threatened under the Endangered Species Act in 1987 due to extensive population declines. Declines have been linked to site conversion of native pine (Pinus spp.) forests for urban development, agriculture, and commercial forest management. We conducted surveys to detect tortoise burrows on corporate timberlands in southern Mississippi and southwestern Alabama during summer 1994. We surveyed 2,759 0.5-ha strip transects on soil types of 9 different suitability categories for gopher tortoises. We found 460 active and 264 abandoned burrows on the 1,380 ha surveyed. Edaphic and vegetative conditions, such as sandy soils and total and midstory canopy coverage, influenced gopher tortoise occurrence. Logistic regression analyses revealed that active burrow occurrence was related positively to deep, sandy soils and related negatively to total canopy closure and fine loam soils with limited sand content. Abandoned burrow occurrence was related positively to increasing midstory canopy closure and selected soil types. Sandy soils and open over-story canopy that created favorable burrowing, nesting, and foraging conditions were important influences in active burrow occurrence. Vegetation management techniques, such as prescribed fire, midstory control, and intermediate forest stand thinning, are recommended on gopher tortoise conservation areas and connective corridor habitats on commercial timberlands. We theorize that restoration of longleaf pine (P. palustris) forests on sandy ridges can produce desirable core habitats and dispersal corridors for gopher tortoises in landscapes dominated by intensively managed pine plantations.
KEYWORDS: American Black Duck, Anas platyrhynchos, Anas rubripes, breeding, competitive exclusion, Consistent Use Index, mallard, waterfowl, waterfowl survey, wetland use
The decline of the American black duck (Anas rubripes) has been attributed to competition from mallards (A. platyrhynchos) that led to exclusive use of fertile wetlands by mallards. Data from annual breeding waterfowl surveys provide instantaneous, single observations of breeding pairs, which are used to estimate breeding population size and evaluate the condition of habitat. Data from these surveys have been used to document habitat use by black ducks and mallards. We used quiet-observation surveys from elevated platforms to study sympatric black ducks and mallards in northern Maine during the breeding season. Our objectives were to document occupancy of wetlands by breeding black ducks and mallards throughout the day during prenesting and early nesting periods to determine whether 1) wetlands were occupied by only a single species, 2) pairs of the same species occupied wetlands throughout the period, and 3) single observations of short duration adequately determine numbers and species using a wetland. We observed ducks at 5-minute intervals from elevated platforms on wetland margins to determine numbers and species of indicated pairs using each wetland over time. We visited 80% of the wetlands ≥2 times, with mean total time per wetland averaging 267 minutes. For each wetland we determined the most frequently observed grouping of black ducks and mallards from all combinations recorded during all intervals (e.g., 1 black duck [BD] pair during 9 intervals; 2 mallard [MA] pairs and 1 BD pair during 22 intervals; 0 pairs during 3 intervals). A single pair, a lone male, or no ducks were recorded during 34% of the 5-minute intervals. For wetlands with ≥2 hours of observations (n=65), all but 2 were used by ≥2 different combinations of ducks. On most wetlands, the most frequent grouping was observed during <40% of the intervals. To simulate aerial surveys, we randomly selected 1 5-minute interval for each wetland. On average, the number of indicated pairs recorded during random 5-minute intervals was less than half of the total black duck pairs (2.0 vs. 4.4, P= 0.009), total mallard pairs (1.1 vs. 2.6, P=0.0001), and pairs of both species combined (3.2 vs. 7.0, P=0.0001) determined for each wetland based on total observations. On wetlands used by both species, random counts detected one or both species 49% of the time. Although 53 of the 65 wetlands observed ≥2 hours were used by both species, random visits detected both species on only 27 wetlands. Our data do not support assertions that the mallard has caused the decline of black ducks through interspecific competition for habitat, or that wetlands are occupied continuously by single pairs that aggressively exclude conspecifics. Our data indicated that single, short-duration visits with disturbance to wetlands are unreliable and inappropriate to document seasonal use of wetlands by breeding black ducks and mallards.
Breeding-bird communities inhabiting northern prairie wetlands have been shown to have higher densities and diversities in wetlands with a well-interspersed 50:50 vegetative cover:water ratio than in those wetlands with a higher or lower proportion of cover. Potential reasons for such a response include increased food or visual isolation and spacing of breeding birds. We manipulated cover:water ratios (75:25, 50:50, 25:75) in Southern Great Plains playas and examined avian response (i.e., species richness, non-waterfowl bird density, and waterfowl density) to these patterns in winter. We found the highest species richness and generally the highest waterfowl densities in the 50:50 cover:water treatment. Because the amount of vegetative food was similar among treatments and waterfowl inhabiting playas during winter are forming pair bonds, it is most likely that the optimal edge and visual isolation provided in the 50:50 cover:water treatment contributed to its high use and richness. Nonwaterfowl bird density was not different among the treatments. Many nonwaterfowl birds using playas in winter, such as McCown's longspur (Calcarius mccownii), occur as nonbreeding feeding flocks, are not forming pair bonds, and likely are not responding to particular cover:water treatments. Playa wetland biologists should create a well-interspersed 50:50 cover:water ratio to optimize waterfowl use and avian species richness.
The 7 taxa of deer introduced to New Zealand are officially regarded as pests but also are valued by hunters and commercial harvesters, who often debate the need for deer population control. Some hunters argue that it should be more cost-effective to enhance existing private hunting effort than to use state-employed cullers to kill deer. To explore that argument, we combined predator–prey and economic theory to predict how net revenue (carcass value minus cost of harvesting it) for a commercial helicopter-based venison-recovery operation was likely to vary with deer density and to result in stable harvest equilibria when marginal net revenue was zero. We then adapted that model to simulate the cost of state-funded deer control and the net satisfaction obtained by ground-based recreational hunters. Key findings were that 1) payment of incentives to commercial harvesters usually will be more cost-effective than state-funded culling, 2) payment of incentives to recreational hunters usually will not be effective unless time costs can be reduced at little monetary cost, and 3) ground-based cullers will be more effective than helicopter-based hunters at attaining low deer densities in dense forest. Key management implications are that commercial hunting can be cost-effectively manipulated to enhance control of deer populations, but neither commercial nor recreational hunting is likely to be a cost-effective alternative to state-funded control where very low densities are required in inaccessible or difficult-to-hunt areas. Although developed for deer control in New Zealand, the models are applicable to any situation in which harvesting is used as a form of population control.
Assuming that a finite biosphere can support infinite development seems logically indefensible, yet the concept of sustainable development has become a dominant conservation paradigm. The story of the endangered Florida Key deer (Odocoileus virginianus clavium) appears to support the legitimacy of sustainable development because Key deer numbers have increased 240% since 1970 while at the same time human numbers in their habitat increased nearly 10-fold. Because fawn mortality is considered the primary density-dependent factor regulating cervid populations as they approach K-carrying capacity, we hypothesized that changes in fawn demographics could elucidate the fallacy in assuming that development was sustainable on Big Pine Key. We determined and compared survival and range sizes for Key deer fawns between 1968–1972 (early urban development) and 1998–2002 (post-urban development). Fawn ranges (95% probability area, 149 to 33 ha) and core areas (50% probability area, 25 to 6 ha) decreased during this period of development while 6-month survival increased (0.47 to 0.96). All fawn mortality was due to anthropogenic causes; the positive relationship between fawn survival and development may be a function of isolating fawns from anthropogenic mortality. If this is true, the relationship is not sustainable because as ranges continue to shrink, they eventually will lack sufficient resources to support a fawn.
Strategies for managing chronic wasting disease (CWD) in urban mule deer (Odocoileus hemionus) populations are needed in Colorado. We captured, tonsil-biopsied, marked, and tested adult mule deer (n=181) to evaluate the feasibility of conducting an urban “test-and-cull” program in Estes Park, Colorado. During December 2002 and April–May 2003, we successfully tested 51 (57%) of the estimated 89 male and 130 (50%) of the estimated 261 female mule deer wintering in Estes Park for evidence of CWD. Nine (18%) males and 6 (5%) females tested positive for CWD infection via immunohistochemistry. All 15 test-positive deer were removed from the population; we culled 13 of these, and 2 died of other causes before being culled. We completed all sampling and inventory work in 34 field days and culled all test-positive deer in another 7 field days. Personnel time associated with sampling, culling, and inventory averaged 5.2 person-hours/deer. Average drug costs varied by combination (tiletamine–zolazepam–xylazine: $22; thiafentanil–xylazine: $66). Additional fixed costs averaged $215/deer for telemetry devices and $60/deer for vehicle and other testing-related expenses. Based on our initial assessment, sampling ≥50% of the mule deer in Estes Park annually is feasible.
Understanding herd organization is important when considering management alternatives designed to benefit or manipulate elk (Cervus elaphus) populations. We studied the seasonal and annual herd organization of cow elk in Custer State Park, South Dakota from 1993–1997 by examining seasonal subherd range size, spatial arrangement, overlap, and site fidelity. Based on social interaction analyses, we combined locations of radiocol-lared cow elk to delineate subherds. We computed 95% kernel home ranges with least-squares cross validation for each subherd by season and year. Subherd overlap and fidelity by season and year were computed using the Volume of Intersection Index (VI) statistic. We identified 5 relatively discrete, resident cow–calf subherds. We observed little overlap in utilization distributions of adjacent subherds. The mean VI score across all subherds and time points (n=140) was 0.06 (SE=0.009), indicating an average 6% overlap in subherd area utilization. Subherd overlap between pairs was 0.08 in fall (SE= 0.021), 0.06 in winter (SE=0.018), 0.06 in spring (SE=0.2), and 0.05 in summer (SE= 0.016). Range sizes were not different between any pairs of seasons or years (F13,52=0.7, P=0.75). Subherd fidelity ranged from 0.41 (SE=0.033) to 0.60 (SE=0.018) overall, indicating differential use within the subherd boundary across years. The ability to distinguish discrete cow–calf subherd units is consistent with other studies and may aid elk management in Custer State Park. However, use patterns within subherd boundaries were inconsistent across years and may reflect human disturbances (e.g., hunting and logging activities), differences in our sampling approach, or changes in matriarchal leadership. Further evaluation into factors affecting space-use patterns is necessary to predict changes in range use within the subherd boundary.
Deer (Odocoileus spp.) can cause substantial damage to agricultural crops, resulting in economic losses for producers. We developed a deer-activated bio-acoustic frightening device to reduce white-tailed deer (O. virginianus) damage in agricultural fields. The device consisted of an infrared detection system that activated an audio component which broadcast recorded distress and alarm calls of deer. We tested the device against unprotected controls in cornfields during the silking–tasseling stage of growth in July 2001. The device was not effective in reducing damage: track-count indices (F1,4=0.02, P=0.892), corn yield (F1,9=1.27, P=0.289), and estimated damage levels (F1,10=0.87, P=0.374) did not differ between experimental and control fields. The size (F2,26=1.00, P=0.380), location (F2,25 =0.39, P =0.684), and percent overlap (F2,25 =0.20, P =0.818) of use-areas of radiomarked female deer did not differ between during- and after-treatment periods. We concluded that the deer-activated bio-acoustic device was not effective in protecting cornfields in this study; however, the device may be more effective in small areas such as gardens or for high-value crops that do not grow tall enough to offer protective cover.
White-tailed deer (Odocoileus virginianus) cause millions of dollars of damage to agricultural crops annually. We tested the effectiveness of propane exploders and Electronic Guards (Pocatello Supply Depot, Pocatello, Id.) for reducing deer damage in cornfields during the silking–tasseling stage of growth. Track-count indices (F2,7=0.70, P=0.532), corn yields (F2,6=0.14, P=0.873), and estimated damage levels (F2,12=1.45 P=0.272) did not differ between experimental and control fields. The size (F2,11=0.08, P=0.924), location (F2,9 =0.30, P =0.750), and percent overlap (F2,9 =0.46, P =0.644) of use-areas of radiomarked female deer in the vicinity of experimental fields did not differ among before, during, and after 18-day treatment periods. In a related study, we placed propane exploders in cornfields within use-areas of 12 radiomarked female deer. The deer did not react appreciably to the devices: the size (F2,17=0.08, P=0.921), location (F2,22=1.37, P = 0.275), and percent overlap (F2,10 = 0.47, P = 0.636) of deer use-areas did not differ among before, during, and after 14-day treatment periods. We conclude that propane exploders and Electronic Guards have limited potential for reducing deer damage to corn at the silking–tasseling stage.
In the 1980s scientists determined that an introduced mountain goat (Oreamnos americanus) population caused negative impacts to subalpine plant communities in Olympic National Park (ONP). These findings resulted in a controversial and costly mountain goat reduction program from 1981–1989. Since 1990 introduced nonnative mountain goats from Montana have successfully colonized Yellowstone National Park (YNP) via the Absaroka and Gallatin mountain ranges. Using systematic aerial surveys from 1997–2001, I documented a breeding goat population inside or within 1 km of YNP that increased from 24 to 96 mountain goats observed (mean observed rate of increase r̄= 0.35). Because of increasing goat populations immediately adjacent to YNP, Montana Fish, Wildlife, and Parks (MFWP) established 2 new hunting districts and 44 mountain goats were harvested near YNP from 1996–2001. The mountain goat is a socially popular “charismatic” species with high watchable-wildlife values. However, within YNP they also are viewed with concern as an exotic species, potentially capable of exploiting fragile subalpine landscapes where, by policy, nonnative ungulates are not welcomed. Based on habitat availability and goat densities to the north, YNP potentially may support 200–300 mountain goats. Important ecological differences between YNP and ONP may reduce the likelihood of negative resource impacts of mountain goats in YNP. However, the speed at which mountain goat numbers and distribution are increasing warrants further habitat and population monitoring to better understand and predict the ecological effects of this new species. Future mountain goat management decisions in YNP should be based on documented impacts of goats on their habitat and other species in YNP and not what has occurred in ONP. Mountain goat management efforts in YNP should acknowledge MFWP's management objective of maintaining viable goat populations in suitable habitats and recognize that goats from Montana will continue to be a source population for future dispersal into and colonization of YNP.
Estimates of survival and cause-specific mortality of white-tailed deer (Odocoileus virginianus) fawns are important to population management. We quantified cause-specific mortality, survival rates, and habitat characteristics related to fawn survival in a forested landscape and an agricultural landscape in central Pennsylvania. We captured and radiocol-lared neonatal (<3 weeks) fawns in 2000–2001 and monitored fawns from capture until death, transmitter failure or collar release, or the end of the study. We estimated survivor-ship functions and assessed influence on fawn survival of road density, habitat edge density, habitat patch diversity, and proportion of herbaceous habitat. We captured 110 fawns in the agricultural landscape and 108 fawns in the forested landscape. At 9 weeks after capture, fawn survival was 72.4% (95% CI=63.3–80.0%) in the agricultural landscape and 57.2% (95% CI=47.5–66.3%) in the forested landscape. Thirty-four-week survival was 52.9% (95% CI = 42.7–62.8%) in the agricultural landscape and 37.9% (95% CI = 27.7–49.3%) in the forested landscape. We detected no relationship between fawn survival and road density, percent herbaceous cover, habitat edge density, or habitat patch diversity (all P>0.05). Predation accounted for 46.2% (95% CI=37.6–56.7%) of 106 mortalities through 34 weeks. We attributed 32.7% (95% CI=21.9–48.6%) and 36.7% (95% CI=25.5–52.9%) of 49 predation events to black bears (Ursus americanus) and coyotes (Canis latrans), respectively. Natural causes, excluding predation, accounted for 27.4% (95% CI=20.1–37.3) of mortalities. Fawn survival in Pennsylvania was comparable to reported survival in forested and agricultural regions in northern portions of the white-tailed deer range. We have no evidence to suggest that the fawn survival rates we observed were preventing population growth. Because white-tailed deer are habitat generalists, home-range-scale habitat characteristics may be unrelated to fawn survival; therefore, future studies should consider landscape-related characteristics on fawn survival.
We characterized microhabitat (structure and microclimate) at 236 mule deer (Odocoileus hemionus) day-beds, 152 diurnal forage sites, and 439 random locations during summers of 1998–2000. Our objectives were to 1) identify important microhabitat characteristics of day-beds and forage sites in untreated forest, 2) compare relative availability of bed and forage sites having these characteristics between forest types, 3) determine whether mule deer selected either forest type disproportionately for these activities, and 4) compare characteristics of day-bed and forage sites between forest types. Mule deer selected bed and forage sites with specific characteristics in untreated forest each year. Site temperature and canopy closure were the most influential attributes in bed-site selection, while forage availability best described forage sites. Availability of characteristic day-bed microhabitat was reduced 50–100%, while forage characteristics increased 31–66% each year in treated forest. Foraging mule deer selected treated forest in 1 year but demonstrated no preference in 2 years. Mule deer continued to use day-beds in both forest types each year as expected based on proportional area of each forest type, but did so in treated forest in 1999 by utilizing a novel suite of microhabitat features. Bed sites in each forest type had similar levels of midstory canopy closure, but treated forest bed sites were warmer in one year, exclusively located under oaks (Quercus gambelii) rather than conifers, and less concealed than untreated forest beds. Small oak stands were the only dense patches retained in the restoration prescription we examined and provided marginal thermal and hiding cover for day-bed use by female mule deer. These differences may increase thermoregulatory stress and the potential for increased disturbance and predation of female mule deer and fawns during summer. We recommend retaining >0.04-ha patches of dense bedding and hiding cover in areas where both forest restoration and mule deer are management concerns.
United States Highway 30 between Kemmerer and Cokeville, Wyoming bisects the migratory route of the Wyoming Range mule deer (Odocoileus hemionus) herd and is the site of hundreds of deer–vehicle collisions each year. We tested the effectiveness of the FLASH™ (Flashing Light Animal Sensing Host, Victoria Gouch, Meridian, Id.) system, designed to detect deer presence on the highway and warn motorists by triggering flashing lights associated with a sign. We collected data on changes in vehicle speed in response to the warning system and conducted a series of experimental manipulations to determine motorist response to the system with various treatments involving the sign, the lights, and the presence of a deer decoy. Motorists in automobiles traveling at night reduced their speed the most (6%) in response to the normal operation of the system, with a mean speed reduction of 6 km/hour. During experimental manipulations motorists reduced their speed 20% when the deer decoy was present in the crossing, and responded less (7%) to the flashing lights and sign. The system tested may be effective in preventing deer–vehicle collisions in areas with a lower speed limit and more local traffic, but we believe it is not suitable for an application with high-speed traffic (i. e., >100 km/hour) and a high proportion of interstate traffic.
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