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We analyzed data for 422 unmarked and 369 radiocollared desert bighorn sheep (Ovis canadensis) translocated into vacant historical habitats in 12 Arizona locations between 1979 and 1995. We evaluated factors potentially influencing predation of radiocollared desert bighorn sheep by mountain lions (Puma concolor) by determining relationships between predation rates, number released, size of releases, escape terrain, available terrain (escape terrain as a percentage of area with slopes ≥40%), habitat quality associated with release locations, and mule deer (Odocoileus hemionus) and predator abundance. We hypothesized that numbers of radiocollared animals released, quality of habitat and available terrain associated with release locations, and relative abundance of mule deer influenced predation of translocated desert bighorn sheep by mountain lions.
The State Soil Geographic Data Base (STATSGO) developed by the Natural Resources Conservation Service is a spatially explicit database of soil characteristics known to influence the distribution, abundance, or quality of vegetation, which ultimately may affect white-tailed deer (Odocoileus virginianus) population phenotype. The national availability of STATSGO makes it an attractive tool for wildlife ecologists to use for explaining variation in deer population morphometrics. We constructed linear regression models relating site-specific mean population 1.5-year female body mass and 2.5-year male antler size to soil pH, organic matter, bulk density, and available water capacity values from STATSGO to evaluate the explanatory power of the database. For comparison, we developed general linear models that related the same deer morphometrics to nominal classification variables that represented 4 soil regions in Mississippi, USA. At the statewide level, regressions using site-specific soil pH, organic matter, bulk density, and available water capacity values from STATSGO did not explain more variation than did regional classification models. Although STATSGO did not generate good models for predicting or explaining localized variation in white-tailed deer morphometrics in Mississippi, it did reveal differences in soil properties that may influence white-tailed deer populations at regional spatial scales. At the statewide level, soil resource region classification models may be a more effective tool because they explained similar variation in deer morphometrics, and model input is easier to obtain.
We simulated dynamics of exploited white-tailed deer (Odocoileus virginianus) herds to study effects of harvest strategy on adult sex ratios. Simulations included 5 levels of adult female mortality (0%, 10%, 20%, 30%, and 40%), 3 levels of adult male mortality (35%, 65%, and 80%), and 3 levels of herd productivity (low, medium, and high) for a total of 45 scenarios. Our simulations were based on density-dependent recruitment models. We also examined a model that included stochastic recruitment. Prehunt adult sex ratios remained stable and generally below 3.5:1 (F:M) at lower relative densities and became much wider above about 70% relative density. Declining recruitment at higher densities was the most important factor controlling adult sex ratios. Adult female mortality affected sex ratios more by influencing recruitment than by direct effects of animals removed. Adult male mortality rates were an important factor controlling sex ratios within the context of relative density. Given the importance of managing white-tailed deer herds to achieve a variety of objectives including biodiversity conservation, hunter recreation, and herd quality, it is essential that managers understand the dynamics of exploited herds.
There is growing concern that populations of migratory ungulates are declining globally. Causes of declines in migratory behavior can be direct (i.e., differential harvest of migrants) or indirect (i.e., habitat fragmentation or land-use changes). Elk (Cervus elaphus) are an important big game species in North America whose migratory behavior is changing in some montane ecosystems. We evaluated evidence and hypotheses for changes in migratory behavior and population decline in one of Canada's largest elk populations, the Ya Ha Tinda. We compared the ratio of migrant to resident elk (M:R) in the population and seasonal spatial distributions obtained from 22 winter and 13 summer helicopter surveys between 1972 and 2005. Timing of migration and the summer distribution for a sample of radiocollared elk also was compared for 1977–1980 (early period) and 2001–2004 (recent). The population M:R ratio decreased from 12.4 (SD = 3.22) in the early period to 3.0 (SD = 1.63). The decrease was greater than expected based on population change. Declines in M:R also mirrored behavior of radiocollared elk. More than 49% of radiocollared elk we monitored resided near the winter range year-round by 2001–2004, and migrants were spending less time on summer ranges. We found winter range enhancements, access to hay fed to wintering horses, recolonization by gray wolves (Canis lupus), and management relocations of elk were most consistent with observed elk population growth (adjusted for harvest and removals) and the change in migratory behavior. However, we could not isolate the effects of specific factors in time-series population modeling. We believe directly relating migrant and resident demography to habitat and mortality factors will be required to understand the mechanisms affecting migratory behavior in this and other montane elk herds.
We studied the characteristics of pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus), and elk (Cervus elaphus) mortalities associated with wire fences along roads in Colorado and Utah, USA, from June 2004 to June 2005. We estimated an average annual mortality occurrence of 0.25 mortalities/km for the wire fences studied (0.08 mule deer mortalities/km, 0.11 pronghorn mortalities/km, and 0.06 elk mortalities/km) or 0.5 mortalities/km of road. The highest wire fence–mortality rates in our study area occurred during August, which coincided with weaning of fawns. Mule deer and pronghorn jumped fences in >81% of observed crossings. Mortalities were largely caused by animals getting caught between the top 2 wires. Mule deer experienced higher fence-mortality rates than elk or pronghorn because they crossed fences more frequently (P < 0.001) and spent more time in road right-of-ways (P < 0.001) than the other species. Juveniles were 8 times more likely to die in fences than adults. Woven-wire fences topped with a single strand of barbed wire were more lethal to ungulates than woven wire with 2 strands of barbed wire above it or 4-strand barbed-wire fences (P < 0.01). There was a direct relationship between the frequency of fence mortalities and ungulate abundance (r2 = 0.83). Traffic volumes were inversely related to fence-mortality frequencies (r2 = 0.50) and ungulate densities along the right-of-way (r2 = 0.50).
Prior to implementing laws and policies regulating water, wildlife, wetlands, endangered species, and recreation, natural resource managers often solicit public input. Concomitantly, managers are continually seeking more effective ways to involve stakeholders. In the autumn of 1999, the Wyoming Game and Fish Department sought to develop a state management plan for its portion of the Yellowstone grizzly bear (Ursus arctos horribilis) population if it was removed from the federal threatened species list. A key aspect of developing this plan was the involvement of federal, state, and local agencies, representatives from nongovernmental organizations, and citizens. Wyoming wildlife managers asked researchers from the United States Geological Survey to demonstrate how the Legal-Institutional Analysis Model could be used to initiate this process. To address these needs, we conducted similar workshops for a group of state and federal managers or staffers and a broad group of stakeholders. Although we found similarities among the workshop groups, we also recorded differences in perspective between stakeholder groups. The managers group acknowledged the importance of varied stakeholders but viewed the grizzly bear planning process as one centered on state interests, influenced by state policies, and amenable to negotiation. The other workshops identified many stakeholders and viewed the decision process as diffuse, with many opportunities for entry into the process. These latter groups were less certain about the chance for a successful negotiation. We concluded that if these assumptions and differences were not reconciled, the public involvement effort was not likely to succeed.
Measuring activity levels in animals provides important information about their behavioral ecology and may be a relevant factor in management and conservation. We tested an individual-based method to discriminate active and passive behaviors on brown bears (Ursus arctos), using a dual-axis motion sensor mounted on Global Positioning System–Global System for Mobile Communications (GPS–GSM) collars. The method takes into account individual variation in activity levels and does not require further calibration. We validated the method through direct observations of captive bears and an extensive survey of wild bear signs in the boreal forest of central Sweden. We found good correspondence between sensor-measured and observed activity on captive bears. Analysis of wild bear signs at GPS locations and its comparison with the collar-based activity status confirmed the possibility of successfully applying the method to study brown bear activity patterns in the wild. The method provided 94.3% correct activity classification on captive bears and about 78.2% on wild bears. We tested the possibility of using this technique to measure increasing levels of activity by analyzing the correlation between the collar-derived numeric activity and the intensity of bear movement. At a broader scale (active vs. passive), the sensor-measured value provided information on the degree of activity, but no correlation was evident at a finer scale (specific behaviors). We suggest that using more sensors in different regions of a bear's body could overcome this difficulty and improve our knowledge of animal behavior in the wild, through remote monitoring of activity levels. We conclude that this method can be useful in the study of behavioral ecology of a wide range of animals, especially species that are difficult to observe or move great distances.
Animal diet investigations typically have been limited to stomach-content analysis, fecal analysis, or direct observation of foraging behavior. More recently researchers have used stable isotopes in tissues that develop during different time periods to examine the assimilated diet of mammals. Hair and bone tissues are used to examine annual and lifetime assimilated diets, whereas metabolically active tissues (e.g., blood, muscle, liver) reflect the assimilated diet over a period of days or months. Using hair tissue to examine assimilated diet at a finer temporal scale would be advantageous because samples can be collected without sacrifice or direct and continuous handling of an animal. We examined the possibility of using hair tissue to distinguish among seasonal assimilated diets of grizzly bears (Ursus arctos) by comparing the isotopic values of whole guardhair (annual assimilated diet), underfur (autumn assimilated diet), and replicate sections of guardhair for individuals within plateau and mountain environments in central British Columbia, Canada. Stable carbon (δ13C) and nitrogen (δ15N) values differed between whole guardhair and underfur for male and female grizzly bears in the mountains and for δ15N for female plateau bears. Consistent with our assumptions, isotopic values (δ15N and δ13C) for the section of guardhair nearest the root overlapped with the underfur isotopic values for 7 of 8 bears. Overlap with subsequent sections was highly variable. Variation among replicates of guardhair sections within bears exceeded variation because of analytical error, indicating that current assumptions about hair growth may not be correct. The need to composite sample hair sections to meet minimum weight requirements precluded an examination of variation in isotopic values among individual hairs. Researchers examining the diets of grizzly bears should consider that differences can be detected between annual (whole guardhair) and autumn (underfur) assimilated diets, and there is potential to use sectioned guardhair to examine assimilated diet at a finer temporal scale; however, we suggest that controlled studies quantifying variation in hair tissue for bears on a constant diet and testing hair growth assumptions are integral to interpreting the temporal variation in assimilated diet using hair tissue.
Snow-track surveys to detect rare carnivores require unequivocal species identification because of management and political ramifications associated with the presence of such species. Collecting noninvasive genetic samples from putative wolverine (Gulo gulo) snow tracks is an effective method for providing definitive species identification for use in presence–absence surveys. We completed 54 backtracks of approximately 1.4 km each and collected 169 hairs and 58 scats. Amplification rates of mitochondrial DNA (mtDNA) used for species identification were 62% and 24% for scats and hairs, respectively. The average distance traveled to collect a sample containing high-quality mtDNA for species identification was 1,330 m. Genetic analysis confirmed 35 snow tracks (64%) as wolverine. The remaining 19 snow tracks consisted of 8 that did not provide samples and 11 that contained nonamplifiable samples. Collection of both hairs and scats provided 28% more track verifications than would have occurred using only one type of sample. Collecting noninvasive samples from snow tracks also may provide individual wolverine identification that may provide a basis for obtaining minimum population estimates, relatedness tests, or mark–recapture population estimates given sufficient sample sizes. To that end, we analyzed nuclear DNA (nDNA) from the same samples to produce individual genotypes. Amplification rates of nDNA from scats and hairs ranged from 25% to 52% and 13% to 16%, respectively, and produced individual genotypes for 23 of the 54 snow tracks (43%).
The frequency of interactions among individuals is vital to understanding many aspects of a species' behavioral ecology. This also is a fundamental aspect of infectious disease epidemiology. However, the number of times an individual animal comes into contact with another is an extremely difficult parameter to estimate. This paper describes radiocollars (proximity detectors) capable of recording close contacts among radiocollared individuals. We conducted laboratory tests using collars alone (i.e., not fitted on an organism) and field tests of collar performance with collars fitted on 42 free-ranging raccoons (Procyon lotor) within a 20-ha portion of the Ned Brown Forest Preserve in northeastern Illinois, USA. During laboratory tests, we determined variation in detection distance within and among collars, effect of collar orientation on detection distances, and accuracy of recorded duration of proximity and identification of contacted collar. Overall variation in detection distance both within and among collars was relatively low, although we observed intrinsic variation in collar strength. We found little variation in horizontal detection distances with collar orientation, although mean distances for vertical tests were greater than most horizontal means. Recorded contact duration deviated from actual time by ≤3 seconds for short-duration (10–300 sec), and by ≤30 seconds for extended-duration (8–14 hr) contacts recorded as a single event. However, there was a tendency for the collars to record extended-duration contacts as multiple events, with the frequency dependent on settings. Identification number of the contacted collar was correctly identified in all cases (n = 1,537). We downloaded 35 of the 42 proximity detectors deployed on free-ranging raccoons. Of these, approximately 57% were functioning properly, 9% exhibited problems apparently correctable in the field, and 34% exhibited problems not correctable in the field. For random pairs of raccoons, daily contact duration and number of contacts (omitting 1-sec contacts) recorded by both detectors did not differ (P ≥ 0.066). Overall, collars produced accurate information in terms of detection range, duration of contact, and contacted collar identification, and represented a promising improvement over previous methods to assess intraspecific contact rates of secretive, nocturnal, or otherwise unobservable species. Because accurate determination of contact rates requires that a population be saturated with detectors, their use may be most appropriate for species readily trapped.
Radiotelemetry provides an opportunity to measure animal behavior when other methods are not feasible, but triangulation errors limit the grain at which habitat relationships can be inferred. Additionally, inferred behavioral patterns often are biased toward times when organisms are accessible; often, for nocturnal organisms, when the organisms are resting. We developed an automated radiotelemetry system that is precise, temporally unbiased, and cost-effective. The system consisted of a sensor grid composed of radio receivers that detect the presence of a radiocollared animal within a measurable, adjustable area. The aerial extent of detection is testable, precise (mean error <0.5 m), and consistent. After the sensors are installed, data collection effort is minimal. We tested this system by collecting microscale habitat-use data on snowshoe hares (Lepus americanus) in eastern Idaho, USA. This system will be useful in applications where extremely precise location data and representative sampling across time are important for assessing use patterns. It is most useful for smaller animals where the spatial constraints are not limiting and Global Positioning System collars are not currently an option.
We evaluated mark–resight estimates of mountain goat (Oreamnos americanus) abundance using paintball marks at Seven Devils and Black Mountain, Idaho, USA. We marked mountain goats with recreational paintball equipment fired from a helicopter. Blue-violet dye marks were difficult to distinguish from dark, soiled areas on goats, while orange, yellow, and red oil-based paint marks were easily recognized, highly visible, and persisted for at least 71 days. Marking rates varied with equipment function and pilot effectiveness and ranged between 6.3 and 14.6 goats marked/hour of flight time. Precision of abundance estimates was reasonable with mark samples ≥51% of N̂. We analyzed a 3-occasion survey at Black Mountain using Program MARK to determine the likelihood and magnitude of potential sources of bias. Model Mb, which allows a behavioral response to capture, was best supported by the data, while model Mt, which allows time-varying capture probabilities, had reasonable support. The pattern of time-varying capture probabilities likely was a by-product of trap-shy behavior. Model Mb was 3 times more likely than model Mt to be the best approximating model, given the data. Behavioral response to marking and time-varying capture probabilities can be accommodated with >2 survey occasions. However, the strong evidence for a behavioral response implies that Lincoln–Petersen estimates of abundance are inappropriate. The set of candidate models did not include a model that would accommodate heterogeneity of individual sighting probabilities, which remains a concern with the mark–resight approach.
Harvest information often forms the basis for deer and turkey management decisions. Thus, for many state agencies, collection of representative harvest data is an essential part of the management program. We compared reporting rates and biological information obtained from mandatory in-person and telephone checking (telecheck) for white-tailed deer (Odocoileus virginianus) and eastern wild turkey (Meleagris gallopavo) in Missouri, USA. We subsequently compared this information to that obtained from commercial meat processors to determine if these data could substitute for in-person check stations for collecting age of harvested deer. To conduct our study we randomly selected a telecheck group and a control group from firearms deer and spring turkey hunters in 2003 and 2004, respectively. The telecheck group called a toll-free number to report deer or turkey harvests; the control group reported at established check stations. We compared the sex, age, and number of reported animals harvested by each group. We also compared the reported harvest for the control groups and statewide permittees. For deer, we found no difference in the total harvest reported by telecheck and control group participants. However, the control group reported harvesting more deer than those in the statewide group (0.78 and 0.59 deer per person, respectively). Concomitantly, we found that a lower proportion of commercially processed deer were 0.5 years of age (0.16 and 0.22 for males and females, respectively) than for those self-processed (0.22 and 0.32 for males and females, respectively). There was no difference between self- and commercially processed male or female deer in the distribution of 1.5- and ≥2.5-year-olds. The reported turkey harvest was higher for telecheck and statewide groups than for the control (0 turkeys, 0.64, 0.63, and 0.67; 1 turkey, 0.28, 0.26, and 0.27; 2 turkeys, 0.08, 0.11, and 0.06 for the telecheck, statewide, and control groups, respectively). Recorded spur length did not differ for telecheck and control groups but was longer for the statewide than for the control group (<2.5 cm: 0.54 and 0.51; 2.5–3.8 cm: 0.44 and 0.44; >3.8 cm: 0.01 and 0.03 for control and statewide groups, respectively). Although harvest reporting between telecheck and control groups differed, the differences were small and the significance may have been an effect of large sample sizes. We suggest that telecheck may serve as a suitable replacement for in-person checking of deer and turkey in Missouri. Lastly, age data from deer 1.5 years of age and older collected at meat processors represented distribution data obtained from in-person check stations.
We present a novel technique using a video serial interface to link a motion-activated, infrared video camera and a weigh-scale to measure supplemental feed consumption by wildlife. This “video-scale” allows us to quantify consumption of various feeds by individual animals to an accuracy of 5 g and to record feeding duration to the second. Using intake rate and total time spent feeding, we calculated comparative use of supplemental feed by animals categorized by species, age, and sex. We present preliminary data on feed consumption and intake rates of wild and tame white-tailed deer (Odocoileus virginianus) and raccoons (Procyon lotor) eating shelled corn, pelleted supplement, and whole cottonseed. Other uses and limitations of the video-scale are discussed.
Abandoned mines provide summer roosts, autumn swarming sites, and winter hibernacula for bats (Chiroptera). Although hibernacula selection has received considerable attention, few studies have examined the characteristics of mines used as summer roosts and autumn swarming sites. Abandoned mines are hazardous and often sealed to prevent human access. Alternatively, abandoned mines sometimes are gated to protect mine-roosting bats by deterring human entrance. However, gates and other mine entrance characteristics may affect bat presence and use. We examined the external characteristics of mines that could be measured safely and quickly to determine if they influenced bat species presence and relative frequency. We surveyed bats at 36 abandoned coal mine entrances during summer 2002 and 47 mine entrances (the same 36 as during summer and 11 additional mines) during autumn 2002 at New River Gorge National River and Gauley River National Recreation Area, West Virginia, USA. We captured 139 bats during summer and 1,733 bats during autumn of 9 different species. During autumn, more bat species used mines with isolated entrances than those with multiple entrances. Our results indicate that gates do not affect bats in terms of presence or frequency of use as much as mine entrance shape and proximity to other portals. Mine entrance size and shape positively influenced bat activity, particularly that of little brown myotis (Myotis lucifugus) and eastern pipistrelle (Pipistrellus subflavus), which were among the most commonly captured species. Spatial proximity of entrances should be considered in bat management decisions concerning abandoned mines.
Prairie grouse populations are difficult to reestablish after extirpation. Following translocation, distances individuals move from the release site appear to affect restoration success. Previous authors have suggested assessing lek, nest–brood, and winter habitat when selecting release sites. We examined movement of 131 (66 M and 65 F) radiomarked Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) translocated during 1999–2002 as part of management effort to restore populations to historical ranges in northeastern Nevada, USA, an area where sharp-tailed grouse have not been observed in the wild since the 1950s. We released grouse at 2 sites. We chose the initial site based on its physiographic and vegetation similarities to capture sites in Idaho, USA, particularly shrub–steppe at lower elevations and mountain shrub at higher elevations, and used it during 1999 and 2000 (34 M, 18 F in 1999; 42 M, 26 F in 2000). Females released at this site moved greater distances than males through time, with no differences between years. We changed the release site based on nest locations of previously translocated females. The second site was 10 km south of site 1 and we used it in 2001 and 2002 (36 M, 22 F in 2001; 14 M, 5 F in 2002). Grouse released at this site moved substantially shorter distances than did the grouse initially released, and movement distances did not differ by gender or year. During 2004 we observed 23 grouse displaying on a lek near site 2 and observed no grouse near site 1. Our results support the hypothesis that nest-site availability is an important component to release-site selection insofar as sharp-tailed grouse in our study moved less when released into habitat that had been selected for nesting by previously released grouse.
It generally is assumed that direct flushing responses to disturbance may affect overwintering bird fitness by altering site use. However, little is actually known about the relationship between the flushing response and resulting patterns of habitat use on a local scale. We examined the association between flushing and local site use among 6 wading bird species in tidal creeks on the Cape Romain National Wildlife Refuge, South Carolina, USA, which is frequently used for recreational activities. Experimental, cumulative boat intrusion caused approximately one-half of individuals of all species except snowy egrets (Egretta thula) to immediately abandon a tidal creek. However, species counts across the refuge tended to be driven primarily by Julian date, tidal stage, and creek width; only 2 species, yellow-crowned night heron (Nyctanassa violacea) and great egret (Ardea herodias), appeared to avoid high-traffic creeks. Overall, patterns of response varied among species, and there was no clear relationship between flushing and site use. Flush rates, thus, may not adequately reflect species sensitivity to human disturbance and should only be used as a management guide in conjunction with other indices such as spatial distribution.
We used recent population data and a deterministic matrix model that accounted for important aspects of raptor population biology to evaluate the likely impact of falconry harvest (including take of different age classes) on wild raptor populations in the United States. The harvest rate at maximum sustainable yield (MSY) ranged from 0.03 to 0.41 for the species examined. At least for peregrine falcons (Falco peregrinus), harvest rate at MSY was greatest for nestlings and lowest for adults. The quality of demographic data for the species influenced MSY. For most species the state of current knowledge probably underestimates the capacity for allowed harvest because estimates of vital rates, particularly survival, are biased low, because emigration is not distinguished from survival. This is offset somewhat by biases that might overestimate sustainability inherent in MSY-based analyses and deterministic models. Taking these factors into consideration and recognizing the impracticality of monitoring raptor populations to determine actual effects of harvest, we recommend that falconry harvest rates for juvenile raptors in the United States not exceed one-half of the estimated MSY up to a maximum of 5%, depending on species-specific estimates of capacity to sustain harvest. Under this guideline, harvest rates of up to 5% of annual production are supported for northern goshawks (Accipter gentilis), Harris's hawks (Parabuteo unicinctus), peregrine falcons, and golden eagles (Aquila chrysaetos); lower harvest rates are recommended for other species until better estimates of vital rates confirm greater harvest potential.
Age-specific studies pertaining to survival and productivity of American black ducks (Anas rubripes) are constrained by the fact that no technique has been developed to reliably determine age as second year or after second year from late winter to late spring. We developed a qualitative age-class scoring technique that can be readily used in the field. When tested on 5 independent observers, known-aged birds (n = 106) were correctly classified with 94–98% accuracy. To reduce subjectivity and provide an objective corroboration of age estimates, we also developed multivariate models from measurements of wing feather variables (weight and length of greater secondary covert 9, and width of tertial covert 5) that determined age with ≥90% accuracy (n = 255). There was ≥94% agreement between qualitative and quantitative age assignments of wild birds caught in spring (n = 172). The application of these age determination techniques should be useful in a host of life-history studies conducted on wintering, spring staging, and nesting grounds.
The 50th anniversary of the publication of Paul Errington's Of Men and Marshes will occur in 2007. Using “landscape” in a figurative as well as a physical sense, we examine Errington's life in wildlife science as well as the places where he conducted his research. While Errington's scientific work on predation has received acclaim, we argue his research also contributed to fundamental changes in cultural and popular views of wetlands. Similar to Aldo Leopold, Errington's writings transcended science and ethics as he wrote about the intrinsic values of marshes. Errington's attempts to translate his scientific experience for a wider audience ultimately contributed to public understanding of the importance of restoring wetlands. As we reflect on the public roles of wildlife professionals, Paul Errington's work provides a visible road map to follow.
Many software tools available to biologists are either case-specific or require the ability to write computer programs. The learning curve for newer Bayesian approaches is much steeper than traditional approaches, often requiring an investment of several years. This article introduces a new free software package, BEAST (Bayesian Ecological Analysis of Statistical Trends), for Bayesian estimation of population trends, which requires the user to do no programming. A wide range of single-species population dynamics models are supported, including single-stage population models, stage-structured population models, and age-structured population models. In addition to Bayesian parameter estimation, this software allows users to do population projections, and may be used as a teaching tool by agencies and universities. I provide an example of a theta-logistic population model of stock pigeon (Columba oenas) breeding pairs. The degree of density dependence for this population was found to be stronger when compared to maximum likelihood parameter estimates available from the literature. Short-term population projections indicate that the number of breeding pairs is relatively stable, indicating that the population is at (or near) carrying capacity. This result is in agreement with the most recent data available, which indicate the breeding counts have remained relatively constant.
We trained students (grades 3–10) through classroom presentations to survey an Oregon white oak (Quercus garryana) stand in Washington, USA, and compared their data to those obtained from professionals. In May and July 2002, 607 students and 8 professionals surveyed 59 and 22 50-m transects, respectively. We enumerated oaks and ponderosa pines (Pinus ponderosa), measured diameter at breast height, and rated the crown shape of oaks. Oak diameter at breast height measurements and tree counts were consistent between students and professionals (α = 0.05), but subjective crown assessments and live or dead status differed. Students tended to overreport relatively rare pines and larger oaks relative to professionals. This project provided resource managers with data describing oak diameter at breast height and distribution while educating students about the ecology of local wildlife habitat.
High white-tailed deer (Odocoileus virginianus) densities in urban areas typically result in human–wildlife conflicts (e.g., deer–vehicle collisions, transmission of disease to humans, and vegetation damage). Controlling deer densities via fertility control generally is more acceptable than lethal removal in many urban areas and can reduce conflicts by stabilizing deer numbers. Contraceptive vaccines that use PZP (porcine zona pellucida) proteins as antigens have been used for many years and generally are regarded as safe and effective. Side effects of immunocontraception may be repeated estruses, an extension of the breeding season, and increased movements and ranges of immunized deer. We evaluated the effects of SpayVac™, a long-lasting, single-dose PZP vaccine on ranges and movements of female white-tailed deer at the Lyndon B. Johnson Space Center near Houston, Texas, USA. We captured, treated, and radiomarked 38 female deer with SpayVac (treatment) and injected 11 deer with a placebo (control). Fawning rates for treated and control deer were 0% and 78%, respectively. We observed no difference in the movements and ranges of SpayVac- versus placebo-treated deer: annual ranges (95% probability area) between treated (x̄ = 82 ± 7 ha) and control (x̄ = 77 ± 14 ha) deer, core areas (50% probability area) between treated (x̄ = 11 ± 1 ha) and control (x̄ = 11 ± 3 ha) deer, and daily movements treated (x̄ = 430 ± 1.5 m) and control (x̄ = 403 ± 3.6 m) deer. However, we did not evaluate the potential effect of immunized females on ranges and movements of male white-tailed deer. Increased ranges and movements may be more pronounced for males than for females.
Endangered black-footed ferrets (Mustela nigripes) are difficult to monitor because of their nocturnal and fossorial habits, but land use and management are influenced by their potential presence. Detector dogs have been suggested as a method for determining ferret presence, although its efficacy has not been thoroughly investigated. We evaluated 2 dogs trained specifically for determining ferret presence in field evaluations conducted in black-tailed prairie dog (Cynomys ludovicianus) colonies at the Conata Basin reintroduction site in South Dakota, USA, during September and October 2003. We tested the dogs on 4 test colonies that had no record of ferret presence and 7 colonies known to have ferrets inhabiting them. One dog was 100% accurate at detecting presence and the other was between 57% and 71% successful at detecting ferrets, with neither dog falsely indicating presence when ferrets were absent. For the 2 dogs, the mean time to detect ferrets on a prairie dog colony was 21 minutes and mean search rate was 26 ha/hour. The mean time to detection on the same sites was 208 minutes for spotlight surveys and mean search rate was 1.6 ha/hour. Although spotlight surveys are necessary for identifying population demographics, well-trained detection dogs show promise for detecting ferret presence in prairie dog colonies.
I assessed the ability of dog–handler teams to recover dead bats (Chiroptera) during fatality searches typically performed at wind energy facilities to determine fatality rates for birds and bats. I conducted this study at the Mountaineer and Meyersdale Wind Energy Centers in West Virginia and Pennsylvania, USA, respectively. Dogs found 71% of bats used during searcher-efficiency trials at Mountaineer and 81% of those at Meyersdale, compared to 42% and 14% for human searchers, respectively. Dogs and humans both found a high proportion of trial bats within 10 m of the turbine, usually on open ground (88% and 75%, respectively). During a 6-day fatality search trial at 5 turbines at Meyersdale, the dog–handler teams found 45 bat carcasses, of which only 42% (n = 19) were found during the same period by humans. In both trials humans found fewer carcasses as vegetation height and density increased, while dog–handler teams search efficiency remained high. Recommendations for evaluating the biases and efficiency when using dogs for bat fatality searches are provided.
With the rapid expansion of geographic information systems (GIS) technology and its integration into the wildlife biology field, it is becoming increasingly clear that having access to the full scope of its analytical tools will greatly improve our ability to study, understand, and manage wildlife populations. We use our long-term, white-tailed deer (Odocoileus virginianus) research project as a case study to highlight the significant advances in GIS that have been benefiting investigations of wildlife. From initiation of our research, we included early GIS capabilities and we attempted to take advantage of advances as they occurred. Herein, we document changes that occurred in “wildlife GIS” over the last 15 years and how we applied them in our work. We identify a list of sources of GIS tools and data that are currently available and discuss their potential value to wildlife researchers and managers.
We describe a computerized nest-monitoring unit that uses a small camera (commonly marketed as a “webcam”) mounted on a telescopic pole to relay digital video and still images to a portable laptop computer carried by the operator. This system captures and archives digital color images of open-cup nesting birds, enabling the operator to determine egg type (host or brood parasite) and number, as well as nestling development stages. These archived photographs represent a permanent record that can be revisited and reused as many times as needed. This system allows researchers to easily create and maintain their own monitoring equipment using readily available materials at very low cost.
Neonate capture can be an important part of ungulate research. Systematic grid searching has been the most common method, but it is time consuming and usually requires a large number of people. A variety of methods have been used by wildlife professionals to capture ungulate neonates. We used a Raytheon PalmIR 250 Digital (Raytheon Commercial Infrared, Dallas, Texas) thermal infrared camera during the coolest time of night to search for deer (Odocoileus spp.) neonates in west-central Texas, USA. Using 2 methods (stationary observation and mobile searching), we detected one fawn and captured none. Efficacy of this technology at our study site may have been limited by the lack of a forest canopy and density of shrubs and herbaceous cover on our study site. Ground cover can obscure a bedded fawn, and direct sunlight on bed site habitat can result in false signals. We suggest wildlife professionals consider vegetation parameters, ungulate density, and road quality before purchasing expensive thermal imaging equipment.
Global positioning system (GPS) technology has greatly improved the ability to investigate animal ecology at fine spatial and temporal scales but many GPS telemetry-based investigations may be underutilizing the technical capabilities of modern transmitters. We estimated eastern timber wolf (Canis lycaon) movement distance and territory size using variable GPS transmitter sampling frequencies to evaluate the effect of programming details on estimated movement patterns, territory size, and transmitter performance. Estimated movement distance decreased exponentially as sampling frequency was reduced from 1 location every 5 minutes to 1 location every 24 hours, implying that intense sampling frequencies were required for accurate measurement of fine-scale wolf movements. Wolf territory size estimates using 95% minimum convex polygons declined with decreasing sampling frequency, whereas estimates using adaptive kernel methods were comparable across a range of sampling intensities. Estimated transmitter battery longevity increased as the interval between fixes was lengthened but transmitter efficiency, defined as the number of successful fixes obtained during battery lifespan of the transmitter, was highest with fix intervals of intermediate length. Although GPS transmitters are effective for documenting fine-scale movements of animals, we argue their performance is strongly dependent upon transmitter programming and scale of analysis. Effective use of GPS transmitters will require study-specific assessment of the trade-offs between sampling needs versus transmitter efficiency and longevity.
A major technology break in snake biology was the publication of surgical protocols for implanting radiotransmitters in the body cavities of snakes. While many researchers have reported using some variant of these protocols successfully, protocol details often vary from study to study and best-practice procedures are not easily determinable given the variety of circumstances over which studies occur. Although professional society standards and federal regulations make explicit recommendations about this surgical procedure, some of the nonstandard techniques recommended for this protocol may raise the eyebrows of institutional animal care and use committees. In this commentary we discuss regulatory and logistical aspects of the intracoelmic radiotransmitter implant procedure for snakes, and we provide a pragmatic framework for choosing among surgical variables.
Effects of herbicide use on forest biodiversity was the topic of a special section in the winter 2004 issue of The Wildlife Society Bulletin. In acknowledging public concerns regarding the toxic effects of herbicides, several of the contributing authors argued that these effects are negligible and that intensifying wood production would be beneficial for forest biodiversity and conservation by reducing habitat conversions. We contend there are other important environmental consequences; hence, responding to increased opportunities for selling wood products by augmenting supply through intensifying production should not be the only option. We argue that it is also important to develop mechanisms to reduce the demand for forest products. We believe the focus of the special section was too narrow, particularly with respect to benefiting biodiversity, because herbicide use also intensifies the export of wood products and, thus, nutrients. Other factors that must be considered include soil acidification caused by biomass export and fertilizer application, as well as additional acidification resulting from aerial emissions. In addition, because of mineral cycle dynamics constraints, intensively managed forests may not be sustainable for wood production, and less so for forest-dependent animals. Extensively exploited forests may deplete mineral reserves, and any intensification likely would speed up the declines. We believe the indirect impact from herbicides through accelerating mineral export and loss needs to be addressed, in particular how it may affect mammals' ability to accumulate essential trace elements. We contend using fertilizer applications as a corrective measure at the landscape level would be cost-prohibitive. Thus, heralding that herbicides, a tool to intensify wood production, benefit forest biodiversity appears premature, given the time scale of forest growth and soil development.
The Cougar Management Guidelines—First Edition was reviewed in the Book Review section of The Wildlife Society Bulletin (Anderson 2006). These guidelines were conceived at the Sixth Mountain Lion Workshop held in 2000. Although member agencies of the Western Association of Fish and Wildlife Agencies (WAFWA) commented on drafts of the guidelines, few, if any, of the concerns raised by member agencies were addressed in the final document. The WAFWA recognizes the need to review and improve the management of all wildlife species; however, when comprehensive management guidelines are developed, all stakeholders—particularly the agencies with management authority—must actively be involved. The WAFWA does not endorse or otherwise sanction the Cougar Management Guidelines. The decision to incorporate Guidelines recommendations rests solely with the individual state or provincial wildlife agency.
In 1997 the Mexican federal government implemented a system of wildlife use and conservation units (UMAs [from its name in Spanish]) as a national strategy to promote wildlife management, biodiversity conservation, and rural development in Mexico. We provide a critique of the first 8 years of UMA operations. We argue that UMAs have resulted in increased introduction of exotic species in an attempt to diversify the sport-hunting opportunities and failed to economically benefit local communities. A lack of technical capabilities needed to conduct wildlife population studies and evaluations to assess harvest rates, favoritism in establishing the UMA network, and the lack of institutional regulation have also impacted program success. We propose some solutions that could enhance the performance of UMAs and wildlife management and conservation in Mexico.
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