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As human pressures continue to alter and degrade natural wetlands, alternative habitats such as created wetlands may become increasingly important to wetland-dependent species. Golf-course ponds and impoundments in Florida often are used both to store water for irrigation and to prevent extensive flooding during the rainy season. These semipermanent water bodies also may provide habitat for waterbirds. To determine the habitat value of constructed golf-course ponds to waterbirds, we quantified the abundance and diversity of waterbirds using 183 ponds on 12 courses in southwest Florida from January through April 2001 and 2002. We also quantified vegetation and hydrological features of ponds to determine their correlation with waterbird site selection. We recorded 10,474 birds representing 42 species during the 2-year period. We categorized species into 6 foraging guilds, which we used for analyses and management recommendations. In general, results from this study indicate that golf-course ponds are capable of attracting many species of waterbirds. However, analysis of site preference resulted in a wide range of pond features selected by each foraging guild. This finding coupled with low densities of birds (<2 birds/ha for most species) suggested that the value of golf-course ponds may be enhanced through vegetation and hydrological modifications designed to appeal to specific guilds.
Although golf-course construction significantly alters natural wildlife habitat, the resulting remnant, disturbed, and introduced landscape patches may provide valuable habitat for birds. Considering the current rate of new course construction, the effects of land consumption and habitat alteration on breeding bird communities in coastal South Carolina are of immediate concern. During summer 2000 and 2001, we sampled 24 golf-course landscape units (GCLU) to assess their value to the breeding bird community. We defined a GCLU as the legally owned parcel of land where a golf course was sited, including the course and all associated development (e.g., residential housing). Sample units (n=24) were selected to represent a gradient of GCLUs ranging from low to high landscape alteration and were subjectively classified a priori into 1 of 3 alteration groups (G1 [low], G2 [medium] or G3 [high]). We conducted Analysis of Variance procedures to determine whether estimations of species richness, Neotropical migrant richness, and degree of conservation concern differed across the gradient. We explored relative strengths of associations between landscape structure (landscape composition and spatial configuration) and avian community parameters at 2 spatial scales using stepwise multiple regression techniques. We used simple linear regression to assess the relationship between percent forested area of the GCLU and avian community parameters. Total number of species and number of Neotropical migrant species, as well as degree of conservation concern of the species present, were higher in less-altered GCLUs (F2, 21<14, P<0.05), and were significantly influenced by percent forested area (adj. R2=0.39–0.57). The majority of birds associated with less-developed landscapes were woodland and scrub–shrub breeding species, while urban-breeding species were found primarily in the more-altered landscapes (χ2=440.3, df=6, n=4757, P<0.001). The area of forest and disturbance patches, size variability in managed turfgrass patches, and measures of spatial complexity proved most useful in explaining variability of response variables due to landscape structure (adj. R2=0.57–0.90).
The goal of our study was to determine how golf courses in the desert environment impact the indigenous bird community and, particularly, to see whether golf courses may serve as surrogate riparian habitats for southwestern birds. We compared the avian communities on 5 golf courses in the Albuquerque, New Mexico area (4 traditional and 1 “naturalistic”) to those of 5 paired natural areas that served as reference sites. We surveyed birds using breeding-season point counts over 2 years and measured several habitat characteristics of each site. In agreement with most other studies of urbanization effects, we found that bird abundance was greater on 4 out of 5 golf courses. In contrast to many studies of urban birds, we found that both total species richness and species diversity was higher on the golf courses in 3 out of 5 cases, and indigenous species richness was higher on all 5 of the golf courses. Of the bird species unique to the golf-course communities, 74% were riparian associates. Although they had high numbers of indigenous species, most of the individuals on golf courses were relatively common generalist species. The naturalistic golf course that was dominated by native vegetation had greater indigenous bird species richness, diversity, and abundance when compared to its reference site and all of the other courses. We conclude that golf courses do have the potential to support riparian bird communities but that their conservation potential can be enhanced through the addition of habitat complexity and structure.
The red-headed woodpecker (Melanerpes erythrocephalus) once was a common species in much of the Midwest and eastern North America in oak (Quercus sp.) savanna, farmlands, and other open habitats with trees. This species has experienced a range-wide population decline over the last century that likely is associated with changes in land management within agro-ecosystems and loss of oak savanna. Due to structural similarities with natural habitats used by the species, we expected that golf courses could provide suitable breeding habitat for red-headed woodpeckers. From mid-May to early August 2002 and 2003, we censused red-headed woodpeckers on 100 randomly selected golf courses in northern and central Ohio, measured habitat characteristics at each course and surrounding each active woodpecker nest, and monitored nesting success of breeding pairs. We recorded 158 adult redheaded woodpeckers on 26 of the 100 censused courses. Golf courses used by redheaded woodpeckers contained trees that were 12% larger in diameter and had approximately twice as many hard-mast trees (e.g., oaks, hickories [Carya sp.], American beech [Fagus grandifolia]), standing dead trees (snags), and dead limbs as courses without woodpeckers. Habitat measurements at 49 active nests indicated that nest patches contained roughly twice as many hard-mast trees, snags, and dead limbs as non-nest habitat plots over the entire course. Most nests (67%) were located in dead limbs of live trees, rather than in snags. Of 16 nests monitored on courses, 75% successfully fledged ≥1 young, and this was comparable to 10 nests monitored off courses, for which 80% successfully fledged ≥1 young. Our findings illustrate that highly modified habitats, such as golf courses, could play a valuable role in the conservation of wildlife associated with open, disturbance-maintained woodlands, including the declining red-headed woodpecker.
Burrowing owl (Athene cunicularia) populations are declining in many portions of their range, and lack of suitable nesting burrows is thought to be one reason for observed declines. Burrowing owls are attracted to golf courses because the birds generally nest and forage in short-grass, open areas, yet golf courses seldom have suitable nesting burrows. We examined the efficacy of installing artificial nesting burrows on golf courses as a way to help restore local burrowing owl populations. From 2001–2004 we monitored over 175 natural burrows off golf courses, 14 natural burrows on golf courses, 86 artificial burrows off golf courses, and 130 artificial burrows on golf courses. Owls located and used 8 of the 130 artificial burrows installed on golf courses (4 were used as nests). Owls selected burrows that were closer to existing natural burrows, farther from maintained areas (areas receiving turf maintenance by golf course staff), and farther from sprinkler heads. All 4 of the artificial burrows used as nests successfully fledged young, and annual site fidelity for owls nesting on golf courses was higher than for owls nesting off golf courses. However, annual fecundity of owls nesting on golf courses was lower than that of owls nesting off golf courses. If golf courses have sufficiently large nonmaintained areas and there are nesting owls nearby, course managers potentially can help in restoring local burrowing owl populations by installing artificial nesting burrows on the periphery of the course. However, the low fecundity on golf courses reported here should be more thoroughly examined before artificial burrows are used to attract owls to golf courses.
We surveyed the avian communities of 87 golf courses during the 2002 breeding season to determine whether golf courses provided significant habitat for birds of conservation concern in Virginia. We defined birds of conservation concern as those with breeding priority scores ≥16 in our region, as classified by Partners in Flight (2002). The species richness and relative abundance of birds on golf courses varied widely, but in general, courses supported few birds of conservation concern. We found that a typical course had <7 species of conservation concern at a relative abundance of <2 birds of conservation concern per hectare. This compared unfavorably to richness and relative abundance values found at reference landscapes selected to represent the land that golf courses replaced in this region. Because some golf courses had >3 times as many species of conservation concern as others, we compared the land cover on the richest and most depauperate golf courses in an attempt to explain what attracted birds of conservation concern to some courses but not others. Proportions of forested land within the golf-course boundaries and within 1.5 km of the center of the course were the best predictors of a course's conservation value. Our results suggested that 1) regional planners should not expect typical golf courses to provide more habitat for birds of conservation concern than alternative land uses, including residential or agricultural uses; and 2) designers of golf courses in this region can increase the conservation value of courses by increasing the amount of forested land on the course.
Analysis of reproductive parameters of birds breeding on golf courses can provide valuable insight into the biological effects of the golf-course environment on wildlife. For 6 seasons (1999–2004) we monitored initiation of breeding, inter-nest intervals, clutch size, brood size, and chick condition of eastern bluebirds (Sialia sialis) in North Carolina with ∼150 nestboxes in available nongolf habitat (hayfields, old fields, pastures) and up to 250 on golf courses. Bluebirds nesting on golf courses initiated their first nests an average of 1 day later and laid slightly smaller clutches (4.4 vs. 4.5) than pairs nesting in nongolf habitat. The mean time interval between spring and summer nests was 3.5 days longer for bluebirds on golf courses. Brood size did not differ significantly between golf and nongolf habitat. Nestlings (the shortest-winged chick in each brood) on golf courses were in slightly but significantly poorer condition than those in nongolf habitat. Using 2 independent measures of condition-quality (residuals from a linear regression of mass on wing3, tail symmetry), we found that adults of both sexes breeding on golf courses were similar to those nesting in non-golf habitat. While these adult data do not rule out the possibility that the poorer performance of bluebirds on golf courses was due to settlement of golf courses by inferior birds, they do suggest that a more direct effect is at least as plausible. Similarly, although we cannot rule out direct effects of chemical contamination or human disturbance, the lower abundance of arthropods on golf courses provides a likely mechanism for the slightly poorer performance of bluebirds breeding there.
We assessed adult reproductive and nesting success, and developmental instability, survival, and condition of nestling eastern bluebirds (Sialia sialis) breeding in nest-boxes on and off golf courses. With this information we tested hypotheses predicting that nestboxes on golf-course habitat provided poor nesting and chick-rearing environments due to pesticide pollution or other factors. Contrary to our prediction, nestboxes on golf courses received 28% more bluebird eggs and produced 17% more fledglings than nestboxes on nongolf sites. Individual nests on golf courses appeared to have slightly reduced probabilities of survival during laying and incubation, but we found no depression in the overall Mayfield survival probabilities. Surprisingly, nestling bluebirds raised in golf-course boxes exhibited 39% less fluctuating asymmetry of their tarsus bones, possibly an indicator that nestlings that survived to fledge had been under less stress during development. This may have resulted from stronger selection against asymmetrical nestlings on golf courses, or it may indicate that golf-course nestboxes provide higher-quality habitat for bluebirds. Our results suggest that for this bird species, nestboxes on the golf-course habitat we studied can provide high-quality rearing environments and may serve as population sources. This may not apply to other species, including most birds of conservation concern, which do not nest in protected artificial cavities or forage directly on turfgrass habitat.
Previous work on gradients of human-altered landscapes has identified golf courses as potentially valuable areas for wildlife conservation. We assessed 6 golf courses in and around Oxford, Ohio that were surrounded by varying degrees of land-use intensity and studied bird communities within these courses to identify factors that promote diverse bird assemblages. We used a Geographic Information System (GIS) and aerial photography to estimate percentages of different land-cover types surrounding each course using buffers at scales of 100–1,000 m. We also measured on-site vegetation characteristics within 50 m of the same points used for bird sampling. We used simple linear regressions between each environmental variable and bird community statistics (abundance, species richness, Shannon diversity, and evenness) to determine which variables had the most influence on bird communities. We found that landscapes surrounding golf courses were the most important determinants of bird diversity and on-site variables were relatively unimportant. Specifically, natural land-cover buffers (forests, riparian areas, and open water) promote bird diversity and residential cover reduces diversity, especially in small buffers immediately surrounding courses. Results were similar when we limited the bird data set to Neotropical migrants or to birds with declining population trends.
On 19 August 2002 an infant was fatally injured by a black bear (Ursus americanus) in Fallsburg, New York. Based on the social amplification of risk theory, we anticipated that media coverage of the incident would affect perceived bear-related risk among residents in New York's black bear range. We compared results from a pre-incident mail survey (March 2002; n = 3,000) and a post-incident telephone survey (September 2002; n = 302) of New York residents in the same geographic regions to determine whether perception of personal risk (i.e., the perceived probability of experiencing a threatening encounter with a black bear) had changed as a result of the infant death. Additionally, we performed content analysis of news stories published between 19 August and 19 September 2002 (n = 45) referencing the incident. The proportion of respondents who believed the risk of being threatened by a bear was acceptably low increased after the incident (81% pre-incident vs. 87% post-incident), corresponding with an increase in print media coverage of black bears during the month following the incident. The majority of media coverage noted the rarity of human fatalities caused by black bears. Stability in risk perception may have been reinforced by media coverage that uniformly characterized the risk of a bear attack as extremely low. Alternatively, existing perceptions of black bear-related risk may have been reinforced by the short-term nature of media coverage after the incident. The fatality did not serve as a focus event that motivated stakeholder groups to promote change in wildlife management policy. Additional bear-related fatalities, however, could create the impetus for a change in risk perception via a social amplification of risk. Wildlife managers should be aware of potential media effects on risk perception and recognize the potential for risk communication to improve the congruence between actual and perceived risk.
The natural recolonization of gray wolves (Canis lupus) into parts of their former range in the upper Midwest of the United States has led to wolves establishing territories in semi-agricultural areas containing livestock. As part of a study on wolf–livestock relationships in a northwestern Minnesota agricultural area, we surveyed rural landowners within and outside of wolf range to assess perceptions regarding the risks wolves pose to livestock (mainly cattle). The mean response score for rural landowners to the statement “I think wolves should be allowed to exist in northwest Minnesota” was between neutral and disagree. There was no difference in mean response scores between rural residents living within wolf range and residents living adjacent to but outside of wolf range. The rural residents' mean response score to the statement “Wolves are causing unacceptable levels of damage to northwest Minnesota's livestock industry” was between neutral and agree. Although there was a statistical difference in mean response scores of residents living within wolf range and residents living outside of wolf range, the scores were not substantially different from each other. While landowners felt wolves were a threat to their livelihood, other factors (market fluctuations, laws and government, diseases, extreme weather, flooding) were ranked as greater threats to the agricultural community. Rural residents both within and outside of wolf range harbored similar negative attitudes toward wolves, even though residents outside of wolf range have not had a population of wolves in their area for >100 years, indicating little change in cultural attitudes toward wolves.
In the northeastern United States, most populations of grassland songbirds occur on private lands. However, little information exists about the attitudes of farmers toward habitat management for this guild. To address this information gap, we surveyed 131 dairy farmers in Vermont's Champlain Valley to assess current hayfield management practices and farmers' willingness to adopt more “bird-friendly” practices. Our results showed a clear trend toward earlier and more frequent hayfield cuts. Farmers indicated they have little flexibility to alter the timing of their cuts on most of their land. However, many farmers (49%) indicated a willingness to adopt alternative management practices on at least a small portion of their land. Combined with the fact that many farmers characterized parts of their land as “wasteland,” or economically unproductive land, this result suggests that some leeway exists for increasing songbird habitat quality on at least portions of dairy farms. Although significant differences existed in the amount of land for which farmers were willing to adopt alternative management based on herd size, acreage, and experience, the directionality of these relationships could not be established except tentatively for herd size, in which case it appeared that farmers with smaller herds were more likely to dedicate a greater percentage of their land to alternative management. The results of this study likely have relevance to dairy farms throughout the northerntier dairy states. Given the increasing trend for agricultural land to be converted into housing, we recommend that extension and education efforts target farmers with large hayfield acreages, encouraging the maintenance of high-quality habitat for grassland songbirds.
Bovine tuberculosis (TB) has been discovered in unprecedented levels in Michigan's white-tailed deer (Odocoileus virginianus) herd. Human practices have facilitated the spread of bovine TB in white-tailed deer, and public cooperation is necessary to reduce the spread of the disease. Social data can determine public support for eradication strategies, as well as identify targets and messages for ongoing communication efforts. We conducted a survey of 5 bovine TB-issue stakeholder groups to assess and compare attitudes toward bovine TB-related topics and support for eradication and eradication policies. We also identified knowledge levels and interest in future bovine TB issue communications and preferences for communication sources. Results indicated that stakeholders supported the bovine TB eradication goal, but were less supportive of specific eradication policies. Stakeholders held different beliefs about threats posed by bovine TB, and about the means through which the disease is transmitted; stakeholder groups also had different levels of bovine TB-related knowledge. A strong majority of respondents (89%) were interested in being informed about new bovine TB issue-related information.
Hispanics are a growing segment of the United States population and will be an increasingly important stakeholder in future allocation and management of natural resources, including wildlife. In the United States, Hispanics now are the largest ethnic minority and will remain so over the next 40 years. Texas supports the second-largest Hispanic population in the United States behind California, and it will have a Hispanic majority by 2040. Some analysts predict that this demographic shift will leave us with a less-educated population with smaller incomes and higher levels of poverty—posing not only a social concern but also a challenge for conservation of wildlife resources. Here we identify shared Hispanic cultural characteristics, such as family, socioeconomic factors, and language, and their importance in planning wildlife outreach programs. Recognizing differences among Spanish-speaking cultures is equally important. Knowledge of cultural characteristics will enable wildlife advocates to better expose wildlife issues in a manner receptive by Hispanics. It is in the best interest of wildlife and wildlife professionals to encourage Hispanic participation in this planning process because of their growing political and economic influence.
Mentoring is the process by which one or more senior professionals guide a protégé through the institutional or organizational socialization process. One common misconception is that the benefits of mentoring primarily accrue to the protégé. We suggest that mentors and protégés benefit in numerous dimensions. The benefits of being a mentor include personal satisfaction, social change, building professional capital, career enhancement, and resource development. The benefits of being mentored include career and psychosocial benefits (Kram 1985). Formalized mentoring can be used to increase recruitment and retention, especially for ethnic minorities and women. In addition, mentoring provides an opportunity to transfer cultural and organizational knowledge associated with specific disciplines to developing professionals. We provide guidelines for mentoring relationships during the preparing, negotiating, enabling, and closing phases of mentoring. Finally, we conclude with some strategies for successful matching and managing the mentoring process.
Natural wetland plant foods meet energetic requirements for waterfowl and sandhill cranes (Grus canadensis) if production surpasses foraging efficiency thresholds. Although knowledge of aboveground plant production and migratory bird use are available to estimate carrying capacity on intensively managed moist-soil wetlands, data are lacking regarding production and use of underground plant foods in managed areas. In 1996 and 1997, we determined use of underground foods by mallards (Anas platyrhynchos) and sandhill cranes on moist-soil managed wetlands where mowing, discing, and sustained flooding treatments were tested to enhance chufa (Cyperus esculentus) production. Although there were no differences among treatments in use of belowground foods, within-treatment analyses showed that avian foraging reduced chufa tubers from 17–27% except in the 1996 sustained flooding treatment. Johnson grass (Sorghum halepense) rhizomes were reduced only in the 1997 mowed and sustained flooding treatments, whereas field bindweed (Convolvulus arvensis) rhizomes were consumed only in the 1997 mowed treatment. Based on use levels, a threshold level of about 500 kg/ha of underground foods should be produced before use occurs. However, use of underground foods also may have been related to the amount of aboveground seed available in each treatment. Mallards initially may have been attracted to flooded wetlands with high aboveground seed production leading to subsequent use of underground foods. By ignoring underground wetland foods, carrying capacity for migratory birds using moist-soil managed wetlands may be underestimated.
Although a few isolated incidences of lead shot ingestion have been reported in ring-necked pheasants (Phasianus colchicus) in Great Britain, no studies have investigated the prevalence of shot ingestion in this species. In this study we investigated the extent of lead exposure in ring-necked pheasants on shooting estates in Great Britain from the ingestion of shot and other sources through gizzard examinations and analysis of wing bones.
We examined 437 ring-necked pheasant gizzards collected from birds shot on 32 shooting estates during spring 1996 and 1997 and during the hunting seasons of 1999–2000 and 2001–2002. We determined wing-bone-lead concentrations in 98 female birds collected in 1997. Gizzard examinations showed an overall ingestion incidence rate of 3.0%. We found no differences in ingestion rates among years, seasons, and sexes. Female pheasants had bone-lead levels ranging from 7–445 ppm (x̄ =48.8± 8.8) dry weight. The birds that had lead in their gizzards in 1997 also had high concentrations of lead in their bones. Female pheasant body condition did not decline with the amount of lead in the wing bones. Our data suggest that game managers on shooting estates should be aware that pheasants are vulnerable to shot ingestion and may need to consider measures to reduce this problem in areas where prevalence is high.
The wild turkey (Meleagris gallopavo) repatriation in the United States and Canada has been a major achievement in wildlife management. This success has led to increasing wild turkey populations and calls to wildlife professionals complaining about wild turkeys causing agricultural damage. A mail survey was distributed to state, federal, and provincial agencies that respond to wildlife crop-damage complaints. Survey recipients were asked to report the number of crop-damage complaints and their severity received from farmers, how many of these complaints were investigated and by what means, how often damage was confirmed when investigated, the severity of actual damage observed, and how frequently the damage was caused by other species. We wanted to compare farmers' perceptions of crop-depredation levels to actual damage as observed by experts. We further assessed the number of complaints received, the severity of the damage, and the economic impact relative to specific agricultural crops. Twenty-three different crops were reported as having confirmed damage caused by wild turkeys. In the majority of these cases (93%) damage was reported as light. In 46% of inspected cases, investigators reported most of the damage (76–100%) was caused by another species. Our results provide wildlife managers with an understanding of the nature of crop depredation relative to the wild turkey.
Arthropod abundance commonly is used as an index for brood-habitat quality for northern bobwhite (Colinus virginianus) chicks. However, conventional arthropod sampling techniques may not measure the abundance of arthropods available to chicks. Human-imprinted chicks have been used to jointly measure arthropod abundance and availability; however, no studies have examined potential differences in growth rates and foraging behavior between pen and wild-strain chicks. Likewise, use of internal ligatures has not been tested. We compared growth (g/day) and foraging rates (g/chick/30 minutes) between pen and wild-strain chicks and foraging rates between ligatured and nonligatured chicks. At 9 days post-hatch, pen-strain chicks (LSMEANS=20.315, SE=0.456) weighed more than wild-strain chicks (LSMEANS=17.665, SE=0.556; F1,1013=32.34, P <0.001). Foraging rate did not differ between ligatured (x̄=0.041, SE=0.007) and nonligatured (x̄=0.028, SE=0.004) chicks (t38=−1.69, P=0.100). Pen-strain chicks consumed slightly greater dry biomass than wild-strain chicks, but both consumed similarsized arthropods. Ligatured, commercially produced chicks may serve as a reasonable biological assay for indexing arthropod availability and brood-habitat quality for wild northern bobwhite chicks.
KEYWORDS: Band-tailed Pigeon, Breeding Bird Survey, mineral sites, Patagioenas fasciata, population index, power analysis, route regression, statistical power
There is no formal population survey specifically designed to index population abundance of band-tailed pigeons (Patagioenas fasciata) throughout their range. Data from the Breeding Bird Survey (BBS), Washington and Oregon Mineral-Site (WAORMS) surveys, and Washington Call Count (WACC) survey offer evidence of long-term population decline. We investigated the potential to augment BBS, WACC, and WAORMS surveys to provide more precise population indices for the Pacific Coast band-tailed pigeon (P. f. monilis) and augment the BBS to index the Interior or “Four Corners” population (P. f. fasciata). We calculated statistical power, the probability of detecting population change given that a change exists, and analyzed survey data to investigate the effect of route length, survey repetition, and sample size. Sample sizes of 50 sites or routes yielded corresponding powers of 99% for WAORMS, 54% for WACC, and 30% for Pacific BBS, to detect a 10% annual change over a 5-year period (a = 0.10). Route length and repetition of surveys had little impact on power. Mineral-site surveys provide the greatest potential to monitor breeding populations and detect short-term trends in the Pacific Coast population. New survey techniques are needed for the Interior band-tailed pigeon.
West Nile virus (WNv) has emerged as a new issue in the conservation of native avifauna in North America. Mortality associated with WNv infection decreased survival of female greater sage-grouse (Centrocercus urophasianus) by 25% across 4 populations in Wyoming and Montana, USA, and Alberta, Canada, in 2003. In 2004 WNv spread to populations in Colorado and California, and female survival in late summer was 10% lower at 4 sites with confirmed WNv mortalities (86% survival) than at 8 sites without (96%). We still have no evidence that sage-grouse show resistance to the virus. The 2004 WNv season was not the catastrophe that many had predicted, and the decrease in prevalence of infection and mortality in sage-grouse, humans, and horses (except in California) has left many wondering if the worst has past. Evidence suggests that risk of infection was low in 2004 because unseasonably cool summer temperatures delayed or reduced mosquito production. Moreover, mortalities occurred 2–3 weeks later in 2004 than in 2003, and the shift to later timing was consistent between years at sites where WNv reduced survival both years. Mosquito surveillance data indicated a sharp decline in prevalence and infection rate of adult C. tarsalis in southeast Alberta, the most northern latitude where WNv reduced survival, in 2003 but not in 2004. A full understanding of the implications of WNv for sage-grouse requires a long-term, coordinated monitoring strategy among researchers and a sensitivity analysis to evaluate the role of WNv in population viability. Epidemiological research examining the prevalence and ecology of the virus among reservoir hosts is crucial.
Using a digital camcorder and commercial wireless microphone and receiver components, we developed an acoustic telemetry system for remotely monitoring and recording a variety of sounds generated by 3 desert mule deer (Odocoileus hemionus eremicus) held in an outdoor enclosure. We offered the deer water and several types of feed and obtained 1,500 minutes of audio-visual records of feeding, drinking, and other behaviors. We determined that attaching a microphone to a shaved patch of the animals' cranial region produced more complete and higher-fidelity signals than did collar placement of the microphone. Based on audible sounds alone, 10 briefly trained observers accurately distinguished among deer feeding, drinking, and ear-flapping bouts, and had good to excellent success in identifying 4 foods consumed by the deer. We also undertook preliminary sound signal analysis of deer feeding bouts but concluded that machine classification and enumeration of deer behaviors will require additional development. Our system provided a simple, relatively inexpensive, but powerful means of monitoring detailed foraging behaviors of ungulates at <200 m. It may thereby facilitate and enhance foraging and time budget studies of captive or approachable subjects.
Although contingent valuation (CV) often has been applied in the wildlife management field, the validity of CV remains a concern. This study explored the convergent and predictive validity of CV in a wildlife-related issue and addressed the use of CV in fee-structure decisions by examining estimates of participation and revenue associated with different deer (Odocoileus hemionus) and elk (Cervus canadensis) hunting license fees in Colorado. We examined convergent validity by comparing CV estimates of resident deer and elk hunting license sales to estimates from an analysis of historic license sales. We examined predictive validity by comparing estimates of nonresident deer and elk license sales to actual license sales after a fee increase took place. With respect to convergent validity, elk license sale estimates from the CV and historic analysis showed strong correspondence, but deer license sales from the 2 methods did not show strong convergence. Predictive validity test results showed that the CV model underestimated actual elk license sales at the increased fee by 31% and overestimated deer license sales by 55%. Implications of the results suggest a need for stronger correspondence in context in hunts between the CV scenario and when the fee increase takes place. Also, issues surrounding information provided to respondents in CV studies should be further explored.
Marking-induced abandonment has been suggested as the most common cause of marking-induced mortality of free-ranging, newborn ungulates in North America. However, there has been no direct study of marking-induced abandonment in free-ranging ungulates, and its relevance to neonate survival is inconclusive. We describe our capture, marking, and monitoring of white-tailed deer (Odocoileus virginianus) neonates born to radiocollared dams in north-central Minnesota over 5 springs (1997, 1999–2002), as it relates to marking-induced or natural abandonment. We assumed that all neonates dying within 4 days post-marking were possible occurrences of abandonment. We captured 89 neonates; 6 (7%) died within 4 days (4 to predation, 2 to unknown causes). We found no conclusive evidence of marking-induced abandonment. Handling had no impact on neonate survival, even though nearly 40% of neonates were handled >15 minutes. Time of marking (post-parturition) was similar among survivors and nonsurvivors; 48% of surviving neonates were captured <24 hours after birth. Eleven neonates (12%) were chased prior to capture, and all survived >4 days post-capture. Hematology, serum indices of nutritional restriction, and body fat content of dams were similar among all neonates. Dams of nonsurviving fawns were older than dams of survivors (8.5 ± 2.1 vs. 5.6 ± 0.4 years). Neonates traveled a mean distance of 162 ± 8 m from their capture site <4 days post-marking, and 76% of all radiocollared dam locations (n = 245) were <200 m from their neonates. Mean distance traveled between capture and mortality sites for nonsur-vivors (159 ± 69 m, n = 6) was similar to mean travel distance of the surviving, radio-tracked neonates (162 ± 8 m, n = 18) within 4 days post-marking. Our findings suggest that risk of marking-induced abandonment in white-tailed neonates is minimal; thus, omission or censoring of suspected cases of marking-induced abandonment in white-tailed neonate survival studies may underestimate natural mortality rates.
Population estimates of white-tailed deer (Odocoileus virginianus) are critical to advancing the process of community-based deer management. One of the first questions raised by residents of suburban areas is “How many deer live in our community?” Our objective was to evaluate the reliability and cost of helicopter-mounted Forward-Looking Infrared (FLIR) in detecting and counting a suburban white-tailed deer population as compared to road counts. We conducted 4 separate road counts 1 hour prior to sunset between June 2001–January 2002. The average number of deer counted based on road counts was 229 (SE = 10.04). We conducted 3 separate flights using a helicopter-mounted FLIR between 2000–2330 hours on 9 January 2002. The average number of deer counted using FLIR was 214 (SE = 18.7). Both population survey methods yielded similar results (P = 0.46). We recommend using FLIR in suburban areas dominated by private property where ground access or site distances may be limited, or where conducting a road count at a slow rate of speed may cause traffic congestion.
In response to apparent declining mule deer (Odocoileus hemionus) numbers in Colorado during the 1990s, buck harvest limitations were identified as a possible mechanism to increase fawn:doe ratios and hence population productivity. Beginning in 1991, the Colorado Division of Wildlife (CDOW) reduced buck harvest in 4 deer management units to provide quality hunting opportunities. We examined effects of limited harvest on December ratios of bucks:100 does and fawns:100 does using data from limited and unlimited harvest units. Annual buck harvest was reduced by 359 bucks (SE = 133) in limited harvest units as a result of limiting licenses. Fawn:doe ratios declined by 7.51 fawns:100 does (SE = 2.50), total buck:doe ratios increased by 4.52 bucks:100 does (SE = 1.40), and adult buck:doe ratios increased by 3.37 bucks:100 does (SE = 1.04) in response to limited harvest. Based on our analysis, factors other than buck harvest were regulating population productivity, and limiting buck harvest to enhance fawn recruitment is not justified in Colorado. Limited buck harvest should be considered an issue of quality hunting opportunity rather than deer productivity.
Biologists commonly use tooth eruption and wear patterns or cementum annuli techniques to estimate age of ungulates. However, in some situations the accuracy or sampling procedures of either approach are undesirable. We investigated the progression of several quantitative measures of wear with age, using permanent first incisors from Yellowstone bison (Bison bison), and tested for differences between sexes and herds. We further investigated the relationship of wear and age to explore an age-estimation method. Labial-lingual width (LLW) correlated best with assigned age (r2=0.66, males; r2=0.76 females). Labial-lingual width differed between sexes, with females showing ∼0.2 mm more wear than males. Additionally, differences in rate of wear existed between bison of the northern and central Yellowstone herds (1.2 and 0.9 mm/year, respectively). We developed a regression formula to test the power of LLW as an estimator of Yellowstone bison age. Our method provided estimated ages within 1 year of the assigned age 73% and 82% of the time for female and male bison, respectively.
Improved understanding of the margins of safe capture, chemical immobilization, and handling of free-ranging animals for research and management relies on the documentation and examination of efforts involving various species, study designs, and environmental conditions. During 1991–2002 we had 984 captures and recaptures of white-tailed deer (Odocoileus virginianus), primarily by Clover trap, under a wide range of winter weather conditions and in an area saturated with wolves (Canis lupus). We captured and recaptured 337 radiocollared females (0.5–15.5 years old) 652 times. Total capture-related mortality was 5.4% (35 of 652). The incidence of capture accidents (e.g., trauma-induced paralysis, death) was 2.9%, and mortality that occurred within 14 days of release was 2.5%. Mean time to mortality for this latter group was 6 days (SE = 1.1 days, n = 16); wolf predation within 11 days was the proximate cause of 50% of these mortalities. A priori, we selected immobilization time for analysis by logistic regression to test for a potential effect of capture and handling on mortality while controlling for known risk factors (age, winter severity) but found no significant effects. Additionally, subsequent comparisons of means and standard errors (SEs) showed no differences among numerous aspects of the capture, immobilization, handling, or associated weather conditions. Success in capture and handling of free-ranging deer results in smaller sample sizes of capture-related deaths (i.e., events), which makes it difficult to infer causal relations between environmental variables, handling procedures, and capture-related mortality. The strength of such studies is that they may serve to demonstrate a range of conditions (environmental variables and handling procedures) over which capture-related mortality can be controlled at acceptably low levels.
The number of helicopter flights used to gain access to backcountry has increased in recent years. Biologists, land managers, and the public have expressed concern about disturbance impacts to mountain goats (Oreamnos americanus) resulting from helicopter activity. We recorded behavioral responses of 122 groups of mountain goats from 347 helicopter overflights at 4 geographic areas in Alaska and analyzed responses in relation to distance and angle from helicopters to mountain goats, reproductive class, season, and area of study. We used multinomial logistic regression modeling combined with a bootstrap randomization procedure to identify factors associated with increased probability of mountain goats being in 1 of the 4 behavioral response categories during helicopter overflights. The probability of a goat group being disturbed was inversely related to distance of the helicopter from the group. Odds of disturbance increased by a factor of 1.25 for every 100-m reduction in approach distance. Approach distances resulting in >90% probability of maintenance were significantly larger where mountain goats had received less prior exposure to helicopters. When mountain goats were disturbed during overflights, a second analysis (i.e., gamma regression model with inverse link function) estimated elapsed time until mountain goats returned to maintenance behavior. The length of time that a goat remained in a disturbed state following overflight did not depend upon any of the covariates; mountain goats remained in a disturbed state for an average of 30.7 seconds (95% CI, 25.7–35.9 seconds). The results offer land managers an opportunity to evaluate risk for permitting helicopter activity.
Habitat for cavity-nesting wildlife is closely tied to the availability of standing dead trees (snags). Large snags (>40 cm dbh) are particularly important because they provide cavity-excavation substrate for both large and small cavity excavators. Historically in the southern United States, common belief has been that the utility of pine (Pinus spp.) snags for cavity nesters occurs for only a short period of time after tree death because pine snags quickly decay and fall to the ground. We studied the deterioration rate and ultimate falling of large pine snags in eastern Texas over a 20-year period (1983–2003). Coinciding with our annual checks of red-cockaded woodpecker (Picoides borealis) cavity-tree clusters, we checked the status and height of all red-cockaded woodpecker cavity trees that died. We determined the cause of death and tree species of 136 cavity tree snags (x̄=25.4 m at death) and monitored their height annually until they were <1 m in height. Five years after tree death, 92 snags (67.6%) were still standing and averaged 13.9 m in height. Ten years after tree death, 21 snags (15.4%) were still standing and averaged 10.0 m in height. After 15 years 4 snags (2.9%) averaging 5.3 m in height still remained standing. Two snags (1.5%), averaging 2.7 m in height, survived through 19 years but had fallen by the end of the twentieth year. Pines dying from wind snap at mid-bole survived longer as snags (x̄=9.7 years) than pines killed by bark-beetles (Dendroctonus spp.) (x̄= 5.9 years). Longleaf pine (Pinus palustris) snags remained standing longer (x̄=8.0 years) than loblolly pine (P. taeda) snags (x̄=6.0 years) (P<0.05), but not longer (P>0.05) than shortleaf pine (P. echinata) snags (x̄=6.6 years).
The increased use of radiotelemetry for studying movement, resource selection, and population demographics in reptiles necessitates closer examination of the assumption that radiotransmitter attachment does not bias study results. We determined the effects of radiotransmitter attachment on fecal glucocorticoid metabolite levels of wild three-toed box turtles (Terrapene carolina triunguis) in captivity. During May 2002 we captured 11 adult three-toed box turtles in central Missouri. We housed turtles in individual pens in a semi-natural outdoor setting. We radiotagged 6 turtles, and the remaining 5 turtles served as controls. We captured and handled all turtles similarly during treatments. We collected feces daily prior to attachment (14 June–05 July 2002), while transmitters were attached (06 July–02 August 2002), and after transmitters were removed (03 August–24 August 2002). We conducted a standard assay validation and found that the assay accurately and precisely quantified fecal glucocorticoid metabolites of box turtles. We did not find a significant effect of radiotransmitter attachment on fecal glucocorticoid metabolite levels of three-toed box turtles (F1,9=0.404, P = 0.541). Fecal glucocorticoid metabolite levels of control and treatment turtles increased significantly during the study (F2,166 =7.874, P = 0.001), but there was no treatment:period interaction (F2, 166 = 0.856, P = 0.427). Additionally, we did not find a significant relationship between glucocorticoid metabolite levels and time in captivity (r2 = 0.01, F1,179 = 2.89, P = 0.091) or maximum daily temperature (r2<0.01, F1,179 = 0.301, P = 0.584). Our results suggested that radiotransmitter attachment did not significantly increase fecal glucocorticoid metabolite levels in adult three-toed box turtles; however, we conducted our study in captivity and sample sizes were small. Thus, more research is needed to assess potential effects of radiotransmitters on turtles in the wild. We believe this study is the first to validate the use of fecal glucocorticoid metabolite measures for reptiles, which might prove useful in other research studies.
Introduced coypu (Myocastor coypus) damage crops and natural vegetation and undermine riverbanks. We controlled coypu with cage traps to protect vegetation in 3 wetlands in the Park of the Rivers Po and Orba (northwestern Italy). During a 3-year trial, coypu were controlled in the Natural Reserve of Valenza (NRV), an area with a low degree of colonization, but not in one with a high immigration rate. In NRV park wardens were involved for 18 man-days of work annually, and the cost was 1,518 Euros (1,867 U.S. dollars) per year. From 2001 a control program was carried on in the 3 areas. Removal densities (0.06–1.3 animal/ha) suggested that 2 trapping periods annually were adequate to slow down coypu population increase. The recovery of yellow waterlily (Nuphar lutea) in 3 plots and colonization of new ponds by vegetation indicated that coypu were maintained at a level sustainable for vegetation development.
To recapture trap-shy Eurasian lynx (Lynx lynx) in Switzerland, we developed a selective and minimally invasive capture system (MICS). The device consists of a blowgun remotely controlled by means of 2 built-in cameras and a swiveling 2-way pan-tilt head. The blowgun is monitored and triggered from a distance of up to 400 m and is capable of shooting darts with high accuracy at distances of about 12 m. We darted lynx at kill sites, but the system generally can be used in any situation where a medium to large mammal stands still for a moment at a predictable distance. The MICS allows selection of specific individuals, thereby avoiding capture of nontarget animals. As there is no holding device, risk of injuries due to capture is minimized. Preliminary data on hematology and serum cortisol levels furthermore indicated that captures with the MICS induced less stress than captures with either box traps or foot-snares. We believe this new system opens new possibilities to capture cautious animals and provides considerable progress regarding animal welfare considerations.
Density of wildlife populations is a key variable for management, yet reliable estimation is elusive. We tested one established method (trapping webs and distance analysis) and one novel method (inverse prediction from capture–recapture data) on a population of brushtail possums (Trichosurus vulpecula) whose density also could be determined by exhaustive removal. The study area was approximately 315 ha of coastal plantation forest surrounded on 3 sides by sand and water. We placed 4 lines of 9 cage traps at 20-m spacing in a square to form a “hollow grid.” We set 5 hollow grids, each comprising 36 traps, for 5 days; we tagged and released possums. We later set 5 trapping webs of 50 traps each at the same sites; we caught possums and removed them over 4 days. Wide-area removal used a combination of acute poisoning and leghold trapping. The estimate of density by inverse prediction (1.88/ha, SE = 0.26) was consistent with the removal estimate (2.27/ha), whereas estimates from trapping webs were positively biased (6.5 to 8.0/ha, depending on method of analysis). The inverse prediction method frees capture–recapture from the straitjacket of conventional grids and should allow accurate landscape-scale estimation of density once the requisite trapping effort is identified.
We evaluated the economic impact of restricting white-tailed (Odocoileus virginianus) buck harvest opportunity to lease hunting groups. We identified 3 similar-sized (655-675-ha) contiguous tracts with visually similar deer hunting quality on a Love County, Oklahoma ranch. Hunting leases were offered on each tract through a sealed bid process. We assigned the state (S), moderate (M), and conservative (C) tracts annual buck harvest limits of 12, 5, and 3, respectively. Other aspects of the leases (term, doe deer and other game harvest opportunity, number of participants, etc.) were identical. We required interested parties to submit a bid on all of the tracts. Thus, each bidder served as a replicate. We analyzed 16 bids and observed a significant difference among tracts (F2, 15 =33.18, P=0.035). Mean bids per hectare for S ($3.24) and M ($3.29) were not different, but the mean bid for C ($2.77) was significantly lower. No lease value was lost by implementing a moderately conservative buck harvest limit under these conditions.
We compared the utility of vaginal implant transmitters (VITs) and field searches for locating elk (Cervus elaphus) calves in southeastern Kentucky during the spring of 2001. Retention of VITs among 40 adult females ranged from 1–276 days (x̄=61.6±8.4 [SE] days). Approximately half of the transmitters (n=19) were expelled prematurely or malfunctioned. Two of 37 (5%) transmitters in translocated females performed as designed and led to calf capture. We captured more calves (n=9 in 2001; n=16 in 2002) by searching areas where elk exhibited parturition behavior. We suggest that manufacturers refine the current VIT design to increase its application and cost-effectiveness.
Passive and active infrared camera systems and, more recently, videography have been used in wildlife research to assist in data collection. Traditional camera systems can be expensive and labor-intensive, and are limited in operation time by film length and battery life. Current camera systems are neither computer- nor network-oriented and do not allow for near real-time retrieval and storage of data. We describe a web-based, digital camera system for monitoring wildlife in remote, inaccessible environments. Between February 2002 and December 2003, our web-based camera system collected 486 digital photographs of west Texas wildlife. The key advantage of our camera system is that it allows for unobtrusive monitoring of secretive and often unobservable species in their natural habitat. Because our system is web-based, high-resolution photographs of wildlife can be posted on a web page for viewing, offering a unique teaching tool for grade school and university students who may not have the opportunity to visit these remote, inaccessible areas. Although our camera system was expensive ($12,000 U.S.), it offers a self-sustaining technique for monitoring wildlife in remote regions that allows for easy data retrieval and storage.
Use of genetic marks to identify individuals and generate population estimates using mark–recapture methodologies has become increasingly common. Recently, brown bear (Ursus arctos) population estimates have been made using DNA isolated from hair follicles as the mark, obtaining hair with a barbed-wire enclosure around a scent lure. While this method has been successfully used in low-density populations, it would be difficult to use in areas with dense concentrations of bears because of the high probability of collecting hair from multiple bears at a single site during a single trap session. We designed and evaluated a single-catch snare to collect bear hair in a dense brown bear population during late summer. We hung snares, modeled after a wolf (Canis lupus) neck snare, on bear trails along streams where bears congregated to feed on spawning salmon (Oncorhynchus spp.). During 2 years 1,000 snares were tripped and 455 contained bear hair. We determined genotypes from 309 hair samples collected. Our single-catch hair snares successfully captured hair, usually with visible follicles, from many bears without using a lure. Our snares were quick and easy to set, so we could replace snares containing hair in the field and remove hair later in a clean area to avoid contamination. Additionally, we could easily move snares, so we could place many snares over a single reach of stream or on several streams.
Capture–recapture methods are widely used to estimate population parameters of free-ranging animals. Closed-population capture-recapture models, which assume there are no additions to or losses from the population over the period of study (i.e., the closure assumption), are preferred for population estimation over the open-population models, which do not assume closure, because heterogeneity in detection probabilities can be accounted for and this improves estimates. In this paper we introduce CloseTest, a new Microsoft® Windows-based program that computes the Otis et al. (1978) and Stanley and Burnham (1999) closure tests for capture–recapture data sets. Information on CloseTest features and where to obtain the program are provided.
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