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1.
Rabies is a widespread zoonotic disease that has reached epizootic proportions in gray foxes (Urocyon cinereoargenteus) in central Texas. Because each species of carnivore has different food preferences and foraging strategies, it is essential that the efficacy of a bait delivery program be examined for gray foxes prior to an oral vaccination program being attempted. Field trials were conducted to determine bait preferences of free-ranging gray foxes to selected baits and odor attractants. Baits consisted of polymer cubes made of either dog food meal or fish meal, and a wax-lard cake that was enhanced with marshmallow flavoring. Attractants added to baits exuded sulfurous, fatty, cheesy, or sweet odors and flavors. During 3,589 operable bait station nights, gray fox visitation and bait uptake rates were 9.2% and 8.3%, respectively. Gray foxes exhibited no preference in bait uptake rates between bait and odor attractant combinations. Gray foxes exhibited no difference in cumulative bait uptake rates between onroad and offroad sites; however, the uptake rate by raccoons was significantly greater for baits placed on roads than for baits randomly placed. Raccoons were the major non-target species competing for baits, being attributed with 73% of the total uptake. Visitation and bait uptake rates by raccoons significantly increased after a 7-day lethal removal of raccoons (n = 37) from the study area. Random distribution of baits is recommended; it reduced bait uptake by non-target species without adversely affecting uptake by gray foxes.  相似文献   

2.
Introduced Rattus norvegicus (Norway rats) caused the decline of Synthliboramphus antiquus (ancient murrelets) and other seabirds breeding on Langara Island (approximately 3,100 ha), British Columbia. Using funds from the litigation settlement following the Nestucca oil spill, Environment Canada eradicated Norway rats using a technique developed in New Zealand which involved dispensing wax baits containing the anticoagulant brodifacoum at 50 ppm from fixed bait stations. Bait stations were placed every 75 to 100 m on a grid over the entire island (1 station/ha). Rats removed bait for 26 days, after which crews placed baits in protective plastic bags in each bait station. Stations loaded with baits were left on the island and rechecked four times over 2 years, after which bait stations and remaining bait were removed. The eradication succeeded. No signs of rats have been detected on Langara Island and its associated islands since January 1996. No rats were trapped during 1,700 trap‐nights following the poison campaign. Incisor marks of rats were not found on apples or oil‐dipped chew‐sticks. Corvus corax (common ravens) likely suffered greater than 50% mortality from the eradication after apparently gaining access to the poison directly from bait stations and from scavenging rat carcasses. A monitoring and response system is being developed in conjunction with current users of the islands. The success on Langara Island demonstrates how the technique proven on small New Zealand islands of less than 300 ha can be effectively extrapolated to much larger islands.  相似文献   

3.
Abstract: Hair-snare sampling has become a popular technique to assess distribution and abundance of felids. Using standard hair-snaring protocols, we sampled for margays (Leopardus wiedii) in Mexico and mountain lions (Puma concolor) in California, USA, without success. However, we noted a preponderance of gray fox (Urocyon cinereoargenteus) hair at sampling stations. Our review of recent literature suggests a pattern of failure to detect target felids in hair-snare surveys conducted within the range of the gray fox. We propose, among several alternative explanations, that marking by gray foxes interferes with the tendency of felids to face-rub at sampling stations.  相似文献   

4.
Abstract

We review ways of individually identifying stoats (Mustela erminea) and similar small mammals from visits to bait stations or to monitoring devices in the field. Tracking devices are the cheapest and most practical method currently available of measuring the presence of a particular species, but there has been little research on the recognition of individuals. Elongation of tracking tunnels, or using sooty plates rather than ink to record prints, may improve detectability of individual markings. Recording visits to bait stations or tracking tunnels from DNA sequencing of hair or skin samples is likely to be prohibitively expensive for many monitoring programmes. Identification of stoats visiting bait stations or tracking tunnels using electronic devices has great potential, but these techniques are impracticably expensive because stoats move over such large areas that individual receivers and data loggers would be needed for each bait station. Chemical bait markers such as rhodamine B may be the most suitable method for identifying which animals have used a particular bait station.  相似文献   

5.
The swift fox Vulpes velox Say, 1823, a small canid native to shortgrass prairie ecosystems of North America, has been the subject of enhanced conservation and research interest because of restricted distribution and low densities. Previous studies have described distributions of the species in the southern Great Plains, but data on density are required to evaluate indices of relative abundance and monitor population trends. We examined regressions of swift fox density (estimated by mark-recapture) on timed-track surveys, scat surveys, and catch-per-unit effort indices. Seventy-nine swift foxes (42 male, 37 female) were captured 151 times during 10 240 trapnights between May 2003 and December 2004 in the Panhandle of Oklahoma, USA. Density estimates, based on mark-recapture data from autumn 2004, were 0.08–0.44 foxes/km2. Survey indices explained 51 to 76% of the variation in estimates of fox density. Our study indicates that surveys of time-to-track encounters and scat deposition rates show promise in monitoring trends in population abundance over large areas.  相似文献   

6.
Anecdotal reports in 2001 suggested that the European Red Fox (Vulpes vulpes) had been deliberately released in Tasmania and thereafter an eradication programme using buried fluoroacetic acid (1080) baits was believed to be a necessary precautionary action until mid‐2013. Prerequisites for the successful eradication of foxes relate to the scale of the undertaking and the ability to collect in situ data such as the distribution and abundance of the target population and measures of the efficacy of the control technique. Previously, 1080 baiting has demonstrated only limited potential as a fox eradication technique on islands when used on a scale between 685 and 2141 times smaller than Tasmania. In the absence of empirical monitoring data confirming the distribution or abundance of extant foxes, buried baiting was targeted to specific landscapes believed to be preferred by foxes. No empirical data was collected concerning the in situ effectiveness of baiting in Tasmania, yet an a priori assumption of lethal efficacy was extrapolated from four heterogeneous mainland studies to suggest that foxes would have only a 0.23 probability of surviving each bait treatment. We show that these studies were unrepresentative of Tasmanian baiting methods used and influenced by imprecise fox population surveys and misreported data. Overall, in the absence of key population monitoring and efficacy data, the ‘precautionary’ baiting strategy adopted did not have a realistic potential to eradicate fox incursions in Tasmania, nor is it an appropriate risk management strategy for other large offshore Australian islands. Contingency plans to counter fox incursions on offshore islands must address the currently inadequate technical capacity to reliably detect and monitor low‐density fox populations, which is an essential component of successful fox eradication.  相似文献   

7.
ABSTRACT Alien rats have impacted native systems worldwide, yet wildlife managers lack techniques to efficiently monitor for rodent invasions where native rodents are present and to control alien rodents sympatric with native rodents. We tested the ability of vertical bait stations to exclude native rodents in the Galapagos Islands, Ecuador. Norway rats (Rattus norvegicus) appeared able to enter all station sizes, whereas black rats (R. rattus) were excluded from larger stations. The endemic rodents Oryzomys bauri and Nesoryzomys narboroughi were unable to enter bait stations of any size, but N. swarthi entered the smallest station. Differences in climbing technique contributed to the advantage of alien rodents over endemic species. Our technique provides wildlife managers in the Galapagos, and potentially other islands with native rodents, a means for early detection and control of alien rats.  相似文献   

8.
In coasts bordering highly productive seas, there can be a flux of resources to the terrestrial ecosystem, and terrestrial carnivores can use marine prey extensively. Two native, endangered species (otter Lontra provocax and culpeo fox Pseudalopex culpaeus lycoides) and two exotic species (mink Neovison vison and grey fox Pseudalopex griseus) inhabit the Beagle coast. The objectives of this paper are: (1) to describe the diet, habitat use and distribution of otters, mink and foxes on the coast of the Beagle channel and (2) to discuss the role of marine resources in the ecological interactions among these species. Diet was determined from the analysis of 245 faeces, and distribution was established from sign surveys. Marine prey occurred in the scats of 98.3, 70.4, 35.5 and 18.2% of otters, mink, culpeo and grey foxes, respectively. Other terrestrial species also use marine resources in Southern Patagonia. All this evidence suggests that the Fueguian coastal channels provide an illuminating example of allochthonous food subsidies from the sea. In the community of four sympatric predators, two native (and endangered) and two exotic, coexistence appears to be facilitated by a renewing marine food subsidy.  相似文献   

9.
Colonies of Reticulitermes spp. were baited with prototype and commercial Sentricon stations (Dow AgroSciences LLC, Indianapolis, IN) to test the efficacy of hexaflumuron in different concentrations and bait matrices and to document reinvasion of the foraging territories vacated by eliminated colonies. Seven colonies of Reticuliternes spp. from two sites were characterized with cuticular hydrocarbon analyses and mark-release-recapture and agonistic behavioral studies. Three colonies were observed as controls and four colonies were baited. When a connection between the bait station and the monitoring station could not be confirmed by mark-release-recapture studies, the results of the baiting were equivocal. The monitoring stations of a colony at our wildland site were devoid of termites 406 d after baiting with one Sentricon station, but became reoccupied with the same species of termites approximately 6 mo after baiting. A colony at the residential site was baited with 0.5% hexaflumuron in the Recurit II bait matrix; 60 d later termites were absent from all monitoring stations. These monitoring stations remained unoccupied for > or = 18 mo. Foraging Reticulitermes spp. appeared in three of the seven monitoring stations 18, 24, and 36 mo after baiting, respectively. Using cuticular hydrocarbon analyses and agonistic behavior studies, we determined that the Reticulitermes spp. occupying these monitoring stations were from three different colonies; none were members of the original colony destroyed by baiting. Another colony at the residential site was baited using a noncommercial, experimental bait; 52 d later termites were absent from all monitoring stations. The monitoring stations remained unoccupied for > or = 9 mo. A different Reticulitermes sp. colony invaded one monitoring station 9 mo after baiting.  相似文献   

10.
Summary In south‐eastern Australia, the introduced Red Fox (Vulpes vulpes) is a major predator of native wildlife and livestock. Fox control in agricultural landscapes is heavily reliant on the laying of poisoned baits by private landholders, yet there have been few assessments of the application or success of landholder‐baiting practices. We evaluated a community‐based fox‐baiting campaign, typical of programs employed throughout the agricultural regions of south‐eastern Australia to control foxes. We recorded the spatial coverage of 1080 baits deployed by landholders, assessed baiting procedures, monitored the survival of six radio‐collared foxes during and after baiting, and compared the spatial coverage and likely effectiveness of the baiting program with two alternative (theoretical) baiting strategies. Relative to other baiting programs, coordination among neighbours was reasonably high, with 37.5% of baited properties (n = 40) adjoining ≥3 neighbouring properties that also contained baits. Nevertheless, the maximum distance from the centre of a baited property to the nearest edge of an unbaited property was <750 m (mean = 380 m ± 147 m SD). On average, 33% (±17% SD) of each fox’s home range overlapped with baited properties, but only two foxes died during the baiting program. The remaining four foxes were still alive 10 weeks after baiting ceased. Modelling of simulated fox home ranges showed that 13.5% contained no bait stations based on the community baiting program, whereas alternative roadside‐ and grid‐baiting strategies (theoretically) delivered baits to all simulated home ranges. Some landholders employed practices that could reduce the effectiveness of baiting programs such as not removing decayed baits before deploying new ones or placing bait stations too close together. Our research illustrates the difficulties of managing a coordinated baiting program on private land that effectively controls foxes. Alternative baiting strategies such as roadside baiting need to be considered to improve fox control in agricultural landscapes.  相似文献   

11.
The status of many carnivore species is a growing concern for wildlife agencies, conservation organizations, and the general public. Historically, kit foxes (Vulpes macrotis) were classified as abundant and distributed in the desert and semi-arid regions of southwestern North America, but is now considered rare throughout its range. Survey methods have been evaluated for kit foxes, but often in populations where abundance is high and there is little consensus on which technique is best to monitor abundance. We conducted a 2-year study to evaluate four survey methods (scat deposition surveys, scent station surveys, spotlight survey, and trapping) for detecting kit foxes and measuring fox abundance. We determined the probability of detection for each method, and examined the correlation between the relative abundance as estimated by each survey method and the known minimum kit fox abundance as determined by radio-collared animals. All surveys were conducted on 15 5-km transects during the 3 biological seasons of the kit fox. Scat deposition surveys had both the highest detection probabilities (p = 0.88) and were most closely related to minimum known fox abundance (r2 = 0.50, P = 0.001). The next best method for kit fox detection was the scent station survey (p = 0.73), which had the second highest correlation to fox abundance (r2 = 0.46, P<0.001). For detecting kit foxes in a low density population we suggest using scat deposition transects during the breeding season. Scat deposition surveys have low costs, resilience to weather, low labor requirements, and pose no risk to the study animals. The breeding season was ideal for monitoring kit fox population size, as detections consisted of the resident population and had the highest detection probabilities. Using appropriate monitoring techniques will be critical for future conservation actions for this rare desert carnivore.  相似文献   

12.
An accurate understanding of harvest trends is required for effective wildlife management. Trapper harvest data represent valuable long-term data for evaluating patterns and trends for wildlife species at broad spatiotemporal scales. Inferring accurate trends from harvest data, however, first requires identifying and controlling for confounding factors that vary independent of abundance. We investigated trends in 43 years of trapper harvest data (1976–2018) from Illinois, USA, for red fox (Vulpes vulpes), gray fox (Urocyon cinereoargenteus), and coyote (Canis latrans) while controlling for factors that may affect trapper effort, including number of effective (i.e., successful) trappers, pelt price, gasoline price, winter unemployment, and winter weather conditions. Annual trapper harvest for red and gray foxes declined and was affected by gasoline price and winter unemployment, whereas annual trapper harvest for coyotes increased and was not strongly affected by other covariates. After adjusting for pelt price, harvest of red foxes was relatively stable, but harvest of gray foxes declined and harvest of coyotes increased. Effects of covariates on harvest per successful trapper varied by species; nevertheless, we detected an increasing trend for coyotes and decreasing trends for gray foxes and red foxes. Concordance across indices for gray foxes and coyotes was consistent with hypothesized declines for gray foxes and increases for coyotes in the midwestern United States. Trends for red foxes varied depending on how we accounted for potential confounding factors and it is unclear if these trends suggest population declines or distribution shifts to urban areas with reduced trapping susceptibility. Our results highlight the importance of understanding sources of variation in harvest data and that their effects can vary across species. © 2020 The Wildlife Society.  相似文献   

13.
This paper describes the design and the preliminary evaluation of an integrated approach to the control of Echinococcus multilocularis in foxes using praziquantel bait. Air distribution of bait in agricultural and recreational areas was combined with distribution of bait by hand in towns and villages to cover the entire fox population in the 213-km2 baiting area. Bait distribution density was 50/km2, and bait was distributed once every 4 weeks. Pre-baiting prevalence was 35% (22–50% CI 95%). During a 1-year period following the first 4 months of bait distribution, only one positive fox was found (prevalence 1%; 0–4% CI 95%). No significant change had occurred in the unbaited control area. This prevalence decline is far more pronounced than in previous fox-baiting studies, which is likely to be due to the increased bait distribution density and baiting frequency, and the inclusion of the ‘urban’ fox population.  相似文献   

14.
Red foxesVulpes vulpes (Linnaeus, 1758) were experimentally removed in two nearby areas located in western Poland to verify the hypothesis about the limiting impact of their predation on the low-density population of brown haresLepus europaeus (Pallas, 1778) (4.4-10.6 ind./km2 in late autumn). In 1996/1997–2001/2002 foxes were culled (mainly in autumn and winter) in the reduction area (32 km2), whereas in the control area (34 km2) intensive culling was carried out only in 2000/2001–2001/2002. Indices of fox and hare spring densities were estimated using spotlight counts, as mean numbers of individuals observed per 10 km of the counting route. Annual changes in the fox density indices were negatively correlated with the bag of foxes, and annual changes in the hare density indices were negatively related to the annual changes in fox density indices. The fox density indices were significantly lower in the reduction area than in the control one only in 2000–2001 (2.8 times, on average), and in the same years, the hare population responded with higher density (1.7 times, on average). The hare responses took place without time delay, which suggests that the changes in fox abundance affected the situation of hares primarily in the autumn-winter season.  相似文献   

15.
The bottom fauna of 5 tributaries of the planned Dobczyce reservoir and the River Raba below the dam was investigated in the preimpoundment period (1983–84). The abundance of macrofauna varied between 46 taxa (Wolnica stream) and 66 taxa (Brzezówka stream). Each station showed individual taxa composition except for the RABA-u and RABA-d (84% similarity). On the basis of 7 different biological indices the stations were divided into 3 categories: unpolluted (Brzezówka), slightly polluted (Bulinka, Trzemésnia and both Raba stations), and moderately polluted (Wolnica). Most sensitive to chemical pollution was the BIOTIC-index. The combination of environmental variables was used to predict biological indices. The most significant relationship (P < 0.01, R 2 = 0.71) was found between the BIOTIC-index and physico-chemical factors. Some problems in the application of indices (sampling, indicator organisms and interpretation of the results) are discussed and local adaptations of methods used are recommended.  相似文献   

16.
《新西兰生态学杂志》2011,19(2):123-130
Percentage non-toxic bait interference is currently used by local authorities to monitor brushtail possum control operations but the validity of the method has not been established. Two models have been proposed to estimate an index of possum density (possums per bait) from a log-transformation of percentage bait interference. In two trials, percentage bait interference and the density index derived from percentage bait interference using the Bamford (1970) model usually increased from night to night. Variation in the number of possums per bait was reduced by dividing the Bamford index by the number of nights baits were put out, as proposed by Jane (1981). The spatial distribution of bait interference along lines of bait stations was random for the first night and usually for at least 5 nights. Rhodomine dye and cyanide poison, alternated at bait stations after at least 5 nights non-toxic baiting, showed that about 83% of possums in one trial and 29% of possums in the other trial interfered with more than one bait on the same night. Increasing the spacing between bait stations reduced the proportion of possums interfering with more than one bait. The number of possums per line killed by cyanide baits after at least 5 nights of non-toxic baiting was strongly correlated with percentage bait interference, with and without logarithmic transformation, on the first night. The possums' apparent ability to remember the location of bait stations from one night to the next means that, in the absence of better advice, the original Bamford (1970) model should be modified as proposed by Jane (1981) to estimate possum density and change in possum density (e.g., from pre- to post-poison).  相似文献   

17.
1. Ants are extremely abundant in lowland tropical forests where they are important predators, plant mutualists, and herbivores. Their complex role in tropical plant–insect food webs can be best assessed by experimental manipulation of their abundance. Historically, ant exclusion experiments have had a small‐scale focus, such as single trees. Here, we test a new ‘whole‐forest' method of ant exclusion, using treated canopy bait stations, in a diverse tropical rainforest in New Guinea. 2. We conducted a 10‐month manipulative experiment in primary and secondary rainforests. In each forest type, a 625 m2 treatment plot was isolated from the surrounding forest and 135 bait stations treated with fipronil, S‐methoprene, and hydramethylnon were placed in trees to suppress ants. Ant activity was monitored in the forest canopy and understorey with an additional 65 stations in treatment and control plots. 3. We achieved a dramatic decline in ant abundance in treatment plots compared with controls in both forest types, with an average decrease in ant numbers per station of 82.4% in primary and 91.2% in secondary forest. In particular, native dominant species Oecophylla smaragdina, Anonychomyrma cf. scrutator in primary forest, and invasive Anoplolepis gracilipes in secondary forest were greatly affected. In contrast, Tapinoma melanocephalum flourished in treatment plots, perhaps benefiting from reduced competition from other ant species. 4. Our study demonstrates that it is possible to selectively eradicate most of the foraging ants in a structurally complex tropical forest. We propose whole‐forest manipulation as a novel tool for studying the role of ants in shaping plant–insect food webs.  相似文献   

18.
Some carnivorous mammals ingest fruit and disperse seeds of forest plant species capable of colonizing disturbed areas in ecosystems. The objective of the present study was to evaluate the dissemination of Arctostaphylos pungens and Juniperus deppeana seeds by the gray fox (Urocyon cinereoargenteus), coyote (Canis latrans), and other carnivores in the Protected Natural Area Sierra Fría, in Aguascalientes, Mexico. Scat collection was undertaken via transects using the direct search method, while the seasonal phenology of A. pungens and J. deppeana was evaluated by recording flower and fruit abundance on both the plant and the surrounding forest floor ground. Seed viability was assessed by optical densitometry via X‐ray and a germination test. It was found that the gray fox, coyote, ringtail (Bassariscus astutus), and bobcat (Lynx rufus) disseminated seeds of A. pungens (212 ± 48.9 seeds/scat) and J. deppeana (23.6 ± 4.9 seeds/scat), since a large proportion of the collected scat of these species contained seeds (28/30 = 93.33%, 12/43 = 27.9%, 6/12 = 50% and 7/25 = 28% respectively). The gray fox, coyote, ringtail, and bobcat presented an average of seed dispersion of both plant species of 185.4 ± 228.7, 4.0 ± 20.0, 12.1 ± 30.4, and 0.8 ± 1.5 per scat; the seed proportions in the gray fox, coyote, ringtail, and bobcat were 89.6/10.4%, 82.3/17.7%, 90.4/9.6%, and 38.1/61.9% for A. pungens and J. deppeana, respectively. The phenology indicated a finding related to the greater abundance of ripe fruit in autumn and winter (p < .01). This coincided with the greater abundance of seeds found in scats during these seasons. Endozoochory and diploendozoochory enhanced the viability and germination of the seeds (p > .05), except in those of A. pungens dispersed by coyote. These results suggest that carnivores, particularly the gray fox, the coyote, and the bobcat, play an important role in forest seed dissemination, and thus forest regeneration, by making both a quantitative and qualitative contribution to the dispersal of the two pioneer species under study.  相似文献   

19.

Neospora caninum, Toxoplasma gondii and Hammondia spp. are coccidian parasites similar in morphology. Molecular techniques are necessary to detect parasite DNA isolated from stool samples in wild canids because they were reported as definitive hosts of N. caninum life cycle. The objective of this study was to develop a highly sensitive and accurate molecular method for the identification of coccidian Apicomplexa parasites in crab-eating fox (Cerdocyon thous) and pampas fox (Lycalopex gymnocercus). Tissue samples from road-killed animals (pampas fox?=?46, crab-eating fox?=?55) and feces (pampas fox?=?84, crab-eating fox?=?2) were collected, and species were diagnosed through molecular assay. PCR was used for the amplification of a fragment of the coccidian Apicomplexa nss-rRNA gene. Additionally, we developed a novel real-time PCR TaqMan? probe approach to detect T. gondii- Hammondia spp. and N. caninum. This is the first report of N. caninum DNA in pampas fox feces (n?=?1), thus it was also detected from pampas fox tissues (n?=?1). Meanwhile, T. gondii was found in tissues of pampas (n?=?1) and crab-eating (n?=?1) foxes and H. triffittae in one crab-eating fox tissue. Despite the low percentage (2.5%) of positive samples, the molecular method developed in this study proved to be highly sensitive and accurate allowing to conduct an extensive monitoring analysis for these parasites in wildlife.

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20.
《Journal of Asia》2014,17(4):717-721
Attract-and-kill bait stations and olive foliage sprayed with insecticidal bait spray and exposed to 0–4 weeks of weather were evaluated for efficacy by olive fruit fly, Bactrocera oleae (Rossi), adult mortality. Mortality in greenhouse cage tests was significantly higher after three days than one day of exposure to non-weathered bait spray on bait stations and foliage, and on bait stations exposed to weather for three weeks. Mortality increased with an increase in insect exposure time, and decreased as bait spray weather exposure increased. Mortality was higher on bait stations than on olive foliage, and treated foliage showed little toxicity after 4 weeks in weather. In a commercial orchard, bait station efficacy was determined by captures of adults on yellow panel traps. Day temperatures were slightly higher on the underside of the station than top from 2 May to 10 July, similar on the top and underside 11 July to 7 August, and slightly lower on the underside from 8 August to 4 September. Fruit length increased from 0.4 on 16 May to 3 cm on 24 September and on 30 May attained 1 cm, the minimum size to produce one adult. No larvae or adults emerged from collected fruit. More adults were captured in an untreated row than a row with bait stations until 22 August and significantly so for the period ending on 11 July. Maximum adult captures occurred during 2 weeks prior to 19 September. Attract-and-kill bait stations would help reduce insecticidal applications and table olive production costs.  相似文献   

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