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1.
Competition between sympatric carnivores has long been of interest to ecologists. Increased understanding of these interactions can be useful for conservation planning. Increased snowmobile traffic on public lands and in habitats used by Canada lynx (Lynx canadensis) remains controversial due to the concern of coyote (Canis latrans) use of snowmobile trails and potential competition with lynx. Determining the variables influencing coyote use of snowmobile trails has been a priority for managers attempting to conserve lynx and their critical habitat. During 2 winters in northwest Wyoming, we backtracked coyotes for 265 km to determine how varying snow characteristics influenced coyote movements; 278 km of random backtracking was conducted simultaneously for comparison. Despite deep snow (>1 m deep), radio-collared coyotes persisted at high elevations (>2,500 m) year-round. All coyotes used snowmobile trails for some portion of their travel. Coyotes used snowmobile trails for 35% of their travel distance (random: 13%) for a mean distance of 149 m (random: 59 m). Coyote use of snowmobile trails increased as snow depth and penetrability off trails increased. Essentially, snow characteristics were most influential on how much time coyotes spent on snowmobile trails. In the early months of winter, snow depth was low, yet the snow column remained dry and the coyotes traveled off trails. As winter progressed and snow depth increased and snow penetrability increased, coyotes spent more travel distance on snowmobile trails. As spring approached, the snow depth remained high but penetrability decreased, hence coyotes traveled less on snowmobile trails because the snow column off trail was more supportive. Additionally, coyotes traveled closer to snowmobile trails than randomly expected and selected shallower snow when traveling off trails. Coyotes also preferred using snowmobile trails to access ungulate kills. Snow compaction from winter recreation influenced coyote movements within an area containing lynx and designated lynx habitat.  相似文献   

2.
Summary We studied sympatric lynx (Lynx canadensis) and coyotes (Canis latrans) to assess how morphological disadvantages to locomotion over snow affected movement patterns. Both species are of similar size and mass, but the feet of lynx are much larger, and coyotes were found to have 4.1–8.8 times the foot-load (ratio of body mass to foot area) of lynx. This resulted in greater mean sinking depths of coyote limbs, although the magnitude of the difference was less than that in foot-load. Coyotes exhibited stronger use of behavioral patterns that reduced negative effects of snow on movements. Coyotes were most abundant at low elevations where snow was shallow, whereas lynx were mostly at higher elevations. Coyotes also used areas at both elevations where snow was shallower than average, while lynx used areas where snow was deeper. further, both species used travel routes where snow was shallower than it was near the track. Coyotes traveled on harder snow and used trails more frequently, thereby tending to reduce sinking depths to those similar to lynx. The behavioral repertoire of coyotes reduced the morphological advantage of large feet possessed by lynx; however, overall sinking depths were still greater in coyotes. Snowshoe hares (Lepus americanus) were the main prey of both species, and their foot-load was less than that of either predator. Hare kills by coyotes occurred after fewer bounds than did those by lynx, and the large difference between foot-loads of both species of predators may have forced coyotes to ambush rather than chase hares, as did lynx.  相似文献   

3.
In the last century, coyotes (Canis latrans) have expanded their range geographically, but have also expanded their use of habitats within currently occupied regions. Because coyotes are not morphologically adapted for travel in deep snow, we studied coyote space use patterns in a deep-snow landscape to examine behavioral adaptations enabling them to use high elevations during winter. We examined the influence of snow depth, snow penetrability, canopy cover, and habitat type, as well as the rates of prey and predator track encounters, on coyote travel distance in high-elevation terrain in northwestern Wyoming, USA. We backtracked 13 radio-collared coyotes for 265.41 km during the winters of 2006–2007 and 2007–2008, and compared habitat use and movement patterns of the actual coyotes with 259.11 km of random travel paths. Coyotes used specific habitats differently than were available on the landscape. Open woodlands were used for the majority of coyote travel distance, followed by mixed conifer, and closed-stand spruce–fir. Prey track encounters peaked in closed-stand, mature Douglas fir, followed by 50- to 150-year-old lodgepole pine stands, and 0- to 40-year-old regeneration lodgepole pine stands. Snowmobile trails had the most variation between use and availability on the landscape (12.0 % use vs. 0.6 % available). Coyotes increased use of habitats with dense canopy cover as snow penetration increased and rates of rodent and red squirrel track encounters increased. Additionally, coyotes spent more time in habitats containing more tracks of ungulates. Conversely, use of habitats with less canopy cover decreased as snow depth increased, and coyotes traveled more directly in habitats with less canopy cover and lower snow penetration, suggesting coyotes used these habitats to travel. Coyotes persisted throughout the winter and effectively used resources despite deep snow conditions in a high-elevation environment.  相似文献   

4.
ABSTRACT Anthropogenic disturbances can promote establishment and growth of predator populations in areas where secondary prey can then become threatened. In this study, we investigated habitat selection of eastern coyotes (Canis latrans), a relatively new predator in the vicinity of an endangered population of caribou (Rangifer tarandus caribou). We hypothesized that coyotes in the boreal forest depend mainly on disturbed habitat, particularly that of anthropogenic origin, because these habitats provide increased food accessibility. Coyotes would likely take advantage of moose (Alces alces) carcasses, berries, and snowshoe hares (Lepus americanus) found in open habitats created by logging. To test these predictions, we described coyote diet and habitat selection at different spatial and temporal levels and then compared resource availability between habitats. To do so, we installed Global Positioning System radiocollars on 23 individual coyotes in the Gaspésie Peninsula, eastern Québec, Canada. Coyotes selected clear-cuts of 5–20 years and avoided mature coniferous forests both at the landscape and home-range levels. Clear-cuts of 5–20 years were found to contain a high availability of moose carcasses and berries, and vulnerability of snowshoe hares is known to increase in clear-cuts. The importance of these 3 food resources was confirmed by the characteristics of core areas used by coyotes and diet analysis. Moose remains were found at 45% of core areas and coyote diet comprised 51% moose on an annual basis. Anthropogenic disturbances in the boreal forest thus seem to benefit coyotes. Our results indicated that the relationship between coyotes and caribou likely involves spillover predation. This knowledge allows managers to consider spillover predation by coyotes as a possible threat for endangered caribou population when the predator depends mainly on habitat of anthropogenic origin and to suggest methods to alleviate it when developing management plans.  相似文献   

5.
ABSTRACT We investigated seasonal patterns in resource selection of Canada lynx (Lynx canadensis) in the northern Rockies (western MT, USA) from 1998 to 2002 based on backtracking in winter (577 km; 10 M, 7 F) and radiotelemetry (630 locations; 16 M, 11 F) in summer. During winter, lynx preferentially foraged in mature, multilayer forests with Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) in the overstory and midstory. Forests used during winter were composed of larger diameter trees with higher horizontal cover, more abundant snowshoe hares (Lepus americanus), and deeper snow compared to random availability; multilayer, spruce-fir forests provided high horizontal cover with tree branching that touched the snow surface. During winter, lynx killed prey at sites with higher horizontal cover than that along foraging paths. Lynx were insensitive to snow depth or penetrability in determining where they killed prey. During summer, lynx broadened their resource use to select younger forests with high horizontal cover, abundant total shrubs, abundant small-diameter trees, and dense saplings, especially spruce-fir saplings. Based on multivariate logistic-regression models, resource selection occurred primarily at a fine spatial scale as was consistent with a sight-hunting predator in dense forests. However, univariate comparisons of patch-level metrics indicated that lynx selected homogenous spruce-fir patches, and avoided recent clear-cuts or other open patches. Given that lynx in Montana exhibit seasonal differences in resource selection, we encourage managers to maintain habitat mosaics. Because winter habitat may be most limiting for lynx, these mosaics should include abundant multistory, mature spruce-fir forests with high horizontal cover that are spatially well-distributed.  相似文献   

6.
Abstract Effectively managing habitat for threatened populations of Canada lynx (Lynx canadensis) requires knowledge of habitat conditions that provide for the ecological needs of lynx. We snow-tracked lynx to identify habitat conditions associated with hunting behavior and predation during winters of 2002–2003 and 2003–2004 in the northern Cascade Range in Washington state, USA. We recorded number and success of predation attempts, prey species killed, and trail sinuosity on 149 km of lynx trails. Lynx killed snowshoe hares (Lepus americanus), red squirrels (Tamiasciurus hudsonicus), and cricetids more than expected in Englemann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) forests, where snowshoe hare densities were highest. Lynx killed prey less than expected in Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) forests and forest openings. We used the sinuosity of lynx trails as an index of quality of habitat hunted. Lynx trails that included predation attempts were more sinuous than trail segments without predation attempts. Lynx trails had greater sinuosity in forest stands with high hare densities dominated by Engelmann spruce and subalpine fir than in stands with low hare densities dominated by Douglas-fir and ponderosa pine or in forest openings. We encourage forest managers to maintain or create sufficient understory cover to support high densities of snowshoe hares as foraging habitat for lynx.  相似文献   

7.
ABSTRACT The roles that diet and prey abundance play in habitat selection of Canada lynx (Lynx canadensis) in the contiguous United States is poorly understood. From 1998–2002, we back-tracked radiocollared lynx (6 F, 9 M) for a distance of 582 km and we located 86 kills in northwestern Montana, USA. Lynx preyed on 7 species that included blue grouse (Dendragapus obscurus), spruce grouse (Canachites canadensis), northern flying squirrel (Glaucomys sabrinus), red squirrel (Tamiasciurus hudsonicus), snowshoe hare (Lepus americanus), least weasel (Mustela nivalis), and white-tailed deer (Odocoileus virginianus). Snowshoe hares (69 kills) accounted for 96% (4-yr average, range = 94–99%) of prey biomass during the sample period. Red squirrels were the second-most-common prey (11 kills), but they only provided 2% biomass of the winter diet. Red squirrels contributed little to the lynx diet despite low hare densities. A logistic regression model of snowshoe hare, red squirrel, and grouse abundance, as indexed by the number of track crossings of use and available lynx back-tracks, was a significant (Wald statistic = 19.03, df = 3, P < 0.001) predictor of habitat use. As we expected, lynx (P < 0.001) selected use-areas with higher snowshoe hare abundance compared to random expectation. However, the red squirrel index had a weak (P = 0.087) negative relationship to lynx use, and grouse was nonsignificant (P = 0.432). Our results indicate that lynx in western Montana prey almost exclusively on snowshoe hares during the winter with little use of alternative prey. Thus, reductions in horizontal cover for hares would degrade lynx habitat.  相似文献   

8.
ABSTRACT

The information content of coyote (Canis latrans) vocalizations is poorly understood, but has important implications for understanding coyote behaviour. Coyotes probably use information present in barks or howls to recognize individuals, but the presence of individually-specific information has not been demonstrated. We found that coyote barks and howls contained individually specific characteristics: discriminant analysis correctly classified barks of five coyotes 69% of the time and howls of six coyotes 83% of the time. We also investigated the stability of vocalization characteristics at multiple distances from the source. Recordings were played back and re-recorded at 10 m, 500 m, and 1,000 m. Vocalization features were measured at each distance and analyzed to determine whether characteristics were stable. Most howl characteristics did not change with distance, and regardless of the distance discriminant analysis was 81% accurate at assigning howls among six individuals. Bark characteristics, however, were less stable and it is unlikely that barks could be used for individual recognition over long distances. The disparate results for the two vocalization types suggest that howls and barks serve separate functions. Howls appear optimized to convey information (i.e. data), while barks seem more suitable for attracting attention and acoustic ranging.  相似文献   

9.
Laura R. Prugh 《Oikos》2005,110(2):253-264
The foraging behavior of predators can have a large influence on community dynamics and has been shown to increase stability in some cases and decrease stability in others. I studied the foraging behavior of coyotes ( Canis latrans ) in the Alaska Range during the peak and decline of a snowshoe hare ( Lepus americanus ) population cycle (1999–2002). Coyote diet was compared with prey availability to test for changes in prey selection and to examine the effect of coyote predation on the vertebrate prey community. Coyotes responded to the hare decline by increasing selection for hares and porcupines, whereas selection for voles, ground squirrels and Dall sheep did not change. Although the study area was characterized by considerable habitat heterogeneity, coyotes utilized the area as a fine-grained environment. Coyote foraging behavior was driven primarily by changes in snowshoe hare abundance, and their sensitivity to change in alternative prey density was low. Predation by coyotes may therefore decrease the stability of alternative prey populations rather than dampening fluctuations. In order for predation to enhance the stability of prey populations, I hypothesize that prey profitability must be determined primarily by abundance.  相似文献   

10.
The establishment of coyote (Canis latrans) populations in urban areas across North America has been accompanied by increased rates of human–coyote conflict. One factor thought to promote physical conflict between coyotes and people or pets is the presence of coyote pups near natal dens; however, this idea has not been tested, and no multivariate study of den selection within cities has occurred. Our objectives were to conduct a multivariate analysis of third- (i.e., home range) and fourth-order (i.e., den sites) habitat selection at dens and determine whether proximity to dens is associated with reports of physical conflict with coyotes. We found 120 dens by following coyote trails using snow tracking within urban green spaces that comprise presumed high-quality habitat for coyotes in Edmonton, Alberta, Canada. We used resource selection functions to assess habitat selection for dens, testing variables related to land cover and anthropogenic features at the third order, and testing microsite habitat features via paired sites at the fourth order. We defined conflict encounters from comments in a community reporting database and used general linear models to assess their spatial proximity to the nearest den and prevalence during the pup-rearing period compared to the rest of the year. Habitat selection was strongest at the fourth order, wherein coyotes selected for abundant hiding cover, steep slopes, and eastern exposure. The prevalence of physical conflict with coyotes increased during the pup-rearing period. Conflict also increased near known dens as an overall effect and when reports occurred outside of naturalized urban areas. These results suggest that coyotes in Edmonton den in green spaces near human development in microsites that minimize detection by people via steep slopes and dense vegetation. We suggest urban wildlife managers increase public safety education about recognition of coyote denning habitat and coyote defensive behaviors, especially outside of naturalized urban areas, because of the observed increase in physical conflict near dens.  相似文献   

11.
Expansion of the coyote’s (Canis latrans) distribution in North America has included most urban areas. Concerns for human safety have resulted in the need to understand the spatial relationship between humans and coyotes in urban landscapes. We examined the space use of coyotes with varying degrees of urban development in the Chicago metropolitan area, IL, USA, between March 2000 and December 2002. We compared home-range size, land use, and habitat use of 41 radio-collared coyotes (5 coyotes residing in developed areas, 29 in less-developed areas, and 7 in a matrix of developed and less-developed areas). The partitioning of coyotes into groups based on their level of exposure to urban development allowed us to examine if differences in use of land types by coyotes was evident in our study area. Coyotes in developed areas had home ranges twice the size of animals in less-developed areas. Nonurban habitats were used by all coyotes in the study area, while urban land was avoided. Coyotes in developed areas had large home ranges and high amounts of urban land in their range, but preferred nonurban habitat. This required the coyotes to travel through a matrix of urban land, thus encountering human activity and possibly increasing the risk of conflict with humans. However, coyotes in developed areas avoided crepuscular times when human activity was highest, suggesting that coyotes in developed areas may reduce conflicts with humans by traveling through the matrix of urban land late at night when the risk of contact with humans is lowest. Coyotes in less-developed areas were less affected by human activity at night and likely posed less risk to humans.  相似文献   

12.
Coyote (Canis latrans) spatial and social ecology are variable, but have been little studied in high-elevation environments. In these temperate ecosystems, large ungulates are prevalent and coyote pack size may be large in order for them to scavenge and defend ungulate carcasses from conspecifics in neighboring packs. We initiated a study to understand the spatial and social ecology of coyotes on the Valles Caldera National Preserve, a high-elevation (2450–3400 m) protected area in northern New Mexico. Our objectives were to (1) describe the home range size and habitat use of coyotes in the preserve, (2) describe coyote movements within and outside of packs, and (3) to evaluate the relationship between coyote social cohesion and the amount of elk (Cervus elaphus) in the coyote diet. We acquired global positioning system and telemetry locations from 33 coyotes from August 2005 to July 2009. We classified 23 coyotes (70 % of individuals) as residents (i.e., territorial) during at least part of the study and ten coyotes (30 %) as transients. Overall mean home range size of resident packs was 10.6 ± 2.2 (SD) km2. Home range size varied between packs, but did not vary by season or year. Coyotes used dry and wet meadow habitats as expected based on availability; coyotes used riparian habitat more than expected, and forests less than expected. Social cohesion did not vary among biological seasons. Alpha coyotes were more socially cohesive with each other than with other pack members, and a transient exhibited temporal–spatial avoidance of pack members while inside the pack’s territory followed by integration into the pack. Contrary to expectations, we found no relationship between coyote social cohesion and the proportion of elk in coyote diets. We concluded that coyote space use and sociality on the preserve were relatively stable year-round despite changes in biological needs, snow depth, and utilization of variously sized prey.  相似文献   

13.
Coyotes (Canis latrans) may affect adult and neonate white-tailed deer (Odocoileus virginianus) survival and have been implicated as a contributor to the decline of deer populations. Additionally, coyote diet composition is influenced by prey availability, season, and region. Because coyote movement and diet vary by region, local data are important to understand coyote population dynamics and their impact on prey species. In southeast Minnesota, we investigated the effect of coyotes on white-tailed deer populations by documenting movement rates, distances moved, and habitats searched by coyotes during fawning and nonfawning periods. Additionally, we determined survival, cause-specific mortality, and seasonal diet composition of coyotes. From 2001 to 2003, we captured and radiocollared 30 coyotes. Per-hour rate of movement averaged 0.87 km and was greater (P = 0.046) during the fawning (1.07 km) than the nonfawning period (0.80 km); areas searched were similar (P = 0.175) between seasons. Coyote habitat use differed during both seasons; habitats were not used in proportion to their availability (P < 0.001). Croplands were used more (P < 0.001) than their proportional availability during both seasons. Use of grasslands was greater during the fawning period (P = 0.030), whereas use of cropland was greater in the nonfawning period (P < 0.001). We collected 66 fecal samples during the nonfawning period; coyote diets were primarily composed of Microtus spp. (65.2%), and consumption of deer was 9.1%. During the study, 19 coyotes died; annual survival rate range was 0.33–0.41, which was low compared with other studies. Consumption of deer was low and coyotes searched open areas (i.e., cropland) more than fawning areas with dense cover. These factors in addition to high coyote mortality suggested that coyote predation was not likely limiting white-tailed deer populations in southeast Minnesota. © 2011 The Wildlife Society.  相似文献   

14.
Prior to 1900, coyotes (Canis latrans) were restricted to the western and central regions of North America, but by the early 2000s, coyotes became ubiquitous throughout the eastern United States. Information regarding morphological and genetic structure of coyote populations in the southeastern United States is limited, and where data exist, they are rarely compared to those from other regions of North America. We assessed geographic patterns in morphology and genetics of coyotes with special consideration of coyotes in the southeastern United States. Mean body mass of coyote populations increased along a west‐to‐east gradient, with southeastern coyotes being intermediate to western and northeastern coyotes. Similarly, principal component analysis of body mass and linear body measurements suggested that southeastern coyotes were intermediate to western and northeastern coyotes in body size but exhibited shorter tails and ears from other populations. Genetic analyses indicated that southeastern coyotes represented a distinct genetic cluster that differentiated strongly from western and northeastern coyotes. We postulate that southeastern coyotes experienced lower immigration from western populations than did northeastern coyotes, and over time, genetically diverged from both western and northeastern populations. Coyotes colonizing eastern North America experienced different selective pressures than did stable populations in the core range, and we offer that the larger body size of eastern coyotes reflects an adaptation that improved dispersal capabilities of individuals in the expanding range.  相似文献   

15.
ABSTRACT Snowshoe hares (Lepus americanus) are an important prey species for Canada lynx (Lynx canadensis) and are considered critical for lynx population persistence. Determination of snowshoe hare distribution and abundance is needed by land management agencies for lynx conservation. An accepted approach for estimating snowshoe hare abundance is the use of fecal-pellet plot counts. Locally derived regression equations are preferred for accurate calibration of pellet counts to snowshoe hare density due to local differences in pellet deposition and decomposition. We used linear regression to examine correlations between snowshoe hare density, as determined by mark–recapture estimates, and pellet plot counts on both uncleared plots and annually cleared plots on the Bridger-Teton National Forest, western Wyoming, USA. We found significant correlations between snowshoe hare density estimates and fecal pellet counts for both uncleared and annually cleared pellet counts; however, the relationship was stronger (higher r) when using pellet counts from annually cleared plots. In addition, we found that adjusting the buffer size by omitting hard habitat edges (not used by hares) around trapping grids improved correlations between snowshoe hare density and fecal pellet counts for both uncleared plots and annually cleared plots. Though precision is sacrificed when using uncleared plots, they may be useful as a coarse index of habitat use by snowshoe hares. Our derived regression equations may be useful to identify important foraging habitat for Canada lynx in western Wyoming. Land managers responsible for conserving snowshoe hare habitat in western Wyoming may use these equations to monitor changes in hare populations among habitats and during prescribed management actions.  相似文献   

16.
Abstract: We related winter habitat selection by Canada lynx (Lynx canadensis), relative abundance of snowshoe hares (Lepus americanus), and understory stem densities to evaluate whether lynx select stands with the greatest snowshoe hare densities or the greatest prey accessibility. Lynx (3 F, 3 M) selected tall (4.4-7.3 m) regenerating clear-cuts (11-26 yr postharvest) and established partially harvested stands (11-21 yr postharvest) and selected against short (3.4-4.3 m) regenerating clear-cuts, recent partially harvested stands (1-10 yr), mature second-growth stands (>40 yr), and roads and their edges (30 m on either side of roads). Lynx selected stands that provided intermediate to high hare density and intermediate cover for hares (i.e., prey access) but exhibited lower relative preference for stand types with highest hare densities where coniferous saplings exceeded 14,000 stems/ha.  相似文献   

17.
The Canada lynx (Lynx canadensis) and the bobcat (Lynx rufus) are closely related species with overlap at their range peripheries, but the factors that limit each species and the interactions between them are not well understood. Habitat selection is a hierarchical process, in which selection at higher orders (geographic range, home range) may constrain selection at lower orders (within the home range). Habitat selection at a very fine scale within the home range has been less studied for both lynx and bobcat compared to selection at broader spatiotemporal scales. To compare this fourth‐order habitat selection by the two species in an area of sympatry, we tracked lynx and bobcat during the winters of 2017 and 2018 on the north shore of Lake Huron, Ontario. We found that both lynx and bobcat selected shallower snow, higher snowshoe hare abundance, and higher amounts of coniferous forest at the fourth order. However, the two species were spatially segregated at the second order, and lynx were found in areas with deeper snow, more snowshoe hare, and more coniferous forest. Taken together, our findings demonstrate that the lynx and bobcat select different resources at the second order, assorting along an environmental gradient in the study area, and that competition is unlikely to be occurring between the two species at finer scales.  相似文献   

18.
Contemporary evolution through human‐induced hybridization occurs throughout the taxonomic range. Formerly allopatric species appear especially susceptible to hybridization. Consequently, hybridization is expected to be more common in regions with recent sympatry owing to human activity than in areas of historical range overlap. Coyotes ( Canis latrans) and gray wolves ( C. lupus) are historically sympatric in western North America. Following European settlement gray wolf range contracted, whereas coyote range expanded to include eastern North America. Furthermore, wolves with New World (NW) mitochondrial DNA (mtDNA) haplotypes now extend from Manitoba to Québec in Canada and hybridize with gray wolves and coyotes. Using mtDNA and 12 microsatellite markers, we evaluated levels of wolf‐coyote hybridization in regions where coyotes were present (the Canadian Prairies, n = 109 samples) and absent historically (Québec, n = 154). Wolves with NW mtDNA extended from central Saskatchewan (51°N, 69°W) to northeastern Québec (54°N, 108°W). On the Prairies, 6.3% of coyotes and 9.2% of wolves had genetic profiles suggesting wolf‐coyote hybridization. In contrast, 12.6% of coyotes and 37.4% of wolves in Québec had profiles indicating hybrid origin. Wolves with NW and Old World ( C. lupus) mtDNA appear to form integrated populations in both regions. Our results suggest that hybridization is more frequent in historically allopatric populations. Range shifts, now expected across taxa following climate change and other human influence on the environment, might therefore promote contemporary evolution by hybridization.  相似文献   

19.
Coyotes (Canis latrans) have colonized northeastern North America only within the past 10-80 yr. We examined feces of coyotes in 2000-01 at three sites in New York (USA) to survey parasites in the region. Two cestodes, nine nematodes, five protozoa, one trematode, and two arthropods were identified from 145 coyote fecal samples. Parasite component community diversity was higher (n = 16 species) in southern New York than in middle and northern sites (nine species each) and infracommunity species richness was greater in southern New York than at the other sites. These differences may reflect the variable diets of coyotes, as well as recent colonization of the region and the mixing of component communities from expanding coyote populations.  相似文献   

20.
Coyote (Canis latrans) removal programs often are initiated despite the potential population regulatory mechanism of parasitism with increased coyote density. We investigated the effect of intensive, short-term coyote removal on population levels of helminths in juvenile and adult coyotes from western Texas. Coyotes were killed by aerial gunning every 3 mo for 2 yr on two 5,000 ha areas, which reduced the overall coyote density of these areas by about 50%. Two other 5,000 ha areas were used as comparison sites where a limited number of coyotes were killed each season. Densities on comparison sites remained stable throughout the study at a mean +/- 1 SE of 0.14 +/- 0.01 coyotes/km2. Twelve helminth species consisting of seven nematodes (Ancylostoma caninum, Physaloptera rara, Toxascaris leonina, Dirofilaria immitis, Spirocerca lupi, Oslerus osleri, and Capillaria aerophila), three cestodes (Taenia pisiformis, Taenia multiceps, and Mesocestoides sp.), one acanthocephalan (Oncicola canis), and one trematode (Alaria marcianae) were found in 252 coyotes. Of these, A. caninum, P. rara, T. multiceps, T. pisiformis, T. leonina, and S. lupi were common species. Rank-transformed values for the mean abundances of A. caninum and T. multiceps and A. caninum, T. multiceps, and S. lupi were reduced in juvenile and adult coyotes, respectively, from the removal sites compared to respective helminth abundances in similar age class coyotes from comparison sites. Because A. caninum has been suggested as a population regulator of coyotes, a coyote removal program that results in a reduced density of coyotes and at the same time causes a reduced abundance of A. caninum, may in fact negate the regulatory effect that A. caninum has on coyote populations.  相似文献   

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