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1.
Dispersal away from the release site is among the main obstacles that reduce translocation success. Scientists should therefore test a variety of translocation methods to reduce dispersal when moving wildlife between sites. The objective of this research was to examine how translocation method (hard‐ vs. soft‐release) and habitat structure (continuous vs. patchy) affect movement of translocated turtles. A hard‐release consists of releasing individuals to their new environment without any prior acclimation, whereas a soft‐release forces animals to spend time at the release site prior to release. Our results suggest that the most effective translocation technique depends upon habitat structure. A soft‐release was effective in minimizing post‐release dispersal of translocated turtles in a continuous lotic habitat as there was no difference in the movement of soft‐released and resident turtles. However, hard‐released turtles undergo extensive movement when translocated to a continuous lotic habitat as hard‐released turtles had greater movement than resident turtles. When the release site consists of a patchy wetland complex, a hard‐release translocation may be effective as there was no difference in the movement between resident and hard‐released turtles. Our study suggests that both the habitat structure of the release site and translocation method play a role in the movement patterns of translocated wildlife. Semi‐aquatic turtles or species with poor vagility may make better candidates for hard‐release translocations in patchy habitats because these species may be less likely or unable to disperse long distances as result of their behavior, physiology, or the structure of the release site.  相似文献   

2.
Wildlife translocations, the deliberate movement of wild individuals from one part of their distribution to another, are increasingly being used as a conservation tool. Despite the popularity of translocations as a conservation technique, translocations are often not successful as a result of excessive movement, poor release site fidelity, and low survival. This study compares the movement patterns, site fidelity, and survival probability of resident and hard-released musk turtles (Sternotherus odoratus) in a complex of patchy distributed wetlands. Our results are different from most translocation studies as the majority of translocated turtles had movement (minimum convex polygon area, total distance moved, number of wetlands used, and the number of movement shifts between wetlands), release site fidelity, and wetland fidelity patterns that were similar to resident turtles. In addition, the survival probabilities of resident and translocated turtles were both high. We believe the combination of poor overland movement capabilities and the patchy distribution of wetlands surrounded by a strong boundary matrix of terrestrial habitat, potentially increased the costs of leaving the wetland. The high costs of travelling overland to more distant wetlands may have constrained the translocated turtles dispersal from the release site and increased release site fidelity. Our study suggests that hard-release translocations may be an effective conservation method for highly aquatic species unlikely to leave the wetland and travel long overland distances.  相似文献   

3.
The adaptation of translocated organisms to a new environment in the first years after their release is crucial in translocation programs because it may affect survival and reproductive success. Therefore, identifying the factors determining resource selection by the relocated animals is essential to improve the planning and the outcome of such programs. Using data collected in 2006–2009 in the framework of a restocking program, we studied the temporal variation of habitat selection in 14 translocated Alpine ibex (Capra ibex) during the year of their release and the following 3 years. We hypothesized a progressive adaptation of the translocated individuals, highlighted by a gradual decrease in the dissimilarities between translocated and resident individuals in ecological characteristics and social behavior. We tested the differences in habitat selection and home range size between the translocated and resident individuals and compared the spatial overlap between the groups. As expected, the dissimilarities decreased annually. The translocated and resident ibex almost immediately selected the same habitat resources, but the translocated individuals required 3 years to become fully socially assimilated. Our results indicated that habitat selection by gregarious species in a new environment is primarily driven by specific ecological requirements and that sociality plays a significant role. The translocated individuals tended to colonize areas already occupied by residents, either to fulfill social requirements and/or because the location of resident individuals may indicate high-quality habitat. This pattern of behavior must be considered in the planning of translocation programs because habitat selection can affect the outcomes of the programs. © 2013 The Wildlife Society.  相似文献   

4.
ABSTRACT The decline of many snake populations is attributable to habitat loss, and knowledge of habitat use is critical to their conservation. Resource characteristics (e.g., relative availability of different habitat types, soils, and slopes) within a landscape are scale-dependent and may not be equal across multiple spatial scales. Thus, it is important to identify the relevant spatial scales at which resource selection occurs. We conducted a radiotelemetry study of eastern hognose snake (Heterodon platirhinos) home range size and resource use at different hierarchical spatial scales. We present the results for 8 snakes radiotracked during a 2-year study at New Boston Air Force Station (NBAFS) in southern New Hampshire, USA, where the species is listed by the state as endangered. Mean home range size (minimum convex polygon) at NBAFS (51.7 ± 14.7 ha) was similar to that reported in other parts of the species’ range. Radiotracked snakes exhibited different patterns of resource use at different spatial scales. At the landscape scale (selection of locations within the landscape), snakes overutilized old-field and forest edge habitats and underutilized forested habitats and wetlands relative to availability. At this scale, snakes also overutilized areas containing sandy loam soils and areas with lower slope (mean slope = 5.2% at snake locations vs. 6.7% at random locations). We failed to detect some of these patterns of resource use at the home range scale (i.e., within the home range). Our ability to detect resource selection by the snakes only at the landscape scale is likely the result of greater heterogeneity in macrohabitat features at the broader landscape scale. From a management perspective, future studies of habitat selection for rare species should include measurement of available habitat at spatial scales larger than the home range. We suggest that the maintenance of open early successional habitats as a component of forested landscapes will be critical for the persistence of eastern hognose snake populations in the northeastern United States.  相似文献   

5.
Box turtles are being extirpated from much of their former range and remaining populations often live in association with anthropogenically altered habitats. This is particularly evident at the northern distributional limit of eastern box turtles (Terrapene carolina carolina) and is an important factor to consider during the winter months when their ability to respond to microclimatic change is limited. Using temperature dataloggers, we studied the hibernal microclimate of box turtles and associated habitat following timber harvests. We monitored the body temperatures of 38 eastern box turtles and collected detailed air and soil profile temperatures of 12 box turtle hibernacula, 6 clearcuts, and 6 adjacent forested areas during the hibernal season (winter 2009–2010). We partitioned the hibernal season into 2 biologically significant thermal periods: hibernation and emergence. The mean hibernation body temperature averaged (3.28° C, SE = 0.09) and corresponded to an average depth of 10 cm. Clearcuts were consistently colder ( = 1.91° C) than forests ( = 2.68° C) and hibernacula ( = 2.77° C) during hibernation, but became the warmest areas during emergence ( = 9.96° C). We found that in the average clearcut, turtles could burrow to approximately 20 cm to attain the average hibernation body temperature or to approximately 15 cm to attain a body temperature no different than those overwintering on colder, northeast-facing slopes in the forest ( = 2.83° C). Alternatively, we found that southwest-facing slopes were warmer and if turtles chose to overwinter only in clearcuts on those slopes, they could remain shallower. All but 1 turtle overwintered in forested areas; however, our study suggests that some timber harvested areas offer various microhabitats exploitable by hibernating box turtles based on soil profile temperatures, slope aspect, and depth of hibernation. © 2012 The Wildlife Society.  相似文献   

6.
With increasing infrastructural development along Brazil’s coast, environmental regulation measures are becoming increasingly necessary in the face of the damage caused by large projects that impact tropical forests. Brazilian legislation supports implementation of translocation programs for impacted fauna, especially threatened species such as the thin-spined porcupine Chaetomys subspinosus (Rodentia, Erethizontidae). Thus, we present a case study of a pioneer translocation program for the thin-spined porcupine in southeastern Brazil. We aimed to analyze the home-range and habitat selection of three translocated porcupines and one resident individual. In addition, we analyzed the success of the translocations. The porcupines were monitored by radiotelemetry for 3–16 months from October 2015 to March 2017 in a mosaic landscape of restinga forests (sandbank forest vegetation) within a eucalyptus matrix. The translocated porcupines had considerably larger home-ranges (14.29–18.36 ha, minimum convex polygon method – MCP) than did the resident animal (1.22 ha – MCP). We observed stabilization in the home-range size curves of the translocated females in the 7th − 9th month of monitoring. All translocated individuals achieved permanence within a preselected area, indicating adaptation to the new area. In addition, individuals showed a clear preference for restinga forests over drained eucalyptus plantations. Thus, our results demonstrate the feasibility of thin-spined porcupine translocations and the importance of maintaining restinga forest remnants outside of protected areas for the conservation and permanence of viable populations of this rodent.  相似文献   

7.
Effective wildlife management requires an understanding of how individuals select environmental factors, although few studies assess how habitat selection may differ over time or between sexes. During the post-breeding period (15 May to 1 Sep), we tracked 146 male American woodcock (Scolopax minor) in Rhode Island, USA, from 2010–2021 to assess how habitat selection varied over time, and 17 females and 51 males during the final 2 years of the study to document sex-specific differences in habitat selection. Males generally had smaller home ranges (35.0 ± 10.7 [margin of error] ha) and preferred habitat mosaics that consisted of forested wetlands, young forest patches, areas of deciduous forest, moist soils with gentle slopes, and riparian corridors. We detected subtle differences between sexes in selection for wetland young forest, upland young forest, percent slope, distance to upland young forest, distance to streams, and distance to moist soils. During 2020–2021, females tended to have larger home ranges (78.7 ± 46.4 ha) than males (35.0 ± 10.7 ha) and more strongly selected sites closer to riparian corridors, while males selected areas that were closer to upland young forest with flatter slopes than the available surrounding landscape. Such sex-specific differences in habitat selection may be related to males and females prospecting for potential breeding sites during this post-breeding period for the following spring. We used the top-ranked habitat selection models for males and females to produce a spatially explicit state-wide map that identifies low-to-high likelihood of use areas that can be used to guide forest management decisions in southern New England to maximize benefits for American woodcock.  相似文献   

8.
1. The hydrologic connectivity between landscape elements and streams means that fragmentation of terrestrial habitats could affect the distribution of stream faunas at multiple spatial scales. We investigated how catchment‐ and site‐scale influences, including proportion and position of forest cover within a catchment, and presence of riparian forest cover affected the distribution of a diadromous fish. 2. The occurrence of koaro (Galaxias brevipinnis) in 50‐m stream reaches with either forested or non‐forested riparian margins at 172 sites in 24 catchments on Banks Peninsula, South Island, New Zealand was analysed. Proportions of catchments forested and the dominant position (upland or lowland) of forest within catchments were determined using geographical information system spatial analysis tools. 3. Multivariate analysis of variance indicated forest position and proportion forested at the catchment accounted for the majority of the variation in the overall proportion of sites in a catchment with koaro. 4. Where forest was predominantly in the lower part of the catchments, the presence of riparian cover was important in explaining the proportion of sites with koaro. However, where forest was predominantly in the upper part of the catchment, the effect of riparian forest was not as strong. In the absence of riparian forest cover, no patterns of koaro distribution with respect to catchment forest cover or forest position were detected. 5. These results indicate that landscape elements, such as the proportion and position of catchment forest, operating at catchment‐scales, influence the distribution of diadromous fish but their influence depends on the presence of riparian vegetation, a site‐scale factor.  相似文献   

9.
High species richness, resource availability and disturbance are community characteristics associated with forest invasibility. We categorized commonly measured community variables, including species composition, topography, and landscape features, within both mature and 15-year-old clearcuts in West Virginia, USA. We evaluated the importance of each variable for predicting the degree of forest invasion by early-establishing exotic invasive plants. Biotic variables, including overall richness (excluding exotic invasive species) and mutually exclusive native and exotic non-invasive species richness, were the strongest indicators of invasibility. Sites that were located on northeast-facing slopes, more mesic conditions, or in clearcuts were more likely to be invaded by exotic invasive plants. Invasion of clearcut sites was more dependent on available microsites (e.g., lower solar radiation, northeast-facing slopes, and lower elevations) within each site than on the condition of the surrounding landscape, whereas invasion into the mature forests was dependent more on the surrounding landscape (e.g., proximity to paved roads). Our results indicate that exotic invasive plant species in our study area respond similarly as other plant species to resource availability and that competitive interactions are relatively unimportant. Current invasion into this landscape is more likely to be a passive reaction to site conditions instead of a driver of change.  相似文献   

10.
《新西兰生态学杂志》2011,31(1):111-116
Translocation is an important tool in the conservation of New Zealand reptiles. Despite this, it is generally not known how Hoplodactylus geckos respond to being translocated, partly because they are difficult to monitor. In this opportunistic study, common geckos (H. maculatus) were captured from a site at Birdlings Flat (South Island, New Zealand) that was destined for destruction, and released in native coastal shrubland km away. Geckos were sampled monthly using pitfall traps and artificial retreats, with only the latter method yielding captures. Ten out of translocated geckos remained at the release site, and translocated animals moved equivalent distances to resident geckos (n = 3) over a -year period following translocation. Although studies spanning multiple decades may be needed to determine whether translocations of Hoplodactylus geckos are ultimately successful given their life-history traits, the development of an effective detection method is nonetheless a useful contribution.  相似文献   

11.
Abstract: To examine effects of relocation on eastern box turtles (Terrapene carolina), we compared home ranges and movement patterns of 10 resident and 10 relocated box turtles in Davidson, North Carolina, USA. Home ranges of relocated turtles were approximately 3 times larger than those of resident turtles when measured by minimum convex polygons, 6 times larger than resident turtles when measured with 95% kernels and 7.5 times larger than resident turtles when measured by 50% kernels. Relocated turtles also moved a greater average distance per day than resident turtles. Additionally, 5 relocated turtles experienced mortality or disappearance compared to no mortality or disappearance of resident turtles. Our results raise questions about the success of relocation as a management strategy for eastern box turtles. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):772–777; 2008)  相似文献   

12.
We explore the effect of differences in landscape structure, arising from habitat loss, on the fine-scale movement behaviors of two congeneric damselflies – Calopteryx aequabilis and C. maculata . Both species require streams for breeding and naiad development and both often use forest for foraging. We compare movement behaviors across three types of landscape: forested landscapes, where stream and forest habitat are adjacent; partially forested landscapes, where streams and forest habitat are disjunct, and non-forested landscapes, where little to no forest habitat is available. We employ a reciprocal transplant experiment to determine the extent to which movement along and away from streams is influenced by landscape structure and historical behavior or morphological adaptations. For both species, we show that both the propensity to move away from streams and rates of net displacement differ among landscape types. Both species move away from streams on landscapes with high or moderate levels of forest cover but neither moves away from streams on landscapes with little or no forest. Furthermore, C. maculata native to predominantly forested landscapes are more likely to move away from streams, regardless of the landscape structure they encounter, than are individuals native to moderately forested or non-forested landscapes. There was no effect of natal landscape on C. aequabilis . Comparisons with microlandscape studies suggest that there may be some general similarities among the different systems but these are clouded by uncertainty regarding the similarity of the underlying processes responsible for observed behavioral responses to landscape structure. Despite this uncertainty, animal movement behaviors are contingent upon the structure of the broader landscape, regardless of the absolute scale of the landscape.  相似文献   

13.
Eastern box turtles (Terrapene carolina carolina) are widely distributed throughout the eastern United States. Although once common throughout much of its distribution, the species has experienced declines in local populations. Understanding resource selection is important for the conservation of this species; however, few data exist on resource selection for eastern box turtles in the southeastern United States. We estimated home range and resource selection for 100 individual turtles in the Blue Ridge, Ridge and Valley, and Cumberland Plateau and Mountains physiographic regions in Tennessee, USA, from 2016 to 2018. We used step-selection functions to investigate eastern box turtle resource selection during May–August 2017 and May–August 2018 at 2 spatial scales. We classified vegetation type, measured vegetation composition and structure, recorded time since fire, and measured coarse woody debris abundance at 1,225 used telemetry locations and 1,225 associated available points. Home range sizes averaged 9.3 ha ± 3.0 (SE) using minimum convex polygon analysis, 8.25 ha ± 2.88 using 95% kernel density analysis, and 1.50 ha ± 0.56 using 50% kernel density analysis. Box turtles selected areas with greater visual obstruction at the 0–0.25-m level, greater amounts of 10-hour and 100-hour fuels (timelag categories used in fire-danger ratings), and greater litter depths compared to available locations. Box turtles were more likely to select areas with greater cover of brambles and coarser woody debris and were less likely to select areas with less vegetation cover. Vegetation type and time since last fire did not affect selection. Our data suggest that management activities that encourage greater understory vegetation cover, greater visual obstruction at the 0–0.25-m level, and greater bramble cover will enhance habitat quality for eastern box turtles. © 2020 The Wildlife Society.  相似文献   

14.
Survival, reproductive and recruitment rates, along with health status, of translocated and resident individuals should be evaluated. However, gathering this information poses logistical constraints and requires long-term studies. Considering the urgent nature of many species’ situations where translocation would be appropriate, fast-assessment techniques should be tested. We assessed the immediate response to translocation of Hermann’s tortoises (Testudo hermanni hermanni) directly from captivity to the wild. Individuals were maintained in captivity 2 to 8 years before being released in spring 2013 into a natural population impacted by fire. During the critical 3 months post-release period, we radio-tracked translocated individuals (N?=?12) and resident tortoises in spring 2013 (N?=?14), plus another batch of resident tortoises in spring 2012 (N?=?9). Movements, behaviours, body condition and body temperature were regularly recorded. All translocated tortoises acclimated well to their novel environment. We found no differences in movement, thermoregulation and body condition between translocated and resident tortoises. Body condition of all tortoises increased rapidly in spring. We found no sign of perturbation in resident tortoises. Contrarily, resident males mated with translocated females. Translocations should be further tested on larger spatial and time scales to improve population restoration programmes, especially in threatened species with limited dispersal ability.  相似文献   

15.
Translocation is an important component of northern bobwhite (Colinus virginianus) recovery efforts, given the scale of their decline and inability to rapidly recolonize recently restored habitat. Repopulating sites in northern latitudes that are distant from reliable source populations may require long-distance trap and transport from southern locales, potentially compounding existing obstacles for this renascent population recovery technique. The landscape connectivity hypothesis predicts that site fidelity and survival would be lower if release properties are small and fragmented and home range sizes would be smaller and dispersal distances would be lower if habitat quality at the release site is perceived to be high and the surrounding matrix is of low permeability. We evaluated this hypothesis to determine if northern bobwhite survival, site fidelity, and resource selection following translocation differed between 2 contrasting landscapes in the Mid-Atlantic region of the United States. We translocated 508 radio-collared northern bobwhites from northern Florida and southern Georgia, to small, fragmented properties on the eastern shore of Maryland and large, contiguous properties in southern New Jersey, USA. We monitored northern bobwhites via radio-telemetry from approximately 1 April through 30 September, 2015–2018, 2–7 times a week. Breeding season (182 days after release) survival varied among sites, and was generally higher at the 2 New Jersey release sites than at the 2 Maryland sites, yet an acclimation period is ostensibly required to obtain reasonable breeding survival estimates to elicit population growth. Site fidelity, maximum dispersal distances, and home range sizes were lower at the smaller, fragmented Maryland properties than the larger New Jersey properties. These results support the landscape connectivity hypothesis such that reduced connectivity in our study decreased site fidelity and survival. Temporal variation in survival was potentially an artifact of translocation stress or maladaptive behavior during initial acclimation to the release sites, indicating that higher stocking rates may be needed to provide adequate founder abundance for translocation success. Northern bobwhites used early-successional cover at all sites, though selection varied based on scale of analysis and landscape context. These vital rate estimates and resource use patterns should be used to guide future translocations within the Mid-Atlantic, provide perspective for this population restoration technique range wide, and stimulate further investigation into limiting factors. © 2020 The Wildlife Society.  相似文献   

16.
Land‐use intensification at local and landscape level poses a serious threat to biodiversity and affects species interactions and ecosystem function. It is thus important to understand how interrelated taxa respond to land‐use intensification and to consider the importance of different spatial scales. We investigated whether and how local land‐use intensity and landscape features affect the predator–prey interaction of bats and insects. Bats and nocturnal insects were assessed on 50 grassland sites in the Schorfheide‐Chorin. We analyzed the effect of local land use and distance to forested areas as a proxy for site accessibility on bats and insects and their biological interaction measured in bat's feeding activity. Insect abundance increased with higher land‐use intensity, while size and diversity of insects decreased. In contrast, bat activity, diversity, and species composition were determined by the distance to forested areas and only slightly by land‐use intensity. Feeding attempts of bats increased with higher insect abundance and diversity but decreased with insect size and distance to forested areas. Finally, our results revealed that near forested areas, the number of feeding attempts was much lower on grassland sites with high, compared to those with low land‐use intensity. In contrast, far from forests, the feeding attempts did not differ significantly between intensively and extensively managed grassland sites. We conclude that the two interrelated taxa, bats and insects, respond to land‐use intensification on very different scales. While insects respond to local land use, bats are rather influenced by surrounding landscape matrix. Hereby, proximity to forests reveals to be a prerequisite for higher bat species diversity and a higher rate of feeding attempts within the area. However, proximity to forest is not sufficient to compensate local high land‐use intensity. Thus, local land‐use intensification in combination with a loss of forest remnants weakens the interaction of bats and insects.  相似文献   

17.
Animals in unfamiliar environments may increase exploratory movements, which may result in predation mortalities (the site familiarity hypothesis). Furthermore, increases in resource dispersion may reduce animal foraging time in small patches, and increase movements and home ranges of animals to acquire sufficient resources (the resource dispersion hypothesis). Little is known regarding effects of site familiarity on translocated birds in fragmented landscapes. We translocated 130 eastern wild turkeys (Meleagris gallapovo silvestris) in a sex ratio of one male to 4 females to 2 study sites that differed in forest fragmentation in MS, USA. Turkeys were captured from sites throughout Mississippi during springs 2009 and 2010. We monitored movements of translocated wild turkeys using radio telemetry. Movement distances and home ranges in 2010 did not differ among birds released in different years, inconsistent with the site familiarity hypothesis. However, movement distances and home ranges of translocated turkeys were greater at the more fragmented site than at the less fragmented site, supporting the resource dispersion hypothesis. Moreover, home range sizes were related positively to within-home-range variability in vegetative greenness measured by the normalized difference vegetation index. Effects of resource dispersion may override effects of site familiarity concerning translocated wild turkeys.  相似文献   

18.
Reclamation of coal mine lands in the eastern United States creates pockets of grassland habitat in an otherwise predominantly forested region. These sites may represent an opportunity for pollinator conservation if they provide valuable foraging habitat for wild bees. To determine site characteristics that influence bee success on reclamation lands, we monitored growth and reproduction of 24 commercially reared bumble bee (Bombus impatiens) colonies placed on 12 former coal mines (aged 2 to 30+ years post‐reclamation) in Ohio, U.S.A. Twenty colonies survived the duration of the experiment (May–August 2014). All colonies produced both new queens (mean 21.0 ± 37.0 SD) and males (36.5 ± 36.5), in proportion to overall colony size. Results of generalized linear models indicate that colony growth and reproduction increased with floral diversity and species turnover, and declined with site area and the proportion of forest in the surrounding landscape. The sex ratio of reproductive offspring was significantly more male‐biased on sites with low flower diversity, underscoring the importance of floral diversity for meeting the higher resource demands of queen production. Floral resource composition and consistency were influenced by site age and surrounding landscape. Older sites had higher floral diversity and species turnover throughout the season than younger sites, and included high‐quality native bee forage plants. We discuss the implications of this study for reclamation project managers seeking to promote bee reproduction and conservation.  相似文献   

19.
Continual population declines in northern bobwhites (Colinus virginianus) have prompted the use of population restoration techniques in conjunction with habitat management to restore their populations. We tested the site familiarity hypothesis to determine if translocation to new environments affected offspring survival and growth rates of bobwhites. We used bobwhites from north Florida and translocated them to a study site in Brunswick County, North Carolina, USA, and monitored birds during April−October 2016 and April−October 2017. We used the corral capture method and modified-suture technique to capture and radio-tag chicks to evaluate offspring growth and survival rates of resident and translocated bobwhites. Offspring survival varied by year and age. We did not find any difference in offspring survival rates of resident and translocated individuals, lending no support to the site familiarity hypothesis with regards to survival. Offspring of resident bobwhites did not grow at a faster rate than offspring of translocated bobwhites, indicating a lack of support for the site familiarity hypothesis in terms of physiological development. Survival, however, is a more important metric for determining post-translocation population dynamics, and our results indicated that translocated bobwhites can reproduce and raise offspring similar to resident counterparts, but both had low survival. © 2019 The Wildlife Society.  相似文献   

20.
Shifts in resource use may be an important mechanism by which organisms can adjust to novel environmental conditions, such as those imposed by climate change. However, for such shifts to be possible, environmental space must exist into which organisms can move. Habitat that ensures successful survival and reproduction is one such critical resource. We studied resource selection of shade cover over nest sites by painted turtles in populations in Illinois (center of range) and New Mexico (southern edge of range). We targeted this habitat feature because shade can influence hatching success and offspring phenotype (including sex in the study species) by affecting nest microenvironments. We found that while turtles in both populations selected nest sites that were shadier than average available sites, overall resource selection differed between the populations. This disparity may have been due to differences in structure of vegetation that provides shade at each site, because areas with high shade cover in New Mexico (low dense thickets) were much more difficult for turtles to access than those in Illinois (dense tree canopy cover). Further, shade cover predicted different parameters of incubation regime at each site, suggesting that turtles must assess dissimilar components of shade cover in order to choose nest sites and predict their future incubation regimes. Our results suggest that shade cover within nesting areas is a key component of painted turtle habitat, and that accessible, highly-shaded nest sites may be limited at the New Mexico site. Maintaining a range of shade cover from which turtles can select nest sites would permit plasticity in nest-site choice to be expressed, which may be important in preventing sex ratio skews due to climate change.  相似文献   

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