共查询到20条相似文献，搜索用时 0 毫秒
1.
Invasive mammalian carnivores contribute disproportionately to declines in global biodiversity. In California, nonnative red foxes (Vulpes vulpes) have significantly impacted endangered ground‐nesting birds and native canids. These foxes derive primarily from captive‐reared animals associated with the fur‐farming industry. Over the past five decades, the cumulative area occupied by nonnative red fox increased to cover much of central and southern California. We used a landscape‐genetic approach involving mitochondrial DNA (mtDNA) sequences and 13 microsatellites of 402 nonnative red foxes removed in predator control programs to investigate source populations, contemporary connectivity, and metapopulation dynamics. Both markers indicated high population structuring consistent with origins from multiple introductions and low subsequent gene flow. Landscape‐genetic modeling indicated that population connectivity was especially low among coastal sampling sites surrounded by mountainous wildlands but somewhat higher through topographically flat, urban and agricultural landscapes. The genetic composition of populations tended to be stable for multiple generations, indicating a degree of demographic resilience to predator removal programs. However, in two sites where intensive predator control reduced fox abundance, we observed increases in immigration, suggesting potential for recolonization to counter eradication attempts. These findings, along with continued genetic monitoring, can help guide localized management of foxes by identifying points of introductions and routes of spread and evaluating the relative importance of reproduction and immigration in maintaining populations. More generally, the study illustrates the utility of a landscape‐genetic approach for understanding invasion dynamics and metapopulation structure of one of the world's most destructive invasive mammals, the red fox. 相似文献
2.
Mark J. Statham James Murdoch Jan Janecka Keith B. Aubry Ceiridwen J. Edwards Carl D. Soulsbury Oliver Berry Zhenghuan Wang David Harrison Malcolm Pearch Louise Tomsett Judith Chupasko Benjamin N. Sacks 《Molecular ecology》2014,23(19):4813-4830
Widely distributed taxa provide an opportunity to compare biogeographic responses to climatic fluctuations on multiple continents and to investigate speciation. We conducted the most geographically and genomically comprehensive study to date of the red fox (Vulpes vulpes), the world's most widely distributed wild terrestrial carnivore. Analyses of 697 bp of mitochondrial sequence in ~1000 individuals suggested an ancient Middle Eastern origin for all extant red foxes and a 400 kya (SD = 139 kya) origin of the primary North American (Nearctic) clade. Demographic analyses indicated a major expansion in Eurasia during the last glaciation (~50 kya), coinciding with a previously described secondary transfer of a single matriline (Holarctic) to North America. In contrast, North American matrilines (including the transferred portion of Holarctic clade) exhibited no signatures of expansion until the end of the Pleistocene (~12 kya). Analyses of 11 autosomal loci from a subset of foxes supported the colonization time frame suggested by mtDNA (and the fossil record) but, in contrast, reflected no detectable secondary transfer, resulting in the most fundamental genomic division of red foxes at the Bering Strait. Endemic continental Y‐chromosome clades further supported this pattern. Thus, intercontinental genomic exchange was overall very limited, consistent with long‐term reproductive isolation since the initial colonization of North America. Based on continental divergence times in other carnivoran species pairs, our findings support a model of peripatric speciation and are consistent with the previous classification of the North American red fox as a distinct species, V. fulva. 相似文献
3.
Elizabeth W. Goldsmith Benjamin Renshaw Christopher J. Clement Elizabeth A. Himschoot Kris J. Hundertmark Karsten Hueffer 《Molecular ecology》2016,25(3):675-688
For pathogens that infect multiple species, the distinction between reservoir hosts and spillover hosts is often difficult. In Alaska, three variants of the arctic rabies virus exist with distinct spatial distributions. We tested the hypothesis that rabies virus variant distribution corresponds to the population structure of the primary rabies hosts in Alaska, arctic foxes (Vulpes lagopus) and red foxes (Vulpes vulpes) to possibly distinguish reservoir and spillover hosts. We used mitochondrial DNA (mtDNA) sequence and nine microsatellites to assess population structure in those two species. mtDNA structure did not correspond to rabies virus variant structure in either species. Microsatellite analyses gave varying results. Bayesian clustering found two groups of arctic foxes in the coastal tundra region, but for red foxes it identified tundra and boreal types. Spatial Bayesian clustering and spatial principal components analysis identified 3 and 4 groups of arctic foxes, respectively, closely matching the distribution of rabies virus variants in the state. Red foxes, conversely, showed eight clusters comprising two regions (boreal and tundra) with much admixture. These results run contrary to previous beliefs that arctic fox show no fine‐scale spatial population structure. While we cannot rule out that the red fox is part of the maintenance host community for rabies in Alaska, the distribution of virus variants appears to be driven primarily by the arctic fox. Therefore, we show that host population genetics can be utilized to distinguish between maintenance and spillover hosts when used in conjunction with other approaches. 相似文献
4.
Alan Robley Katie Howard Michael Lindeman Rhet Cameron Andrew Jardine David Hiscock 《Ecological Management & Restoration》2016,17(1):63-69
Reducing predation by introduced predators on seasonally vulnerable prey is of interest to biodiversity and game managers around the world. In Australia, the Red Fox (Vulpes vulpes) is a significant predator of freshwater turtle nests, destroying up to 93% of nests. We used a nonrandomized intervention study to assess the effectiveness of a short‐term (3‐week) but broad‐scale baiting operation in reducing the level of nest predation on artificial turtle nests around a complex lake system during a major flooding event in north‐western Victoria. Estimates of fox occupancy declined from 0.58 (0.44–0.70 95% CI) to 0.34 (0.21–0.46 95% CI) following fox control. Modelling of nest‐survival rates indicated there was no significant change in survival rates. Effective short‐term predator control to protect seasonally vulnerable prey is desirable and achievable. Knowledge of underlying predator density, predator–bait encounter and consumption rates, and the optimal duration of short‐term control is needed to reduce the risk to prey. 相似文献
5.
Clive A. Marks Ivo Edwards David Obendorf Filipe Pereira Graham P. Hall 《Ecological Management & Restoration》2014,15(3):196-203
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
6.
Predators,fire or resources: What drives the distribution of herbivores in fragmented mesic forests?
William L. Geary Bronwyn A. Hradsky Alan Robley Brendan A. Wintle 《Austral ecology》2020,45(3):329-339
Trophic interactions and disturbance events can shape the structure and function of ecosystems. However, the effects of drivers such as predation, fire and climatic variables on species distributions are rarely considered concurrently. We used a replicated landscape‐scale predator management experiment to compare the effects of red fox Vulpes vulpes control, time‐since‐fire, vegetation type and other environmental variables on native herbivore distributions. Occurrence data for four native herbivores and an invasive predator – the red fox – were collected from 240 sites across three baited (for lethal fox control) and three unbaited forest blocks (4659–9750 ha) in south‐western Victoria, Australia, and used to build species distribution models. The herbivore taxa were as follows: red‐necked wallaby Macropus rufogriseus, black wallaby Wallabia bicolour, grey kangaroo Macropus fuligenosus and Macropus giganteus and common brushtail possum Trichosurus vulpecula. Fox control and fire had little effect on herbivore occurrence, despite the literature suggesting it can influence abundance, while climate, proximity to farmland and topography were more influential. This may be because the region’s high productivity and agricultural pastures subsidise food resources for both predators and prey within the forest blocks and so dampen trophic interactions. Alternatively, these drivers may affect herbivore abundance, but not herbivore occurrence. Understanding the drivers of herbivore distributions is an important step in predicting the effects of herbivory on other species, particularly after management interventions such as predator control and prescribed burns. 相似文献
7.
Kenneth F. Kellner Jacob E. Hill Mariela G. Gantchoff David W. Kramer Amanda M. Bailey Jerrold L. Belant 《Ecology and evolution》2020,10(16):8705-8714
Measuring wildlife responses to anthropogenic activities often requires long‐term, large‐scale datasets that are difficult to collect. This is particularly true for rare or cryptic species, which includes many mammalian carnivores. Citizen science, in which members of the public participate in scientific work, can facilitate collection of large datasets while increasing public awareness of wildlife research and conservation. Hunters provide unique benefits for citizen science given their knowledge and interest in outdoor activities. We examined how anthropogenic changes to land cover impacted relative abundance of two sympatric canids, coyote (Canis latrans), and red fox (Vulpes vulpes) at a large spatial scale. In order to assess how land cover affected canids at this scale, we used citizen science data from bow hunter sighting logs collected throughout New York State, USA, during 2004–2017. We found that the two species had contrasting responses to development, with red foxes positively correlated and coyotes negatively correlated with the percentage of low‐density development. Red foxes also responded positively to agriculture, but less so when agricultural habitat was fragmented. Agriculture provides food and denning resources for red foxes, whereas coyotes may select forested areas for denning. Though coyotes and red foxes compete in areas of sympatry, we did not find a relationship between species abundance, likely a consequence of the coarse spatial resolution used. Red foxes may be able to coexist with coyotes by altering their diets and habitat use, or by maintaining territories in small areas between coyote territories. Our study shows the value of citizen science, and particularly hunters, in collection of long‐term data across large areas (i.e., the entire state of New York) that otherwise would unlikely be obtained. 相似文献
8.
Karin Norén Mark J. Statham Erik O. Ågren Marja Isomursu Øystein Flagstad Nina E. Eide Thomas Bjørneboe G. Berg Lene Bech‐Sanderhoff Benjamin N. Sacks 《Global Change Biology》2015,21(9):3299-3312
Population expansions of boreal species are among the most substantial ecological consequences of climate change, potentially transforming both structure and processes of northern ecosystems. Despite their importance, little is known about expansion dynamics of boreal species. Red foxes (Vulpes vulpes) are forecasted to become a keystone species in northern Europe, a process stemming from population expansions that began in the 19th century. To identify the relative roles of geographic and demographic factors and the sources of northern European red fox population expansion, we genotyped 21 microsatellite loci in modern and historical (1835–1941) Fennoscandian red foxes. Using Bayesian clustering and Bayesian inference of migration rates, we identified high connectivity and asymmetric migration rates across the region, consistent with source‐sink dynamics, whereby more recently colonized sampling regions received immigrants from multiple sources. There were no clear clines in allele frequency or genetic diversity as would be expected from a unidirectional range expansion from south to north. Instead, migration inferences, demographic models and comparison to historical red fox genotypes suggested that the population expansion of the red fox is a consequence of dispersal from multiple sources, as well as in situ demographic growth. Together, these findings provide a rare glimpse into the anatomy of a boreal range expansion and enable informed predictions about future changes in boreal communities. 相似文献
9.
Carolin Scholz Jasmin Firozpoor Stephanie Kramer‐Schadt Pierre Gras Christoph Schulze Sophia E. Kimmig Christian C. Voigt Sylvia Ortmann 《Ecology and evolution》2020,10(16):8855-8870
Some carnivores are known to survive well in urban habitats, yet the underlying behavioral tactics are poorly understood. One likely explanation for the success in urban habitats might be that carnivores are generalist consumers. However, urban populations of carnivores could as well consist of specialist feeders. Here, we compared the isotopic specialization of red foxes in urban and rural environments, using both a population and an individual level perspective. We measured stable isotope ratios in increments of red fox whiskers and potential food sources. Our results reveal that red foxes have a broad isotopic dietary niche and a large variation in resource use. Despite this large variation, we found significant differences between the variance of the urban and rural population for δ13C as well as δ15N values, suggesting a habitat‐specific foraging behavior. Although urban regions are more heterogeneous regarding land cover (based on the Shannon index) than rural regions, the dietary range of urban foxes was smaller compared with that of rural conspecifics. Moreover, the higher δ13C values and lower δ15N values of urban foxes suggest a relatively high input of anthropogenic food sources. The diet of most individuals remained largely constant over a longer period. The low intraindividual variability of urban and rural red foxes suggests a relatively constant proportion of food items consumed by individuals. Urban and rural foxes utilized a small proportion of the potentially available isotopic dietary niche as indicated by the low within‐individual variation compared to the between‐individual variation. We conclude that generalist fox populations consist of individual food specialists in urban and rural populations at least over those periods covered by our study. 相似文献
10.
Michael T. Main Robert A. Davis David Blake Harriet Mills Tim S. Doherty 《Diversity & distributions》2020,26(9):1083-1092
11.
Use of livestock guardian dogs (LGDs) to reduce predation on livestock is increasing. However, how these dogs influence the activity of wildlife, including predators, is not well understood. We used pellet counts and remote cameras to investigate the effects of free ranging LGDs on four large herbivores (eastern gray kangaroo, common wombat, swamp wallaby, and sambar deer) and one mesopredator (red fox) in Victoria, Australia. Generalized mixed models and one‐ and two‐species detection models were used to assess the influence of the presence of LGDs on detection of the other species. We found avoidance of LGDs in four species. Swamp wallabies and sambar deer were excluded from areas occupied by LGDs; gray kangaroos showed strong spatial and temporal avoidance of LGD areas; foxes showed moderately strong spatial and temporal avoidance of LGD areas. The effect of LGDs on wombats was unclear. Avoidance of areas with LGDs by large herbivores can benefit livestock production by reducing competition for pasture and disease transmission from wildlife to livestock, and providing managers with better control over grazing pressure. Suppression of mesopredators could benefit the small prey of those species. Synthesis and applications: In pastoral areas, LGDs can function as a surrogate top‐order predator, controlling the local distribution and affecting behavior of large herbivores and mesopredators. LGDs may provide similar ecological functions to those that in many areas have been lost with the extirpation of native large carnivores. 相似文献
12.
Elise M. Furlan Dianne Gleeson Christopher M. Hardy Richard P. Duncan 《Molecular ecology resources》2016,16(3):641-654
Imperfect sensitivity, or imperfect detection, is a feature of all survey methods that needs to be accounted for when interpreting survey results. Detection of environmental DNA (eDNA) is increasingly being used to infer species distributions, yet the sensitivity of the technique has not been fully evaluated. Sensitivity, or the probability of detecting target DNA given it is present at a site, will depend on both the survey method and the concentration and dispersion of target DNA molecules at a site. We present a model to estimate target DNA concentration and dispersion at survey sites and to estimate the sensitivity of an eDNA survey method. We fitted this model to data from a species‐specific eDNA survey for Oriental weatherloach, Misgurnus anguillicaudatus, at three sites sampled in both autumn and spring. The concentration of target DNA molecules was similar at all three sites in autumn but much higher at two sites in spring. Our analysis showed the survey method had ≥95% sensitivity at sites where target DNA concentrations were ≥11 molecules per litre. We show how these data can be used to compare sampling schemes that differ in the number of field samples collected per site and number of PCR replicates per sample to achieve ≥95% sensitivity at a given target DNA concentration. These models allow researchers to quantify the sensitivity of eDNA survey methods to optimize the probability of detecting target species, and to compare DNA concentrations spatially and temporarily. 相似文献
13.
- Camera traps are used increasingly to estimate population density for elusive and difficult to observe species. A standard practice for mammalian surveys is to place cameras on roads, trails, and paths to maximize detections and/or increase efficiency in the field. However, for many species it is unclear whether track‐based camera surveys provide reliable estimates of population density.
- Understanding how the spatial arrangement of camera traps affects population density estimates is of key interest to contemporary conservationists and managers given the rapid increase in camera‐based wildlife surveys.
- We evaluated the effect of camera‐trap placement, using several survey designs, on density estimates of a widespread mesopredator, the red fox Vulpes vulpes, over a two‐year period in a semi‐arid conservation reserve in south‐eastern Australia. Further, we used the certainty in the identity and whereabouts of individuals (via GPS collars) to assess how resighting rates of marked foxes affect density estimates using maximum likelihood spatially explicit mark–resight methods.
- Fox detection rates were much higher at cameras placed on tracks compared with off‐track cameras, yet in the majority of sessions, camera placement had relatively little effect on point estimates of density. However, for each survey design, the precision of density estimates varied considerably across sessions, influenced heavily by the absolute number of marked foxes detected, the number of times marked foxes was resighted, and the number of detection events of unmarked foxes.
- Our research demonstrates that the precision of population density estimates using spatially explicit mark–resight models is sensitive to resighting rates of identifiable individuals. Nonetheless, camera surveys based either on‐ or off‐track can provide reliable estimates of population density using spatially explicit mark–resight models. This underscores the importance of incorporating information on the spatial behavior of the subject species when planning camera‐trap surveys.
14.
Samuel G. Roberts Rebecca A. Longenecker Matthew A. Etterson Katharine J. Ruskin Chris S. Elphick Brian J. Olsen W. Gregory Shriver 《Journal of Field Ornithology》2017,88(2):115-131
As saltmarsh habitat continues to disappear, understanding the factors that influence the population dynamics of saltmarsh breeding birds is an important step in the conservation of these declining species. Using 5 yrs (2011–2015) of demographic data, we evaluated and compared apparent adult survival and nest survival of Seaside (Ammodramus maritimus) and Saltmarsh (A. caudacutus) sparrows at the Edwin B. Forsythe National Wildlife Refuge in New Jersey, USA. We determined the effect of site management history (unditched vs. ditched marshes) on adult and nest survival to aid in prioritizing future management or restoration actions. Apparent adult survival (61.6%, 95% CI: 52.5–70.0%) of Seaside Sparrows averaged > 1.5 times greater than that of Saltmarsh Sparrows (39.9%, 95% CI: 34.0–46.2%). Nest survival and predation and flooding rates did not differ between species, and predation was the primary cause of nest failure for both species. Apparent adult survival and nest survival did not differ between unditched and ditched marshes for either species, indicating that marsh ditching history may not affect the quality of breeding habitat for these species. Because predation was the primary cause of nest failure for both species in New Jersey, we suggest that future studies should focus on identifying predator communities in salt marshes and the potential for implementing predator‐control programs to limit population declines. 相似文献
15.
16.
Fabin A. Rubalcava‐Castillo Joaquín Sosa‐Ramírez Jos J. Luna‐Ruíz Arturo G. Valdivia‐Flores Vicente Díaz‐Núez Luis I. Íiguez‐Dvalos 《Ecology and evolution》2020,10(6):2991-3003
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
17.
Tina E. Berry Sylvia K. Osterrieder Dáithí C. Murray Megan L. Coghlan Anthony J. Richardson Alicia K. Grealy Michael Stat Lars Bejder Michael Bunce 《Ecology and evolution》2017,7(14):5435-5453
The analysis of apex predator diet has the ability to deliver valuable insights into ecosystem health, and the potential impacts a predator might have on commercially relevant species. The Australian sea lion (Neophoca cinerea) is an endemic apex predator and one of the world's most endangered pinnipeds. Given that prey availability is vital to the survival of top predators, this study set out to understand what dietary information DNA metabarcoding could yield from 36 sea lion scats collected across 1,500 km of its distribution in southwest Western Australia. A combination of PCR assays were designed to target a variety of potential sea lion prey, including mammals, fish, crustaceans, cephalopods, and birds. Over 1.2 million metabarcodes identified six classes from three phyla, together representing over 80 taxa. The results confirm that the Australian sea lion is a wide‐ranging opportunistic predator that consumes an array of mainly demersal fauna. Further, the important commercial species Sepioteuthis australis (southern calamari squid) and Panulirus cygnus (western rock lobster) were detected, but were present in <25% of samples. Some of the taxa identified, such as fish, sharks and rays, clarify previous knowledge of sea lion prey, and some, such as eel taxa and two gastropod species, represent new dietary insights. Even with modest sample sizes, a spatial analysis of taxa and operational taxonomic units found within the scat shows significant differences in diet between many of the sample locations and identifies the primary taxa that are driving this variance. This study provides new insights into the diet of this endangered predator and confirms the efficacy of DNA metabarcoding of scat as a noninvasive tool to more broadly define regional biodiversity. 相似文献
18.
Robert C. Lonsinger Eric M. Gese Steven J. Dempsey Bryan M. Kluever Timothy R. Johnson Lisette P. Waits 《Molecular ecology resources》2015,15(4):831-842
Noninvasive genetic sampling, or noninvasive DNA sampling (NDS), can be an effective monitoring approach for elusive, wide‐ranging species at low densities. However, few studies have attempted to maximize sampling efficiency. We present a model for combining sample accumulation and DNA degradation to identify the most efficient (i.e. minimal cost per successful sample) NDS temporal design for capture–recapture analyses. We use scat accumulation and faecal DNA degradation rates for two sympatric carnivores, kit fox (Vulpes macrotis) and coyote (Canis latrans) across two seasons (summer and winter) in Utah, USA, to demonstrate implementation of this approach. We estimated scat accumulation rates by clearing and surveying transects for scats. We evaluated mitochondrial (mtDNA) and nuclear (nDNA) DNA amplification success for faecal DNA samples under natural field conditions for 20 fresh scats/species/season from <1–112 days. Mean accumulation rates were nearly three times greater for coyotes (0.076 scats/km/day) than foxes (0.029 scats/km/day) across seasons. Across species and seasons, mtDNA amplification success was ≥95% through day 21. Fox nDNA amplification success was ≥70% through day 21 across seasons. Coyote nDNA success was ≥70% through day 21 in winter, but declined to <50% by day 7 in summer. We identified a common temporal sampling frame of approximately 14 days that allowed species to be monitored simultaneously, further reducing time, survey effort and costs. Our results suggest that when conducting repeated surveys for capture–recapture analyses, overall cost‐efficiency for NDS may be improved with a temporal design that balances field and laboratory costs along with deposition and degradation rates. 相似文献
19.
ROGER A. H. DRAYCOTT REW N. HOODLESS MAUREEN I. A. WOODBURN & RUFUS B. SAGE 《Ibis》2008,150(S1):37-44
The Common Pheasant Phasianus colchicus is currently the most abundant, widespread and economically important gamebird in Europe. The Game and Wildlife Conservation Trust has undertaken several recent studies of Pheasant breeding ecology to improve the management of this species. Although predation is often the most important cause of nest failure in declining ground-nesting birds in agricultural landscapes, the causes of predation and the identity of predators are often unknown. In this paper, we analyse data from approximately 450 nests of radiotagged hen Pheasants collected from six sites between 1990 and 2003 and present results on the fate and survival rates of Pheasant nests in relation to habitat, predation control and other covariates. Survival rates during the laying stage and incubation stage were 28 and 37%, respectively, and overall nest survival was 10%. Nest predation rates were significantly lower on two sites where intensive predation control was undertaken than on four sites with only low levels of predation control. Red Foxes Vulpes vulpes and corvids were the most important nest predators, accounting for at least half of all predation events. We assess these results in the context of other ground-nesting farmland birds. 相似文献
20.
Noninvasive faecal DNA sampling has the potential to provide a wealth of information necessary for monitoring and managing endangered species while eliminating the need to capture, handle or observe rare individuals. However, scoring problems, and subsequent genotyping errors, associated with this monitoring method remain a great concern as they can lead to misidentification of individuals and biased estimates. We examined a kit fox scat data set (353 scats; 80 genotypes) for genotyping errors using both genetic and GIS analyses, and evaluated the feasibility of combining both approaches to assess reliability of the faecal DNA results. We further checked the appropriateness of using faecal genotypes to study kit fox populations by describing information about foxes that we could deduce from the 'acceptable' scat genotypes, and comparing it to information gathered with traditional field techniques. Overall, genetic tests indicated that our data set had a low rate of genotyping error. Furthermore, examination of distributions of scat locations confirmed our data set was relatively error free. We found that analysing information on sex primer consistency and scat locations provided a useful assessment of scat genotype error, and greatly limited the amount of additional laboratory work that was needed to identify potentially 'false' scores. 'Acceptable' scat genotypes revealed information on sex ratio, relatedness, fox movement patterns, latrine use, and size of home range. Results from genetic and field data were consistent, supporting the conclusion that our data set had a very low rate of genotyping error and that this noninvasive method is a reliable approach for monitoring kit foxes. 相似文献