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Francesca Marini Simone Ceccobelli Corrado Battisti 《Wetlands Ecology and Management》2011,19(2):159-164
Following an apparent increase of local population density of coypu (Myocastor coypus) in a Mediterranean remnant wetland, we developed a pilot study aimed to evaluate a specific control program. Inside the
study area, we performed three transects per month from August 2008 to July 2009, grouping data in bimonthly periods. The
water level in the study area showed a maximum in December–January, significantly decreasing from late spring to summer and
significantly increasing from late summer to winter. Sampled individuals mainly occurred in Phragmites reed beds and in rush beds (dominance of Carex sp., Juncus sp. Bolboschoenus sp.). The index of mean relative density of coypu individuals ranged between 1.40 (February–March) and 5.72 (October–November)
with an evident increase in late summer–autumn. During this period, mean density of runways was higher in reed beds than in
rush beds, with differences tending to significance. In summer, the network of channels in reed beds, locally used for fishery
farm, may maintain a water level suitable for the coypu. These results (preference for reed beds and increase of coypu density
in late summer–autumn) should be considered when coypu populations are under control program, at least in the Mediterranean
region where there is a scarcity of available data. 相似文献
3.
The robust design is a method for implementing a mark-recapture experiment featuring a nested sampling structure. The first level consists of primary sampling sessions; the population experiences mortality and immigration between primary sessions so that open population models apply at this level. The second level of sampling has a short mark-recapture study within each primary session. Closed population models are used at this stage to estimate the animal abundance at each primary session. This article suggests a loglinear technique to fit the robust design. Loglinear models for the analysis of mark-recapture data from closed and open populations are first reviewed. These two types of models are then combined to analyze the data from a robust design. The proposed loglinear approach to the robust design allows incorporating parameters for a heterogeneity in the capture probabilities of the units within each primary session. Temporary emigration out of the study area can also be accounted for in the loglinear framework. The analysis is relatively simple; it relies on a large Poisson regression with the vector of frequencies of the capture histories as dependent variable. An example concerned with the estimation of abundance and survival of the red-back vole in an area of southeastern Québec is presented. 相似文献
4.
The southeastern mountains of Spain represent the southernmost limit of the genus Austropotamobius and the species A. pallipes (Lereboullet). The taxonomic position of this isolated crayfish in southern Spain is not clear, being genetically close to
A. italicus, but morphologically distinct. A severe decline occurred during the 1980s, especially due to expansion of the alien species
Procambarus clarkii, a North American freshwater crayfish and a vector of the aphanomycosis disease. In order to design a strategy for native
crayfish conservation, recent trends in native crayfish populations, influence of isolation and habitat variables on their
survival and possibilities for their recovery through restocking were studied. A decline in populations was observed between
1991 and 2002 (from 26 to 14 populations), and a total extinction could be predicted within the next 13 years. Two well-defined
periods of rapid extinction rates were detected, 1991–1994 (1.25 populations/year) and 1999–2002 (1.50 populations/year).
Main causes of extinction for these two periods were invasion by P. clarkii and mortality by unknown causes, respectively. The isolation variables had some positive effects on survival of populations
but these cannot offer a sufficient guarantee, since several cases of extinction can be affected by a large component of stochastic
factors, including random catastrophes. On the other hand, survival trials and restocking experiments showed that it was possible
to recover lost habitats, when P. clarkii was absent and environmental conditions were good. It is concluded that it is possible to avoid extinction of the native
crayfish populations; however, the conservation strategies must be based on an urgent stocking/restocking program. 相似文献
5.
Thomas C. Wanger Iris Motzke Samuel C. Furrer Barry W. Brook Bernd Gruber 《Ecological Research》2009,24(2):345-353
Rapid and reliable estimation of population size is needed for the efficient monitoring of animal populations of conservation
concern. Unfortunately, technical advances in this area have not been paralleled in uptake in conservation, which may be due
to difficulties in implementation or the lack of general guidelines for application. Here we tested five different methods
used to estimate population size [capture–mark–recapture (CMR), finite-mixture models, model averaging of finite-mixture models,
accumulation curve methods (ACM), and the line transect method (LT)] using extensive capture–recapture data of the giant day
gecko (Gekkonidae, Phelsuma madagascariensis grandis, Gray 1870) at the Masoala rainforest exhibit, Zurich Zoo. When the complete data were analyzed [30 sessions (and 27 sessions
for the LT)], all methods except the LT produced similar estimates of population size. The simple ACM gave a small coefficient
of variation (CV), but did not cover the most likely value of population size at moderate sampling effort. Nevertheless, the
ACM was the only method that showed a reasonable convergence when subsets of data were used. CMR and Pledger models included
the reference value in their confidence intervals (CI) after 25 and 30 sessions, respectively. Although model averaging did
slightly improve the estimate, the CV was still high for the full dataset. Our method of using subsets of data to test the
robustness of estimates is simple to apply and could be adopted more widely in such analyzes to evaluate sensitivity to method
of evaluation. In conclusion, simple accumulation methods showed similar efficiency to more complex statistical models, and
are likely to be sufficiently precise for most conservation monitoring purposes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
John D. Willson Christopher T. Winne Brian D. Todd 《The Journal of wildlife management》2011,75(1):36-45
Although mark-recapture methods are among the most powerful tools for monitoring wildlife populations, the secretive nature of some species requires a comprehensive understanding of the factors that affect capture probability to maximize accuracy and precision of population parameter estimates (e.g., population size and survivorship). Here, we used aquatic snakes as a case study in applying rigorous mark-recapture methods to estimate population parameters for secretive species. Specifically, we used intensive field sampling and robust design mark-recapture analyses in Program MARK to test specific hypotheses about ecological and methodological factors influencing detectability of two species of secretive aquatic snakes, the banded watersnake (Nerodia fasciata), and the black swamp snake (Seminatrix pygaea). We constructed a candidate set of a priori mark-recapture models incorporating various combinations of time- and sex-varying capture and recapture probabilities, behavioral responses to traps (i.e., trap-happiness or trap-shyness), and temporary emigration, and we ranked models for each species using Akaike's Information Criterion. For both banded watersnakes and black swamp snakes we found strong support for time-varying capture and recapture probabilities and strong trap-happy responses, factors that can bias population estimation if not accommodated in the models. We also found evidence of sex-dependent temporary emigration in black swamp snakes. Our study is among the first comprehensive assessments of factors affecting detectability in snakes and provides a framework for studies aimed at monitoring populations of other secretive species. © 2010 The Wildlife Society. 相似文献
7.
Daniela M. Simeonovska-Nikolova 《Journal of Ethology》2007,25(1):41-48
The social interactions between Apodemus agrarius and A. flavicollis, and their behavioral responses to conspecific and heterospecific odors, were studied in male–male and female–female interspecific
dyadic encounters, and an attraction–avoidance test was used in order to clarify the behavioral mechanisms which control their
relationships in wild populations. The experiments were carried out at the beginning and at the end of the breeding season—in
spring and in autumn. In spring the aggressiveness was higher than in autumn. Males of both species showed attraction to conspecific
odors from the opposite sex, while the females were indifferent. In autumn both males and females displayed attraction to
conspecific odors from the same sex. However, mice of both species showed avoidance to heterospecific odors from the same
and the opposite sex in spring, and indifference to heterospecific odors from the same and the opposite sex in autumn. Based
on these findings, it could be assumed that the patterns of social interactions and responses to conspecific and heterospecific
odors undergo seasonal changes in their life cycle. Probably the avoidance response to heterospecific odors could serve as
a spacing mechanism to avoid aggressive encounters between A. agrarius and A. flavicollis in syntopic habitats during the breeding period. 相似文献
8.
Frank J. Rahel 《Environmental Biology of Fishes》1989,24(4):301-306
Synopsis Aggression by nest-guarding male johnny darters, Etheostoma nigrum, against intruding crayfish was investigated in laboratoy experiments and field observations. In the laboratory, darter success
in chasing crayfish, Orconectes rusticus, from the nest site was inversely related to crayfish size. Small crayfish (less than 15 mm carapace length) were routinely
evicted from the nest area by nips directed at the posterior end of the abdomen. Although such aggressive behavior was less
successful against larger crayfish, even the largest crayfish tested (carapace length 30–32 mm) were chased from the nest
area in 33% of the trials. Those large crayfish that entered nests often remained despite repeated attacks by the male johnny
darter and egg predation was observed. In a small Ohio stream, openings to johnny darter nests were generally between 7 and
13 mm. Thus crayfish with a carapace height greater than 13 mm (corresponding to a carapace length greater than 29 mm) would
not be able to enter johnny darter nests. In field observations, male Johnny darters successfully defended nests against another
crayfish species (Orconectes sanborni, carapace length 12–29 mm). Together, aggressive behavior and small size of nest entrances allow the johnny darter to successfully
reproduce in areas with abundant crayfish.
The Unit is sponsored jointly by the United States Fish and Wildlife Service, The Ohio Department of NaturalResources, and
The Ohio State University. 相似文献
9.
Sara Persson Britt-Marie Bäcklin Hans Kindahl Björn Brunström Ulf Magnusson 《European Journal of Wildlife Research》2011,57(5):1057-1063
The objectives of this study on the reproductive system of wild male mink (Neovison vison) were to determine the influence of age, nutritional status and season on reproductive traits and to produce baseline data
that may be used in environmental monitoring programmes. The 117 male mink included in the study were killed by hunters all
over Sweden (from latitude 56° N to 67° N) during August to the end of April from 2005 to 2008. The weights of penis, testes,
and epididymides were lower, the anogenital distance was shorter and the diameter of seminiferous tubules was less in juveniles
compared with adult mink (p < 0.0001–p = 0.0024). There was a positive effect (p < 0.05) of nutritional status on the baculum length and on the anogenital distance, but not on any of the other reproductive
traits. The season of sampling influenced the penis, testes and epididymes weights and the diameter of seminiferous tubules
(p = 0.008–p < 0.0001). During spring, 86% of the mink had sperm in their epididymides, whereas the corresponding figure for autumn was
3%; in addition, when the average diameter of the tubules reached 138 μm, sperm were present in the epididymides. Sperm morphology
was analysed in 29 of the mink, and the percentage of morphologically defect sperm were generally low. Taken together, this
study suggests that when assessing male reproductive data in wild mink populations, season must be taken into account as well
as whether the individuals are juvenile or adult. In contrast, the nutritional status seems not to be of any major significance. 相似文献
10.
11.
Non-indigenous crayfish often have major ecological impacts on invaded water bodies, and have contributed to the decline of
native crayfish species throughout Europe. The American signal crayfish, Pacifastacus leniusculus, is the most widespread invasive crayfish in Great Britain, where the zebra mussel, Dreissena polymorpha, is similarly an invasive pest species. The potential for the American signal crayfish to regulate zebra mussel populations
was investigated through a series of laboratory experiments. Crayfish were found to be highly size selective, consuming significantly
more of the smallest size class of zebra mussels offered (7–12 mm), over medium (16–21 mm) and large (25–30 mm). Crayfish
feeding rate on zebra mussels was not altered when mussels were presented clumped together in natural druses compared with
mussels in a disassembled druse. Crayfish spent significantly more time foraging when mussels were unattached, and a greater
proportion of attacks were on medium and large than on small mussels (83% of attacks were on medium and large mussels when
unattached as opposed to 47% when on druses). Individual crayfish feeding rate decreased significantly at densities of > ~5
crayfish m−2. Signal crayfish are, therefore, unlikely to be able to significantly impact established populations of zebra mussels in
the wild, although zebra mussels have the potential to provide crayfish with a substantial food source. 相似文献
12.
Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption–as when certain members of the population are either easier or more difficult to capture than other animals–can lead to biased and inaccurate demographic estimates. We built within-year and among-years Cormack-Jolly-Seber recaptures-only models to identify causes of capture heterogeneity for a population of colonially nesting cliff swallows (Petrochelidon pyrrhonota) caught using mist-netting as a part of a 20-year mark-recapture study in southwestern Nebraska, U.S.A. Daily detection of cliff swallows caught in stationary mist nets at their colony sites declined as the birds got older and as the frequency of netting at a site within a season increased. Experienced birds’ avoidance of the net could be countered by sudden disturbances that startled them into a net, such as when we dropped a net over the side of a bridge or flushed nesting cliff swallows into a stationary net positioned at a colony entrance. Our results support the widely held, but seldom tested, belief that birds learn to avoid stationary mist nets over time, but also show that modifications of traditional field methods can reduce this source of recapture heterogeneity. 相似文献
13.
The swift fox Vulpes velox Say, 1823, a small canid native to shortgrass prairie ecosystems of North America, has been the subject of enhanced conservation
and research interest because of restricted distribution and low densities. Previous studies have described distributions
of the species in the southern Great Plains, but data on density are required to evaluate indices of relative abundance and
monitor population trends. We examined regressions of swift fox density (estimated by mark-recapture) on timed-track surveys,
scat surveys, and catch-per-unit effort indices. Seventy-nine swift foxes (42 male, 37 female) were captured 151 times during
10 240 trapnights between May 2003 and December 2004 in the Panhandle of Oklahoma, USA. Density estimates, based on mark-recapture
data from autumn 2004, were 0.08–0.44 foxes/km2. Survey indices explained 51 to 76% of the variation in estimates of fox density. Our study indicates that surveys of time-to-track
encounters and scat deposition rates show promise in monitoring trends in population abundance over large areas. 相似文献
14.
Julian D. Olden Julia M. McCarthy Jeffrey T. Maxted William W. Fetzer M. Jake Vander Zanden 《Biological invasions》2006,8(8):1621-1628
The rusty crayfish, Orconectes rusticus, is one of America’s best-known non-indigenous crayfishes, having been identified as extirpating native crayfishes and disrupting
local aquatic ecosystems. Over the past 40–50 years, rusty crayfish have spread from its historical range in the Ohio River
drainage (U.S.A.), to waters throughout much of Illinois, Michigan, Wisconsin, and Minnesota and parts of 11 other states,
Ontario (Canada) and the Laurentian Great Lakes. Using a comprehensive dataset based on all known historical records and extensive
present-day surveys (n = 2775) this study reports on the invasion history of rusty crayfish, with observations on concomitant declines of native
crayfishes in Wisconsin over the past 130 years (1870–2004). We found that rusty crayfish occurrences have increased from
7% of all crayfish records collected during the first 20 years of their invasion (1965–1984) to 36% of all records during
the last 20 years, and that rusty crayfish have replaced the northern clearwater crayfish (O. propinquus) and virile crayfish (O. virilis) as the most dominant member of the contemporary crayfish fauna. In light of our results we discuss the introduction, establishment
and integration phases of the rusty crayfish invasion and provide preliminary predictions of the potential distribution of
rusty crayfish in Wisconsin lakes based on critical environmental requirements. 相似文献
15.
In many species of mammals, adults play an important role in influencing the survival and/or reproduction of juveniles. Adult
males could have a negative effect on population density when their absence becomes a limiting factor in female fertilization.
We tested the hypotheses that the absence of overwintering males (adult males) reduces the population growth rate through
a delay in the onset of reproductive activity of Cohort 1 females in Calomys venustus populations. The study was carried out in two control and two experimental enclosures (0.25 ha). Adult males were removed
after their offspring were born. Weekly trapping sessions were carried out from spring to autumn. To estimate population growth
rates (λ), apparent survival (ϕ) and seniority probability (γ) were estimated using capture–mark-recapture models. Models were constructed with these two parameters and recapture probability
(p) constrained to vary as a function of time, enclosure and/or treatment. We derived estimates of population growth rates through
the estimates of ϕ and γ. The best models for ϕ and γ did not show a treatment effect. Variability between the four enclosures was greater than between control and experimental
enclosures. Enclosures had different growth rates at the beginning of the study but were equaled at the end. Temporal variation
in population growth rates was a result of temporal variation of γ. The two controls showed the highest growth rates earlier in time. The results did not support the hypothesis tested in this
study. It seems that the number of overwintering males do not affect the population growth rate. 相似文献
16.
V. Sommer 《Human Evolution》1988,3(4):261-278
During a 15 month study on free ranging langurs (Presbytis entellus) at Jodhpur, Rajasthan, India, 5 adult male replacements were observed as a result of nontroop male invasions into the home
ranges of 3 neighbouring one-male troops comprising 16–28 members each. Jodhpur langurs have no breeding season. Periods of
instability during resident male changes lasted 11–119 days. Linear dominance hierarchies could be detected within the 3 main
rival male bands of 2, 5, and 28–35 members. The respective alphas drove their allies away after their bands succeeded cooperatively
at occupying a troop. During gradual replacements interim residencies alternated with multi-male stages. A large band's alpha
may have had better chances to win the competition, since adult and nonadult allies functioned as “buffers” in agonistic encounters.
The role of kin selection in structuring the composition of male bands and male coalitional behaviour cannot yet be quantified.
Tactical “deceit” of powerful males to cause unrealistic expectations and in this way agonistic engagement of less strong
males can be ruled out. “Sneaking copulations” is a proximate advantage for subordinate supporters, since they participated
in 61.9% of all sexual interactions. Female promiscuity might reflect a strategy to induce male-male competition and thus
select for a strong resident. 相似文献
17.
The potential impact of introduced species on rare taxa is of particular concern to conservation biologists. We evaluate the
impacts of western mosquitofish (Gambusia affinis) and virile crayfish (Orconectes virilis) on experimental populations of a threatened species, the White Sands pupfish (Cyprinodon tularosa). Forty experimental pupfish populations were exposed to one of four treatments; (a) 1 crayfish, (b) 4 crayfish, (c) 5 adult
mosquitofish and (d) control. Pupfish population size and biomass was monitored over the duration of one breeding season.
A repeated measure multiple analysis of covariance revealed a significant effect of treatments on response variables (population
size and biomass) (P<0.0001). Mosquitofish had a significant effect on population size and biomass (P=0.0330). The effect of one crayfish was not significant (P=0. 0683). However, 4 crayfish had a significant effect (P<0.0001) on population size. We use these data, along with information on environmental tolerances of crayfish and mosquitofish,
to evaluate risks for specific pupfish populations.
An erratum to this article is available at . 相似文献
18.
Christina Dagmar Buesching Michael Heistermann David W. Macdonald 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(9):865-871
Elevated testosterone levels can lower condition and increase parasites. We analysed testosterone in 84 blood samples of wild
European badgers Meles meles collected at regular intervals (winter = mating season; spring = end of mating season; summer = minor mating peak; autumn = reproductive
quiescence), and related variation to body condition, subcaudal gland secretion, parasite burden, and bite wounding. All males
showed elevated levels in winter and low levels in autumn. In neither season did testosterone correlate with fitness-related
parameters. However, two different endocrinological phenotypes existed in spring and summer. Whilst some males lowered their
testosterone to levels comparable to autumnal quiescence (Type 1), others maintained elevated levels comparable to those during
winter (Type 2). In spring and summer high levels were correlated with lower body condition and increased parasite burden,
and Type 2 males tended to suffer higher mortality rates than Type 1. No animals older than 6 years adopted phenotype 2, indicating
that males either switch phenotypes with age or that Type 2 results in lower life expectancy, evidencing the costs of male
reproduction in badgers. 相似文献
19.
Greg G. Sass Thad R. Cook Kevin S. Irons Michael A. McClelland Nerissa N. Michaels T. Matthew O’Hara Matthew R. Stroub 《Biological invasions》2010,12(3):433-436
Invasive silver carp (Hypophthalmichthys molitrix) populations have expanded greatly in the Upper Mississippi River System (UMRS) since their introduction in the early 1970s.
We conducted a Chapman-modified, continuous Schnabel mark-recapture population and biomass estimate for silver carp (106–901 mm)
in the La Grange reach, Illinois River during 2007–2008. We estimated a total of 328,192 (95% CI 231,226–484,474) silver carp
(2,544 per river km 1,792–3,756) comprising 705 (95% CI; 496–1,040) metric tons of biomass (5.5 metric tons per river km 3.8–8.1).
Long Term Resource Monitoring Program (LTRMP) data from the La Grange reach showed an exponential increase in silver carp
catches since 1998, with an intrinsic rate of increase approaching 84%. In 2008, silver carp comprised about 51% of the total
LTRMP annual fish collection. To our knowledge, this large river reach may contain the greatest ambient densities of wild
silver carp in the world. Our findings provide a target for reduction efforts and also emphasize the importance of the La
Grange reach as a source population for potential expansion of the species to the Laurentian Great Lakes. 相似文献
20.
Understanding drivers of temporal variation in demographic parameters is a central goal of mark-recapture analysis. To estimate the survival of migrating animal populations in migration corridors, space-for-time mark–recapture models employ discrete sampling locations in space to monitor marked populations as they move past monitoring sites, rather than the standard practice of using fixed sampling points in time. Because these models focus on estimating survival over discrete spatial segments, model parameters are implicitly integrated over the temporal dimension. Furthermore, modeling the effect of time-varying covariates on model parameters is complicated by unknown passage times for individuals that are not detected at monitoring sites. To overcome these limitations, we extended the Cormack–Jolly–Seber (CJS) framework to estimate temporally stratified survival and capture probabilities by including a discretized arrival time process in a Bayesian framework. We allow for flexibility in the model form by including temporally stratified covariates and hierarchical structures. In addition, we provide tools for assessing model fit and comparing among alternative structural models for the parameters. We demonstrate our framework by fitting three competing models to estimate daily survival, capture, and arrival probabilities at four hydroelectric dams for over 200 000 individually tagged migratory juvenile salmon released into the Snake River, USA. 相似文献