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1.
In the Alps tourism, land-use practices and climate change may cause a loss of suitable habitat of rock ptarmigan (Lagopus muta helvetica). Hence, there is a need for basic research on population densities and habitat requirements of this species as a basis for
long-term monitoring studies. So far, in the Austrian Alps, no accurate data on densities and trends of rock ptarmigan populations
are available. We carried out counts of calling cocks in the southeastern part of the Austrian Alps (Nockberge National Park,
Carinthia, Austria) between 31 May and 1 July 2003 and evaluated the distribution of male rock ptarmigan territories. The
spring density of 5.4 territorial cocks per square kilometre was similar to densities in the Swiss Alps but higher than spring
population densities in the Italian Alps and the Pyrenees. To investigate summer habitat use, we established a grid mapping
of habitat parameters and rock ptarmigan signs. In total, 38 squares with signs of rock ptarmigan presence were recorded (i.e.
32% of all recorded squares). The presence of rock ptarmigan was significantly correlated with cover of rock and rock ptarmigan
preferred habitat patchiness. Our study provides a useful reference for future monitoring of this species in the alpine distribution
range considering the potential decrease and fragmentation of alpine habitats resulting from climate change and human impacts. 相似文献
2.
This paper describes a census technique that gives estimates of rock ptarmigan cocks’ number per unit area during the breeding
season. This method originated from the need for an effective technique for estimating bird densities in mountainous and inaccessible
zones like the Pyrenean chain. The bird census was carried out using a point–count method, which is recommended for uneven
areas. To maximize sampling efficiency, we established sampling points at <500-m distances, in order to detect a maximum of
calling birds within the sample areas. Birds localized at distances >250 m were excluded. We postulate that all birds are
recorded in a 250-m radius around the observer. We carried out counts of calling rock ptarmigan cocks in the border between
the Principality of Andorra and Ariège Department, France, from April to June during three consecutive years (2005–2007).
The estimated spring density of 10.4 cocks per 100 ha was higher than densities reported in literature, in other parts of
the Pyrénées and the Alps. Our study provides a useful reference for future monitoring of this species in its mountainous
distribution range. 相似文献
3.
4.
Two recent studies on territory occupancy rates of goshawk Accipiter gentilis and gyrfalcon Falco rusticolus report a 2–3-year-delayed numerical response to grouse numbers, which is a requirement for a hypothesis of predator-generated
grouse cycles. The time lags were assumed to reflect the average age of sexual maturity in the raptor species. In southern
Norway, however, subadult (two-year-old) goshawk hens occupied only 18–25% of territories where occupancy was not recorded
in the preceding year, and there was no significant relationship between the proportion of subadults among recruits and grouse
indices two years earlier. We argue that territory occupancy rates are not appropriate indices of total raptor population
levels, but rather reflect the proportion of territorial pairs that attempt to nest. Because this depends on the body condition
of the hens, fluctuations in other important winter resident prey species (most important for the goshawk) and winter weather
(most important for the gyrfalcon) should also be addressed. During 1988–2006, the annual proportion of goshawk territories
with recorded nesting attempts in southern Norway was most closely related to the preceding autumn’s population indices of
black grouse Tetrao tetrix and mountain hare Lepus timidus, whereas the annual proportion of gyrfalcon territories with observations of falcons or with confirmed breeding attempts
in central Norway were best explained by population indices of willow grouse Lagopus lagopus and ptarmigan L. mutus from the previous autumn, and by December temperatures. Hence, our studies do not support the predation hypothesis for grouse
cycles. 相似文献
5.
Ilse Storch 《Oecologia》1993,95(2):257-265
The use of habitat by female and male adult capercaillie Tetrao urogallus during summer and autumn was studied by comparing the distribution of radio locations of birds with the availability of habitat at forest stand, home range and landscape level in an area of the Bavarian Alps, Germany. Capercaillie preferred forests with structural features typical of their main distribution range, the boreal forest: they selected large patches of old forest with moderate canopy cover of about 50%, and a well developed field layer with high proportions of bilberry Vaccinium myrtillus. Hens selected both home ranges and sites within home ranges in old forest. Ranges selected by cocks did not differ from availability in the study area, but they preferred old forest within their ranges. The size of home ranges was negatively related to bilberry cover both in hens and cocks. The distribution of bilberry also determined habitat use by capercaillie at the landscape scale. The study demonstrated that bilberry is the major determinant of the selection of habitat by capercaillie in landscapes with sparse and fragmentary cover of ericaceous shrubs, such as central Europe. 相似文献
6.
Aditya Singh Tommy C. Hines Jeffery A. Hostetler H. Franklin Percival Madan K. Oli 《European Journal of Wildlife Research》2011,57(1):15-26
The manner by which animals use space and select resources can have important management consequences. We studied patterns
of habitat selection by northern bobwhites (Colinus virginianus) on Babcock-Webb Wildlife Management Area, Charlotte County, Florida and evaluated factors influencing the sizes of their
home ranges. A total of 1,245 radio-tagged bobwhites were monitored for 19,467 radio days during 2002–2007. The mean ( ± 1
SE) annual home range size, estimated using the Kernel density method, was 88.43 ( ± 6.16) ha and did not differ between genders.
Winter home ranges of bobwhites (69.27 ± 4.92 ha) were generally larger than summer home ranges (53.90 ± 4.93 ha). Annual
and winter home ranges were smaller for bobwhites whose ranges contained food plots compared to those that did not; however,
the presence of food plots did not influence summer home ranges. We used distance-based methods to investigate habitat selection
by bobwhites at two scales: selection of home ranges within the study site (second-order selection) and selection of habitats
within home ranges (third-order selection). Across both scales, bobwhites generally preferred food plots and dry prairie habitat
and avoided wet prairies and roads. This pattern was generally consistent between genders and across years. Our data indicate
that management practices aimed at increasing and maintaining a matrix of food plots and dry prairie habitat would provide
the most favorable environment for bobwhites. 相似文献
7.
Organisms living in arctic and alpine environments are increasingly impacted by human activities. To evaluate the potential impacts of global change, a better understanding of the demography of organisms in extreme environments is needed. In this study, we compare the age-specific demography of willow ptarmigan (Lagopus lagopus) breeding at arctic and subalpine sites, and white-tailed ptarmigan (L. leucurus) breeding at an alpine site. Rates of egg production improved with age at the alpine and subalpine sites, but the stochastic effects of nest and brood predation led to similar rates of annual fecundity among 1-, 2-, and 3+-year-old females. All populations had short generation times (T<2.7 years) and low net reproductive rates (R
0<1.2). Stable age distributions were weighted towards 1-year-old females in willow ptarmigan (>59%), and to 3+-year-old females in white-tailed ptarmigan (>47%). High damping ratios (ρ>3.2) indicated that asymptotic estimates were likely to match natural age distributions. Sensitivity and elasticity values indicated that changes in juvenile survival would have the greatest impact on the finite rate of population change (λ) in willow ptarmigan, whereas changes to the survival of 3+-year-old females would have a greater effect in white-tailed ptarmigan. High survivorship buffers white-tailed ptarmigan in alpine environments against the potential effects of climate change on annual fecundity, but may make the species more sensitive to the effects of pollutants or harvesting on adult survival. Conversely, processes that reduce annual fecundity would have a greater impact on the population viability of willow ptarmigan in arctic and subalpine environments. If these same demographic patterns prove to be widespread among organisms in extreme environments, it may be possible to develop general recommendations for conservation of the biological resources of arctic and alpine ecosystems. 相似文献
8.
Francesco Bisi Mosé Nodari Nuno Miguel Dos Santos Oliveira Elisa Masseroni Damiano G. Preatoni Lucas A. Wauters Guido Tosi Adriano Martinoli 《European Journal of Wildlife Research》2011,57(2):305-312
Populations on the limits of species’ distribution can show different behavioral adaptations to strong ecological pressure
than in the central part of the range. We investigated space use patterns of alpine mountain hare (Lepus timidus) at two areas on the southern edge of the species’ range. We monitored 34 hares between 2005 and 2008, estimating home range
size, overlap, and site fidelity, and compared our results with space use in Scottish and North-European populations. Home
ranges of mountain hares did not differ between two study areas with different habitat types. Subadult animals used larger
ranges than adults and both age groups reduced home range size in autumn, a period that might be critical for hares due to
changes in diet and/or high energy expenditure during the previous breeding season. Home ranges in these alpine populations
were smaller than in Scandinavian populations but within the range of populations in different habitat types in Scotland.
Seasonal home ranges overlapped considerably, but differed among the sexes: male–female overlap was higher than same sex (male–male
and female–female) spatial overlap. Seasonal shifts of home ranges were small, and site fidelity remained high over the seasons,
suggesting that resource distribution remained constant throughout the year and that the knowledge of an intensively frequented
area is an important element of habitat quality. We concluded that habitat structure and availability of mates interact in
affecting mountain hare space use in alpine habitats. 相似文献
9.
Krzysztof Schmidt Włodzimierz Jędrzejewski Henryk Okarma Rafał Kowalczyk 《Ecological Research》2009,24(1):207-214
Various species of large predators are reported to influence each other through interference or exploitation competition that
may affect demography and survival of the subordinate species. We analyzed spatial relationships between grey wolf (Canis lupus) and Eurasian lynx (Lynx lynx) in Białowieża Primeval Forest (BPF, eastern Poland) to determine how they partitioned the space. The wolves (n = 8) and lynx (n = 14) were radio-tracked in 1991–1999. Three wolves and seven lynx were radio-tracked simultaneously in 1994–1996. Territories
of wolf packs and home ranges of lynx overlapped considerably (76% of wolf territories and 50% of lynx home ranges, on average).
In three cases, their core areas were also overlapping. Wolf-lynx dyads with overlapping home ranges were simultaneously located
at distances from 0 to 28 km from each other. We found neither avoidance nor attraction between wolves and lynx occupying
the same areas. We concluded that in BPF, the two large predators coexist due to specialization on different preferred prey
and heterogeneous habitat. 相似文献
10.
According to the European Bird Directive (Council Directive 79/409/EEC of 2 April 1979 on the conservation of wild birds),
particular efforts must be made to preserve the Rock Ptarmigan (Lagopus muta helvetica) and its habitats. Protection and management of this species require basic knowledge of the current status of each of its
populations. Within the Austrian distribution range of Rock Ptarmigan, only two study sites from the inner parts of the Alps
have been investigated and no data on the most eastern pre-alpine populations are available. In the present study, we conducted
simultaneous counts of calling Rock Ptarmigan cocks and recorded calling activities. We calculated spring densities for alpine
and pre-alpine study areas and compared them. Spring densities for different habitat types in one study area were observed
and compared. Spring densities and calling activities differed between study sites, even within the most eastern border of
distribution. Generally, spring densities seem to be higher in alpine habitats than in pre-alpine study sites. In one alpine
study area, the highest spring densities were found for habitat patches with a heterogeneous mixture of rocky surface and
dwarf pine. 相似文献
11.
Erica Di Pierro Ambrogio Molinari Guido Tosi Lucas A. Wauters 《Ecological Research》2008,23(3):529-542
When animal home ranges overlap extensively in species lacking overt territorial behaviours, identifying exclusive core areas
within individual ranges can be difficult. By analysing the size and overlap of successively smaller core areas among individual
Eurasian red squirrels (Sciurus vulgaris), we determined exclusive areas within the home ranges of resident males and females. Possible effects of habitat composition
and food supplies were explored by monitoring squirrels in different conifer forests and during years with low and high tree
seed production. Using outlier-exclusive cores (OEC) revealed that the total ranges consisted of large sally zones (on average,
35% of the total minimum convex polygon [MCP] range) around home ranges with multi-nucleate cores. The mean OEC home range
size did not differ between the sexes but was larger with poor food availability. Home ranges (99% incremental cluster polygons
[ICP]) overlapped extensively between sexes (average overlap high food–low food: males by females 21–40%, females by males
43–45%) and among males (males by males 26–44%), while intrasexual overlap among females was low (9–10%). The overlap of inner
cores among females rapidly approached zero, suggesting the intrasexual territoriality of 75% core areas. This was not the
case among male squirrels, for which intrasexual overlap averaged only 4% at 50% but 18% at 75% core areas. Even the smallest
inner cores had some degree of intersexual overlap, indicating that complete territoriality did not occur in this species.
Female home ranges were more strongly affected by annual fluctuations in food supplies than male ranges. Females reduced the
size of their food-based intrasexual territories when food availability increases. Males probably benefit from using larger
home ranges and core areas, which overlap with the ranges of several females, by increasing their probability of successful
mating. 相似文献
12.
Mogens Trolle Andrew J. Noss Edson De S. Lima Julio C. Dalponte 《Biodiversity and Conservation》2007,16(4):1197-1204
The maned wolf (Chrysocyon brachyurus) is threatened by large-scale habitat loss, in particular due to conversion to agricultural land. This is the first published
study on maned wolf density and the first test of individual identification from camera-trap photographs. We present results
from two Brazilian regions: the Cerrado and the Pantanal. Using capture–recapture analysis of camera-trap data, we estimated
densities per 100 square kilometers of 3.64 ± 0.77 individuals at the Cerrado site and 1.56 ± 0.77 individuals at the Pantanal
site. Parallel radio-telemetry studies at the Pantanal site showed that maned wolves occupied home ranges of 39–58 km2 (mean = 50.3 ± 7.67 km2). Our study in the Cerrado took place in a private farm with a mixture of agricultural land and native habitats, representative
of the majority of the present-day Cerrado. Whereas many other mammalian species have suffered in the region, our results
show that the maned wolf may cope better with this highly fragmented landscape than one might have feared. Finally, the paper
briefly compares maned wolf density with density of puma (Puma concolor) in the Pantanal site. 相似文献
13.
Seasonal home range dynamics and sex differences in habitat use in a threatened,coastal marsh bird 下载免费PDF全文
A comprehensive understanding of spatiotemporal ecology is needed to develop conservation strategies for declining species. The king rail (Rallus elegans) is a secretive marsh bird whose range historically extended across the eastern United States. Inland migratory populations have been greatly reduced with most remaining populations inhabiting the coastal margins. Our objectives were to determine the migratory status of breeding king rails on the mid‐Atlantic coast and to characterize home range size, seasonal patterns of movement, and habitat use. Using radiotelemetry, we tracked individual king rails among seasons, and established that at least a segment of this breeding population is resident. Mean (±SE) home range size was 19.8 ± 5.0 ha (95% kernel density) or 2.5 ± 0.9 (50% kernel density). We detected seasonal variation and sex differences in home range size and habitat use. In the nonbreeding season, resident male home ranges coincided essentially with their breeding territories. Overwintering males were more likely than females to be found in natural emergent marsh with a greater area of open water. Females tended to have larger home ranges than males during the nonbreeding season. We report for the first time the use of wooded natural marsh by overwintering females. Brood‐rearing king rails led their young considerable distances away from their nests (average maximum distance: ~600 ± 200 m) and used both wooded natural and impounded marsh. King rails moved between natural marsh and managed impoundments during all life stages, but the proximity of these habitat types particularly benefitted brood‐rearing parents seeking foraging areas with shallower water in proximity to cover. Our results demonstrate the importance of interspersion of habitat types to support resident breeders. Summer draining of impounded wetlands that are seasonally flooded for wintering waterfowl allows regrowth of vegetation and provides additional habitat at a critical time for wading birds. 相似文献
14.
Xingyi Gao Weikang Yang Jianfang Qiao Jun Yao Kefen Xu 《Frontiers of Biology in China》2008,3(4):385-391
This article presents the distribution and status of bustards, which are listed as first-category protected animals according
to the survey results during 1990–2002 in China. The Chinese populations of Otis tarda dybowskii are breeding in south-west of Heilongjiang Province, western Jilin Province, east and middle Inner Mongolia, north Ningxia
Hui Autonomous Region, and Gansu Province. A few can winter in the south breeding-range. Its winter-range lies from the south
to the Yellow River, as far as to Guizhou Province and Jiangxi Province. Its population number is about 200–300 or 500–800.
The Chinese populations of O. t. tarda are breeding in the north and west of Xinjiang. It is unclear about its winter-range, which is presumed to be in south Asia.
Recently we found individuals wintering in Chabuchaer and west Xinjiang. The population number is about 2000–3000. The habitat
in breeding range includes steppe, grassland, desert grassland, and farmland. The habitat in winter range is the beach of
rivers and lakes, meadows, meadow-grassland, and wheatland. The Chinese populations of Chlamydotis undulata macqueeni are breeding in the fringe of the Jungar Basin, the banks of the Ulungur River, Balikun and south Turpan Basin in Xinjiang,
west Inner Mongolia, and west Gansu. NortheastMulei in eastern Jungar Basin of Xinjiang is the main breeding-range in the
world. The bird uses desert and desert grassland as its habitat. Its winter-range is west Asia and south Asia. Its population
number is about 2000. The Chinese populations of Tetrax tetrax are breeding in north Xinjiang, and China is located on the east border of its breeding-range. Its habitat is grassland and
semi-desert, and its winter-range lies in south Asia. Its population in China is very scarce. In addition, we analyzed the
causes of their endangerment and put forward protection tactics of Chinese Bustards.
__________
Translated from Arid Zone Research, 2007, 24(2): 179–186 [译自: 干旱区研究] 相似文献
15.
Urbanization results in widespread habitat loss and fragmentation and generally has a negative impact upon native wildlife, in particular ground‐dwelling mammals. The northern brown bandicoot (Isoodon macrourus; Marsupialia: Peramelidae) is one of relatively few native Australian ground‐dwelling mammals that is able to survive within urbanized landscapes. As a consequence of extensive clearing and urban development within the city of Brisbane, bandicoots are now restricted to the mostly small (<10 ha) bushland fragments scattered across the city landscape. Our study examined the behavioural ecology of northern brown bandicoots within habitat fragments located on a major creek‐line, using mark‐recapture population monitoring and radio telemetry. Bandicoots at monitored sites were found to occur at high densities (typically one individual ha?1), although one‐third of the populations were transient. Radio tracking revealed that bandicoots had relatively small home ranges (mean 1.5 ± 0.2 ha) comprised largely of bushland/grassland with dense, often weed‐infested ground cover. Bandicoots sheltered by day in these densely covered areas and also spent most time foraging there at night, although they occasionally ventured small distances to forage in adjacent maintained parklands and residential lawns. We suggest that introduced tall grasses and other weeds contribute to high habitat quality within riparian habitat fragments and facilitate the persistence of high density populations, comprised of individuals with small home ranges. The generalized dietary and habitat requirements of northern brown bandicoots, as well as a high reproductive output, undoubtedly facilitate the survival of the species in urban habitat fragments. Further research is required on other native mammal species in urbanized landscapes to gain a greater understanding of how best to conserve wildlife in these heavily modified environments. 相似文献
16.
Population responses of Japanese serow (Capricornis crispus) to clear-cut logging and planted tree growth were studied by a direct count of the number observed in three areas, Takiyama
(305 ha), Gentouziro (270 ha), and Tanokashira (324 ha), near Wakinosawa Village, Aomori Prefecture, Japan, during 1976–89.
At Takiyama, a mature mixed forest ofThujopsis dolabrata var.hondai andFagus crenata decreased from 73 to 39% coverage of the area due to clear-cutting during 1978–83. The serow population maintained a relatively
low stable density (3–6 individuals per km2) until 1985–87, and increased 5–10 years after the clear-cutting, reaching 9–10 km−2 in 1988. At Gentouziro and Tanokashira, young plantations of Japanese cedar (Cryptomeria japonica) covered about half of each area. The population densities between 1980 and 1983 were relatively high (14–19 km−2), but declined thereafter, reaching 10–14 km−2 in 1988–89. These results indicated that the density increase resulted from an improvement of food supply due to growth of
scrub following the clear-cutting, and that the density decline resulted from a habitat change due to growth of planted Japanese
cedar and a decrease in the food supply. In Wakinosawa Village, serow density began to increase 5–10 years after forest cutting,
and the high population density, about three- or six-fold larger than that in mature forest, is expected to be maintained
for about 20 years after logging. 相似文献
17.
In Europe, the Quaternary is characterized by climatic fluctuations known to have led to
many cycles of contraction and expansion of species geographical ranges. In addition,
during the Holocene, historical changes in human occupation such as colonization or
abandonment of traditional land uses can also affect habitats. These climatically or
anthropically induced geographic range changes are expected to produce considerable
effective population size change, measurable in terms of genetic diversity and
organization. The rock ptarmigan (Lagopus muta) is a small-bodied grouse
occurring throughout Northern hemispheric arctic and alpine tundra. This species is not
considered threatened at a continental scale, but the populations in the Pyrenees are of
concern because of their small population size, geographical isolation and low genetic
diversity. Here, we used 11 microsatellites to investigate genetic variations and
differentiations and infer the overall demographic history of Pyrenean rock ptarmigan
populations. The low genetic variability found in these populations has been previously
thought to be the result of a bottleneck that occurred following the last glacial maximum
(i.e., 10 000 years ago) or more recently (i.e., during the last 200 years). Our
results clearly indicate a major bottleneck affecting the populations in the last tenth of
the Holocene. We discuss how this decline can be explained by a combination of unfavorable
and successive events that increased the degree of habitat fragmentation. 相似文献
18.
Ole-Gunnar Støen Per Wegge Stian Heid Olav Hjeljord Christian Nellemann 《European Journal of Wildlife Research》2010,56(5):789-795
The increasing development of recreational resorts and second homes in mountain regions worldwide require substantial infrastructure, and have large impact on habitats and ecosystems. We hypothesized that developed areas would attract predators and lead to higher predation on willow ptarmigan and lower their abundance. In a 500-km2 study area in south-central Norway, we sampled the density of territorial cocks in spring and the breeding success of willow ptarmigan along a 3-km gradient extending out from clusters of cabins. We also sampled red fox scats and corvid birds and measured nest predation on artificial nests across this gradient. Densities of cocks in the spring and of adults and brood sizes in August did not vary along the gradient. However, the density of chicks in August was higher beyond 1.5 km from cabin areas, presumably because more hens lost their clutches in the vicinity of cabins. This was supported by the results from the artificial nest experiment where significantly more nests were depredated near cabin areas than further away. The number of scats of red fox along trails increased with distance from cabins, whereas more corvid birds were observed near cabins. We conclude that corvid birds were the main cause of higher loss of ptarmigan nests near cabin areas, which led to lower production of chicks. Breeding density, however, did not seem to vary along the gradient, presumably because of suitable habitat for breeding and little human activity in these areas during the period of pair formation and nesting. 相似文献
19.
20.
Summary Distribution and size of 38 capercaillie Tetrao urogallus leks were related to amount and configuration of old forest patches in two south-east Norwegian coniferous forests. The smallest occupied patch was 48 ha containing a solitary displaying cock. All patches larger than 1 km2 contained leks. Number of cocks per lek increased with increasing patch size. Number of leks per patch increased in a step-wise manner with one lek added for each 2.5–3 km2 increase in patch size. In large patches there was one lek per 3–5 km2 old forest, and density of lekking cocks was 2–2.5 per km2. In small patches density of cocks varied considerably. Density of cocks was not related to patch isolation or patch shape. However, among leks surrounded by 50–60% old forest within a 1 km radius, number of cocks increased with increasing old forest fine-graininess. We argue that when old forests cover more than 50%, a fine-grained mosaic may support higher densities of lekking cocks than a coarse-grained mosaic. Conversely, when old forests cover less than 50%, a fine-grained mosaic is unfavourable, because each old forest patch becomes too small and isolated. Finally, we present a predictive model of how old forest fragmentation influences density of leks, number of cocks per lek, and total density of cocks. 相似文献