三种犬科动物春季洞穴特征

2004年4月-2005年6月在内蒙古达赉湖国家级自然保护区对20个狼穴、27个赤狐洞穴、33个沙狐洞穴进行测量调查,结果如下：3种犬科动物洞穴的洞口朝向无显著差异,赤狐和沙狐洞穴在洞口倾角、洞口直径、第一洞道长度3个特征上无显著差异,洞口直径可作为判别狼穴与其它两者洞穴的依据。影响狼春季洞穴选择的前3位主要因子是隐蔽、人为干扰和水源。影响赤狐春季洞穴选择的前3位主要因子是地形、水源、和人为干扰。影响沙狐春季洞穴选择的前3位主要因子是微气候、人为干扰和食物。通过对3种犬科动物春季洞穴生境选择的比较发现：3种动物洞穴都有远离人为干扰,提高隐蔽性的趋势;不同的是赤狐和狼的洞址都靠近水源,沙狐洞址则远离水源;3种动物在地形及坡位选择上也存在差异,赤狐和狼的洞穴多位于平地。而沙狐洞穴多位于坡地的坡顶,且洞穴周围啮齿类数量显著大于赤狐洞穴和狼穴。柳灌丛、干旱苇塘、高草坡地分别是赤狐、狼、沙狐偏爱的生境类型。3种犬科动物中洞穴生态位宽度最大的是狼（0．5051）,其次为赤狐（0．4292）,最小为沙狐（0．2591）。其中狼与赤狐洞穴空间生态位重叠指数较高,达到了0．4692,沙狐与赤狐洞穴空间生态位重叠指数最低,只有0．2356。     

内蒙古东部草原地区赤狐繁殖期对洞穴的选择

通过对内蒙古东部草原地区赤狐的２５个洞穴观测,运用系统聚类分析的方法,研究了赤狐繁殖期的洞穴选择。结果表明,影响赤狐繁殖期洞穴选择的主要因子是水源,其次是坡向、坡位和坡度,人为干扰、隐蔽程度及洞口朝向等因子对其影响作用不明显。繁殖期赤狐的最适洞穴选择为：阳坡或半阴半阳坡、下坡位、坡度５°～２５°、距水源５００～１０００ｍ。     

狼洞穴空间格局及生境选择的分析

内蒙古东部草原地区狼洞穴空间分布格局及其生境选择的聚类分析结果表明,影响狼洞穴分布的主要因子为人类活动干扰和水源距离,其次为隐蔽条件、坡位和坡度,狼选择洞穴的最适生境为陡坡,洞口北向,隐蔽条件中等以上,距人为干扰大于１０００ｍ和距水源小于１０００ｍ的地方     

四川西部石渠地区夏季藏狐巢穴选择的生境分析

通过对四川石渠地区夏季藏狐洞穴生境选择的研究 ,以水源距离、洞口朝向、坡向、坡度、坡位、植被类型及鼠兔和鼠类洞穴等 7项指标为变量 ,运用主成分分析和聚类分析相结合的方法对收集到的 5 4个藏狐洞穴样本进行了分析。主成分分析在 4个主成分下达到 85 %的显著性。在第一主成分中水源距离、坡度和坡位是重要的影响变量 ,在另外 3个主成分中鼠类洞穴数量以及植被类型两变量也非常重要。聚类分析显示 ,5 4个洞穴样本在 3个水平上聚成 5类。藏狐易于选择草甸地带 ,中缓坡和低坡位 ,坡向多为阳坡或半阳坡 ,水源距离小于5 0 0m的地方筑巢 ,其穴口朝向多位于 135°～ 36 0°之间。此外 ,鼠兔和鼠类洞穴在藏狐洞穴样方内的出现 ,但数量变异较大 ,揭示小型哺乳动物和藏狐之间可能存在着复杂的相互关系。通过对四川石渠地区夏季藏狐洞穴生境选择的研究 ,以水源距离、洞口朝向、坡向、坡度、坡位、植被类型及鼠兔和鼠类洞穴等 7项指标为变量 ,运用主成分分析和聚类分析相结合的方法对收集到的 5 4个藏狐洞穴样本进行了分析。主成分分析在 4个主成分下达到 85 %的显著性。在第一主成分中水源距离、坡度和坡位是重要的影响变量 ,在另外 3个主成分中鼠类洞穴数量以及植被类型两变量也非常重要。聚类分析显示 ,5 4     

中华漠王Platyope proctoleuca chinensis(鞘翅目:拟步甲科)对微生境的选择

动物对栖息地选择是复杂的,探索其内在机制对寻求维持动物多样性的有效方法具有重要意义。以古尔班通古特沙漠的地表甲虫优势种——中华漠王(Platyope proctoleuca chinensis)(鞘翅目:拟步甲科)为研究对象,2007—2008年连续2年采用陷阱捕获法监测其在不同生境下的种群数量和洞穴数量,分析该甲虫在景观和微尺度环境下对栖息地的选择。结果表明:在景观尺度上,与垄间相比,中华漠王更喜欢在沙丘上活动,在沙丘不同坡面上,中华漠王在背风坡的种群数量大于迎风坡;在微尺度上,中华漠王喜好沙丘上部的微环境,在背风坡上部种群数量相对更多;洞穴数量在景观和微生境2种尺度上的分布基本与种群数量空间分布一致。此外,中华漠王对微生境的选择与洞穴建立的难易程度有关,而洞穴的建立与土壤质量密切相关,特别是土壤的物质组成及其硬度。     

野生大鲵繁殖洞穴生态环境的初步研究

为了探明野生大鲵(Andrias davidianus)自然繁殖所需要的主要生态条件,给人工养殖条件下大鲵的自然繁殖提供生态学依据,对张家界国家级大鲵保护区境内野生大鲵的栖息繁殖洞穴进行生态学考察。对海拔、洞口的宽度与高度等10个生态因子进行定量观测和主成分分析,结果表明,影响大鲵选择繁殖洞穴的主要因子是海拔、洞口高度、洞底组成,以及洞穴中水的透明度、pH、流速、饵料丰度7个因子。对大鲵繁殖洞穴相连河段进行调查,发现多为山溪流。对繁殖洞穴中水的溶解氧、化学耗氧量、硫化物等5项主要指标进行检测,除硫化物外,其他指标多达到国家饮用水的水质标准,可见大鲵自然繁殖对洞穴与水质的要求较高。     

大鲵栖息地环境的初步研究

2001年4月至8月,对湖南省壶瓶山自然保护区河流中大鲵(Andrias davidianus)的栖息洞穴,首次使用量化指标进行分析。通过主成分分析发现,大鲵栖息洞穴处的水深、洞口宽、水流速度和河底的组成是影响大鲵选择洞穴的主要因子,而海拔高度和洞口高的影响不大。同时,对重庆市酉阳县、陕西省太白县、河南省卢氏县大鲵自然保护区和新安县青要山大鲵自然保护区大鲵的栖息河流特征进行了调查。结果表明大鲵的栖息河流类型可分为溪流、U型河流、平底型河流和暗河4类,而且大鲵对其栖息洞穴的质量要求较高。     

影响武夷山景区松墨天牛种群动态变化的因素分析

为了监测武夷山景区松墨天牛Monochamus alternatus Hope的发生,防范松材松材线虫Bursaphelonchus xylophilus病的入侵,于2005-2007年每年4-9月,在武夷山景区10个地点进行了调查,研究了气象因素和环境因素对松墨天牛数量变化的综合影响规律及其程度,对调查结果进行了矢量递进因子分析。结果表明：环境因子和气象因子是松墨天牛羽化孔数和诱集成虫数变化的主要因素,影响松墨天牛成虫诱集数的环境因子按重要性排列依次为：郁闭度、地被物覆盖率、海拔、林龄、坡位、坡向和树高;影响羽化孔数的环境因子按重要性排列依次为：郁闭度、地被物覆盖率、树高、林龄、海拔、坡位和坡向。影响松墨天牛诱集成虫数和羽化孔数的气象因子按重要性排列依次为：月平均温度、最高与最低温差、总降雨量（mm）、气压（hpa）和平均湿度（%）。单从环境因子和气象因子的统计数据分析,环境因子的重要性次序是：坡位、郁闭度、地被物覆盖率、海拔（m）、 林龄（a）、树高（m）、坡向;气象因子的重要性次序是：气压（hpa）、 平均温度 （℃）、最高与最低温差（℃）、 总降雨量（mm）、平均湿度（%）。按月分析和按年度分析时其相对重要性基本上是一致的。结论认为,环境因子和气象因子对松墨天牛的数量变化有重要影响。     

北京东灵山不同坡位辽东栎(Quercus liaotungensis)叶属性的比较

植物在山地环境中生存不仅受到海拔等大尺度地形因子的影响,坡位等小尺度地形因子也会对植物产生影响.不同坡位上光照、温度、土壤养分和水分等均会影响到植物的资源利用策略.为比较不同坡位对辽东栎资源利用策略的影响,在北京东灵山海拔1000～1800 m的辽东栎分布范围内针对比叶面积、叶氮含量和叶干物质含量3个重要的叶属性进行了研究.ANOVA统计分析发现,地形和土壤养分及水分等环境因子在不同坡位上出现变化,但只有土壤有机质含量有显著差异.在叶属性中,干物质含量在上坡位最高,下坡位最低,在坡位间差异极显著.比叶面积与叶干物质含量在不同坡位间均成反比关系,在上坡位比叶面积变化一定的情况下,叶干物质含量的变化幅度最小;而比叶面积与叶氮含量仅在上坡位成反比关系.这些结果说明坡位对辽东栎的叶属性有一定的影响,尤其是上坡位的影响最大.     

不同坡位沙棘光合日变化及其主要环境因子

沙棘是我国干旱半干旱地区重要的生态经济树种,被广泛应用于黄土高原造林活动中。为探明不同坡位沙棘光合特征及影响沙棘光合作用的主要环境因子,在沙棘生长旺盛期分坡位测定光合特性及环境因子日变化进程,并采用通径分析法分析各环境因子对沙棘净光合速率的直接和间接影响。结果表明：1、各环境因子之间存在相互作用,光合有效辐射是空气温度变化的主要驱动因子,而空气温度变化引起的空气密度变化对空气相对湿度和CO2浓度有显著影响。在上、中和下坡位环境变化可以分别解释85.6%、86.0%和 55.22%净光合速率的变异。2、下坡位沙棘净光合速率最小,日均值为9.38μmol/m2/s,上、中坡位分别为14.22μmol/m2/s,15.94μmol/m2/s。3、10:00之前中上坡位沙棘水分利用效率明显高于下坡位,但3坡位沙棘水分利用效率日均值无明显差异。4、上坡位净光合速率主要受到光合有效辐射、空气相对湿度的影响;中坡位光合有效辐射仍为主要环境因子,此外空气温度和空气湿度之间的相互作用对净光合速率也有一定影响,为主要限制因子;下坡位影响沙棘光合速率主导因素为光合有效辐射。5、沙棘在10:00之前光合有效辐射和空气湿度较高而空气温度较低的环境下,净光合速率和水分利用效率最高。作为阳生物种,沙棘需要足够的光照维持生长,而以往研究表明适度水分胁迫可以提高沙棘光合过程中对水的利用效率。本研究所选流域年降水量535mm,中上坡位水分胁迫并非十分严重。因此,种植于中上坡位的沙棘即可接受足够光照（特别是10:00以前的光照）进行光合保证生长速率,又能在光合过程中保持较高水分利用效率,符合干旱半干旱地区生态经济发展的需求。     

Natal den selection by sympatric arctic and red foxes on Herschel Island,Yukon, Canada

In the twentieth century, red fox (Vulpes vulpes) expanded into the Canadian Arctic, where it competes with arctic fox (Vulpes lagopus) for food and shelter. Red fox dominates in physical interactions with the smaller arctic fox, but little is known about competition between them on the tundra. On Hershel Island, north Yukon, where these foxes are sympatric, we focused on natal den choice, a critical aspect of habitat selection. We tested the hypothesis that red fox displaces arctic fox from dens in prey-rich habitats. We applied an approach based on model comparisons to analyse a 10-year data set and identify factors important to den selection. Red fox selected dens in habitats that were more prey-rich in spring. When red foxes reproduced, arctic fox selected dens with good springtime access, notably many burrows unblocked by ice and snow. These provided the best refuge early in the reproductive season. In the absence of red foxes, arctic foxes selected dens offering good shelter (i.e. large isolated dens). Proximity to prey-rich habitats was consistently less important than the physical aspects of dens for arctic fox. Our study shows for the first time that red foxes in the tundra select dens associated primarily with prey-rich areas, while sympatric arctic foxes do not. These results fit a model of red fox competitively interfering with arctic fox, the first detailed study of such competition in a true arctic setting.     

Spatial patterns of red fox (Vulpes vulpes) dens in a semi-arid landscape of North Africa

Different patterns of the use of space by red foxes ( Vulpes vulpes ) depend mainly on the distribution and availability of food patches. Nevertheless, other key resources such as suitable areas for dens can also influence the territory size and social organization of this predator. In fact, landscape modifications such as habitat patchiness made by human activities (agricultural practices, urbanization) should create ample unfavourable zones for den settlement. Several studies focused on the distribution and use of dens by the red fox in different habitat types but we do not have any data on the den settlement and habitat composition in the semi-arid regions of North Africa. This study was carried out at Djerba island (SE Tunisia), virtually deprived of surface water and with a semi-arid climate because of the bordering Sahara desert. We used line and random transects to find fox dens. The spatial pattern of dens varied mainly in different habitat types and geoclimatic regions. Highly fragmented areas were also occupied by foxes that built dens close together inside small suitable patches. Fox dens had fewer entrances in more arid regions and they mainly faced the south. Habitat selection was influenced by water availability and irrigated tree plantations that modify soil textures allowing digging of dens. Moreover, asphalt roads limit den settlements. We suggest that the choice of denning sites by foxes depends on persisting harsh conditions and human activities.     

Finding the right home: distribution of food resources and terrain characteristics influence selection of denning sites and reproductive dens in arctic foxes

We examined 83 arctic fox (Alopex lagopus) dens on Bylot Island (Canada) during the summers of 2003–2005, to determine how arctic foxes select a denning site among potential sites, and a breeding den among existing dens. We compared denning sites to random locations in a 425 km² study area (landscape scale) and to other potential denning sites in a 100 m radius (local scale). Dens were located on mounds or in slopes and were closer to streams than expected. Sites with low snow cover in spring, high ground temperature, high depth to permafrost, and steep and southerly exposed slopes were preferred. Of the 83 dens, 27 were used at least once for reproduction from 2003 to 2005. We show with a resource selection function analysis that an attractive force (distribution of food resources) and an apparently repulsive one (presence of other dens in the vicinity) affected selection of dens for reproduction. We generate testable hypotheses regarding the influence of food and social factors on the denning ecology of arctic foxes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Den distribution and den use by the red foxVulpes vulpes japonica in Kyushu

The distribution of dens and den use by the red fox was studied in Kumamoto Prefecture between 1968 and 1982. A total of 80 dens were classified into natal, residential, and temporarily-visited dens. Natal dens comprised 12.4% of all dens. Relative proportions were quite stable for a long period. This indicates a constant number of reproducing females in the area for a considerable length of time. Seasonally the utilization of den showed three peaks in February, May and October. The peaks coincided well with the peaks of reproductive activity of female foxes. The results of multiple regression analysis of distribution of dens with respect to selected environmental parameters around densites indicated that the fox selectively utilize open land, rather than densely vegetated areas. The persistence of dens, the selective utilization by foxes of open land and the sizes of dens were all related to the breeding activities of female foxes inhabiting the area. Reproductive females usually used plural dens (“den group”) in one reproductive season. The numbers of those females occuring in the area were maintained at a steady level for fairy long periods. These indicate that the existence of a stable social relationship between females mediated through occupancy of “den groups.”     

Seasonal food habits of corsac and red foxes in Mongolia and the potential for competition

Competition often occurs between sympatric species that exploit similar ecological niches. Among canids, competition may be reduced by partitioning resources such as food, time, and habitat, but the mechanisms of coexistence remain poorly understood, particularly among fox species. We described the food habits of two foxes that live sympatrically across northern and central Asia, the corsac fox (Vulpes corsac) and red fox (V. vulpes), by analyzing scats collected during a field study in Mongolia. We analyzed 829 corsac and 995 red fox scats collected from April 2005 to August 2007 and tested the extent to which food partitioning occurred. The diets of both species consisted mainly of insects followed by rodents, but also included birds, reptiles, large mammal remains (carrion), plant material (including fruits and seeds), and garbage. Despite high overlap in the proportion of food items consumed, differences existed between species in overall diet with corsacs more frequently consuming beetles, but proportionally fewer crickets and large mammal remains than red foxes. We detected interspecific differences during the pup rearing and dispersal seasons, when prey was abundant, but not during the breeding season, when prey was scarce and diet overlap highest. Each species’ diet also differed seasonally and exhibited moderate overall breadth. Corsacs consumed proportionally more beetles and rodents during pup rearing and crickets during dispersal relative to other seasons, whereas red foxes consumed proportionally more crickets during pup rearing and dispersal and more rodents and large mammals during pup rearing and breeding relative to other seasons. Our results suggest that partitioning of food resources during most of the year facilitates coexistence, and that the potential for competition is highest during winter months.     

Red fox takeover of arctic fox breeding den: an observation from Yamal Peninsula, Russia

Here, we report from the first direct observation of a red fox (Vulpes vulpes) intrusion on an arctic fox (Vulpes lagopus) breeding den from the southern Arctic tundra of Yamal Peninsula, Russia in 2007. At the same time, as a current range retraction of the original inhabitant of the circumpolar tundra zone the arctic fox is going on, the red fox is expanding their range from the south into arctic habitats. Thus, within large parts of the northern tundra areas the two species are sympatric which gives opportunities for direct interactions including interference competition. However, direct first-hand observations of such interactions are rare, especially in the Russian Arctic. In the present study, we observed one red fox taking over an arctic fox breeding den which resulted in den abandonment by the arctic fox. On July 19, eight arctic fox pups were observed on the den before the red fox was observed on the same den July 22. The pups were never seen at the den or elsewhere after the red fox was observed on the den for as long as we stayed in the area (until August 10). Our observation supports the view that direct interference with red fox on breeding dens may contribute to the range retraction of arctic foxes from the southern limits of the Arctic tundra in Russia.     

Exclusion by interference competition? The relationship between red and arctic foxes

The distribution of many predators may be limited by interactions with larger predator species. The arctic fox in mainland Europe is endangered, while the red fox is increasing its range in the north. It has been suggested that the southern distribution limit of the arctic fox is determined by interspecific competition with the red fox. This has been criticised, on the basis that the species co-exist on a regional scale. However, if the larger red fox is superior and interspecific competition important, the arctic fox should avoid close contact, especially during the breeding season. Consequently, the distribution of breeding dens for the two species would be segregated on a much smaller spatial and temporal scale, in areas where they are sympatric. We tested this hypothesis by analysing den use of reproducing arctic and red foxes over 9 years in Sweden. High quality dens were inhabited by reproducing arctic foxes more often when no red foxes bred in the vicinity. Furthermore, in two out of three cases when arctic foxes did reproduce near red foxes, juveniles were killed by red foxes. We also found that breeding arctic foxes occupied dens at higher altitudes than red foxes did. In a large-scale field experiment, red foxes were removed, but the results were not conclusive. However, we conclude that on the scale of individual territories, arctic foxes avoid areas with red foxes. Through interspecific interference competition, the red fox might thus be excluding the arctic fox from breeding in low altitude habitat, which is most important in years when food abundance is limited and competition is most fierce. With high altitude refuges being less suitable, even small-scale behavioural effects could scale up to significant effects at the population level.     

Arctic fox versus red fox in the warming Arctic: four decades of den surveys in north Yukon

During the last century, the red fox (Vulpes vulpes) has expanded its distribution into the Arctic, where it competes with the arctic fox (Vulpes lagopus), an ecologically similar tundra predator. The red fox expansion correlates with climate warming, and the ultimate determinant of the outcome of the competition between the two species is hypothesized to be climate. We conducted aerial and ground fox den surveys in the northern Yukon (Herschel Island and the coastal mainland) to investigate the relative abundance of red and arctic foxes over the last four decades. This region has undergone the most intense warming observed in North America, and we hypothesized that this climate change led to increasing dominance of red fox over arctic fox. Results of recent surveys fall within the range of previous ones, indicating little change in the relative abundance of the two species. North Yukon fox dens are mostly occupied by arctic fox, with active red fox dens occurring sympatrically. While vegetation changes have been reported, there is no indication that secondary productivity and food abundance for foxes have increased. Our study shows that in the western Arctic of North America, where climate warming was intense, the competitive balance between red and arctic foxes changed little in 40?years. Our results challenge the hypotheses linking climate to red fox expansion, and we discuss how climate warming’s negative effects on predators may be overriding positive effects of milder temperatures and longer growing seasons.     

Structure of arctic fox (Alopex lagopus beringensis) colonies in the northern extremity of Bering Island

Data on the spatial structure of an Arctic fox (Alopex lagopus beringensis) colony were obtained in July-August 1995, using walk counts and observations near living dens around the Northern rookery of the northern fur seals located on Bering Island (Commander Islands). The home ranges of 31 Arctic fox families (61 adults and 145 pups inhabiting 66 dens) were found over 27 km of the coastline. Sixty individuals (3 adults and 57 pups) were marked by color ear-tags. Among adult foxes, 24 (39.3%) were recognized as females and 12 (19.7%) as males; the sex of 25 (41.0%) foxes was not recognized. Among 57 marked cubs, 26 (45.6%) were females and 31 (54.4%) were males. The best studied families (13) had 3–11 pups (6.7 ± 0.7, on average). The survival of cubs at an age younger than 2.0–2.5 months was 82.5%; 30.8% of the families consisted of more than two adults. The distribution of the Arctic fox dens and home ranges along the coastline has been studied; specific features of the location of dens have been described. In the studied area, Arctic foxes have been foraging on birds (67.6% of dens with food remains), northern fur seals (40.5), other marine mammals (13.5), Pacific salmon (29.7), and reindeer (2.7%), as well as on amphipods and voles. Rich constant food sources (rookeries, marine bird colonies, and spawning places of the blueback salmon) were found in 7 home ranges of the Arctic fox; 6 home ranges included temporary food sources (spawning streams of the humpback salmon); and 18 home ranges were poor in food resources. Arctic foxes whose home ranges lie within 6–7 km around a “food patch” used the concentrated food resources together. Food resources are supposed to become important only after the raised pups turn to self-feeding. Differences in the use of space, foraging and breeding of the two Arctic fox subspecies (A. l. beringensis and A. l. semenovi), and arrangement of colonies around the northern fur seal rookeries are discussed.     

Summer food composition and food niche overlap of the raccoon dog, red fox and badger in Finland

Diets of raccoon dog, red fox and badger were studied in southern Finland from 1990 to 1996 by collecting faeces from dens and latrines during May-July of each year. The frequency of occurrence and relative volume of each food item in the faeces were calculated. The raccoon dog was the most and the red fox the least omnivorous of these carnivores, according to the diversity index. Diet composition of all these species varied among areas, indicating that they are opportunistic feeders. Mammals and birds constituted the bulk of the fox diet, while invertebrates, frogs and plants were most frequently eaten by the badger. The frequency of earthworms in badger faeces varied between 16 and 77%, according to area. Voles and shrews were important to the raccoon dog, but it also frequently consumed other food items. The food niches of the badger and the raccoon dog overlapped more than that of the red fox and other species. The red fox was more carnivorous and fed on larger prey items than the others, but the food composition of the red fox in the present study reflects the prey carried to the den for the pups; thus, the diet of adult foxes may be more similar to that of the raccoon dog. In conclusion, these 3 carnivores share many resources, suggesting that competition may occur among them: however, their diets also differ to some extent, which helps them to avoid competition. Furthermore, the badger and the raccoon dog are dormant during winter, when food is scarcest, which may be the reason why all these species can coexist in rather unproductive boreal forests.