Implications of an individualistic lifestyle for species conservation: lessons from jealous beasts

Polecat populations show a very low genetic diversity and a high inbreeding coefficient. Furthermore, the estimate of effective population size is alarmingly low. Polecats Mustela putorius populations are structured into scattered breeding sub-units usually made up of one male and two females, according to a polygynous mating system. Because a strict spatio-temporal segregation was observed between males and females, we propose to call individualistic such species. We suggest that the solitary habits of individualistic species may result in or worsen a high inbreeding and exacerbate their conservation issue, a crucial perspective for critically endangered species such as the European mink.     

Trophic status and feeding habits of the European Polecat Mustela putorius L. 1758

The trophic status of the European Polecat Mustela putorius was studied through a review of the diets of 18 different populations in Europe. Rodents represented the principal prey in 10 sites (55.5%) and were a prey of secondary importance in seven sites (38.8%). Anurans prevailed in three sites (17%) but constituted the second food category in eight others (44%). The ascendant hierarchical classification showed a relatively unvarying diet in Europe. The frequency of birds and invertebrates were important in the diversification of the diet, indicated by the value of the food niche index, whereas rabbits were more significant in southern regions. The constant incidence of predation on woodland rodents and amphibians gave a particular status to the Polecat and showed it to be a generalist feeder well adapted to the mid-European region.     

Functional response and area‐restricted search in a predator: seasonal exploitation of anurans by the European polecat,Mustela putorius

A study of the feeding habits and movements of 11 radiotracked polecats Mustela putorius in western France revealed that seasonal predation upon agile frogs, Rana dalmatina, was directly influenced by prey abundance and distribution. Although dietary structure showed the importance of mammalian prey (71.5%), polecats exploited nocturnal, terrestrial anurans in spring (31.6%). The periodic activity of anurans at spawning sites led both to a maximum density in spring and to a patchy distribution. The monthly variations in anuran dietary occurrences were associated with changes in frog availability. The functional response of polecats to frog density was sigmoidal shaped (type 3 response). Frog consumption rate increased more slowly than prey density but frogs were actively removed at higher density. It is therefore suggested that frog populations were moderately affected by the predator and this density dependent effect tends to stabilise anuran populations. Predation upon anurans was also correlated with a prey dispersion index as revealed by a polynomial regression. Polecats concentrated their predation on spawning congregations of the breeding adult frogs. Movements were smallest in spring and polecats changed their track length by increasing the difference between a succession of small movements and of longer journeys towards profitable sites. Changes in movements correlated with the anuran dispersion index and the response was sigmoidal (polynomial regression) revealing an area‐restricted search. This response may be regarded as an ‘aggregative response’ according to the first part of the definition of Begon et al. (1996) . Functional and area‐restricted search responses to the frog abundance and dispersion constitute an original example of predator‐prey coexistence strategies among vertebrates. I suggest that such predation could be favoured by the individualistic habits of the mustelid.     

The use of fumigants and anticoagulant rodenticides on game estates in Great Britain

Several studies have highlighted the potential risk to nontarget wildlife associated with accidental exposure to vertebrate control agents. In order to provide information that may assist in the mitigation of this problem, we questioned 215 gamekeepers in Great Britain about the use of vertebrate control agents on the land for which they were responsible. Fumigants were used to control Rabbits Oryctolagus cuniculus by 59% of gamekeepers. Use of fumigants was more common than on farms in general. 91% of gamekeepers reported the use of rodenticides, 95% of which were anticoagulants. Patterns of rodenticide use were similar to those on arable farms, though chlorophacinone and warfarin were used more commonly on game estates. Future studies of the exposure of nontarget wildlife to anticoagulants should be expanded to include these compounds. Rodenticides were apparently used in accordance with label recommendations in most cases. However, better information and guidelines for users may improve standards of agent application and reduce potential risks to nontarget wildlife.     

Effects of mammalian predators on partridge populations

Many ecologists have argued that predation is of little consequence in the regulation of gamebird numbers and that predator control in game management is a waste of time. Their case has included two lines of evidence; firstly, gamekeepers do not appear to be reducing predator numbers significantly; secondly, mortality by predation appears to be compensatory and therefore has little impact on gamebird populations as a whole. However, a closer examination of the activities of gamekeepers indicates that they do reduce predation pressure either by reducing or completely removing some predator species, or by temporarily reducing their number on a local basis. Recent research including an investigation of partridge population processes explored with a computer simulation model indicates that predation does regulate both autumn and spring densities. Other factors play an important role only when predators are removed.     

The ecological effects of the decline in Rabbits (Oryctolagus cuniculus L.) due to myxomatosis

The Rabbit (Oryctolagus cuniculus) population in the British Isles increased rapidly from the 1800s to 1950 due to climatic amelioration, predator reduction and agricultural changes. It became the major vertebrate pest of agriculture, causing an estimated £50 million in damage and lost production each year. Myxomatosis reached Britain in 1954-55 causing 99-9% mortality in some Rabbit populations and, carried by the mosquito and flea vectors, the disease spread rapidly. The consequent decline in the Rabbit population caused dramatic changes in agriculture and the native fauna and flora. It promoted woodland regeneration and increased grassland and cereal production; herb and grass height increased, flowering was noticeable and plant successions ensued. Some small legumes and annual plants became extinct locally and much floristically rich vegetation became dominated by a few grass species or shrubs. The increased grass growth probably promoted an increase in the number of many invertebrate species as well as in the vole (Microrus agrestis). Some species of insect became reduced in number and the Large Blue Butterfly (Maculinea arion) has become extinct (1979) since the decline of the ant (Myrmica spp.) fauna necessary to rear the butterfly larvae. Breeding sites for the Sand Lizard (Lacerta ugilis), Stone Curlew (Burhinus oedicnemus) and Wheatear (Oenanrhe oenanthe) have been reduced by habitat change. Immediately after myxomatosis many predator populations suffered from a lack of Rabbit prey with consequent poor breeding success, but those able to switch to voles, and other predators which are no longer taken in Rabbit trapping, have increased in numbers, e.g. Fox (Vulpes vulpes), Polecat (Mustela putorius), Short-eared Owl (Asio Barnmeus) and Kestrel (Falco tinnunculus). Others such as the Stoat (Mustela ermineu) and the Buzzard (Buteo buteo) declined immediately after myxomatosis through lack of prey and have recovered in nubers only slowly; the Peregrine falcon population has declined partly as a result of lack of open habitat. The breeding success of many predators was also reduced. Parasites of the Rabbit also declined; the flea (Spilopsyllus cuniculi), roundworms and tapeworms, as well as coccidiosis carried by Rabbits and particularly affecting young hares (Lepus europaeus) were all considered to be affected. Species such as the Pheasant Phasianus spp., the hare and the Roe Deer (Capreolus capreolus) increased their use of woodland habitat and/or benefited from the increased food available. Rats (Rartus nomegicus) appeared to decline following increased predation and loss of habitat. In Australia similar vegetational changes occurred in many areas after the introduction of myxomatosis and predators such as the Fox and Wedge-tailed Eagle (Aquila audax) were reduced by control measures following increased predation on sheep. Many bird and marsupial species were reduced in number after the loss of Rabbit prey or on becoming an alternative prey item. In Britain the loss of the fur industry has been outweighed economically by the increased agricultural production and reduced control and maintenance costs following myxomatosis. Since myxomatosis appeared Rabbit numbers have increased only slowly, probably because of increased predator pressure on low density populations and the periodic recurrence of the disease. Rabbit behaviour may have changed so that burrows are not used as much as in the past, Rabbit trapping has ceased and many habitats have been lost. Rabbit numbers could still reach moderate densities but a reversal of many of the ecological effects of my xomatosis is unlikely.     

Spatial and temporal patterns of artificial nest predation in mountain birch forests fragmented by spruce plantations

Studies of ground-nesting birds stress the importance of high nest losses as a factor influencing population dynamics. In particular, nest predation has been found to be accentuated in human-modified forest landscapes. In boreal ecosystems, the assemblage of nest predators is likely to be temporally variable. Thus, multi-year predation studies are required in order to highlight the temporal aspects of habitat and edge-specific ground-nest predation. On this basis, we conducted a 3-year predation study in Northern Norwegian mountain birch forests which had been fragmented by spruce plantations. Track boards were used to identify predators in different habitat and edge types. We used logistic regression to assess the importance and consistency of spatial and temporal predictors for the predation rate of six predator species. Total predation rates were high and were higher in the second and third year (range 89.9–96.7%) compared to the first year of the study (range 57.1–75.3%). Mammalian predation decreased while avian predation increased over the 3 years. Red fox (Vulpes vulpes) and hooded crow (Corvus cornix) were the dominant predators, followed by raven (Corvus corax) and magpie (Pica pica). Pine marten (Martes martes) and stoat (Mustela erminea) predation was low and almost absent in two of the years. Within the study years, predator species exhibited different temporal trends, probably owing to species-specific functional responses. While some edge types were preferred consistently over time by the dominant predators, the spatial pattern of predation was mainly due to unexplained large-scale differences among landscape blocks. This large-scale pattern was constant over the three study years despite the strong temporal fluctuation in predation rates within and between years.     

Biology of the Polecat Mustela putorius: a literature review

The available literature on the biology of the European Polecat ( Mustela putorius ) is collated. Aspects covered are general biology and systematics, distribution, physical characteristics, variation, skeletal characteristics, habitat, general behaviour, diet and predatory behaviour, breeding, juvenile development, population structure, mortality, parasites and diseases, relations with man, and history in Britain. Notes on field signs are also included. Recent and current research on Polecats both in Great Britain and on the European continent are then reviewed and some new information is reported. An extended bibliography lists all major and many minor publications on M. putorius , together with selected references to feral Ferrets ( M. furo ) and Polecat-Ferrets ( M. putorius x M.furo ).     

Recent history,current status,conservation and management of native mammalian carnivore species in Great Britain

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Predation risk of eggs and nestlings relative to nest‐site characteristics of the Bull‐headed Shrike Lanius bucephalus

Appropriate nest‐site selection is one of the most important ways to minimize loss of reproductive investment due to predation. We determined the environmental characteristics associated with nest predation during the incubation and nestling periods of arboreal nesting Bull‐headed Shrikes on the oceanic Minami‐Daito Island where the predator community has low species diversity and includes only three introduced mammals: Ship Rat Rattus rattus, Japanese Weasel Mustela itatsi and Feral Cat Felis catus. Egg predation declined with increasing grassland cover around nests, whereas nestling predation declined with increasing nest concealment and nest height. Our results suggest that effective nest‐site characteristics for avoiding nest predation differ during the incubation and nestling periods and are dependent on the predator species and their search strategies, at least in habitats with low predator species diversity.     

Home ranges and movement patterns in a vulnerable polecat<Emphasis Type="Italic">Mustela putorius</Emphasis> population

Home range characteristics and movement patterns of four female and six male polecatsMustela putorius Linnaeus, 1758 were studied in Luxembourg using radiotelemetry. Home range size of polecats ranged from 42 to 428 ha with an average of 181 ha. The mean (± SE) home range size of males of (246±45 ha) was significantly larger than that of females (84±17 ha). Polecats concentrated 50% of their space use in only 15% of their home range possibly indicating a patchy environment. Comparing our data with other studies in Europe, polecats seem to occupy approximately the same home range size (except in Switzerland) regardless of population density. Average distance traveled per night by males was 3.6 times greater than that of females. Also, seasonal variation in movements was observed in males but not in females.     

Introduced cats Felis catus eating a continental fauna: inventory and traits of Australian mammal species killed

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Ant seed predation,pesticide applications and farmers' income from tropical multi‐cropping gardens

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Diet,Prey Selection,and Predation Impact of Black-Backed Jackals in South Africa

ABSTRACT To investigate the role of black-backed jackals (Canis mesomelas) as predators, we studied diet, prey selection, and predation impact of jackals on 2 game ranches in South Africa that differed in ungulate diversity and biomass. Results showed that large (>15 kg) ungulate species dominated jackal diets throughout the year on both the less diverse (range of ingested biomass across seasons = 39–78%) and more diverse (26–69%) game ranch. Other important food items included medium-sized mammals (1–3 kg; 1–26%) and fruit (2–69%), whereas small mammals comprised 3–11% of ingested biomass across seasons on both sites. Jackals were not random in consumption of ungulates, and consumption patterns suggested jackals actively hunted certain species rather than consumed them as carrion. During ungulate birthing periods, jackals consumed almost exclusively those ungulate species that were hiders (i.e., fawns were hidden in tall vegetation away from herd) regardless of ungulate densities, suggesting that primarily fawns were preyed upon. Among hiders, there was a negative relationship (P = 0.01) between body size and percent of population consumed by jackals, indicating smaller species were more susceptible than larger species to jackal predation. Consequently, springbok (Antidorcas marsupialis) were always selected over other ungulate species on both sites, and this species was the most impacted by jackal predation. In contrast, ungulate species that were followers (i.e., fawns immediately followed mothers within protection of the herd) were scarcely or not at all consumed by jackals, regardless of body size or density. Medium-sized mammals were selectively consumed over ungulates, and there was a negative relationship (P < 0.01) between consumption of berries and ungulates, indicating alternative food resources influenced consumption of ungulates on our study sites. Our results will help wildlife managers in Africa identify ungulate species susceptible to jackal predation, and can be used to develop management strategies for reducing jackal predation in areas where it is problematic.     

Activity Pattern of Polecats Mustela putorius L. in Relation to Food Habits and Prey Activity

The activity pattern of polecats Mustela putorius L. was studied by radiotracking five males and four females in the wetlands of western France from Jul. 1988 to Mar. 1992. Polecats were nocturnal throughout the year with no differences between males and females. The diel activity remained moderate (31 %). Seasonal food habits were characterized by the exploitation of anurans in spring, while rodents were preyed upon from summer to winter. Seasonal changes in the activity rhythm of polecats appeared synchronized with the activity of the main prey. It is suggested that the activity patterns exhibited in different periods of the year are a result of changes in feeding tactics.     

Leopard diets and landowner perceptions of human wildlife conflict in the Soutpansberg Mountains,South Africa

Human-wildlife conflict between carnivores and livestock and game owners is an issue of high conservation concern and has led to the global decline of many large carnivore species. Research has shown that carnivores are often blamed for higher levels of predation of livestock and game than actually occurs and this often leads to retaliatory killing. The aim of this study was to obtain information via scat analysis on the range of prey species taken by leopards in the Soutpansberg Mountains, South Africa, and combine these data with self-reported accounts of livestock predation from local landowners to examine differences between real and perceived leopard predation. Results showed that despite landowners reporting frequent events of leopard predation of livestock and introduced farmed game across the Soutpansberg farming community, no evidence of these species were found in leopard diets. The most frequently eaten species by relative biomass were bushbuck, hyrax and vervet monkeys; in contrast, the farmers reported cattle and impala as often being taken by leopards. Despite sharing the landscape with domestic cattle and introduced game, leopards in the Soutpansberg do not frequently utilise these species as prey and instead focus their diets on wild species. Human-carnivore conflict can be reduced by overcoming the mismatch between actual and perceived levels of predation via landowner education, effective anti-predation measures, an improved government response to reports of livestock predation and potentially giving economic value to problem animals via trophy hunting.     

Current and future impacts of nest predation and nest-site competition by invasive eastern grey squirrels Sciurus carolinensis on European birds

1. The eastern grey squirrel (hereafter ‘grey squirrel’) is considered one of the most damaging invasive alien species in Europe, with negative effects on native ecosystems. Despite it being widely perceived as a significant predator of bird eggs and chicks and as a competitor for nest sites, evaluation of the grey squirrel’s impact on European bird populations has been hindered by limited empirical data.
2. The aim was to review the incidence of grey squirrels as nest predators of and nest-site competitors with European birds, and to use this information to identify species at potential risk of negative effects from within the grey squirrel’s expanding range in continental Europe.
3. A comprehensive literature review was conducted, and the data were used alongside additional new data, to assess nest predation and competition by grey squirrels in their current European range. Bird species were grouped by nest-site type, which was used to predict the impact on similar species groups in regions of continental Europe predicted to be colonised by grey squirrels in the current century.
4. Camera-monitoring and field evidence for 12 bird species and 12420 nests in Britain showed that grey squirrels rarely depredated eggs or chicks, affecting just 0.5% of nests. Nest-site competition was also minor, with grey squirrels occupying 0.8% of 122 small tree cavities and 14% of 57 larger cavities. At least 69 bird species in continental Europe could be exposed to potential nest predation or competition from expanding grey squirrel populations within the current century, but population-level effects currently appear to be unlikely.
5. Current evidence shows that grey squirrels are unlikely to be significant predators of or competitors with nesting birds in their present or projected range in Europe. However, further studies of more species in different regions would be valuable, particularly in urban and suburban habitats.

     

The stoat Mustela erminea population decline in northern Belarus and its consequences for weasels Mustela nivalis

Abstract

In northern Belarus, we have documented a decline in the local stoat Mustela erminea population following the naturalisation of the American mink Mustela vison. The most likely cause is the reduction in the density and distribution of the main prey of stoats, the riparian voles (the water vole Arvicola terrestris and the root vole Microtus oeconomus), due to excessive predation by mink. Since the stoat population has declined, the number of weasels Mustela nivalis in marshlands has increased and their mean body mass has increased, correlated with the higher number and mean weights of rodents available for weasels in marshland compared with forest habitats.     

Absence of effects of predator control on nesting success of Northern Lapwings Vanellus vanellus: implications for conservation

The control of generalist predator populations is increasingly adopted as a management tool to combat declines in ground‐nesting bird populations. However, compensatory predation by uncontrolled species frequently occurs, so determining the relative impacts of different predatory species, and hence the relative benefits of their control, can be difficult. Islands, with their reduced faunas, provide natural experimental units for investigating specific predator–prey interactions in detail. We studied Northern Lapwing Vanellus vanellus breeding success on an island where feral Ferrets Mustela furo and Hooded Crows Corvus cornix were subjected to trial control regimes over 2 years. In both years, Lapwing hatching success was >80%, with neither Ferret nor Crow control selected as important predictors. Fledging rates in both years were 0.7 young per pair, despite highly effective predator removal, although Crow control potentially resulted in compensatory predation by Common Ravens C. corax. Neither mustelid nor corvid control produced significant immediate benefits for Lapwings. This suggests that mesopredator release of mustelids in mainland situations is unlikely to be a consistent threat to Lapwing, and provides further evidence that declines in this species are unlikely to be tackled successfully through predator management alone.     

鼬科动物线粒体DNA控制区结构分析

利用PCR技术获得紫貂(Martes zibellina)和黄喉貂(Martes flavigula)线粒体DNA控制区全序列,并结合从GenBank中下载的9种鼬科动物相应序列,用ClustalX排序后对控制区结构进行分析,识别出延长终止序列区、中央区和保守序列区3个区域,指出了一个终止相关序列ETAS1及8个保守序列(CSB-F、E、D、C、B、1、2和3),并给出了序列通式,在CSB1和CSB2之间发现不同形式的短重复序列.此外,以狼为外类群,应用邻接法构建鼬科线粒体控制区全序列的系统进化树,结果表明:臭鼬亚科最先从鼬科中分化出来,随后剩余类群分为两大支系,即貂属种类与貂熊聚为一支,并与獾亚科的狗獾形成姐妹群;另一支为水獭亚科的物种与鼬属的林鼬形成姐妹群,再与虎鼬聚在一起,狗獾与貂属的紫貂亲缘关系最近,水獭亚科与鼬属亲缘关系最近.