Multi-annual density fluctuations and habitat size enhance genetic variability in two northern voles

In order to gain a better understanding of the consequences of population density cycles and landscape structure for the genetic composition in time and space of vole populations, we analyzed the multiannual genetic structure of the two numerically dominant, sympatric small rodent species of northernmost Fennoscandia. Red voles Myodes rutilus and grey-sided voles M. rufocanus were trapped in the subarctic birch forest along three fjords over five years. Along each fjord, there were four or five altitudinal transects each with five trapping stations. Spring and fall population densities were estimated from mark–recapture data. Grey-sided voles exhibited higher amplitude density fluctuations than red voles. Polymorphism at eight or nine microsatellite loci, determined in 1228 voles, was used to estimate local genetic diversity and differentiation among samples. Genetic diversity was higher in grey-sided voles than in red voles. Spring densities had no effect on local genetic diversity or on differentiation. The amplitude of density fluctuations and the extent of favorable habitat (sub-arctic birch forest) surrounding each site had a positive effect on genetic diversity, and the amplitude of density fluctuations had a negative effect on differentiation in red voles, for which fluctuating populations were compared with more stable populations. The harmonic mean of densities, reflecting average population sizes, had a negative effect on genetic diversity in red voles, but a positive effect in grey-sided voles, for which only fluctuating populations were compared. No other effects were significant for grey-sided voles. A temporal assignment test showed that the spatial structure was more stable in time for populations with more stable population dynamics. Altogether our results suggest that high amplitude density fluctuations lead to more gene flow and higher genetic diversity in vole populations.     

Arrival and habitat use by Lapwings Vanellus vanellus in the early breeding season

The arrival on the breeding grounds and habitat use in relation to agricultural land use by Lapwings Vanellus vanellus was compared in rough grazing and arable study areas in the Midland Valley of Scotland. First arrivals took place in early February. Males preceded females and territory occupation by the males began soon after first arrival. During the pre-breeding period birds remained in flocks and day time habitat use and activity was strongly influenced by the lunar cycle. Birds fed mainly in those habitats in which prey (leatherjackets and earthworms) were most plentiful, and in which their feeding success was high. The choice of nesting habitat was not influenced by food availability in the immediate vicinity of the nest site but by the crypticity of the clutch and incubating adults. On rough grazing birds preferred unimproved land while on arable land spring cereal was the preferred habitat. The choice of actual nesting field on the arable land was influenced by the risk of predation and the proximity of suitable feeding fields for the adults and chicks.     

Dry season habitat use by critically endangered white-shouldered ibis in northern Cambodia

We present the first scientific study of white-shouldered ibis Pseudibis davisoni habitat preferences in dry dipterocarp forest. Foraging sites included seasonal pools, forest understorey grasslands and fallow rice fields, with terrestrial sites used more following rainfall. Habitat and anthropogenic effects in logistic models of foraging site selection were examined by multimodel inference and model averaging. White-shouldered ibis preferred pools with greater cover of short vegetation (<25 cm) and less of the boundary enclosed, and forest sites with greater cover of bare substrate and lower people encounter rate. At forest sites, livestock density was positively related to bare substrate extent and thus may improve suitability for foraging ibis. At pools, livestock removed tall vegetation between the early and late dry season indicating their importance in opening up foraging habitats after wet season growth. However, by the late dry season, pools with greater livestock density had less short vegetation, the habitat favoured by ibis. Conservation strategies for white-shouldered ibis must consider a range of habitats, not just seasonal wetlands, and should incorporate extensive grazing and associated burning practises of local communities. Further understanding of the effects of these practices on vegetation, prey abundance and prey availability are therefore needed for effective conservation of this species. This will also develop our understanding of potentially beneficial anthropogenic influences in tropical environments.     

Home range size and overlap in female root voles: effects of season and density

In small mammals living in highly seasonal environments, observationalstudies show that female home range size and exclusiveness aresmaller in the nonbreeding winter season than in the breedingsummer season. This has led to the notion that nonbreeding femalesare more social and decrease territorial behavior during winter.However, because territoriality decreases with increasing populationdensity, and density normally increases during the breedingseason, the effects of density and season on social structureare usually confounded. To find out which of the 2 factors explainsspace use, we experimentally established 3 high-density and3 low-density root vole (Microtus oeconomus) populations inlate spring and monitored the populations into the nonbreedingwinter season. Population sizes were controlled throughout thebreeding period to minimize seasonal variation in density. Homerange sizes were larger in founder females than in field-bornfemales but did not change with season or density. Area exclusivelyused by individual females was lower in winter than summer,and founder females decreased exclusiveness as density increased.We argue that this seasonal pattern of space use might be causedby variation in benefits of group living, whereas founder femalesalso responded to density-dependent competition by reducingarea exclusively used.     

Species richness,relative abundances and habitat use in local assemblages ofSorex shrews in Eurasian boreal forests

Using a large body of observational data on the occurrence ofSorex shrews in boreal forests, we test two models that predict the structure of small mammal communities along a gradient of increasing habitat productivity. Tilman’s (1982) model predicts a humped curve of species richness along productivity gradients. In contrast, we found a linear increase in species richness with increasing logarithm of the pooled density of shrews, which we use as a measure of habitat productivity for shrews. The model of Hanski and Kaikusalo (1989) assumes a trade-off between exploitative and interference competitive abilities, and it predicts that the size structure of small mammal communities should shift from the dominance of small species (superior in exploitative competition) in unproductive habitats to the dominance of large species (superior in interference competition) in productive habitats. Shrew assemblages show such a shift. Though it is not possible to draw definite conclusions about the role of interspecific competition from our observational data, the changing size structure of local shrew assemblages with increasing habitat productivity is a predictable feature of their community structure.     

The capture of voles and shrews by male and female ermine Mustela erminea in captivity

The capture of meadow vole Microtus pennsylvanicus and short-tailed shrew Blarina brevicauda by male and female ermine Mustela erminea was observed in an indoor enclosure which simulated field conditions. We made 114 trials using 15 different male and 17 different female ermine. Each trial involved one ermine deprived of food for either 0, 10 or 20 h, and only one individual of either prey species. In most trials, the hunting efficiency (indicated by search and handling durations, and number of captures) of male ermine was greater than that of females. Females hardly ever captured shrews, whereas males hunted them successfully independently of the level of food deprivation. However, when deprived of food for 20 h, females spent less time than males in searching for voles. These results suggest that smaller females may be specialized and more effective at hunting meadow voles than larger males under severe food deprivation. This advantage may allow them to channel a greater proportion of energy into reproduction.     

Age and season determine European rabbit habitat use in Mediterranean ecosystems

Knowledge about the factors determining habitat use is especially interesting for herbivores living under seasonal climates as they have to deal with food shortage during the drought season. In this context, different-aged individuals are expected to respond differently to seasonal variations because nutritional requirements and predation risk can vary with age. We investigated adult and juvenile European rabbit (Oryctolagus cuniculus) habitat use in a Mediterranean ecosystem of central Spain, during spring, summer and winter. Relationships between adult and juvenile rabbit pellet abundances and 11 environmental variables related to food availability and refuge density were analysed by means of multiple regression, and evaluated using information theory to identify the set of models best supported by the data. Density of warren entrances was the more constant predictor of habitat use for juvenile rabbits in all the seasons. Herbaceous vegetation volume had a negative influence and was the strongest predictor for adult rabbit habitat use in spring and winter. In summer, green vegetation cover became the strongest positive habitat use predictor. These results suggest that adults prefer to forage in low volume swards ensuring a wide sensory range for the detection of approaching predators. However, the arrival of summer and its associated food depletion forces them to shift toward more open productive areas where green vegetation persists, but at the expense of higher predation risk. Seasonal variation induces minor changes in juvenile habitat use due to their strong dependence on warrens. Thus, our results show that rabbit habitat use is influenced by animal age and seasonal variations in resources.     

Habitat use by singing voles and tundra voles in the southern Yukon

Summary We investigated how far competitive interactions influence the use of habitats and relative abundance of two species of Microtus in the southwestern Yukon. We worked in the ecotone between alpine tundra and subalpine shrub tundra where populations of singing voles (Microtus miurus) and tundra voles (M. oeconomus) overlap little.We removed tundra voles from shrub tundra on one live-trapping area to look at the effect on the contiguous population of singing voles in alpine tundra. The removal of tundra voles did not affect the distribution or relative abundance of singing voles. The spatial distribution of these species and their movements within habitats suggest that they have a strong habitat preference.Populations of small mammals in the area are extremely dynamic and the relative importance of competitive interactions may change as density varies. At present we have no evidence that competition affects habitat use in M. miurus.     

Studies on the helminth parasites of voles and shrews from Wales

The incidence and degree of infestation of the Bank vole, Clethrionomys glareolus , the Skomer vole, C. skomerensis , the Common shrew, Sorex araneus and the Pygmy shrew, S. minutus have been studied from a rough grassland and woodland area, Aberystwyth and from Skomer Island in Wales. In addition, small numbers of the Short-tailed vole, Microtus agrestis and the Water shrew, Neomys fodiens were examined for helminth parasites, when they became available. Seven new host records and six new British records are listed. The number of species of helminths in shrews, which consisted largely of digeneans and cestodes, was greater than that in voles. This is undoubtedly linked with differences in the feeding habits of the two hosts.
In Aberystwyth, where the composition of the helminth fauna was found to be more varied than that from Skomer Island, one species of nematode showed evidence of seasonal variation in the degree of infestation of Clethrionomys glareolus and four species, one digenean, two cestodes and one acantocephalan in Sorex araneus. The factors affecting this seasonal fluctuation in parasite numbers are discussed.     

Home range,habitat use,and activity patterns of free-roaming domestic cats

We used radio-telemetry and collar-mounted activity sensors to compare home range size, habitat use, and activity patterns of owned and unowned free-roaming cats on the outskirts of Champaign-Urbana, Illinois, USA. Owned cats (3 M, 8 F) had smaller home ranges than unowned cats (6 M, 10 F), but we failed to detect consistent differences in home range size between the sexes or among seasons. Home ranges of unowned cats included more grassland and urban area than predicted based on availability in all seasons, and farmsteads were selected in fall and winter. Within home ranges, unowned cats shifted their use of habitats among seasons in ways that likely reflected prey availability, predation risk, and environmental stress, whereas habitat use within home ranges by owned cats did not differ from random. Unowned cats were more nocturnal and showed higher overall levels of activity than owned cats. Space use and behavioral differences between owned and unowned cats supported the hypothesis that the care a cat owner provides influences the impact a cat has on its environment, information that is important for making decisions on controlling cat populations. © 2011 The Wildlife Society.     

Regional environments, life-history patterns, and habitat use of spirostreptid millipedes in arid regions

Among diplopods with desert populations, only three species of Spirostreptida have been studied in an ecological context. The present review compares regional environments, life-history patterns, and uses of habitat by Orlhoporus ornatus (Girard) from southwestern North America, Archispirostreptus tumuliporus judaicus (Attems) from the eastern Mediterranean seaboard, and Harpagophora nigra (Attems) from southwestern Africa. Published and unpublished studies are used to explore evidence for convergence among these species, as opposed to traits adapting them to physical aspects of given regions or habitats. Unlike A. t. judaicus, O. ornatus and H. nigra are relatively restricted to arid habitats, although populations of all three species experience a variety of rainfall regimes and regional topographies. Where studied, O. ornatus and H. nigra hibernate during the long, often cool or cold dry season; they forage following warm-season rains. A. t. judaicus , in contrast, forages during its long, warm dry season and hibernates in the cool, wet winter. Populations from the Judaean and Negev deserts differ from those inhabiting a mesic habitat (Megiddo) closer to the coast in regard to rates of development, seasonal activity and seasonal water balance. Convergence in the form of well-developed desiccation resistance characterizes the two strictly desert species. All three species, together with other subtropical millipedes exposed to long dry seasons, are convergent with respect to patterns of diel surface activity and use of shelter. However species- and habitat-specific life-history features such as the seasonal timing of dormancy and emergence tend to mask convergence at the habitat level. Hence, the independent evolution of the three species with desert populations has resulted in life histories and habitat use that combine a moderate amount of convergence with considerable opportunistic adaptation to regional and local conditions.     

Migration patterns and habitat use by passerine and near-passerine migrant birds in eastern Africa

Palaearctic migrant passerines and near-passerines which visit eastern Africa can be divided into six groups based on the latitude of their final wintering area. Species wintering further north in Africa tend (a) to breed in more southern parts of the Palaearctic, (b) to prefer drier habitats and (c) to feed more from the ground than those wintering further south. Many species use quite narrow passage routes through eastern Africa and, for some species, passage is centred further east in spring than in autumn. Southward migration can take more than 4 months from the Palaearctic breeding grounds and many birds stopover in the northern tropics from September to November. By contrast, the return migration takes only about 6 weeks. The timing and strategy of migration within Africa can be broadly related to seasonal patterns of rainfall and vegetation.     

Do lambs affect feeding habitat use by lactating female mouflons in spring in areas free of predators?

The purpose of this study was to see if mouflon ( Ovis gmelini ) females with lambs have feeding habitats similar to other sex-age classes in spring, in an area without large natural predators. Parous ewes restricted themselves to rocky and poor nutritive habitats but lambed within their winter home range. Once in matriarchal groups, females with lambs ≥ three days old fed more on rocky areas and stayed closer to safe terrain than did other mouflons which more frequently used slope tops, patches containing herbs, and pastures around a little village. Segregation between the two categories of mouflons was reduced when lambs were several weeks old during the peak growing season. Seclusion of parous females may be explained by potential predation by foxes on neonates, an asocial tendency, the need to form mother-young bonds and the necessity for the young to develop locomotor skills. Rocky areas may also provide favourable microclimatic conditions. Two non-exclusive hypotheses may account for the tendency of lactating females to remain near 'escape' terrain. First, the anti-predator strategy could be driven in the absence of predators because of phylogenetic inertia. Secondly, the anti-predator strategy may be learned during the autumn hunting season and exhibited during the lambing season even without predation.     

Summer movements,predation and habitat use of wolves in human modified boreal forests

Grey wolves (Canis lupus), formerly extirpated in Finland, have recolonized a boreal forest environment that has been significantly altered by humans, becoming a patchwork of managed forests and clearcuts crisscrossed by roads, power lines, and railways. Little is known about how the wolves utilize this impacted ecosystem, especially during the pup-rearing summer months. We tracked two wolves instrumented with GPS collars transmitting at 30-min intervals during two summers in eastern Finland, visiting all locations in the field, identifying prey items and classifying movement behaviors. We analyzed preference and avoidance of habitat types, linear elements and habitat edges, and tested the generality of our results against lower resolution summer movements of 23 other collared wolves. Wolves tended to show a strong preference for transitional woodlands (mostly harvested clearcuts) and mixed forests over coniferous forests and to use forest roads and low use linear elements to facilitate movement. The high density of primary roads in one wolf’s territory led to more constrained use of the home territory compared to the wolf with fewer roads, suggesting avoidance of humans; however, there did not appear to be large differences on the hunting success or the success of pup rearing for the two packs. In total, 90 kills were identified, almost entirely moose (Alces alces) and reindeer (Rangifer tarandus sspp.) calves of which a large proportion were killed in transitional woodlands. Generally, wolves displayed a high level of adaptability, successfully exploiting direct and indirect human-derived modifications to the boreal forest environment.