Habitat Associations Of Small Mammals Research Articles

Landscape-scale habitat associations of small mammals on the western coast of Hudson Bay

Availability of suitable habitat affects the distribution and abundance of Arctic fauna, influencing how species respond to climate change and disturbance from resource extraction in the region. We surveyed Arctic ground squirrels (Urocitellus parryii (Richardson, 1825)) using distance sampling transects and concurrently counted microtine rodent burrows. Abundance of Arctic ground squirrels and microtine burrows was positively correlated with terrain ruggedness. Microtine burrows were more abundant inland and in areas with freshwater, whereas Arctic ground squirrels were more often found at low elevation without freshwater. Arctic ground squirrel abundance was positively related to the normalized difference water index, a proxy for vegetation water content, whereas microtine burrows were weakly correlated with the normalized difference vegetation index. Our study highlights the habitat associations of ecologically significant small mammals in an underrepresented Arctic study area.

Temporal variation in small nonvolant mammal (Cricetidae and Didelphidae) microhabitat associations in the Upper Paraná Atlantic Forest

Many questions concerning habitat preferences of Neotropical small mammals remain unanswered. These questions include where the animal lives within and among the available habitats, and the temporal (seasonal and interannual) variation in the habitat associations. The objectives of this research were: (1) to determine the associations of non-volant small mammal species (Rodentia and Didelphimorphia) with specific microhabitat characteristics including vegetation structure in an area near the western boundary of the Upper Paraná Atlantic Forest, and (2) to evaluate seasonal and interannual variation in those associations. Three grids were sampled in three seasons (Dry, Wet, Variable) during two years (2015-2017). The four predominant small mammal species (Gracilinanus agilis, Akodon montensis, Hylaeamys megacephalus, and Oligoryzomys nigripes) were evaluated for seasonal and interannual variation in habitat preferences. Each of the four exhibited seasonal and/or interannual variation in microhabitat preferences for three to six of the 17 environmental variables analyzed. This is the first study to explicitly evaluate temporal variation in habitat associations of small mammals in the Atlantic Forest ecoregion. The temporal patterns of habitat association among these four predominant species reveal a complex spatially and temporally dynamic composition and structure in this small mammal community.

Habitat associations of small mammals in the foothills of the Drakensberg Mountains, South Africa

AbstractMountains provide important habitats for many species and often have high levels of biodiversity and endemism. Habitat associations of terrestrial small mammals were investigated at Wakefield Farm at the foothills of the Drakensberg Mountains, South Africa from July 2015 to January 2016. Sherman live traps were used to capture small mammals on 35 grids in six different habitats. A total of 472 individuals, from 14 species, were recorded, comprising: 10 rodents, three shrews and one golden mole. Species diversity differed across habitats and seasons. The riparian habitat had the highest species richness, diversity and abundance of small mammals. Species composition also differed across habitats with the indigenous forest and rocky outcrops supporting the most distinct assemblages.

Small mammals exhibit limited spatiotemporal structure in Sierra Nevada forests

Forests in the Sierra Nevada, similar to those across the continent, have been substantially altered by logging, fire exclusion, and other human activities. Current forest management emphasizes maintenance or restoration of resiliency in the face of contemporary disturbance factors that include wildfire, climate change, continued urbanization, and invasive species. We evaluated responses of small mammals to forest management by monitoring a series of 12 replicate trapping grids in compositionally homogeneous forest over 8 years, and implemented 2 levels of canopy thinning. Livetrapping efforts (119,712 trap-nights) yielded 15,613 captures of 2,305 individuals of 13 species, and although forest structure was significantly influenced by canopy treatments, small mammal numbers and assemblage composition were not. To better understand this we assessed habitat associations of small mammals at 599 census points on 75 transects established in a stratified random manner throughout Plumas National Forest. We analyzed these data with 2 complementary forms of constrained ordination (canonical correspondence and canonical correlation) that extract major gradients in 1 data set (e.g., distribution of small mammal captures) and explain these in terms of measured variables from a 2nd data set (e.g., habitat and environmental measurements). Over 3 years and 57,504 trap-nights of effort we captured 1,367 individuals of 11 species. Both forms of ordination exposed significant associations between small mammals and underlying habitat metrics, but they explained remarkably little variation in these data, suggesting that small mammals are responding only modestly to habitat variation as expressed by the available environmental variables measured at each plot. We followed this with stepwise multiple Poisson regression to build models of habitat associations of these species. We applied model-averaging and employed Akaike's information criterion corrected for small sample size (AICC) to evaluate candidate models. Reflecting ordination results, competitive models (e.g., those with Akaike differences [ΔAICC] < 2.0) cumulatively explained little variation (12–36%) and regression coefficients were very low. Hence, both ordination and Poisson multiple regression suggest that the limited response by small mammals to canopy thinning primarily reflects the generalist habits of the common species in this forest. We propose that anthropogenic influences have led to structural homogenization of these forests, even across > 800 m of elevation, such that habitat specialists (e.g., old-forest-dependent species such as Myodes [Clethrionomys] californicus and Glaucomys sabrinus) have become less common due to the lack of suitable habitat. Further efforts should target nonforested habitats (meadows and riparian corridors), but results presented here suggest that managers should strive to increase heterogeneity at large spatial scales and especially to promote the development of mature forest structure.

Effects of Repeated Captures on Body Mass and Survival of Dusky-Footed Woodrats in a California Oak Woodland

Abstract Trapping sessions consisting of repeated captures are routinely used to assess demography, social organization, and habitat associations of small mammals. Some capture-recapture analyses require a high number of trapping occasions for precise estimates, but repeatedly capturing an animal may have adverse effects on individuals and populations. During 2002–2006, we examined patterns of capture, changes in body mass, and longer-term survival in a population of dusky-footed woodrats (Neotoma fuscipes). During 10 trapping sessions of 3 nights each, we captured 1,824 woodrats 4,705 times. Captures per individual averaged 1.6/trapping session. Nearly all woodrats (91%) lost mass at a rate of 3.5%/capture. Mass loss was cumulative over consecutive days, averaging ca. 3.5% of body mass after the second capture and 6.8% after the third capture. Woodrats lost slightly more mass during trapping sessions in the fall than during sessions in the spring. Percentage of change in mass was not associated with age ...

Habitat associations of small mammals in southern Brazil and use of regurgitated pellets of birds of prey for inventorying a local fauna

We inventoried terrestrial small mammals in an agricultural area in southern Brazil by using trapping and prey consumed by Barn Owls (Tyto alba) and White-tailed Kites (Elanus leucurus). Small mammals were trapped in three habitat types: corn fields, uncultivated fields ("capoeiras"), and native forest fragments. A total of 1,975 small mammal specimens were trapped, another 2,062 identified from the diet of Barn Owls, and 2,066 from the diet of White-tailed Kites. Both trapping and prey in the predators' diet yielded 18 small mammal species: three marsupials (Didelphis albiventris, Gracilinanus agilis, and Monodelphis dimidiata) and 15 rodents (Akodon paranaensis, Bruceppatersonius iheringi, Calomys sp., Cavia aperea, Euryzygomatomys spinosus, Holochilus brasiliensis, Mus musculus, Necromys lasiurus, Nectomys squamipes, Oligoryzomys nigripes, Oryzomys angouya, Oxymycterus sp.1, Oxymycterus sp.2, Rattus norvegicus, and Rattus rattus (Linnaeus, 1758)). The greatest richness was found in the uncultivated habitat. We concluded that the three methods studied for inventorying small mammals (prey in the diet of Barn Owls, White-tailed Kites, and trapping) were complementary, since together, rather than separately, they produced a better picture of local richness.

Habitat associations of small mammals in farmed landscapes: implications for agri-environmental schemes

Abstract The small mammal community in 21 localities of north-western Spain was evaluated in the light of land use composition. The two geomorphologic categories characterising the study area, the main use of the land (arable/pastoral) and main crop types of each sampling locality were used as potential predictors of the relative abundance of five common small mammal species. The Common vole, Microtus arvalis showed a weak relationship with land uses, probably due to the recent colonisation process this species experienced in the study area. The relative abundance of the Algerian mouse, Mus spretus and the Lusitanian pine vole, Microtus lusitanicus was best explained by models built at the broadest regional scale, the former being more abundant in the eastern area, the latter in the western area. The Greater white-toothed shrew, Crocidura russula showed a positive relationship with grassland coverage, whilst the Wood mouse, Apodemus sylvaticus benefited from increasing proportions of fallow lands within the landscape. These two species are then expected to respond positively to those agri-environmental schemes including the increase of fallows and grassy vegetation within the arable landscape (EU recommendations). However, further efforts are needed to predict, at least qualitatively, the response of other small mammal species to the changing farmed landscape. This is especially true for two endemic species occurring at this area: the Cabrera vole, Microtus cabrerae and the Lusitanian pine vole, and for which this kind of information is almost absent.

Small Mammal Habitat Associations at Patch and Landscape Scales in Oregon

Abstract To investigate multiscale habitat associations, we examined patterns of capture rates of small mammals in thirty 250–300 ha landscapes in the central Oregon Coast Range. We compared capture rates of 14 species within ≥7 patch types to expected capture rates based on sampling effort. We used landscape level capture rates to test for associations with percent area (composition) and 8 pattern indices at the landscape scale. Capture rates of 10 of 14 small mammal species were higher in conifer and/or mixed large sawtimber patch types. At the landscape scale, capture rates of 6 of 14 species of small mammals were positively associated with the area of patch types. The pattern of patches on the landscape may influence the distribution of 5 small mammal species in this region. We conclude that some small mammals may respond to landscape pattern and/or composition, while other small mammals may not respond to either landscape pattern or composition. Our results suggest that mature forest habitat, patch richness, pattern, and composition are key landscape features that should be considered in management plans, particularly when biodiversity of forest floor mammals is a management objective. FOR. SCI. 48(2):255–264.

Scale Dependence and Scale Independence in Habitat Associations of Small Mammals in Southern Temperate Rainforest

Although field biologists commonly employ methodologies that either are time-tested or are believed (usually for very good reason) to be suitable to the conditions that are encountered, it is rare that results generated using differing methods can be compared on a single fauna. We reanalyze data from three studies conducted on the small mammal fauna of Valdivian temperate rainforests in southern Chile. By restricting our analyses to a relatively homogeneous habitat type we avoid many problems associated with studies over large spatial scales, such as increased species richness via beta diversity. The studies involve a temporal transect, an elevational transect, and a latitudinal transect, and comprise a spatially nested series. Because these studies differed in their initial objectives, they employed different methodologies, both in the field and during subsequent data analysis. At all scales of analysis there is notable overlap in habitat use by all species. Although we observed some seasonal differences in habitat use by species, these were not substantial and involved a small subset of the species. At a local scale, numerically dominant species selected non-random microhabitats but co-occurred with other species more frequently than expected by chance. At a larger spatial scale species appeared to select large subsets of the macrohabitat (i.e., mesohabitat), providing patterns suggestive of apparent competition among species. At an even larger spatial scale, that of temperate southern South America, we predict that species assemblages will again exhibit positive associations. Thus, views on the importance of competition and other biological processes depend critically on the spatial and temporal scales over which observations are made.

Modeling Habitat Suitability for Small Mammals in Chihuahuan Desert Foothills of New Mexico

Desert arroyos make up only 2-4% of the desert landscape but may be unique habitat for some wildlife species. Habitat suitability models for small mammals could indicate habitat condition in these uncommon areas and, through monitoring, provide a tool for arid lands wildlife management. During 1993 and 1994, we modeled habitat associations for 18 species of small mammals in 6 habitats associated with desert foothills in the Sacramento Mountains, New Mexico. Habitat associations of small mammals remained relatively consistent through time, although community abundance decreased 34% from spring 1993 to fall 1994. These habitat associations allowed us to use discriminant analysis to model habitat associations based upon designation of habitat as capable of supporting high, moderate, or low relative abundance. The procedure successfully classified 80-93% of habitats as supporting high, moderate, or low abundance of 13 species of heteromyid and murid rodents. Murid rodents (Peromyscus, Reithrodontomys, Neotoma, Sigmodon) were found primarily within arroyos where shrub diversity, canopy cover, and height were greatest compared to surrounding habitats. The modeling approach described herein should be useful to managers because stochastic temporal change in the relative abundance of small mammals is effectively removed from consideration.

Quantitative Habitat Associations of Small Mammals in a Temperate Rainforest in Southern Chile: Empirical Patterns and the Importance of Ecological Scale

Multivariate analyses of distributions of small mammals identified important habitat associations in a precordilleran temperate rainforest in southern Chile. Significant differences in vegetation were found between summer (January–March) and winter (July–August) periods, indicating that multiple-season studies may be necessary to fully assess habitat preferences of small mammals. Three species of sigmodontines ( Akodon olivaceus, Abrothrix longipilis, Abrothrix sanborni ), and a putative A. longipilis × A. sanborni hybrid, showed moderate habitat preferences with considerable interspecific overlap. Habitat associations of Oligoryzomys longicaudatus , a sporadic resident, were significantly different from those of the akodonts, perhaps reflecting transient status in the community; other species generally had insufficient captures for quantitative comparisons. These patterns of habitat association differ from those of previous studies and suggest the consequences of methodological, spatiotemporal, and demographic factors in the interpretation and detection of multivariate ecological relationships.

Species Diversity, Selectivity, and Habitat Associations of Small Mammals from Coastal California

Species Diversity, Selectivity, and Habitat Associations of Small Mammals from Coastal California

Small mammal habitat associations in poletimber and sawtimber stands of four forest cover types

Small mammal distribution was examined in poletimber and sawtimber stands of four forest cover types in northern New England: northern hardwoods, red maple, balsam fir, and red spruce-balsam fir. During 1980 and 1981, eight stands on the White Mountain National Forest, NH, were sampled with four trap types (three sizes of snap traps and one pit-fall) for 16 000 trap-nights. Trapping was conducted during four 5-day periods in June and July. A total of 1206 individuals of seven species — Blarina brevicauda (short-tailed shrew), Sorex cinereus (masked shrew), Sorex fumeus (smokey shrew), Sorex hoyi (pygmy shrew), Clethrionomys gapperi (boreal red-backed vole), Peromyscus maniculatus (deer mouse), and Napaeozapus insignis (woodland jumping mouse) — were captured. Blarina brevicauda, S. fumeus, and N. insignis were more abundant in hardwoods ( P > 0.001). Only P. maniculatus was more numerous in softwoods ( P < 0.05). S. cinereus was more abundant in fir than in spruce-fir stands ( P < 0.001) and S. hoyi and C. gapperi did not occur differentially among habitat types. Possible causes of these relationships are the lower tree density and basal area and the greater amount of ground cover in hardwoods than in softwoods. Abundances of these seven species were typical, except that S. hoyi was notably more common than previously documented.

Quantitative Habitat Associations of Small Mammals along an Elevational Transect in Temperate Rainforests of Chile

Distribution and abundance of small mammals in temperate Andean rainforests are correlated with elevation. To interpret such patterns, we examined elevational variation in habitats and habitat use by small mammals. Elevation accounts for significant variation in 22 of 24 habitat metrics, reflecting the diminishing stature and more open canopies of higher-elevation rainforests. Principal-components analysis of habitat shows significant multivariate effects of elevation. Mammal species differ significantly in use of about half of the habitat variables, in ways generally consistent with morphology, behavior, and diet. Abundant species appear to occupy typical habitats along the transect, whereas rarer species are associated with more distinctive habitat types. Species overlap substantially in their use of habitats, but analyses of trap captures indicate that species are segregated at finer spatial scales. Spatial segregation at this scale may contribute to the coexistence of abundant species and congeners. Elevational variation in habitat and specific habitat associations provide a plausible explanation for correlations of mammalian distribution and abundance with elevation.

Habitat Selection and Species Interactions: An Experimental Analysis with Small Mammal Populations

Habitat associations and habitat utilization patterns of small mammals (Sorex cinereus, Blarina brevicauda, Peromyscus leucopus, Microtus pennsylvanicus, and Zapus hudsonius) were experimentally investigated in three communities (Broadmoor, Great Island, and Nantucket) in eastern Massachusetts (USA). Structure of the habitat was ordinated using principal components analysis. Habitat associations of small mammals colonizing experimental trapping grids where all individuals were regularly removed were compared with control grids using multiple linear regression. Intergrid differences in habitat selection were observed in one population of Blarina, two populations of Peromyscus, three populations of Microtus, and one population of Zapus. Differences in habitat associations in four populations could be attributed at least partly to differences in habitat structure. An index of habitat utilization (discrimination) was developed using discriminant function analysis. Peromyscus showed large increases in discrimination on the experimental grids, whereas one population of Microtus showed a decrease in discrimination on the experimental grid. Seasonal discrimination values were regressed on seasonal density estimates of small mammals on the control grids to quantify the relationship between population density and habitat utilization in the Peromyscus and Microtus populations. The Peromyscus populations and the Broadmoor Microtus population demonstrated the predicted negative relationship between intraspecific population density and discrimination. The Great Island Microtus population showed a positive relationship between density and discrimination, which could be explained by the structure of the habitat. There was no linear relationship between Microtus density and discrimination on Nantucket, but discrimination followed a pattern similar to that of density. No significant relationships were found between habitat discrimination and densites of other small mammal species. These results suggest that intraspecific competition was more important than interspecific interactions in determining habitat use patterns, and that habitat selection was an important determinant of structure in these small mammal communities.

Seasonal food habits of marten in south-central Alaska

Studies of the diet of marten (Martes americana) and the abundance and habitat associations of small mammals were conducted in south-central Alaska for 2 years. Marten were found to eat primarily arvicolid (= microtine) rodents. Other important food items were sciurid rodents, fruits, and birds. Strong seasonal variation in the importance of arvicolid rodents was associated with changes in their density as indicated by trapline capture success. Northern red-backed voles (Clethrionomys rutilus) dominated the diet of marten when they and other arvicolids were generally scarce, whereas tundra voles (Microtus oeconomus) and meadow voles (M. pennsylvanicus) were the primary prey when arvicolids were abundant. Arvicolid species exhibited strong differences in habitat associations and habitat niche breadth. Red-backed voles were found in a wide range of habitat types, but tundra voles and meadow voles were limited to herbaceous and low shrub meadow habitats, where they attained high local densities. Similarities in patterns of prey preference by marten among several North American sites are described. The effects of patterns of habitat use by arvicolid rodents on the food habits of marten are discussed.