Relative Abundance Of Small Mammals Research Articles

Location matters: survival of artificial nests is higher in small grassland patches and near the patch edge

Nest survival is an important part of breeding success in grassland ecosystems, and the location of nests can determine vulnerability to different predators. We conducted an experiment with artificial nests to evaluate jointly the predation rate on nests at different spatial scales (landscape, patch and tussock) and the relative abundance of potential nest predators (small mammals and birds) in a temperate grassland area. In November 2014 and 2016, we installed 288 artificial nests in Common Pampas Grass Cortaderia selloana grasslands in the southeastern Pampas region, Argentina. The nests were placed in two 10‐ha plots in a continuous grassland patch (c. 900 ha) within a reserve and in two small grassland patches (1.5 and 1.8 ha) in an agricultural matrix (landscape‐scale), at the patch edge and inside the patches (patch‐scale), and at two heights within the tussock grass (tussock‐scale). In 2016, we also conducted live trapping of small mammals and surveyed birds along strip transects at the sampling sites. Nests located in patches within an agricultural matrix and near the edge had greater relative survival than those set in the reserve and inside the patches, respectively. This might be explained by the lower relative abundance of small mammals that we found outside the reserve. Artificial nest survival values recorded at the landscape‐scale contrasted with those previously observed for natural nests. Our results could be partly explained by differences in nest density between agro‐patches and those within the reserve. Future studies could also evaluate the role of parental nest defence on nest survival.

Fire exclusion and fire return interval affect small mammal populations in longleaf pine forests

Longleaf pine (Pinus palustris) forests are among the most fire-dependent forest types in the world and once dominated much of the southeastern United States. Loss and fragmentation of longleaf pine shrank its distribution to approximately 4% of its historic range; as a result, longleaf pine forests currently receive much conservation and restoration emphasis. In all cases, this emphasis includes prescribed fire. Prescribed fires promote herbaceous understories which maintains habitat for some small mammals, but fires can also result in temporary declines of small mammal populations. Therefore, short return intervals may not allow small mammal populations to recover between fires, and long return intervals may result in declining habitat quality and reduced small mammal abundance. During the first phase of our research, we studied the long-term influence of prescribed fire on small mammals. We annually estimated small mammal abundance and species richness during 2001 – 2014 in eight longleaf pine-dominated plots in southwestern Georgia, USA. Plots were either biennially burned (reference) or had fire excluded during the study. Small mammal species richness was similar in fire-excluded and reference sites. Overall small mammal abundance was greatest in reference plots. Five species were captured with sufficient frequency to justify species-specific analyses. Of these, three (hispid cotton rats, Sigmodon hispidus; oldfield mice, Peromyscus polionotis; and house mice, Mus musculus) were more abundant in reference plots. For the second phase of our research, we reintroduced fire in half of the fire excluded plots (burned during 2015, 2016, and 2017) and began sampling small mammals in three additional plots that were burned annually since 2003. We collected data during 2017 and 2018 for this phase of the research to evaluate small mammal response to four prescribed-fire return intervals (annual growing season burns since 2003, biennial burns since 2001 (reference), fire excluded since 2001, and fire excluded since 2001 and then burned during 2015, 2016, and 2017). Small mammal species richness was not affected by burn interval. Cotton rat abundance was greater in reference plots than in other treatments, whereas cotton mice (Peromyscus gossypinus) and oldfield mice were most abundant in the annually burned treatment. Three prescribed fires occurred in fire reintroduced plots prior to sampling, but these fires were insufficient to restore small mammal abundance to that of annually or biennially burned plots. Our work provides further evidence that fire is important for maintaining habitat for some small mammals and that time between fires has a species-specific effect on small mammal abundances. Thus, manipulating fire return interval is a promising tool for managing relative abundance of small mammals and likely other wildlife.

Microhabitat, altitude and seasonal influence on the abundance of non-volant small mammals in Mount Rungwe forest nature reserve

A study on microhabitat, altitudinal and seasonal influences on small mammal abundance in Mount Rungwe Nature Forest Reserve, Tanzania was carried out from March 2019 to February 2020 during the wet and dry seasons. Live traps were used in six grids and six transect lines for capturing small mammals at the low, mid, and high elevations (1700–2600 m.a.s.l.). Generalized linear models were used to examine the effects of microhabitat characteristics, altitude, and seasons on the relative abundance of small mammals. A total of 444 rodents and shrews were recorded on 4320 trap nights. Rodent species recorded included Beamys hindei, Cricetomys ansorgei, Dendromus insignis, Grammomys ibeanus, Graphiurus murinus, Lophuromys machangui, Praomys delectorum, and one shrew, Crocidura sp . Overall, P. delectorum was the most dominant species in all elevations, with 68.9% of all captures. Mid elevation had a higher abundance of small mammals (Estimate ± SE = 1.17 ± 0.49, Z = 2.37, p = 0.0176). Species abundance was influenced differently by elevation. While P. delectorum decreases with increasing elevation, L. machangui increases with an increase in elevation. Although overall small mammal abundance was not affected by microhabitat variables (Estimate ± SE = −0.08 ± 0.13, Z = −0.67, p = 0.5050), individual species ( P. delectorum and L. machangui ; Estimate ± SE = 0.13 ± 0.06, Z = 1.95, p = 0.05 and −0.31 ± 0.09, Z = 3.34, p = 0.0008 respectively) were affected differently. While P. delectorum abundance showed a positive correlation and increased with an increase in PCA1 in GLM, L. machangui had a negative trend that shows they were affected differently. Small mammal abundance, on the other hand, was affected by season and, in particular, rain, with low abundance during heavy rains and dry cold periods (Estimate ± SE = 0.51 ± 0.14, Z = 3.6, p = 0.0003 and 0.3 ± 0.15, Z = 2.08 p = 0.04 respectively). In general, the results show that microhabitat parameters, elevation, and season influenced small mammals’ abundance in MRFNR. This outcome indicates that altering the microhabitat could have an impact on the small mammal assemblage and particularly their abundance. Thus, microhabitat, elevation, and season influence small mammal abundance and can be used as a proxy for evaluating the biodiversity of montane tropical small mammal communities.

Small mammal relative abundance within riparian ecosystems of the Blue Mountains

There is a growing interest and investment in restoring riparian areas in the Pacific Northwest to protect biodiversity and water quality, and to restore quality habitat for threatened fish species. However, these management activities change vegetation conditions and potentially impact terrestrial species in these ecosystems. Our objective was to estimate associations between small mammals and 4 broad cover types—conifers, shrubs, grasses, and forbs—in riparian areas within the Blue Mountains of northeast Oregon, USA. We estimated abundances and spatial association for 10 small mammal species using a multispecies hierarchical abundance model and mark-recapture data collected on 36 sites from 2014 to 2017. We predicted that forest-associated species would be more abundant with greater conifer cover, that increases in shrub cover would favor most species, and that increases in grass and forb cover would favor grassland-associated species. Yellow-pine chipmunks (Tamias amoenus) were positively associated with conifer cover, while long-tailed voles (Microtus longicaudus) and montane voles (Microtus montanus) were negatively associated with conifer cover. Associations with shrub cover were positive for bushy-tailed woodrats (Neotoma cinerea), deer mice (Peromyscus maniculatus), and yellow-pine chipmunks, but negative for montane voles. Bushy-tailed woodrats and montane voles were negatively associated with grass cover. This study is the first to characterize the riparian small mammal communities in this region and provides insights on the effects of restoration activities on riparian ecosystems in dry interior forests and grasslands. We suggest that riparian plantings, a ubiquitous restoration practice, will increase the relative abundances for some, but not all, small mammal species. We also demonstrate use of a new multi-species abundance model that can be a powerful tool for analyzing mark-recapture data because it allowed us to extend the scope of our analysis to data poor species by pooling information with data rich species.

Species composition of small mammals in key biotopes near Kolomak (Kharkiv Oblast)

The study of the species composition and biotope preferences of small mammals around Kolomak had been carried out for four years (2017–2020). During the study period, 9 species of mouse-like rodents and 3 species of insectivores were found. No Cricetulus migratorius, Terricola subterraneus or Microtus oeconomus were found from the theoretically expected species already known for this area. Around Kolomak, 11 biotopes were investigated, including maple-linden oak forest, agrocenoses, dry and flooded meadows, which are located along the banks of a pond and in a gully-ravine system. The first year of research was in a year of high abundance (2017), and then 9 species were immediately discovered, but species with small abundance, such as Crocidura suaveolens, Sorex minutus, and Micromys minutus, were found in years with a small relative abundance of small mammals. Myodes glareolus, Sylvaemus tauricus and Sylvaemus uralensis are dominant species in the captures. According to the trapping results, 2017 was the year of high relative abundance of small mammals, 2018 was the year of the lowest relative abundance, 2019 and 2020 were years with an average relative abundance. During the study period, 6 species were identified in forest biotopes (Apodemus agrarius, Sylvaemus tauricus, Sylvaemus uralensis, Myodes glareolus, Sorex araneus, and Dryomys nitedula). In ecotones with floodplain biotopes, 8 species were found (Apodemus agrarius, Sylvaemus sylvaticus, Sylvaemus uralensis, Mus musculus, Micromys minutus, Myodes glareolus, and Sorex araneus). Four species (Mus musculus, Sylvaemus sylvaticus, Sylvaemus uralensis, and Microtus levis) were discovered near human settlements. In general, biotopes with the greatest species diversity and number of caught individuals are ecotones of dry and floodplain meadows. In years of high abundance, both species diversity and the number of individuals caught in the oak forest and in ecotones near the pond increased. It should be noted that Myodes glareolus was caught in clear-cuts during the two years (2019-2020) only in the summer of 2020. Earlier, not a single specimen of this species was caught there, although there is a dense weed grass cover in this area and the shrub layer has also grown up in some places, and the clear-cut is surrounded by oak forest.

Connection between prey composition and the landscape structure in the hunting area of Barn Owl’s (Tyto alba) in Baranja (Croatia)

Background and purpose: The assumption that the species composition and the relative abundance of small mammals in pellets of Barn Owls reflects the landscape structure of the hunting area is tested, based on habitat preferences of small mammals identified from pellets collected in the hilly and lowland parts of Baranja county (Croatia). Materials and methods: During 2007 we collected 2395 whole pellets and their fragments in 21 localities, from which 6613 prey remains were identified as belonging to small mammals (99.5%) of 23 species. The correlation between the relative abundance of mammal species and landscape structures (habitat types and landscape features) was tested. Results: There was a significant correlation between the relative abundance of seven small mammal species and the proportion of particular landscape structure classes. The number of small mammal species showed a negative correlation with the area of inland marshes. The evenness of the small mammal fauna grew with the mosaicity of landscape and the length of the borders in the owl’s hunting area. In the total prey the Common Vole (Microtus arvalis) dominated with more than 62%, which indicates its population outbreak. The diversity and evenness of small mammals in the hilly and lowland regions did not differ. Conclusions: We found significant correlations between the relative abundance of some small mammal species and the landscape structure classes in the owls’ hunting area. Our results suggested that the diversity of small mammals increases as the mosaic of the landscape increases, while the degree of population outbreak of the Common Vole decreases. These relationships should be taken into consideration when designing landscapes or changing land use.

Validation of hair tubes for small mammal population studies

Survey techniques available to sample mammals have multiplied during the last decades. They offer new opportunities for sampling and monitoring populations, but before widespread use they need to be validated and calibrated to more traditional approaches. We conducted a quantitative assessment of hair tubes designed to monitor common small mammals by comparing results to live-trapping data. Hair tubes are inexpensive, easy to use, and noninvasive, which offers benefits regarding animal ethics. We considered the shape of the tube, application in field conditions, and validated hair-tube results in 3 different habitats based on experimental and field sampling in 2 countries. Tube size selected species entering into the tubes, with shrews detected in small tubes only and rodents in larger tubes. The number of tubes visited (with hair sample) was proportional to the number of individuals captured in live traps. Overall, tubes performed better than traps, detecting individuals where traps did not, making this technique promising for inventory of rare species. The sampling pattern was robust across wood, grassland, and cultivated field habitats and across seasons, which suggests that the proportion of hair tubes visited is a robust indicator of relative abundance of small mammals. In the context of population studies, hair tubes cannot replace trapping because the identification of species or individuals from hair collected in tubes is difficult and costly. We recommend combining hair tubes with livetrapping for increased efficiency and before species identification based on DNA sampling is applied to large-scale population studies.

Small mammal community response to early meadow\u2013forest succession

BackgroundWith farmland afforestation becoming common policy in many European Union countries, we studied how early forest succession (from meadow to young stand) influences small mammal species composition, diversity, abundance and biomass. Despite numerous investigations into forest succession, almost no attention has been given to the small mammal community change in the early-successional forest ecosystems, starting with the pre-forest habitat and ending with stand formation and the establishment of tree dominance. We compared small mammal communities in meadows at the initial stage of regrowth (with saplings less than 10 cm in height), in young forest (5–10 years old) and more advanced forest (15–20 years) in both cases of human-induced forest succession, where the trees had been planted, and natural forest succession, where natural regrowth of meadows had occurred.ResultsThe greatest diversity of small mammal species was recorded in the meadow (H = 2.95), with a lower diversity found in the young forest (H = 2.61) and even lower in the advanced forest (H = 2.04), the last habitat being the most monodominantic. The order of species dominance from Microtus sp. (M. arvalis, M. agrestis), Myodes glareolus, Apodemus flavicollis, Sorex araneus, A. agrarius in the meadow changed to M. glareolus, S. araneus, M. arvalis, M. agrestis in the young forest and to M. glareolus, A. flavicollis, S. araneus in the advanced forest. The lowest relative abundance of small mammals was recorded in the meadow (18.19 ± 2.27 ind. Per 100 trap-days), with Microtus voles being the most abundant. Relative abundance was higher in the young forest (22.72 ± 2.25 ind. Per 100 trap-days), with Myodes glareolus being the most abundant (7.59 ± 0.96 ind. Per 100 trap-days) and at its highest in the advanced forest (23.91 ± 2.77 ind. Per 100 trap-days), again with M. glareolus being the most abundant (15.54 ± 2.35 ind. Per 100 trap-days).ConclusionsThus, our analysis suggests that that during early meadow-forest succession, the diversity of the small mammal community declines – the number of species decreases as typical meadow species are lost due to the transformation of the habitat and one or a few species became dominants. However, the relative abundance of the small mammals increases. Biological indices of small mammal communities differed between natural and human-induced meadow-forest succession.

Converting Abandoned Hayfield to Switchgrass Increases Small Mammal Relative Abundance

Switchgrass (Panicum virgatum L.) has been identified as a versatile and broadly useful bioenergy feedstock, with potential for use in coal-fired power plants as well as ethanol production. However, in order for switchgrass use to markedly influence energy production, conversion to this grass species must occur at a large scale. Little is known about the potential ecological consequences of widescale conversion of land to switchgrass. This study was conducted to identify potential effects of switchgrass planting on small mammal populations. An abandoned perennial cool season grass hayfield in central Kentucky was subdivided into two fields; one field was planted with switchgrass and the control field was maintained as an unmanaged hayfield. Small mammal relative abundance was quantified using a tracking method through the third year following switchgrass planting. Small mammal relative abundance was greater in the switchgrass field than in the control field. Vegetative community analysis showed the control field was dominated by tall fescue, suggesting that thickness of stand and/or fescue toxicity may have been a factor in reduced small mammal abundance. These data suggest that conversion of abandoned old fields to switchgrass will not have a negative effect on small mammal populations. Further research should target potential mechanisms for this variation in small mammal relative abundance, as well as other species in the community which may be affected by conversion to switchgrass.

SPECIES COMPOSITION, HABITAT ASSOCIATION AND RELATIVE ABUNDANCE OF SMALL MAMMALS IN BORENA SAYINT NATIONAL PARK, SOUTH WOLLO, ETHIOPIA

Small mammals are ecological regulators in natural habitats. During the present investigation, species composition, distribution and relative abundance of small mammals were studied in Denkoro Forest, South Wollo, and Ethiopia from 2011 to 2012. In this investigation, Capture-Mark-Recapture (CMR) method was used. Data were collected during the wet and dry seasons by using Sherman live-traps (7.6× 8.9 × 22.9 cm. size) and snap-traps, and the traps were randomly laid at different trap sites of the habitats. The area of each live-trap grid was 70 ×70 m. Each of the grids consisted of seven lines, 10 m apart, with a trap station at every 10 m. A total of 49 Sherman traps was set in each grid, for 3 consecutive days. Ten species of small mammals belonging to rodents and insectivores were recorded from the study area. Additional two rodent species (Hystrix cristata and Trachyoryctes splendens)were sighted, but not captured. The small mammals trapped were Lophuromys flavopunctatus (35.7%), Otomys typus (28.5%), Stenocephalemys griseicauda (14.6%), Arvicanthis dembeensis (9.1%), Crocidura flavescens (5.9%), Stenocephalemys albipes (1.9%), Crocidura fumosa (1.4%), Desmomys harringtoni (0.8%), Mus Mahomet (0.6%) and Dendromus lovati (0.3%). Population abundance and species composition of small mammals varied from habitat to habitat and from season to season. Lophuromys flavopunctatus and O. typus were the most widely distributed and abundant species, whereas S. albipes, C. fumosa (in the forest), D. harringtoni, D. lovati and M. mahomet (in the farmland) were restricted species. Seasonal variation and availability of food resulted in variation in abundance and distribution of small mammals from habitat to habitat. Disturbance of small mammals by plant trampling and cutting should be stopped since small mammals are a source of diet to the endemic Ethiopia wolf and other carnivores.

Estimating the relative abundance of small mammals when there is no record of catching effort

Estimates of local population abundances, which require carefully designed sampling procedures, can provide valuable information on population size and density. Even though small mammals are one of the most widely studied vertebrate groups, many surveys have not recorded basic information to estimate local abundances, for instance catching effort. Here we suggest a simple comparative trapping frequency index that can be used as an alternative to the relative abundance index in data sets that only contain the number of species and individuals collected, thus lacking information on sampling effort. To compare trapping frequency and relative abundances we used capture records from more than four years, from seven species of rodents and two marsupial species collected by the Brazilian Plague Service. We calculated the trapping frequency index of each species as the proportion of trapped individuals per total of all individuals caught. We found that this trapping index was significantly correlated with a relative abundance index (number of captured individuals divided by number of trap nights). Our findings suggest that the proposed index may be useful for comparisons in situations where data on catching effort is lacking. The index may also provide a simple, though approximate quantification of relative local abundances, with possible applications in comparative studies (e.g. meta-analysis). We suggest that this index is used in studies that do not focus on obtaining accurate population parameter estimates, but which nonetheless contain data that can still offer a representative measure to compare local population abundances.

Habitat loss, fragmentation and degradation effects on small mammals: Analysis with conditional inference tree statistical modelling

Anthropogenic habitat loss, fragmentation and degradation often co-occur in a landscape and their relative influence on a native animals’ health and survival can be difficult to determine. We examined the influence of these environmental variables on the estimated relative abundance of some small mammal species in a large area (∼2500km2) of southeastern Australia. Using the agile antechinus (Antechinus agilis) as a model, we also examined the association between these variables and three population performance indices, mass-size residuals (MSR; indexing fat reserves), the neutrophil/lymphocyte ratio (N:L; indexing physiological stress) and red blood cell counts (RBC; indexing regenerative anaemia). Study sites were in either highly disturbed and fragmented, or relatively undisturbed, continuous Eucalyptus forest.We generated conditional inference tree statistical models to identify the relative importance of up to 49 ecological variables in explaining variation in small mammal abundance and performance indices. Habitat loss was important in explaining small mammal abundance, as were the abundances of the same species in neighbouring study sites. The models also suggested that the habitat area required to support a ‘healthy’ population was greater in the larger species examined. Autocovariates of neighbouring site same-species abundances and habitat fragmentation were the next most important influences on small mammal relative abundance, implying that metapopulations may be important for population persistence, especially in bush rats (Rattus fuscipes). Habitat degradation, reflected in structural and floristic features, was less important, but explained some variance in relative abundances. For agile antechinus populations, time of year, degree of forest fragmentation and extent of native tree cover were important in explaining performance indices. Results indicated that habitat reduction per se was a significant threatening process for small mammals. Habitat loss requires at least the same research attention as that currently devoted to anthropogenic habitat fragmentation and degradation.

Relative abundance of small mammals in nest core areas and burned wintering areas of Mexican Spotted Owls in the Sacramento Mountains, New Mexico

Mexican Spotted Owls (Strix occidentalis lucida) are common in older forests within their range but also persist in many areas burned by wildfire and may selectively forage in these areas. One hypothesis explaining this pattern postulates that prey abundance increases in burned areas following wildfire. We observed movement to wintering areas within areas burned by wildfire by four radio-marked Mexican Spotted Owls in the Sacramento Mountains, New Mexico. These movements occurred during the winters of 2004–2005 and 2005–2006, with some owls migrating in both winters and others in only one. Wintering areas of these owls occurred within the perimeters of two wildfires that burned in May 2000 and April 2002, respectively. We estimated relative prey abundance and biomass during December 2006 within paired burned wintering areas and nest core areas used by these owls. Species richness and relative abundance of small mammals were greater in the burned wintering areas than in the associated nest core areas for all four owls, and estimated prey biomass ranged from 2–6 times greater in burned wintering areas relative to the paired nest core areas. Burned wintering areas used by these owls were similar in elevation to their nest core areas, and likely experienced similar weather conditions during winter. These results suggest that wintering owls moved to areas with greater food resources, rather than to areas with milder weather. They further suggest that relative prey abundance was greater in burned wintering areas than in the nest core areas >5 years post-fire, and that these burned wintering areas provided important habitat for Mexican Spotted Owls in our study area during an energetically stressful season.

Marten and fisher responses to fluctuations in prey populations and mast crops in the northern hardwood forest

AbstractMany forest tree species produce seed (mast) crops that are consumed by a variety of wildlife species and these pulsed resources may mediate interactions among predator and prey populations. In the northern hardwood forests of New York, we investigated interactions among mast production, prey abundance, and harvests of American martens (Martes americana) and fishers (Martes pennanti) during 1988–2009. Mast production for beech (Fagus grandifolia), sugar maple (Acer saccharum), and mountain ash (Sorbus americana) was synchronous and an alternate‐year pattern in production was evident for most of the time series. We documented considerable temporal variation in summer small mammal relative abundance and our numerical response models received substantial support for 5 of the 8 species, indicating lagged responses to autumn mast crops. Trap response of martens to the autumn production of beech mast and mountain ash berries was immediate and numerical responses to the relative abundance of small mammal prey occurred during the preceding summer. The age structure of the marten harvest differed based on the dominant alternate‐year pattern of summer prey relative abundance and autumn mast production (χ24 = 33.06, P < 0.001). The proportion of juvenile marten in the autumn harvest was 52% and 34% following summers when small mammal relative abundance was high and low, respectively and these differences resulted in a persistent cohort effect that was apparent until age 3.5. Trap response of fishers to the autumn production of beech mast was immediate and numerical responses to the relative abundance of Sciurid prey occurred during the preceding summer. Marten and fisher harvests fluctuated similarly among New York, Maine, and New Brunswick, which may indicate regional synchronization of mast crops and responses of martens and fishers to similar prey dynamics. A better understanding of how food availability influences demographic responses and trapping vulnerability of martens and fishers would aid our ability to manage harvests of these species on a sustained yield basis. © 2011 The Wildlife Society.

Small mammal community changes during succession of the planted forest

Small mammal communities were investigated in three stages of meadow-forest succession (natural meadow, <10 years old forest plantation, and 15 years old spruce–birch forest stand) in the Pakruojis forest, north Lithuania, in 2007–2010. A total of 11 small mammal species were registered: nine in the natural meadow and in the forest plantation, and six in the forest stand. We found that under gradual change of the natural meadow to the young forest and later to the mixed forest stand, the diversity of the small mammal community decreased. Typical open habitat species were still present in the sapling stage, but already lost in the forest stand. The growing relative abundance of small mammals was due to the increased numbers of Myodes glareolus instead of Microtus voles.

Impacts of Agriculture on the Diet and Productivity of Mackinder's Eagle Owls (Bubo capensis mackinderi ) in Kenya

ABSTRACTLand conversion for agriculture is an increasing threat to biodiversity conservation, but its ecological effects on African birds is practically unknown. We investigated the impacts of agriculture on the diet and productivity of a small, disjunct population of Mackinder's eagle owls (Bubo capensis mackinderi ) in central Kenya. Owl diet was determined by analysis of pellets and other remains and compared to small mammal populations estimated by live trapping in two habitats. Small mammal abundance was low and averaged 7.4 small mammals/ha in farms and 0.5 small mammals/ha in grassland. Owls consumed a wide diversity of prey. The majority were mammals (87%) followed by birds (7%) and insects (5%). The percentage of small mammals in owl diet correlated positively with the relative abundance of small mammals during monthly trapping sessions. Diet composition did not influence owl breeding success. Farming activities affected owl diet composition through crop production. The amount of maize, peas, and carrots growing in farms was correlated with the abundance of Mastomys sp. and Procavia sp. in the owl's diet. Agricultural activities had a large effect on Mackinder's eagle owl diet by increasing the abundance of certain small‐mammal prey and attracting owl prey to farms, though farming practices harmful to owls were observed.

The influence of habitat and landscape on small mammals in Estonian coastal wetlands

We investigated the influence of habitat type and landscape composition on small mammal relative abundance and diversity in coastal wetlands in western Estonia. Seventy live-trap lines in eight representative habitats, across six wetlands revealed seven species. The most diverse habitats were reed bed and scrub woodland, whereas tall grasslands had the highest biomass. Short grass was low in species richness and relative abundance. Small mammal relative abundance, richness, and biomass were positively correlated with tall grass and mosaic habitats and negatively correlated with lower shore habitats and bare ground. Our study indicates potential nature conservation conflicts between small mammals and other biodiversity priorities in wetlands.

Planning timber harvest of residual forest stands without compromising bird and small mammal communities in boreal landscapes

Numerous efforts have been invested in designing and configuring residual forest stands in Canadian boreal forest to preserve their overall biodiversity. Now that several landscapes have been partially logged, the next issue in forest management involves the planning of residual forest stand harvesting without compromising wildlife populations. Residual stands can be cut when adjacent regeneration reaches 3 m in height according to current regulations in several Canadian provinces (e.g., Québec, Ontario, Alberta, and British-Columbia). However, little is known on whether such regenerating habitat (RE-3m) can maintain wildlife communities similar to those found in unharvested mature forest (CO). We estimated the relative abundance of small mammals and forest birds in RE-3m and CO habitats and characterized landscape and stand structures. These variables were then compared between the two contrasting successional stages and were used to build habitat use models (HUMs) for 21 species. CO and RE-3m differed with regard to several landscape characteristics and stand structure variables as a result of logging. Snowshoe Hare, Northern Flicker, Alder Flycatcher, Ruby-crowned Kinglet, White-throated Sparrow and Magnolia Warbler were more abundant in RE-3m than CO, while Red-backed Vole, Brown Creeper and Golden-crowned Kinglet exhibited lower abundances in RE-3m. No significant differences in abundance were observed for the 12 other species. Species HUMs were highly significant and explained between 64.3 and 99.1% of the total variability in abundance. Following variance partitioning, stand structure variables accounted for most of the explained variability (54.2%) while landscape characteristics accounted for only 28.7%. No difference in species richness was observed but community evenness was greater in CO than RE-3m. Our results suggest that current regulations may threaten the maintenance of 3 out of 21 censused species for which abundances were significantly lower in regenerating 3 m tall stands. As stand structure explained a large amount of variability in abundance, it should be considered during timber harvest planning in both mature and regenerating stands. Until we know more on whether the current regulations are suitable for maintaining overall biodiversity, our results suggest that some mature forest stands should be maintained within managed landscapes for a complete logging rotation period.

Are hedgerows the route to increased farmland small mammal density? Use of hedgerows in British pastoral habitats

Linear habitats are becoming increasingly common as a consequence of habitat fragmentation, and may provide the sole habitat for some species. Hedgerows are linear features that can vary substantially in structure and quality. Having surveyed 180 hedgerows, in four locations, and sampled their small mammal communities we examined the effect of physical hedgerow attributes on the abundance of small mammal species. Using three elements of landscape structure, we explored whether variation was best explained by the Random Sample Hypothesis (that small islands represent a random sample of those species populating larger areas), or by the Fragmentation Hypothesis (that species abundance will decrease with a loss of habitat area). We tested the relationship between the relative abundance of small mammals and 1. hedgerow connectivity; 2. total habitat availability and 3. local habitat complexity. We then explored the predictive power of combinations of these habitat variables. Connectivity was a positive predictor of wood mice Apodemus sylvaticus, and hedgerow gappiness was a negative predictor of bank voles Clethrionomys glareolus. The total amount of habitat available (hedgerow width, height and length) was a positive indicator of total small mammal biomass. These results support the Fragmentation Hypothesis that species abundance and distribution decrease with a loss of habitat area. The preservation of linear and associated habitats may therefore be important in maintaining metapopulations of the species we studied.

Small Mammal Communities in the Fragmented Landscape in Lithuania

Species composition and abundance of small mammals, as well as changes in small mammal communities after the abandonment of agriculture fields, were studied in forest fragments and the surrounding field matrix. The most common species in the forest fragments was the bank vole (Clethrionomys glareolus), in the fields – the common vole (Microtus arvalis). C. glareolus and the yellow-necked mouse (Apodemus flavicollis) had the highest frequency of occurrence, both recorded in 82% of the investigated forest fragments. Other species were less common. The relative abundance of small mammals did not differ in the surrounding field matrix and the forest fragments irrespective of their size. In small forest fragments, species composition of small mammals was not stable. After the abandonment of the surrounding field, the diversity of a small mammal community in the forest fragments decreased. Our study suggests that C. glareolus was the only small mammal species in the forest fragments that positively responded to matrix changes from the start of the forest re-growth in the former agricultural field during the first years of succession.