Live-trapping Of Small Mammals Research Articles

White-footed mouse (Peromyscus leucopus) response to restoration of grassland alvar

Grassland alvar is a rare plant community that occurs throughout North America and northern Europe, and may require control of encroaching vegetation to be maintained or restored. We evaluated the hypothesis that restoration techniques used to restore the alvar ecosystem do not lead to declines in small mammal abundance. More specifically, we used a Before-After Control-Impact (BACI) design to compare how two methods of vegetation control, prescribed burns and mechanical removal, affected small mammal populations. The restoration was conducted beginning in 2019 on Pelee Island, Ontario, Canada. Live trapping of small mammals and associated vegetation sampling were conducted before and after on treatment and control locations. The only small mammal species to be caught during the study was the white-footed mouse ( Peromyscus leucopus (Rafinesque, 1818)), which had an observed decrease across all treatment sites and the control site. Generalized linear mixed effects models demonstrated that the main effects of treatment and year best explained mouse abundance at the site level. Interannual variability appeared to explain more variation in mouse abundance than treatment effects. Our study did not provide strong evidence that the vegetation control measures we employed might limit white-footed mouse abundance.

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.

Estimating the density of small mammals using the selfie trap is an effective camera trapping method

Camera trapping to study wildlife allows for data collection, without the need to capture animals. Traditionally, camera traps have been used to target larger terrestrial mammal species, though recently novel methods and adjustments in procedures have meant camera traps can be used to study small mammals. The selfie trap (a camera trapping method) may present robust sampling and ecological study of small mammals. This study aimed to evaluate the selfie trap method in terms of its ability to detect species and estimate population density. To address this aim, standard small mammal live trapping was undertaken, immediately followed by camera trapping using the selfie trap. Both methods were set to target the arboreal sugar glider (Petaurus breviceps) and semi-arboreal brown antechinus (Antechinus stuartii). The more ground-dwelling bush rat (Rattus fuscipes) was also live trapped and recorded on camera. Across four survey areas, the probability of detection for each of the three species was higher for selfie traps than for live trapping. Spatially explicit capture-recapture models showed that selfie traps were superior at estimating density for brown antechinus and sugar gliders, when compared to simulated live trapping data. Hit rates (number of videos per various time intervals) were correlated with abundance. When correlating various hit rate intervals with abundance, the use of 10-min hit rate was best for predicting sugar glider abundance (R2 = 0.94). The abundance of brown antechinus was estimated from selfie traps using a 24-h hit rate as a predictor (R2 = 0.85). For sugar gliders, the selfie trap can replace live trapping as individuals can be identified through their unique facial stripes and natural ear scars, and thus used in capture-recapture analysis. This method may be useful for monitoring the abundance of other small mammal species that can also be individually recognized from photographs.

Results of a small terrestrial mammal survey in the remote Boé region of Guinea‐Bissau, with discovery of two new shrew records for the country

AbstractThe Boé region in the south‐east of Guinea‐Bissau has remained untouched by large‐scale human influence and development due to its isolated location. The region consists mainly of savannah interspersed with gallery forests and hosts a unique and valuable biodiversity though very little is known of small terrestrial mammal diversity. In 2013, a terrestrial small mammal live trapping survey was conducted around Béli, a small village in the South of the Boé region. Five survey locations of three ecotypes were selected, and a combination of pitfall traps and live traps was used to capture and release small mammals. A selection of mammals that could not be identified as well as accidental mortalities in the traps were collected as voucher specimens and sent to Naturalis Biodiversity Center in the Netherlands. Over 96 survey days, a total of 331 small terrestrial mammals were trapped from 21 unique species, which include two new species records for the country: shrew species Crocidura lamottei and Crocidura crossei. Extrapolation from species accumulation curves suggested an overall species richness of 22 species for the region, with substantial differences in community composition among sampled habitats. The results of this study are an important part of the scientific record for small terrestrial mammals in the Boé region and set a baseline reference for future conservation efforts.

Habitat type impacts small mammal diversity in the Ukaguru Mountains, Tanzania

Abstract We assessed the habitat association of the diversity and abundance of small mammals in the Ukaguru Mountains within the Eastern Arc Mountains, Tanzania. An estimation of the vegetation parameters and live-trapping of small mammals for three consecutive nights per month for 21 months were carried out in farmland, disturbed and intact forests. A total of 1196 individual small mammals comprising 13 species were captured. Species diversity and evenness in intact forest were much higher compared to disturbed forest. Principal component analysis (PCA) explained 87.7% of the variance with two factors. The study suggests vegetation and habitat disturbances are factors responsible for the observed diversity of small mammals in the Ukaguru Mountains. Mastomys natalensis, Mus triton and Praomys delectorum accounted for 90.0% of total captures. M. triton and M. natalensis were the most abundant in farmland with 46.8 and 42.8% of total captures respectively and associated with the herbaceous vegetation. P. delectorum correlated with litter depth and trees and accounted for 90.0 and 80.0% total captures in disturbed and intact forests respectively but the mean abundances in both habitats were not significantly different (p = 0.72).

Activity overlap between mesocarnivores and prey in the Central Mongolian steppe

Research on the ecology and behaviour of mesocarnivores and their prey is scant in Mongolia. We investigated activity patterns of a guild of mesocarnivores (red fox, Pallas’s cat and beech marten) and their prey (Siberian marmot, Daurian pika, Brandt vole, Mongolian gerbil and Mongolian silver vole) using 21 camera traps (effort = 1155 camera days) in Central Mongolia from 25st of May to 20th August 2019. Activity patterns of mesocarnivores were cathemeral (i.e. no difference between diurnal, nocturnal and crepuscular detections, although activity peaked at sunrise). Among prey, the Siberian marmot and the Daurian pika were diurnal, whereas the Mongolian gerbil and the Mongolian silver vole were not generally crepuscular. Beech marten, the smallest mesocarnivore species, was temporally segregated from the other (and larger) mesocarnivore species. Temporal segregation between mesocarnivores and prey was evident between the following pairs: red fox vs Brandt’s vole and Mongolian gerbil; Pallas’s cat vs Siberian marmot, Brandt’s vole and Mongolian gerbil; and beech marten vs Siberian marmot, Daurian pika and the Mongolian silver vole. Activity overlap between mesocarnivores and prey ranged considerably. Activity overlap between the beech marten and prey was lower than that of the other mesocarnivores. Temporal overlap among mesocarnivores and between mesocarnivores and prey seemed to be related to species-specific traits, while also being mediated by local prey abundance. We suggest future surveys should be stratified based on habitat and on the target species, while also integrating different survey methods (e.g. camera traps and live trapping of small mammals).

Bird and small mammal community composition and abundance in upland open habitats and early conifer forests

Anthropogenic land-use change, such as commercial afforestation, is a significant driver of shifts in ecological communities and species abundance. In this study, the consequences of afforestation of upland habitats for two distinct animal groups, birds and small mammals, were examined by comparing open moorland, early pre-thicket conifer forests (2–4 years post-replanting) and late pre-thicket conifer forests (6–8 years post-replanting) across 24 upland study sites in Ireland. Field data were collected using bird point counts, live trapping of small mammals and detailed vegetation surveys. A total of 17 bird species and four small mammal species were detected. Both groups showed contrasting patterns of abundance between moorland and pre-thicket forests, with bird density being higher in moorland, while small mammal abundance was higher in pre-thicket forests. Bird diversity was lowest in moorland and highest in late pre-thicket forests, while small mammal diversity was highest in moorland and lowest in late pre-thicket forests. Our study shows that afforestation can alter the abundance and community composition of bird and small mammal populations and that the consequences of land-use change associated with afforestation in upland areas vary across different taxa. Our findings have important implications for forest management practices and conservation of upland habitats and species.

Small-mammal assemblages in piggeries in a developing country: relationships with management practices and habitat complexity

Abstract ContextPig production is increasing in developing countries and is increasing the coexistence of different production systems regarding management practices. Small mammals can cause major economic and sanitary problems on pig farms. The interactions among small mammals, production practices and habitat complexity have been sparsely studied. AimsThe aim was to compare small-mammal assemblages on extensive and intensive pig-production systems, and to analyse the relationship with environmental characteristics and management practices. MethodsSeasonal live-trapping of small mammals within 18 farms (under intensive or extensive management) was performed in central Argentina, simultaneously with a survey of environmental and management practices. Multiple regression analyses were performed to assess the relation between infestation levels and environmental characteristics. Key results In total, 472 small mammals were captured, including the exotic murids Rattus norvegicus, R. rattus and Mus musculus, three native sigmodontines, namely, Akodon azarae, Oligoryzomys flavescens and Oxymycterus rufus, and two native marsupials, namely, Didelphis albiventris and Lutreolina crassicaudata. The location of waste deposits, the density of cats, the frequency of rodent control and the way pig food was stored influenced wild small-mammal abundance; exotic rodent species were lower when the density of cats increased. Rattus norvegicus was more abundant where rodent control was not frequent or null, contrary to M. musculus. Both species were more abundant in food and pig sheds, whereas native species were associated with vegetated areas outside of sheds. Also, A. azarae was associated with the density of pigs. Didelphis albiventris was more abundant on extensive farms, whereas L. crassicaudata was captured on intensive farms. Conclusions Small-mammal abundance did not respond to the type of production system per se, but exotic species abundance was influenced by management decisions. The most important human behaviours related to exotic rodent infestation were the possession of cats, the frequency of rodent control and the way waste and pig feed were managed. Implications Our findings highlighted the need for integrated studies on factors influencing the dynamics of rodent populations in commercial piggery systems, for the development of effective pest management. Management recommendations need to assess environmental complexity and human behaviour as important moderators of the population dynamics of small mammal species in and around piggeries.

Differences in the diet and trophic niche of three sympatric carnivores in a marshland

In order to conserve wetlands, it is crucial to have reliable knowledge of population and community processes. Our aims were to explore the dietary differences that allow coexistence of carnivores belonging to different trophic guilds, and to detect the presence of the relict Pannonian root vole subspecies (Microtus oeconomus méhelyi) within the Kis-Balaton marshland (Hungary). The 1-year dietary study was based on faecal analysis of the main mammalian predators of the area, i.e. red fox (Vulpes vulpes), martens (Martes spp.) and Eurasian otter (Lutra lutra). Small mammals, mainly Microtus species and water vole (Arvicola amphibius), were the primary foods for each carnivore. The dietary pattern of the otter was unique among European studies. Analysis of frequency data and estimated consumed biomass data revealed significant interspecific and intraspecific (seasonal) foraging differences among the three predators. Based on diets and live trapping of small mammals, foxes and martens selected voles, they selected against mice and shrews. The selection of the root vole was confirmed from faecal samples of foxes and martens. Consequently, faecal analysis of common carnivores can be an effective monitoring tool in providing data about prey species under special habitat conditions. Thus, it may contribute to wetland conservation indirectly.

Patch‐burn grazing increases habitat heterogeneity and biodiversity of small mammals in managed rangelands

AbstractHabitat heterogeneity is a key driver of biodiversity in many ecosystems. Wildlife inhabiting the native prairies of North America evolved in a heterogeneous mosaic of habitat conditions created by fire and grazing by native ungulates. Current rangeland management practices in the tallgrass prairie ecosystem evenly distribute fire and grazing across management units and promote homogeneous habitat conditions. Patch‐burn grazing is a rangeland management strategy that seeks to restore heterogeneity to rangelands via fire‐grazing interactions. Our 3.5‐year study tested the effects of patch‐burn grazing on habitat heterogeneity and small mammal community dynamics in the Flint Hills ecoregion of eastern Kansas. To study the ecological effects of patch‐burn grazing, we sampled habitat conditions and the small mammal community. We assessed habitat conditions once each growing season in a negative control that was annually burned and grazed, a positive control that was burned every four years and ungrazed, and within each of three units of a patch‐burn grazing experiment (PBG) managed with rotational fire. Habitat conditions were significantly different among treatments, and a principal components analysis showed that the patch‐burn grazing treatment had higher canopy cover of forbs and habitat heterogeneity than our two control units. To sample the small mammal community, we conducted monthly live trapping of small mammals on two randomly located trap grids in each of our two controls and three units of our PBG treatment. Small mammal diversity was significantly higher in the patch‐burn grazing treatment and in the positive control, vs. the negative control. Moreover, a canonical correspondence analysis showed that a fire‐grazing interaction was the major driver structuring small mammal communities. Patch‐burn grazing is an effective strategy for restoring heterogeneity to vegetative structure and composition, and can increase biodiversity of small mammals in managed rangelands in the tallgrass prairie ecosystem.

Effects of livestock grazing and habitat characteristics on small mammal communities in the Knersvlakte, South Africa

We studied the influence of different livestock grazing intensities and habitat types on small mammals in the Knersvlakte, South Africa. The Knersvlakte belongs to the Succulent Karoo Biome, a biodiversity hotspot. We placed a total of 22 plots in areas of two grazing intensities (moderate and intensive) and two major habitat types (quartz fields and loamy soils). On these plots, we carried out small-mammal live trapping (90 traps during four nights) and estimated the cover of different vegetation layers. In total, 140 small mammal individuals from ten species were caught during 7920 trap nights. All species occurred on loamy soils, but only four in quartz fields. The small-mammal community on intensively-grazed plots was a subset of that on moderately-grazed plots. The most abundant species on loamy soils were Macroscelides proboscideus and Rhabdomys pumilio and in quartz fields M. proboscideus and Gerbillurus paeba. Generalised linear models revealed that habitat type had the strongest influence on abundance and diversity of small mammals. Vegetation cover mainly had indirect influences, via the habitat type, on abundance, diversity and the body condition of small mammals. Overall, the intensities of livestock grazing showed no effect on abundance and diversity.

Reducing accidental shrew mortality associated with small-mammal livetrapping II: a field experiment with bait supplementation

Accidental mortality is pervasive in small mammal livetrapping studies and presents a welfare concern for the particularly vulnerable shrews (Soricomorpha: Soricidae). Although small mammal researchers are aware of this problem and generally suspect that high mortality rates are caused by nutritional constraints and potentially high moisture requirements, these hypotheses have not been widely tested and the problem persists for lack of a practical solution. We conducted a field experiment to assess the effects of providing either high-energy palatable food or water supplements on mortality rates of Blarina brevicauda and Sorex spp. using standard small mammal livetrapping techniques. Water supplements had no effect on shrew mortality, but mortality rates declined by 49% for B. brevicauda and by 64% for Sorex spp. when sunflower seed bait was supplemented with 4 g of mealworms (Tenebrio molitor) compared to controls. Furthermore, the addition of mealworms as a bait supplement eliminated the adverse effect on mortality of the length of time that Sorex were in traps prior to release. The supplementation of live-trap baits with mealworms, therefore, represents a practical method for small mammal researchers to reduce accidental shrew mortality during small mammal livetrapping.

Reducing accidental shrew mortality associated with small-mammal livetrapping I: an inter- and intrastudy analysis

Shrews (Soricomorpha: Soricidae) are particularly vulnerable to mortality associated with small-mammal livetrapping. We compiled data on mortality rates and protocols from 16 different small-mammal studies and analyzed 16 years of livetrapping data from a single study in Algonquin Provincial Park, Ontario to assess factors affecting shrew mortality. In the comparison across studies, accidental mortality ranged from 10% to 93%. Mortality was lower in studies conducted in locations and at times of year with warmer average temperatures. We found no differences in mortality among bait and trap types across these 16 studies. In our intrastudy analysis from Algonquin Park, Sorex spp. experienced high mortality (81%) regardless of environmental conditions. In contrast, northern short-tailed shrews had low overall mortality (13%), but mortality increased on rainy nights and on colder nights when overnight temperatures dropped below 10°C. Comparisons between 2 trapping protocols within Algonquin Park suggested that both Blarina brevicauda and Sorex sp. experienced higher mortality in Sherman compared with Longworth traps, but these effects were confounded by other differences in methodology between studies. Although we found evidence consistent with some shrew mortality being caused by caloric constraints, experimental studies on bait supplements are necessary to test whether providing high-calorie baits is an efficient method to reduce the widespread shrew mortality that occurs in small-mammal livetrapping studies.

Effects of urbanization on small-mammal communities and the population structure of synurbic species: an example of a medium-sized city

Theories concerning the impact of urbanization on ground-dwelling mammals are mainly based on large-city studies. We investigated whether the negative effects of urbanization are evident in smaller urban areas, where green areas are usually less isolated from their natural surroundings. Livetrapping of small mammals (Rodentia and Soricomorpha) was conducted between 2007 and 2010 in 15 patches within the city of Lublin (Poland) (147.5 km2, population 354 000) and 15 patches in its agricultural surroundings. A decline in species richness and diversity along an urbanization gradient and an increase in the abundance of species best adapted to the city environment (synurbic species) were observed. The main factors influencing ground-dwelling mammals was isolation of green patches, while the management type of green areas had no significant effect. The genus Apodemus Kaup, 1829, particularly the striped field mouse (Apodemus agrarius (Pallas, 1771)), was the most urban biased. Within the city, A. agrarius alters its habitat preferences and life-history parameters (body mass, seasonal fluctuations, winter survival). Understanding the factors influencing ground-dwelling mammals in medium-sized cities will enable measures to be implemented that could reduce the negative effects of urbanization during urban expansion.

The seasonal diet of British pine marten determined from genetically identified scats

AbstractKnowledge of a carnivore's foraging behaviour is central to understanding its ecology. Scat‐content analysis provides a non‐invasive way to collect such information but its validity depends on attributing scats to the correct species, which can prove problematic where similarly sized species occur sympatrically. Here we provide the first description of the diet of European pine marten Martes martes in Scotland based on genetically identified scats (n = 2449). Concurrent small mammal live trapping also allowed us to determine preferential selection of small mammal species. We found the marten diet was almost entirely formed by three principal foods: Microtus agrestis (39%), berries (Sorbus aucuparia and Vaccinium myrtillus: 30%) and small birds (24%). The seasonal dominance of these foods in the diet suggested a facultative foraging strategy, with a short period in which the diet was more generalized. A discrepancy in the occurrence of Microtus in the diet (77% of small mammals consumed) and marten home ranges (12% of small mammals trapped) indicated a frequency‐independent preference for this prey, one which differentiated British marten from marten in continental Europe. Microtus were the marten's staple prey and taken with relative consistency throughout the year, even at times when rodent populations were at their least abundant. Martens supplemented their diet with small birds and fruits as these foods became abundant in summer. The diet became generalized at this time, reflected by a threefold increase in diet niche breadth. Microtus consumption was significantly reduced in autumn, however, when their populations peak in abundance. The autumn diet was instead dominated by fruit; an abrupt dietary switch suggesting a frequency‐dependent preference for fruit irrespective of the abundance of alternative prey.

Effects of management options on mammal richness in a Mediterranean agro-silvo-pastoral system

Non-flying mammal richness and distribution were studied in a landscape matrix consisting of a highly managed agro-silvo-pastoral system dominated by a cork oak woodland (montado) to test the predictions of the Intermediate Disturbance Hypothesis (IDH). Sampling consisted on detection of mammalian signs of presence, along with the use of scent stations and small mammal live-trapping. Results were analyzed using generalized linear models, considering land uses, landscape metrics and grazing intensity and gave support to the predictions of the IDH. Pure forestry and intensive agricultural uses showed lower species richness than the silvopastoral system, whilst landscape heterogeneity and riparian corridors were shown to be most beneficial to mammal species richness, with small mammals being directly and negatively affected by grazing intensity. The increasing use of the montado for raising cattle has led to landscape homogenization by means of grazing and shrub clearance for pasture cultivation and this, combined with incremented stocking rates, constrains species richness. In this landscape context, watercourses assume a relevant role as patches of suitable habitat providing shelter, food, movement corridors and dispersion routes for mammals. Recent options of fencing forest patches with good forest natural regeneration or with a high diversity/density of Mediterranean maquis, and restoring degraded watercourses, both to improve landscape heterogeneity, appear to positively affect the mammal community. This is a current challenge in terms of monitoring and research.

Seed survival on experimental dishes in a central European old‐growth mixed‐species forest – effects of predator guilds, tree masting and small mammal population dynamics

Predation of tree seeds can be a major factor structuring plant communities. We present a three year study on tree seed survival on experimental dishes in an old‐growth forest in central Europe in Austria. We addressed species specific, spatial and temporal aspects of post‐dispersal seed predation. Seeds of Norway spruce Picea abies, European beech Fagus sylvatica, and silver fir Abies alba were exposed on dishes in different types of exclosures which allowed access only to specific guilds of seed predators. Removal experiments were carried out in two old‐growth forests and a managed forest (macro‐sites), including micro‐sites with and without cover of ground vegetation. We conducted the experiment in three consecutive years with a mast year of beech and spruce before the first year of the study. The seed removal experiments were combined with live trapping of small mammals being potential seed predators. Our experiments showed a distinctly different impact of different predator guilds on seed survival on the dishes with highest removal rates of seeds from dishes accessible for small mammals. We observed differing preferences of small mammals for the different tree species. Seed survival in different macro‐ and micro‐habitats were highly variable with lower seed survival in old growth forests. In contrast to our assumption, and in contrast to the satiation hypothesis which assumes higher seed survival in and directly after mast years, seed survival was lower in the year following the mast year of beech when a population peak of small mammals occurred and higher in intermast periods when subsequently small mammal population crashed. This suggests a higher importance of sporadic masting shortly after mast years in intermast periods for establishment of forest trees provided that pollination efficiency is high enough in such years. Combined with the high seed mortality observed after the mast year, this corroborates the important role of seed predation for forest dynamics. An altered synchrony or asynchrony of masting of different tree species and changed masting frequencies through climate change may thus lead to strong and non‐linear effects on forest dynamics.

Geographic variation in fruit colour is associated with contrasting seed disperser assemblages in a south-Andean mistletoe

Fruit colour influences fruit choice by seed dispersers. The mistletoe Tristerix corymbosus (Loranthaceae) produces mature fruits of two different colours in two different biomes: yellow in the Chilean matorral and green in the temperate forest of southern South America. We conducted field surveys to establish the association between fruit colour and disperser identity throughout the entire geographical range of T. corymbosus. We selected 22 populations, eight of which were located in the Chilean matorral and 14 in the temperate forest south of the matorral. To identify the seed dispersers of the mistletoe we used direct observation, camera traps, and live-trapping of small mammals. We also report experiments to assess fruit selection by seed dispersers based on differences in colour. The assemblages of dispersers of T. corymbosus differ between the two biomes: yellow fruits in Chilean matorral are exclusively dispersed by three bird species while green fruits in the temperate forest are exclusively dispersed by a marsupial. The differences in the assemblages of seed dispersers can be explained by differences in food-finding strategies between the two assemblages. Green fruits in temperate forest are not easily detected by birds, while colour might not be an important cue for the marsupial because it is nocturnal and uses other senses to locate food. We propose that the association between the marsupial and the green-fruited mistletoe constitutes an ecological fitting rather than the outcome of a co-evolutionary process. The marsupial might have allowed the mistletoe T. corymbosus to retain green coloration in mature fruit, a condition to which it is preadapted by a slower ripening process in temperate forest populations.

Biodiversity assessment (rodents and avifauna) of five forest reserves in the Brong-Ahafo Region, Ghana

A faunal inventory of five forest reserves in the Brong-Ahafo Region was undertaken to determine the ecological status or levels of degradation of the reserves using birds and small mammals as bio-indicators. The methodology involved live-trapping of small mammals and recording bird species using ad hoc observations timed transect walks along trails and transects. Fifty individuals of nine species of rodents were recorded, with Mastomys erythroleucus (multimammate mouse) being the most abundant. Small mammal species diversity was highest (H’ = 1.88) and lowest (H’ = 0.98) in Tain II and Tain I forest reserves, respectively. The presence of some savanna species in some of the reserves indicated high levels of degradation. Fifty-four bird species, representing 22 families, were recorded, with 16 of the species being under national conservation protection. It is recommended that the reserves be zoned into smaller management areas to enable more efficient management, through initiation of reforestation programmes, anti-poaching patrols, research, and long-term monitoring. There is the need for intensive education of the local inhabitants on wildlife conservation awareness.

Feeding habits of Great Grey Shrike (Lanius excubitor) wintering in north-eastern Poland: does prey abundance affect selection of prey size?

Diet composition and prey selection of wintering Great Grey Shrike (Lanius excubitor) were studied at two sites in north-eastern Poland: in the Mazurian Lakeland and at Bialowieza Glade. The feeding habits of shrikes were recorded on the basis of 1582 prey items found in 1220 pellets, collected in years 1998-2003. Live-trapping of small mammals showed that in both habitats, Microtus voles predominated in rodent communities, with higher densities of the Common Vole (M. arvalis) in the Mazurian Lakeland, and the Root Vole W. oeconomus) in Bialowieza. At both sites, the two main shrike prey groups were small mammals and insects, with a lesser contribution of other prey (passerines, lizards and frogs). Voles comprised between 69 and 86% of consumed food biomass, while other small mammals comprised only 5-13% of prey biomass. Shrikes selectively hunted the Common Vole, especially in the habitat with a lower abundance of this species. On the other hand, in the habitat with a higher abundance of Common Voles, shrikes selected smaller individuals from this population, a feature that was not recorded in the habitat where the Root Vole was predominant. Therefore, intra- and inter-specific prey selection appears to be interrelated and dependent on prey abundance. The prey stored (here, prey impaled on thorns and spikes) by shrikes differed from the prey consumed. The Root Vole was not stored but occurred in the shrike diet. Frogs, newts and lizards were more often stored than consumed. Analysis of the proportion of skulls, pelvises and thigh-bones in pellets, suggests that at the end of winter and in early spring when voles numbers decline, shrikes consumed more whole vole bodies compared to the autumn.