Live-trapping Of Mammals Research Articles

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.

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.

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.

Small Mammal and Plant Community Responses to Mechanical Disturbance and Rest in Wyoming Big Sagebrush Grassland

Our aim in this study was to evaluate short-term (2 years) responses of several attributes of small mammal populations (species richness, abundance, diversity, and similarity) and plant community dynamics (species richness, canopy cover, above-ground biomass production, and diversity) to the mechanical disturbance associated with interseeding. Small mammal live trapping and vegetation sampling were conducted in 2004 and 2005 on replicated 1 ha study plots in a native Wyoming big sagebrush (Artemisia tridentata Nutt ssp. wyomingensis Beetle & Young)-grassland that were: 1) mechanically disturbed in April 2003 and rested from grazing during the study (mechanical); 2) rested from grazing (rested); and 3) moderately grazed by cattle (grazed). Deer mice (Peromyscus maniculatus), northern grasshopper mouse (Onychomys leucogaster), and sagebrush vole (Lemmiscus curtatus) were the primary small mammal species captured during 7776 trap nights in 2004 and 2005. Small mammal diversity was greater for the mechanical (H′ = 1.22) than the rested (H′ = 0.85) treatment with the grazed treatment intermediate. Plant community variables of species richness, diversity, similarity, and above-ground biomass production did not differ among treatments. Canopy cover of the dominant species, Wyoming big sagebrush, was reduced 20–34% by the mechanical disturbance (6.9% ± 1.0) compared to rested (8.6% ± 0.6) and grazed (10.4% ± 1.0) plots. The mechanical disturbance affected approximately 10.5% of the ground surface area but this had little impact on short-term small mammal or plant community dynamics in this rangeland ecosystem.

Dynamics of Leishmania chagasi infection in small mammals of the undisturbed and degraded tropical dry forests of northern Colombia

The infection rate with Leishmania chagasi and the population dynamics of small mammals were studied in an undisturbed forest reserve (Colosó) and an area of highly degraded forest (San Andrés de Sotavento [SAS]) in northern Colombia, both endemic for visceral leishmaniasis. Live trapping of mammals was done every month, and species, age, sex and reproductive status determined. L. chagasi was detected in samples of skin or spleen by the polymerase chain reaction, after extraction of deoxyribonucleic acid using specific primers (DB8/AJS3), and dot blood hybridization. Didelphis marsupialis was found to be infected in Colosó ( 3 21 , 14·3%) and SAS ( 13 137 , 9·5%); its relative abundance was higher in SAS ( 93 113 , 82% of the captures). Although Proechimys canicollis was also found to be infected in Colosó ( 3 34 , 8·8%) and SAS ( 2 4 ), its relative abundance was much lower (4%) in SAS than in Colosó (56% of 77 animals captured). Sciurus granatensis, Marmosa robinsoni, Heteromys anomalus, Zygodontomys brevicauda and Metachirus nudicaudatus were less common, and no L. chagasi infection was detected in them.

The small-mammal community of a dry-tropical forest in central Thailand

ABSTRACTSmall mammal live-trapping was carried out in a dry tropical forest mosaic in Huai Kha Khaeng Wildlife Sanctuary, central Thailand. Trapping was done in two forest types in three seasons.Maxomys surijerwas the dominant species in both plots. The three most abundant species in each plot accounted for > 90% of all captures. Community structure, density, relative abundance, biomass, age structure of populations, and habitat usage of some small mammal species varied by forest type and season. The dry evergreen/mixed deciduous forest type supported a greater abundance and biomass of small mammals than the mixed deciduous/dry dipterocarp forest type in all seasons, although species richness was the same. The greatest density, biomass, and home-range size forMaxomys surijeroccurred in the rainy season in both forest types. Seasonal changes in ratios of adults and subadulls of several species suggested a breeding peak at the end of the dry season or beginning of the rainy season. The mixed deciduous/dry dipterocarp forest showed a drastic drop in numbers, density, and biomass of small mammals six weeks after a fire burned through it.

Inter–trap movement and estimating rodent densities

The area and inter–trap distance of small mammal live trapping grids can seriously influence observed movement patterns and estimates of animal densities. This paper examines inter–trap movement (ITM) according to inter–trap distance, time of the year, weather and numbers captured for the wood mouse, Apodemus sylvaticus, and the bank vole, Clethrionomys glareolus, in an oak wood in southern England. The analysis is based on live trapping data collected in three studies over an eight–year period. Trap spacing affected inter–trap movement, including the statistic, ‘Mean Distance Moved’ between successive captures (MDM), of different species and sexes of rodents in different and predictable ways. No association was found in MDM between males and females of the same species, MDM and time of the year or MDM and weather. However, there was a weak negative association between MDM and numbers captured, particularly in mice. Using an independent method of assessing effective grid area, the usefulness of the MDM in correcting grid areas for the estimation of animal densities is discussed.