Abundance Of Small Mammals Research Articles

Keanekaragaman Mamalia Kecil Pada Empat Tipe Tutupan Lahan Di Kesatuan Pengelolaan Hutan (KPH) Batutegi, Provinsi Lampung

The diversity of small mammals has a vital role as a bioindicator of a managed area in the forest. This research was conducted to determine the small mammals in four types of land cover in the agroforestry management area of ​​KPH Batutegi. Sampling was carried out using traps in the four types of land cover. Species diversity was analyzed by diversity index, evenness, dominance, and abundance. The results of this study indicate that the variety, evenness, and abundance of small mammals are low due to land cover conditions, elevation, and the behavior of small mammals in their habitat. The dominant small mammals are Rattus tiomanicus sabae and Maxomys baeodon because they have a high level of adaptation to various habitats. Twelve small mammals were found in the agroforestry cover, ten individuals in the forested cover, four individuals in the monoculture coffee cover, and two individuals in the private land. The management of the Batutegi KPH shall counsel the community to prevent land clearing, which causes damage to forest sustainability, to maintain the existence of small mammals.

Ancient DNA reveals interstadials as a driver of common vole population dynamics during the last glacial period

AbstractAimMany species experienced population turnover and local extinction during the Late Pleistocene. In the case of megafauna, it remains challenging to disentangle climate change and the activities of Palaeolithic hunter‐gatherers as the main cause. In contrast, the impact of humans on rodent populations is likely to be negligible. This study investigated which climatic and/or environmental factors affect the population dynamics of the common vole. This temperate rodent is widespread across Europe and was one of the most abundant small mammal species throughout the Late Pleistocene.LocationEurope.TaxonCommon vole (Microtus arvalis).MethodsWe generated a dataset comprised of 4.2 kb long fragment of mitochondrial DNA (mtDNA) from 148 ancient and 51 modern specimens sampled from multiple localities across Europe and covering the last 60 thousand years (ka). We used Bayesian inference to reconstruct their phylogenetic relationships and to estimate the age of the specimens that were not directly dated.ResultsWe estimated the time to the most recent common ancestor of all last glacial and extant common vole lineages to be 90 ka ago and the divergence of the main mtDNA lineages present in extant populations to between 55 and 40 ka ago, which is earlier than most previous estimates. We detected several lineage turnovers in Europe during the period of high climate variability at the end of Marine Isotope Stage 3 (MIS 3; 57–29 ka ago) in addition to those found previously around the Pleistocene/Holocene transition. In contrast, data from the Western Carpathians suggest continuity throughout the Last Glacial Maximum (LGM) even at high latitudes.Main ConclusionsThe main factor affecting the common vole populations during the last glacial period was the decrease in open habitat during the interstadials, whereas climate deterioration during the LGM had little impact on population dynamics. This suggests that the rapid environmental change rather than other factors was the major force shaping the histories of the Late Pleistocene faunas.

Species richness and abundance of small mammals from Nimba region, Northeastern Liberia

This study was carried out in a biodiversity hotspot within the Nimba region located in the northeastern part of Liberia. The Nimba region is known to harbor exceptional fauna diversity. However, the small mammal communities in Nimba region are poorly documented. The aim of this study was to determine the species richness and relative abundance of rodents and shrews in five sites: Bento, East Nimba, Gangra-Yuelliton, Tokadeh and Vayampah. A total of 244 individual of small mammals comprising 18 species were trapped on 4,375 trap nights. Rodent species recorded include: Arvicanthis rufinus, Dephomys defua, Grammomys buntingi, Graphiurus lorraineus, Hybomys planifrons, Hybomys trivirgatus, Hylomyscus simus, Lemniscomys striatus, Lophuromys sikapusi, Malacomys edwardsi, Mastomys erythroleucus, Mus muscoloides, Mus setulosus and Praomys rostratus. Shrew species were Crocidura eburnea, Crocidura jouvenetae, Crocidura muricauda and Crocidura obscurior. The most dominant species was Hylomyscus simus (22.95%), followed by Praomys rostratus, Crocidura muricauda and Crocidura eburnea. The highest species richness was recorded at Gangra-Yuelliton and lowest at Tokadeh. Diversity indexes were higher at East nimba (H’ = 2.01; 1-D = 0.82) and Gangra-Yuelliton (H’ = 2.00; 1-D = 0.83) and lower at Tokadeh (H’ = 1.57; 1-D = 0.75). Similarity index revealed high resemblance in species composition between Bento and Vayampah. The lowest similarity was observed between Tokadeh and Gangra-Yuelliton. This study highlighted the high biological diversity of small mammal communities in Liberia's Mount Nimba region. Thus, this zoological group should now be taken into account in the biodiversity conservation strategies of Mount Nimba

Interpreting the mammal deposits of Cloggs Cave (SEAustralia),GunaiKurnaiAboriginal Country, through community‐led partnership research

AbstractPalaeontological animal bone deposits are rarely investigated through research partnerships where the local First Nations communities have a defining hand in both the research questions asked and the research processes. Here we report research undertaken through such a partnership approach at the iconic archaeological site of Cloggs Cave (GunaiKurnai Country, East Gippsland), in the southern foothills of SE Australia's Great Dividing Range.A new excavation was combined with detailed chronometric dating, high‐resolution 3D mapping and geomorphological studies. This allowed interpretation of a sequence of stratigraphic layers spanning from a lowermost excavated mixed layer dated to between 25,640 and 48,470 cal BP, to a dense set of uppermost, ash layers dated to between 1460 and 3360 cal BP. This long and well‐dated chronostratigraphic sequence enabled temporal trends in the abundant small mammal remains to be examined.The fossil assemblage consists of at least 31 taxa of mammals which change in proportions through time. Despite clear evidence that the Old Ancestors repeatedly carried vegetation into the cave to fuel cool fires (no visible vegetation grows in Cloggs Cave), we observed little to no evidence of cooking fires or calcined bone, suggesting that people had little involvement with the accumulation of the faunal remains. Small mammal bones were most likely deposited in the cave by large disc‐faced owls,Tyto novaehollandae(Masked Owl) orTyto tenebricosa(Sooty Owl).Despite being well dated and largely undisturbed, the Cloggs Cave assemblage does not appear to track known Late Quaternary environmental change. Instead, the complex geomorphology of the area fostered a vegetation mosaic that supported mammals with divergent habitat preferences. The faunal deposit suggests a local ancestral landscape characterised by a resilient mosaic of habitats that persisted over thousands of years, signalling that the Old Ancestors burned landscape fires to encourage and manage patches of different vegetation types and ages within and through periods of climate change.Read the freePlain Language Summaryfor this article on the Journal blog.

Species composition, relative abundance and habitat association of non-volant small mammals in Menz Guassa Community Conservation Area, central Ethiopia

Small mammals are a diverse group of animals and studying such group is vital. This study documents species composition, relative abundance and habitat association of non-volant small mammals in Menz Guassa Community Conservation Area, central Ethiopia. Data were collected using capture mark-release technique in different habitats of the study area from October 2019 to August 2020 and analysed by descriptive statistics and Shannon-Wiener diversity index. A total of 724 individuals of rodents and insectivores were sampled over 1176 trap nights. Of these 418 individuals were newly captured while the remaining 306 were recaptured with an overall trap success of 35.5 %. Five species of rodents namely Lophuromys flavopunctatus, Stenocephalemys griseicauda, Otomys typu s, Arvicanthis blicki and Dendromus lovati , and two species of insectivores, Crocidura baileyi and C. thalia were sampled. The most abundant species identified in the study was L. flavopunctatus followed by S. griseicauda , while the least was D. lovati with relative abundances of 66.7 %, 14.8 % and 0.2 %, respectively. The rodent and insectivore species were statistically significantly associated with their habitats (χ 2 = 10.44, df = 3, p < 0.05) with high association recorded in Euryops habitat 128 (30.6 %). High diversity of small mammals was recorded in Erica-Festuca dominated habitat (H’ = 1.176) followed by Festuca-Euryops habitat (H’= 1.114) and the least was recorded in Festuca habitats (H’= 0.977). Small mammals showed variation in abundance across habitats between seasons but the difference was not statistically significant (F (1, 6) = 0.017, p > 0.05). Most of the rodents and insectivores were sampled during the night. Stenocephalemys griseicauda , D. lovati and C. baileyi were exclusively nocturnal while O. typus and L. flavopunctatus were predominantly diurnal in activity. There was relatively higher small mammal diversity in Menz Guassa Community Conservation Area. Further molecular study needs to be conducted to identify more non-volant small mammals in the area, more especially cryptic species.

Plague circulation in small mammals elevates extinction risk for the endangered Peñasco least chipmunk

Wildlife diseases are a major concern for species survival around the world. Vector-borne diseases, in particular, are problematic for both humans and wildlife. Plague is an introduced disease to North America where many species have low natural resistance to infection by the causative bacterium, Yersinia pestis. Plague in the United States is often associated with large-scale epizootic events that impact rodent populations. However, we need more information regarding the effects of plague at enzootic levels and in species that rarely if ever experience epizootic events. New Mexico is a state that experiences regular epizootic plague events in several species of rodents but comparatively less is known about enzootic plague impacts within rodent communities in New Mexico. The Peñasco least chipmunk (Neotamias minimus atristriatus) is state-listed as endangered in New Mexico and is a candidate for listing under the federal Endangered Species Act. It likely has been extirpated from the southern portion of its range and is now observed only at high elevations in isolated areas in the White Mountains. We evaluated plague presence in the more abundant small mammal species associated with these chipmunks. We used an F1 antigen plague-specific vaccine and a placebo injection to test whether plague was present and reducing survival in western deer mouse (Peromyscus sonoriensis) and vole (Microtus spp.) populations in the Lincoln National Forest. The effect of plague on survival differed among years and sites. Monthly apparent survival was up to 60 % higher for rodents given the vaccine compared to those given a placebo. Our results suggest that plague is likely impacting the small mammal community in the Lincoln National Forest and is even present at higher elevation sites where the Peñasco least chipmunk was most recently extirpated. Because least chipmunks are highly susceptible to plague, our results suggest that this disease may be an important factor in the population decline of the Peñasco least chipmunk.

Engineering by cape ground squirrels affects biodiversity in semi-arid grasslands

Burrowing mammals that disproportionately affect their physical environment, creating habitat and providing resources for other organisms, are considered ecosystem engineers. Such modifications are particularly important in dry grassland environments, where low precipitation and soil nutrients limit plant growth. We tested 5 hypotheses about the impact of Cape ground squirrels (Xerus inauris) on plants and animals in a semi-arid grassland of South Africa. At each burrow cluster and paired control site without burrows, we estimated plant cover, height, and richness using quadrats, and invertebrate and small mammal abundance and richness using pit-fall traps and mark-recapture, respectively. We determined nitrogen concentrations in grasses on and off burrows and measured carbon and nitrogen stable isotopes in plants and squirrel hair to determine squirrel diet. Burrows had greater plant cover and richness, particularly more shrubby vegetation, but plant height and nitrogen concentrations did not differ on and off burrows. Invertebrate and small mammal abundance and richness were greater on burrows. Squirrel disturbances in semi-arid grassland improved conditions for disturbance-dependent shrubs, which were rarely consumed by squirrels but are valuable forage for antelope and provide cover for invertebrates and small mammals. By altering habitat for plants reliant on disturbance, Cape ground squirrels enhance grassland biodiversity.

The abundance of small mammals is positively linked to survival from nest depredation but negatively linked to local recruitment of a ground nesting precocial bird.

Generalist predators using small mammals as their primary prey are suggested to shift hunting alternative prey such as bird nests, when small mammals are in short supply (the alternative prey hypothesis, APH). Nest survival and survival of young individuals should be positively linked to small mammal abundance and negatively linked to predator abundance, but little information exists from survival of chicks, especially until recruitment. We test these predictions of the APH using 13 years (2002–2014) of life history data from a ground nesting shorebird breeding on coastal meadows. We use small mammal abundance in the previous autumn as a proxy for spring predator abundance, mainly of mammalian predators. We examine whether small mammal abundance in the spring and previous autumn explain annual variation in nest survival from depredation and local recruitment of the southern dunlin Calidris alpina schinzii. As predicted by the APH, survival from nest predation was positively linked to spring small mammal abundance and negatively linked to autumn small mammal abundance. Importantly, local recruitment showed opposite responses. This counterintuitive result may be explained by density‐dependent survival. When nest depredation rates are low, predators may show stronger numerical and functional responses to high shorebird chick abundance on coastal meadows, whereas in years of high nest depredation, few hatching chicks lure fewer predators. The opposite effects on nest and local recruitment demonstrate the diverse mechanisms by which population size variation in primary prey can affect dynamics of alternative prey populations.

Small mammals in a mountain ecosystem: the effect of topographic, micrometeorological, and biological correlates on their community structure

An increasing number of studies have investigated spatial and temporal patterns in species richness and assemblage composition in mountain ecosystems along altitudinal gradients. Small mammals have been successfully used as indicators of environmental health and as proxies of biodiversity. However, information about the composition and distribution of species assemblages in the mosaic of habitat and rocky landform types at a high altitude is still lacking for most of the mountain regions. Through the use of live traps and camera trapping, we described the small mammal community living above the treeline of the Western Dolomites (Italian Alps), investigating the species richness, abundance of individuals and community composition in relation to topographic, micrometeorological, mesohabitat, and biological correlates. A total of five species and 50 individuals were sampled, analysed, and released. At the extremes of the analysed altitudinal range (i.e. 1900 vs 2900 m a.s.l.), community composition was completely different and species richness was related to elevation, steepness, and vegetation cover. At the same time, the taxonomic distinctness of ground-dwelling arthropods (namely carabid beetles and spiders), a proxy of habitat complexity, showed higher values in areas with a greater small mammal species richness. We found a positive effect of steepness and rocky landform type “carsism” on the number of captured individuals, showing the importance of the availability of shelters and underground burrows for the sampled species. As a confirmation of the altitudinal shift for these species in relation to the ongoing climate change, we detected a negative impact of sub-surface ground temperature on small mammal abundance during the monitoring period. In conclusion, small mammals represent an excellent model for understanding the evolutionary processes of ecosystems, population dynamics under changing environmental conditions, and habitat vulnerabilities.

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.

Effect of traditional livestock grazing on abundance of small mammals and activity of mountain vizcacha in the high central semi-arid Andes

Livestock grazing is common and widespread in the high Andean region; however, few studies have evaluated the effects of traditional camelid grazing (llamas and alpacas) on small and medium sized mammals. We studied small mammals in Sajama National Park in Bolivia. We evaluated the association between livestock abundance and 1) the abundance of small mammals, and 2) small mammal activity patterns. In a grid of 36 sampling stations, small mammals were divided into two study groups, according to their body size and the trophic group. We assessed small mammal abundances with grids of live capture traps and vizcacha with camera traps. We performed GLM and Basic Kernel Density estimation analyses for associations between livestock abundance and abundance of small mammals, and small mammal activity patterns, respectively. The presence of mountain vizcacha and rodents was less likely where livestock abundance was higher. Herbivores and granivores, but not omnivores, were also negatively affected by higher livestock abundance. The diurnal activity patterns of mountain vizcachas declined when livestock abundance was higher. We suggest some alternatives for livestock management plans to minimize the negative effects of traditional livestock on small mammals.

Population and Community Responses of Small Mammals to Single-tree Selection Harvest in Laurentian Hardwood Forests

Small mammals are ubiquitous members of vertebrate communities that are sensitive to habitat change. In the Great Lakes region of North America, small mammal communities have changed rapidly, but experimental tests of potential mechanisms are lacking. Using a before-after, control-treatment design, we quantified the response of small mammals to single-tree selection harvest in Laurentian hardwood forests of Wisconsin, United States. We documented changes in forest structure and small mammal abundance, species diversity, and community similarity from silvicultural treatment. Treatment reduced tree density and canopy cover and increased mean tree diameter, woody stem density, variation in woody stem density, and volume of coarse woody debris. Peromyscus and northern short-tailed shrews (Blarina brevicauda) were dominant community members across treatments and years. White-footed mice (P. leucopus) outnumbered woodland deer mice (P. maniculatus gracilis) before treatment, but declined by almost fifty percent after treatment; deer mice and total rodent (i.e., Rodentia) abundances were unchanged. Small mammal species diversity increased twofold following treatment. Our experiment identified species-specific responses within Peromyscus to timber harvest: white-footed mice, the numerically dominant and generalist species, were most sensitive to habitat change, and their response produced cascading effects to small mammal community structure. Future experiments should assess these small mammal responses in a multi-year framework and quantify their effects on the broader vertebrate community.

Relative efficiency of two models of snap traps for sampling boreal small mammals

AbstractSnap traps have long been a cost‐effective means of monitoring small mammal (&lt;60 g) diversity and abundance, particularly at larger spatial or temporal scales. Yet, studies on the relative efficiency of snap trap models are surprisingly rare in the literature. We assessed the relative efficacy of Victor Mouse and Woodstream Museum Special snap traps for sampling boreal small mammals. Paired traps were set for 2–3 nights at 40–50 trapping stations at each of 110 sites, for a total sampling effort of 28,910 trap nights. We captured 1,013 small mammals representing 13 species. Overall, Museum Special traps caught almost twice as many small mammals as Victor traps. There was no difference in the sex or age‐class of the overall capture in the 2 trap models. However, Museum Special traps were triggered without capturing a small mammal 31% more often than Victor traps. Results for the six most frequently captured species (Myodes rutilus, Microtus pennsylvanicus, Microtus oeconomus, Microtus xanthognathus, Peromyscus maniculatus, and Sorex cinereus) mirrored those for overall captures. Moreover, the percent of the total capture in Museum Special traps ranged between 57–80% for each of the above species, indicating species‐specific responses to trap type. Our data further demonstrate the superior ability of Museum Special traps to capture boreal small mammals compared to Victor traps, which is likely attributed to a more sensitive trigging mechanism. Implications of our results suggest caution when mixing trap models in monitoring programs, or when interpreting results obtained with different trap models. We encourage similar comparisons in different biomes with different small mammal assemblages as trap performance is likely species specific.

English

Habitat type and their vegetation composition play important role in determining the abundance and diversity of animals including small mammals, hence any change in habitat type will influence their abundance and spatial distribution. This study aimed at investigating the influence of habitat types (that is, Wetland grassland, Miombo and Vachellia woodlands) on small mammal abundance, diversity, and richness in the Usangu area, in southern part of Ruaha National Park, in Tanzania. Sherman and pitfall plastic bucket traps were employed both for trapping small mammals. A total of&nbsp; 92 small mammals were captured in 2124 trap nights giving 13% trap success representing two families, namely, Muridae (6 species) and Soricidae (1 species). Furthermore, trap success differed among habitat types with the highest being in wetland grassland. Species diversity was higher in Vachellia woodlands compared to other habitat types. It would therefore seem that wetland grassland and Vachellia woodland habitats are very crucial in maintaining small mammal abundance and diversity in Usangu Area. Therefore, future management plan should incorporate these refuge habitats for continued existence of small mammals in Usangu. Further study is warranted in wet season in order to have comparison information that will assist in management of small mammal in Usangu.&nbsp; &nbsp; Key words:&nbsp; Conservation, habitat preferences, habitat restoration, Miombo woodlands, rodents, Ruaha National Park, Tanzania, Vachellia woodlands, wetland grassland.

Вплив осушувальної меліорації на кількісний та видовий склад дрібних ссавців

The article is devoted to the research on the abundance and species composition of small mammals in the territory of central Ukraine (Cherkasy, Poltava, and Kyiv oblasts) affected by land development by drainage. The drainage areas of the studied region are located mainly in fens, which in most cases are connected with river valleys. The vegetation there used to be represented by reed sets with thickets of reed–mace as well as various sedges and horsetails. The drainage process consists of several stages. It is possible to outline four of them within the studied areas. The aim of the research was to analyse the influence drainage has on the abundance and species composition of small mammals. In total, 4161 rodents and shrews were captured at a sampling effort of 60 890 trap-days. It was found that drainage is a strong anthropogenic factor that shapes the abundance and species composition of small mammals within the drained lands of central Ukraine. It was revealed that the species diversity of small mammals decreases essentially as the area of drainage grows. In general, with drainage, the number of hydrophilous species decreases sharply or they become extinct, whereas the number of species that prefer open habitats increases. At the same time, the general diversity index (H) reaches the greatest value in areas of the second stage of drainage, and, as drainage works expand, the species diversity decreases significantly. The abundance dynamics of small-mammal species both by habitats and drainage stages is presented. The research results make it possible to understand some patterns drainage causes to the fauna of shrews and rodents, and, accordingly, the specifics of adaptation of the latter to those patterns. The obtained data can be used to estimate and foresee the number of small mammals within different regions of Ukraine, to develop measures to control harmful rodents in drainage areas, to predict the real scale of economic damage caused by them, and to elaborate some theoretical issues in biogeography.

Revealing the real-time diversity and abundance of small mammals by using an Intelligent Animal Monitoring System (IAMS).

It is challenging to reveal the real-time spatio-temporal change of diversity and abundance of animals in natural systems by using traditional methods. The rapid advancement of new technologies such as the Internet of Things, artificial intelligence, and big-data processing, provide opportunities for developing novel technologies for monitoring biodiversity and population abundance of animals with high efficacy and accuracy. In this study, by using a recently developed Intelligent Animal Monitoring System, named "Vector Intelligent Monitoring System (VIMS)", we investigated the real-time diversity and abundance of small mammals in the Banruosi forest, Dujiangyan region, southwest China. To make a comparison of the VIMS with traditional methods, we also surveyed the diversity and abundance of small mammals using wired live traps. Compared to live traps, the VIMS has several advantages such as automatic data collection, intelligent identification of species, data visualization, whole-day and all-weather operation, little disturbance to animals, real-time monitoring, and is capable of revealing more small mammal species. However, the VIMS also has several disadvantages over live traps such as lower trapping efficiency and being more expensive than live traps. Our results suggest that the VIMS can be a complementary method to traditional ones in monitoring the real-time spatio-temporal change of diversity and abundance of small mammals (especially rare species). In addition, the VIMS is useful in monitoring other small animals like small carnivores, birds, amphibians, and reptiles.

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.

Invasive rat drives complete collapse of native small mammal communities in insular forest fragments

As tropical forests are becoming increasingly fragmented, understanding the magnitude and time frame of biodiversity declines is vital for 21st century sustainability goals. Over three decades, we monitored post-isolation changes in small mammal species richness and abundance within a forest landscape fragmented by the construction of a dam in Thailand.1,2 We observed the near-complete collapse of species richness within 33 years, with no evidence of a recolonization effect across repeatedly sampled islands. Our results further revealed a decline in species richness as island size decreased and isolation time increased, accelerated by the increasing dominance of the ubiquitous Malayan field rat, Rattus tiomanicus. This species was already hyper-abundant on smaller islands in the initial surveys (1992-1994, 66% of individuals) but became monodominant on all islands, regardless of island size, by the most recent survey (2020, 97%). Our results suggest that insular forest fragments are highly susceptible to rapid species loss, particularly due to the competitive nature of Rattus accelerating the rate at which extinction debts are paid. To mitigate these impacts, reducing the extent of habitat degradation, as triggered by fragmentation and exacerbated by isolation time, can help to sustain native biodiversity while averting Rattus hyper-abundance.

Multi-scale analysis of habitat fragmentation on small-mammal abundance and tick-borne pathogen infection prevalence in Essex County, MA.

Habitat fragmentation and heterogeneity transform otherwise contiguous tracks of forest into smaller patches in the northeastern U.S. and likely impact abundances, movement patterns, and disease transmission pathways for small-mammal communities at multiple scales. We sought to determine the structure of a small-mammal community in terms of mammal abundance and infection prevalence of Borrelia burgdorferi sensu stricto (s.s.), Anaplasma phagocytophilum, and Babesia microti within a fragmented landscape in Essex County, Massachusetts, USA. We studied communities at multiple spatial scales, including vegetation, edge type, and landscape (including 200-m, 500-m, and 1000-m radii) scales. A total of 16 study sites were chosen to represent four edge types: interior forest, pasture edge, natural edge, and residential edge. At each site, we trapped small mammals and conducted vegetation surveys and GIS analysis. Upon capture, a tissue sample was collected to analyze for presence of pathogens. Northern short-tailed shrew (Blarina brevicauda) abundance did not differ based on edge type, whereas abundance of the white-footed mouse (Peromyscus leucopus) was greatest at pasture edges, although the relationship was relatively weak. White-footed mouse abundance was negatively associated with amount of forested area within a 500-m radius, whereas northern short-tailed shrew abundance demonstrated a positive relationship with fragmentation indices at the 200-m radius. White-footed mice captured at interior-forest habitat were more likely be infected with B. burgdorferi (s.s.) than individuals from edge habitat. Greater prevalence of B. burgdorferi infection of white-footed mice in forest interiors compared to edge habitats counters previous studies. Reasons for this and implications are discussed.

Weather, fire, and density drive population dynamics of small mammals in the Brazilian Cerrado

AbstractUnderstanding the relative importance of exogenous and endogenous factors in natural population dynamics has been a central question in ecology. However, until recently few studies used long-term data to assess factors driving small mammal abundance in Neotropical savannas. We used a 9-year data set, based on monthly captures, to understand the population dynamics of two scansorial small mammals inhabiting the Brazilian Cerrado: the semelparous gracile mouse opossum (Gracilinanus agilis), and the iteroparous long-tailed climbing mouse (Rhipidomys macrurus), the two most abundant species at Panga Ecological Station (Uberlândia/MG). We tested the impact of two fires that occurred in 2014 and 2017 on the abundance of both populations. Also, we used Royama’s framework to identify the role of the endogenous system (intraspecific competition) and exogenous factors (annual rainfall, days with minimum and maximum temperatures, annual minimum Normalized Difference Vegetation Index [NDVI], and Southern Oscillation Index) in population dynamics. Extensive and severe fires had a lasting, negative impact on the studied populations, probably by reducing the carrying capacity of the environment. Both populations were influenced by negative first-order feedback, indicating density-dependent effects. Moreover, the endogenous system and the annual minimum NDVI operated as vertical effects determining G. agilis dynamics, while the R. macrurus population was governed by the vertical effects of 1-year lagged rainfall. Our results support the contention that small mammal population fluctuations are driven by the interaction between endogenous (density-dependent) and exogenous factors, which in this study were mainly associated with habitat complexity. Despite ecological similarities shared by both species, their response and recovery time to disturbances and environmental variables varied, probably due to their contrasting life histories. Hence, we emphasize the need to consider species life histories to understand the responses of small mammals to extreme events and reinforce the importance of long-term studies that evaluate the combined effects of endogenous and exogenous variables on population dynamics.