Small Mammal Assemblages Research Articles

The last 20,000 years of climate change in the Iberian Peninsula characterized by the small-mammal assemblages

Climate and environments have undergone significant changes throughout the Earth's history, which are reflected in the faunal record. In that sense, small mammals provide valuable palaeoecological insights due to their close relationship with their associated environments. Our research investigates the dynamics of small mammal communities in the Iberian Peninsula from the Late Pleistocene to the Holocene, comparing regional environmental variations as well as anthropogenic impacts. Our review of the small mammal assemblages from 26 archaeological sites across the Iberian Peninsula revealed a differential response of the small mammal communities between the northern and southern areas. The colder climatic conditions which characterized the Late Pleistocene favoured the presence of mid-European species (e.g., Alexandromys (Oecomicrotus) oeconomus, Chionomys (Chionomys) nivalis) in northern regions until the Mid Holocene, while other taxa today restricted to northern Iberia (e.g., Arvicola amphibius, Microtus gr. (Euarvicola) arvalis, Sorex araneus-coronatus) reached southern regions during the Last Glacial Maximum but disappeared at the beginning of the Holocene period. Palaeoenvironmental reconstructions indicate predominantly open landscapes and colder climates in the Late Pleistocene, with increased forest cover during the Early-Mid Holocene in northern areas. In contrast, the southern regions exhibited more stable environments compared to the northern ones. Our results underscore how the great environmental diversity and interactions between natural and anthropogenic factors affected the composition of Iberian small mammal communities during the last 20,000 years. Most specifically, during the Late Holocene, biogeographical patterns of the small mammals are mostly affected by anthropic activities, with changes in the distribution of some species (Microtus (Iberomys) cabrerae), and the entrance of new ones (synanthropic species).

Socio-environmental factors associated with small mammal assemblage and Leptospira prevalence in Suburban Areas of Terengganu, Malaysia

Objective: To examine the socio-environmental factors associated with the assemblage of small mammals and the prevalence of Leptospira pathogen in poor suburban communities of Terengganu, Malaysia. Methods: We trapped small mammals from 119 trapping points scattered around three suburban communities of Terengganu using sausage-baited live traps. On the average, we set up five traps for three nights at each sampling point during the trapping period. Kidneys of captured animals were harvested and processed for Leptospira investigation. Additionally, environmental survey was conducted at each trapping point to obtain information about possible variables supporting small mammal assemblage. We used a generalized linear model to evaluate the effect of different socio-environmental variables on small mammals’ assemblage. Results: A total of 89 small mammals, specifically, Rattus norvegicus (n=39), Rattus rattus (n=27), Rattus exulans (n=10), Suncus murinus (n=11), and Tupaia glis (n=2) were captured from 1 385 trap nights. Fourteen individuals (15.7%) of the captured animals tested positive for Leptospira bacteria using PCR detection. Results of our generalized linear model showed only residences bordering vacant lots as the variable positively associated with small mammal occurrence in the three study sites. Conclusions: Small mammal community, especially the often neglected species, could harbour and potentially contribute towards pathogenic Leptospira maintenance in the study sites. To adequately control small mammals’ population and subsequent human zoonoses transmission, it is critical to advocate and promote appropriate infrastructure and suburban services, together with good hygiene practices that can reduce the animals’ access to food and harborage.

Small mammal assemblages in heterogeneous landscapes at the Southern tip of Italian peninsula evidence clear eco-biogeographic patterns

We investigated the frequencies of sympatric small mammal species in 12 habitat-types located in the extreme south of the Italian peninsula (Calabria) using trapping techniques. Ten species were detected with Apodemus sylvaticus, the most abundant species. The assemblages of small mammal species recorded in the 12 selected habitat types revealed clear ecological and biogeographical patterns in the extreme southern tip of the Italian peninsula. Ecologically, we observed a clear dissimilarity between a guild of species linked to thermo-xerophilous habitat types and a comparable guild of mesophilous species linked to forest and sciaphilous habitat types. The differences among communities inhabiting in different habitat types also emerged in rarefaction curves, DCA analysis and Whittaker plots. Thus, all these sets of analyses were consistent in their interpretation of the variation of small mammal community structure along the gradient (β-diversity) among habitat types. From a biogeographical point of view, this is an apparent expression of a clear North–South gradient pattern that was already observed at the species level with Calabria being characterized by a strong impoverishment in species’ richness and diversity (“peninsula effect”). However, this rationale has been based so far on indirect data of small mammals preyed upon and recorded in owl’s pellets: the fact that a similar pattern was obtained also using small mammals recorded by traps indicates that the results were robust and generalizable. Ecological factors at the local scale and biogeographical factors at the peninsular scale could explain the community patterns that we observed in the present study.

Analysis of the Early Pleistocene small mammals from Pirro Nord 13 (Apricena, southern Italy) and their implications for reconstructing the palaeoenvironment of the early human occupation in Europe

The Pirro Nord quarry (Apricena, Foggia, southern Italy, 41°48′6″N, 15°23′5″ E) is a well-known palaeontological and archaeological locality comprising an abundant and diverse Early Pleistocene vertebrate assemblage of mammals, birds, amphibians, and reptiles related to the Late Villafranchian and Early Biharian mammal ages. In this study, we describe the small mammal assemblages (insectivores, rodents, and bats) excavated between 2010 and 2022 to reconstruct the palaeoenvironment surrounding the site using Habitat Weighting and the Bioclimatic model methods. The rodent assemblage comprises mostly Allophaiomys cf. ruffoi, Apodemus sp., and Hystrix refossa, whereas Eliomys cf. intermedius was reported for the first time. Insectivores includes Talpa gr. minor-caeca; Asoriculus sp.; Erinaceus praeglacialis; and Sorex sp. Bats are represented by Rhinolophus ferrumequinum, Rhinolophus gr. euryale-mehelyi, Myotis gr. myotis-blythii, Myotis sp., and Miniopterus schreibersii. Landscape reconstruction attested to the presence of a rich and diverse environment with open areas and forest patches surrounding the Pirro Nord 13 site. The climate was slightly colder than that of current times in the same area, with higher precipitation. The presence of different ecosystems near the sites constituted suitable conditions for the first human dispersion in Europe, as already revealed by evidence from Barranco León D, Atapuerca TE7–14, and Fuente Nueva 3 elsewhere on the Iberian Peninsula. The study of small mammal assemblages improves our understanding of the chronological boundaries of the human occupation of Pirro Nord 13, adding important information in the context of the first peopling of the Mediterranean region between 1.6 and 1.3 million years ago.

The Hasli Formation of the Irchel Plateau – A key record for older Early Pleistocene interglacial sediments in northern Switzerland

In the Alpine region of Central Europe, terrestrial Early Pleistocene deposits with preserved faunal and botanical remains are rare. The predominantly gravelly Höhere Deckenschotter (HDS) deposits of northern Switzerland and adjoining south-western Germany are considered the oldest Quaternary sediments in the northern Alpine Foreland, linked with the first extensive Quaternary Alpine glaciations.This multidisciplinary study investigates the Hasli Formation (HF), a unique silty unit with well-preserved biological remains within an HDS sequence at the Irchel Plateau north of Zürich, providing new climatic and environmental data for these exceptional deposits, as well as crucial information about their age. Systematic mapping of the HF, in addition to the underlying and covering gravel units, has been coupled with sedimentary logging and biostratigraphic analysis at several sites. The HF is present over an area c.4 by up to 1.4 km, and where studied is 1.6–6.2 m thick. The sediments and biological material are indicative of overbank deposits accumulating within the damp floodplain of a large meandering river.The recovered small mammal remains are from eight arvicolid species or genera, including Mimomys pliocaenicus, M. reidi/tigliensis and Clethrionomys cf. kretzoii, which became extinct c.1.8 Ma, and Pliomys episcopalis/simplicior, which first appeared c.2 Ma ago. The over 75k identified molluscs, include c.72k coming from 89 terrestrial species and over 3k from 28 aquatic taxa. The molluscan faunas from all locations where the HF has been studied share important biostratigraphic marker species, and indicate analogous climatic and environmental conditions. The marker species include several that became extinct during the Early Pleistocene, of which Clausilia stranzendorfensis and Cochlostoma salomoni, present throughout the HF, are the most important as they disappeared c.1.8 Ma. Many marker species have modern or palaeo-distributions that lie far to the west, south and east of the Swiss Plateau, showing that the climate was much warmer than today, typical for the Tiglian warm stage. The alluvial floodplain was covered by rather dense, mature woodland.Amino acid (AA) analysis shows that molluscan remains from the HF are among the oldest of the Quaternary shell material studied from across the Swiss Plateau. Palaeomagnetic data shows a change from reversed to normal polarity within the upper part of the HF. When combined, the small mammal and molluscan remains, palaeomagnetic measurements, AA geochronology and sedimentary data, suggest an age of 2.1–1.8 Ma for the HF. Recently produced cosmogenic dates bracket the age of the HDS gravels beneath the HF to depositional periods between 2.6 and 0.9 Ma, with the youngest ages being in disagreement with our findings. The abundance and diversity of the molluscs from the Irchel Plateau, with several rare extinct species, together with a notable small mammal assemblage, make this a key palaeontological site and an important reference point for European Quaternary biostratigraphy.

Archaeological evidence of rodent consumption in North Africa: The Middle Stone Age of the rock shelter Ifri n'ammar in northeastern Morocco

This study presents undeniable evidence of anthropogenic exploitation of small mammals in Ifri n'Ammar rock shelter, located in the northeast of Morocco. Among the rodent species found at this site, Ctenodactylus gundi predominates in the assemblage of small mammals between approximately 130 ± 8 ka and 83 ± 6 ka. The taphonomic analysis of the fossil remains of this species, discovered alongside other components of the archaeological assemblage, clearly indicates that during the Middle Stone Age (MSA), humans consumed this species. Therefore, they are considered the main agents responsible for the accumulation of dental and postcranial remains of this species recorded in the shelter. Since the early Upper Pleistocene, bone elements bearing cut-marks and burn traces unequivocally attest to the consumption of this rodent by the hunter-gatherers at the Ifri n'Ammar rock shelter. Our findings regarding the exploitation of this species by humans in the northeastern region of Morocco are corroborated by ethnographic data, demonstrating that North African populations captured and consumed this large-sized rodent until the last century. The species Ctenodactylus gundi is known for its diurnal activity, gregarious and social habits, as well as its preference for rocky and arid environments.

Late-Holocene environmental conditions revealed by a small mammal assemblage in mountain areas of Northwestern Argentina

Based on a diverse Late-Holocene (1889–1743 cal yrs BP) small mammal assemblage (14 species, 204 individuals) resulting from the trophic activity of owls, we reconstruct the paleoenvironmental conditions of Las Chacritas area, Catamarca Province, northwestern Argentina. Twenty modern and one additional Late-Holocene samples from the region were used as comparative parameters in the paleoenvironmental reconstruction. Through direct comparison with a present-day assemblage from Las Chacritas, and using Nonmetric Multidimensional Scaling, spatial and temporal beta diversity (employing the Sorensen dissimilarity index), and the temporal beta diversity index (TBI) including all the small mammal samples, we quantitatively reconstruct the relationships among modern and Late-Holocene assemblages. Direct comparison showed significant differences, with relative abundances changing markedly over time, with several species of the Late-Holocene assemblage absent in the modern sample whereas many species frequent in the modern community absent in the Late-Holocene. NMDS analysis associated the Late-Holocene assemblage with modern samples of western drier environments. Beta diversity was low for presence-absence and moderate for abundance data, with higher contribution of turnover than nestedness, although for abundance data the proportion of nestedness was higher. TBI showed high variation among both Holocene sites and their present-day counterparts, whereas species gains dominated in modern samples. Our results suggest that the habitats surrounding Las Chacritas have modified markedly since the Late-Holocene. Presence of species today frequent in arid environments and absence of forest-dwelling species suggest that open, dry and relatively rocky habitats characterized this area in that interval.

An investigation into the utility of eastern barn owl pellet content as a tool to monitor small mammal diversity in an arid ecosystem

AbstractConsidering several logistical limitations associated with live trapping in arid environments, owl pellet analysis provides a potentially useful alternative to estimate small mammal diversity. Owl pellet analysis has been used to estimate local small mammal diversity under the assumption that the method can reliably reflect the composition of local small mammal assemblages. However, the validity of owl pellet contents for use in ecological assessments has not been established. Thus, the present study aimed to determine the potential for eastern barn owl (Tyto delicatula) pellet analysis to improve the monitoring of small mammals in arid Australia. We analysed two ecological datasets from Pilungah Reserve on the northern boundary of the Simpson Desert in central Australia to assess their effectiveness for detecting expected small mammal species: 250 owl pellets collected from a known roosting site and 5 years of small mammal records from historical, long‐term trapping surveys. Species composition and detection probability of mammals varied depending on the method used. Owl pellet analysis returned higher species richness overall, while traditional trapping methods indicated a higher probability of detecting certain mammal species (e.g., the wongai ningaui Ningaui ridei, brush‐tailed mulgara Dasycercus blythi and the hairy‐footed dunnart Sminthopsis hirtipes). Importantly, analysis of owl pellets revealed two mammal species that had never been detected at the study site (dusky hopping mouse Notomys fuscus and Carpentarian false antechinus Pseudantechinus cf. mimulus). We suggest that owl pellet analysis could be particularly valuable when used as a precursor or in concert with traditional trapping to monitor and assist in the conservation of small mammal species in arid environments.

Some like it burnt: species differences in small mammal assemblage in a Mediterranean basin nearly 3 years after a major fire

The habitat accommodation model (HAM) is a theoretical framework that predicts wildlife community recovery based on their habitat requirements. While post-fire habitat-related research is well documented in the Mediterranean basin, studies specifically focusing on HAM are scarce. Here, we described the small mammal assemblage in a Mediterranean area ~3 years after a fire, specifically examining three functional small mammalian categories: ground-foraging insectivorous, ground-foraging herbivorous/granivorous, and arboreal-foraging species. The study was conducted in Monte Pisano (Italy), where fire burnt ~12 km2 in September 2018. A stratified random sampling was adopted, basing on burnt status and forest type. In each of the 50 sites, during late spring-summer 2021, 12 hair-tubes were deployed, and collected hairs were taxa-attributed based on morphology. A presence/absence dataset was built, and db-RDA was used to explore assemblage composition, and single-species occupancy models to test specific hypotheses. The relative abundance of ground-foraging herbivorous/granivorous was higher in the burnt area, characterised by a dense undergrowth, which could be related to anti-predatory strategies and food opportunities. Insectivorous could be in a recolonisation phase, masking their earlier absence, which could explain why their abundance was not associated with any factor tested. Arboreal-foraging species were associated with forest type, indicating a primary role for tree cover and other factors such as rocky cover and likely in situ survival. The HAM was overall confirmed also in Mediterranean basin ecosystems. This may facilitate predictions about post-fire animal successions, which in turn may provide valuable insights into post-fire management practices and biodiversity conservation strategies.

Late-Holocene stability and recent changes in small mammal communities in north-central Andean forests of Patagonia

Past and current climatic and environmental changes have contributed to configure actual species distributions and abundances. Knowing their evolution over time allows discrimination between natural and anthropogenic causes in current composition of faunal communities. We evaluate the changes in small mammal assemblages from the north-central Patagonian Andean forests since the Late-Holocene to recent times and their relationship with the environmental modifications driven by human activities. A bone sequence from Población Anticura archaeological site (lower Manso river valley, Río Negro province, Argentina) was studied, which encompasses a time span from the early Late-Holocene (3350 ± 100–2270 ±80 years BP) to final Late-Holocene (1420 ± 70–530 ±50 years BP) and Historical times (480 ± 70–280 ±40 years BP). The species composition indicates that forest environment established in the area from at least the Late-Holocene (dominance of Loxodontomys micropus, with subordinate frequencies of Abrothrix olivacea, A. hirta, Geoxus valdivianus, Irenomys tarsalis, and Paynomys macronyx), with patches of (or near to) open environments (presence of Reithrodon auritus and cavids). It is remarkable the presence of cavids, which increased their abundance in the sequence towards Historical times but disappeared nowadays. The low frequencies (<10%) of the rodent Oligoryzomys longicaudatus along the entire sequence is also relevant, since this rodent is the reservoir of the Andes strain of the Hantavirus (ANDV), which causes pulmonary syndrome. This mouse dominates the small mammal assemblages from forests and ecotonal shrublands of northwestern Patagonia (abundances exceed 50% in owl pellets recently collected from the study area). Current configuration of forest and ecotonal assemblages, particularly the high abundance of O. longicaudatus, should be mainly linked to anthropogenic causes, including the introduction of cattle, land clearing, and the advance of introduced plant species such as the sweet briar ( Rosa eglanteria). Particularly, this exotic shrub offers shelter and additional food for O. longicaudatus, turning their shrublands into spaces of high epidemiological risk.

Drivers of functional diversity in small-bodied mammals across a deforestation frontier in the Southern Brazilian Amazon

Deforestation remains the most pervasive driver of biodiversity erosion across tropical forests. Understanding how species can cope with such habitat changes is particularly important along the rapidly expanding agricultural frontiers. To do so, we used a functional perspective examining small mammal responses to habitat loss, fragmentation, and degradation across the ‘Arc of Deforestation’ in the Southern Brazilian Amazon. Small mammals were surveyed using a combination of conventional and pitfall traps across 20 forest fragments—ranging from 42 to 4743 ha—in addition to two relatively continuous forest sites (> 7000 ha). These fragments lie isolated by a cattle pasture matrix of varying grazing intensity. We then analysed taxonomic and functional diversity patterns—represented by Simpson Diversity and Rao Quadratic entropy indices—in Generalised Linear Models containing local- to landscape-scale predictors of variation. Further, we used a functional trait composition approach based on community-weighted mean trait values to depict and predict small mammal functional variations across this degradation gradient. From a total of 847 individuals recorded belonging to 24 taxa, functional responses tended to follow the taxonomic diversity, both increasing with fragment area. The functional dimension further was promoted by low fire-related disturbance. Functional trait composition was mainly driven by habitat quality, represented by tree density, arthropod biomass, and fire-related disturbance. Our results reinforce that small forest fragments sustain depauperate small mammal assemblages both taxonomically and functionally. Accounting for habitat quality further allows for boosting the persistence across functional groups. Our findings can be used to improve the efficiency of management practices thereby maximising the multiple dimensions of small mammal diversity and their associated ecosystem services across tropical deforestation frontiers.

Landscape and farm environmental structure determinants of small mammal assemblages in agroecosystems of central Argentina

Abstract Natural processes and patterns are altered by human activity at different spatial and temporal scales, affecting species assemblages and population traits, modifying mechanisms or regulating dynamics at different scales. However, little is known about the influence of landscape structure on small mammal assemblages and populations on farms. Thus, in this work, we aimed to study the effect of landscape and environmental characteristics at the farm scale on the assemblage and populations of native and introduced small mammals in pig and dairy farms located in Buenos Aires province, Argentina. Our results showed that farms in contexts of higher environmental diversity at the landscape scale have higher species richness. Our results also showed that variations in assemblage composition were associated with the quantity of water body surfaces, cattle food, small mammal refugia, and impervious surfaces at the farm scale—and with woodland, grassland, and natural vegetation cover at the landscape scale. The abundance of commensal murids was higher on farms near towns, with higher vegetation cover at the farm scale and/or in landscape contexts with fewer crops. The abundance of Akodon azarae was higher on farms with a lower amount of cattle food at the farm scale and crop patches in the landscape. The abundance of Didelphis albiventris was higher during spring on farms with a low proportion of bare ground, while that of Lutreolina crassicaudata was higher on farms with high vegetation cover and a lower number of water body surfaces. These results show the relevance of multiscale determinants in the development of ecologically based management strategies to control pest small mammals.

Small mammal assemblage in Gunung Tebu Forest Reserve, Terengganu: An environmentally sensitive area in East Coast Peninsular Malaysia

Effective spatial planning plays a pivotal role in defining the progress and growth of a certain region. One aspect of spatial planning by PLANMalaysia involves the incorporation of environmentally sensitive areas (ESAs), which comprises eleven different landscape management. Integrating biological features is crucial when defining ESA Permanent Forest Reserve, as relying solely on physical attributes may not accurately reflect the true sensitivity of the environment. Therefore, there is a need to gather biological information to strengthen existing ESA. A study was conducted in Gunung Tebu Forest Reserve (GTFR) from April to July 2023. Multiple trapping approaches were deployed to assess volant and non-volant small mammal assemblage. In total, 155 individuals comprised of 31 species of small mammals were documented with the highest species abundant recorded by Maxomys rajah (n = 29) and Leopoldamys sabanus (n = 27). The diversity indices were varied throughout five sampling sessions, (Shannon = 1.841 to 2.543), (Simpson = 0.7951 to 0.9056). Comparison on species assemblage between GTFR and forest reserves in Hulu Terengganu showed a moderate similarity level. This finding offers the most recent insight of the small mammals in GTFR and highlights the significance of conserving and preserving (ESA) in permanent forest reserves.

Study on the relation of the characteristics of the capture sites with the Leptospira spp. occurrence in bats and rodents from Yucatan, Mexico

This study aims to describe the natural Leptospira occurrence in small mammals from Yucatan, Mexico, and to explore the relation between the characteristics of the capture sites and the Leptospira occurrence. Bats and rodents were captured in five sites of Yucatan state, and from them, a kidney fragment was collected that was used in the genomic DNA extraction. Leptospira DNA was identified by PCR targeting the 16S-rRNA and LipL32 genes. Additionally, a bioinformatic analysis was carried out to know the Leptospira species and was corroborated with a phylogenetic tree. The assemblage of small mammals was compound of 82 (51.2 %) bats and 78 (48.8 %) rodents. A global frequency (bats plus rodents) of Leptospira occurrence of 21.2 % (34/160) was observed; in bats, it was 21.9 % (18/82), and in rodents, 20.5 % (16/78). The phylogenetic trees based on LipL32 gene showed that the recovered sequences most closely resemble the species L. borgpetersenii and L. noguchii. The ordination of the capture sites with tropical deciduous forests as original vegetation is more related to the abundance of Leptospira-infected rodents. The ordination of the capture sites with tropical sub-deciduous forests as original vegetation is more related to the diversity of Leptospira-infected bat species. The canonical ordering of the capture sites is by the original vegetation type and the diversity and abundance of Leptospira-infected bat and rodent species.

Shrew Communities in Mediterranean Agro-Ecosystems of Central Greece: Associations with Crop Types, Land Uses, and Soil Parameters.

Shrew communities play a crucial role in a diverse range of natural, urban, and agricultural ecosystems. We used Barn owl diet analysis as the ideal proxy to assess small-mammal distribution patterns on large spatial scales. More than 10,000 pellets were analyzed from Thessaly, the largest agricultural prefecture located in central Greece. A total of more than 29,000 prey items were identified, one of the largest datasets used in similar analyses in Europe. Three discrete shrew species were present in Thessaly agricultural plains, central Greece (Güldenstädt's shrew Crocidura gueldenstaedtii, Bi-coloured shrew Crocidura leucodon, and Pygmy white-toothed shrew Suncus etruscus), which comprised a total of 7452 shrews, representing 25.64% of the total small-mammals' dataset. C. gueldenstaedtii and S. etruscus demonstrated strong associations with heavy argillaceous-clay soils and Vertisol soil types, whereas S. etruscus was also associated with non-irrigated land and non-intensive cultivated plots. C. leucodon demonstrated no significant associations to any environmental gradient and demonstrated habitat plasticity, most possibly shaped by existing resources and competition. Our study highlights the important insights gained from Barn owl diet analysis in respect of small-mammal assemblages on broad geographical scales, and the inclusion of soil parameters as drivers of habitat suitability and distribution patterns for small-mammal responses.

Forest stability during the Holocene in Santa Catarina, southern Brazil revealed by small mammals from Gruta do Presépio

Quaternary small mammals are important proxies for paleoenvironmental reconstructions. The Brazilian record, although famous and continuously growing, is hampered by poor chronological control due to the nature of most of the published assemblages. Here, we present a taphonomic analysis and paleoenvironmental reconstruction based on marsupials, bats, and rodents (480 remains) from the Gruta do Presépio archeological site (GPR, hereafter), Santa Catarina State, southern Brazil. The site is a rock shelter located in an Atlantic Forest biome, an important biodiversity hotspot. The GPR sedimentary sequence spans the Early Holocene (8330 ± 30 years 14C BP) to recent Historical time (after the arrival of Europeans). Most of the small mammal remains were deposited by strigiforms, although for the oldest units some strongly digested remains could indicate the activity of diurnal birds or carnivorous mammals. The GPR small mammal assemblages include 28 taxa (five marsupials, nine chiropterans, and 14 rodents). Most of them indicate the occurrence and persistence of forested environments during the Holocene around the site, which is in overall agreement with regional palynological data. A major community change, implying the increment of rodents allied to disturbed ecosystems (e.g. Akodon, Oligoryzomys, Mus), is very recent and reflects human forest clearance as a signature of the Anthropocene.

The positive response of small terrestrial and semi-aquatic mammals to beaver damming

Ecosystem engineers, such as the Eurasian beaver, Castor fiber, transform habitats, thereby creating favourable conditions for other species and increasing biodiversity. Multiple studies have revealed that beaver ponds are valuable habitats for invertebrates and vertebrates, including other mammals, but the impact of watercourse damming on the fauna of small terrestrial rodents and shrews has not yet been documented. We tested the hypothesis that the presence of beaver dams and consequent flooding enrich the small mammal assemblage both quantitatively and qualitatively. We live-trapped small mammals at nine beaver-modified sites on 300-metre transects alongside dammed watercourses, starting from the dam through to the pond to the sections with unmodified lotic conditions. The abundance and species richness of trapped small mammals were highest near the dams and declined with distance. Additionally, five out of 12 trapped species significantly decreased their abundance with linear distance along the shoreline from the dam and none revealed the opposite trend. Four species were more abundant on plots subjected to beaver-related inundation (especially Sorex minutus and Micromys minutus), while none were present solely on uninundated plots. Among the semi-aquatic species, two water shrews benefited from beaver activity in different ways. Neomys milleri occurred only in flooded sections, while N. fodiens preferred unmodified sections, but was the most numerous species closer to the dams, as per known patterns of competitive displacement observed in Central Europe. An important factor affecting small mammals, the herbaceous layer cover, appeared to be interdependent with damming. We provide the first unequivocal evidence that the presence of beaver dams facilitate the abundance and diversity of small mammals, presumably due to increased food abundance, availability of shelter and habitat connectivity. Beaver-created wetlands may act as potential refuges for species most susceptible to the consequences of anthropogenic climate change.

It’s about time: small mammal communities and Lyme disease emergence

Theory predicts that biodiversity changes due to climate warming can mediate the rate of disease emergence. The mechanisms linking biodiversity-disease relationships have been described both theoretically and empirically but remain poorly understood. We investigated the relations between host diversity and abundance and Lyme disease risk in southern Quebec, a region where Lyme disease is rapidly emerging. We found that both the abundance of small mammal hosts and the relative abundance of the tick’s natural host, the white-footed mouse (Peromyscus leucopus), influenced measures of disease risk in tick vectors (Borrelia burgdorferi infection abundance and prevalence in tick vectors). Our results suggest that the increase in Lyme disease risk is modulated by regional processes involving the abundance and composition of small mammal assemblages. However, the nature and strength of these relationships was dependent both on time and geographic area. The strong effect of P. leucopus abundance on disease risk we report here is of significant concern, as this competent host is predicted to increase in abundance and occurrence in the region, with the northern shift in the range of North American species under climate warming.

Choosing between human trash and trashed forests: Resilience in nonvolant Atlantic Forest small mammals

Open pit rubbish dumps generate serious environmental problems both in Brazil and elsewhere. The goal of this study was to evaluate the occurrence patterns of an assemblage of small flightless mammals in the area of a landfill deactivated 19 years ago. During nine campaigns, three different sites located in a subtropical protected area near the city of Matinhos, Paraná coast, southern Brazil, were sampled. The selected places were an artificial clearing where urban waste had previously been dumped (Area 1), a site with less anthropic influence with tree species and a poorly developed understorey (Area 2), and a site with well-formed vegetation, with herbaceous, shrubby and tree strata well developed (Area 3). The total capture effort was 5210 trap-nights; 109 captures were made of 82 individuals from five species of Rodentia (all from the subfamily Sigmodontinae) and three species of marsupials (Order Didelphimorphia). The most conserved site (Area 3) had higher abundance than areas 1 and 2 (binomial test; P<0.05). Area 1, considered the most affected, showed less species richness (n=6) than the other two areas (7 and 8 species), although this may be affected by the lower number of captures. The diversity in Area 1, estimated by the Shannon index, was lower than in areas 2 and 3 (Hutcheson’s t tests; H’=1.26 for Area 1 vs. 1.76 and 1.68 for Areas 2 and 3, respectively), although the composition of the assemblage did not differ significantly between the areas (PERMANOVA; P=0.085). Our results show that even after 19 years of inactivity, the deposited waste is still having a negative impact on the environment, and highlight the resilience of some native small mammal species in exploiting the resources of degraded areas.

Redefining the MIS 3 climatic scenario for Neanderthals in northeastern Iberia: A multi-method approach

One of the major challenges in scientific research is to understand past climate and the mechanisms of climate change. Small vertebrates, and especially rodents, are very sensitive to shifts in climate and habitat, and their variations over time in terms of taxa and abundance can be successfully used to reconstruct past environments. The vast array of approaches to palaeoclimatic reconstruction reflects the great effort that has gone into this line of investigation. Recently, the UDA-ODA discrimination technique has been postulated as a more reliable ecologically-based methodology compared to the classical MER method.To provide biogeographical information to be analysed by the UDA-ODA discrimination technique, the distributions of four species (Sorex minutus, Chionomys nivalis, Talpa europaea and Crocidura russula) documented in levels O, N, E and D of the Abric Romaní site were processed. The results reveal a statistical difference between the climatic values for the occupied distribution areas (ODA) and those for the uncertain distribution areas (UDA). This technique was then applied to small-mammal assemblages from the above-mentioned levels of Abric Romaní, to test whether the use of the ODAs of the species improves the precision of the climatic reconstruction compared to the atlas distributions of the species used in MER procedures. Our results suggest an improvement in the discrimination analysis over the previous MER reconstructions when wider distributions for an assemblage are obtained. The coldest values obtained for level O of Abric Romaní seem to reinforce the pollen interpretation of the level as coetaneous with a cold period. For the whole MIS 3 climatic scenario for Neanderthals, a colder and wetter climate is derived from the small-mammal analysis. However, as different methods and analyses have inherent limitations, a standardization of the methods applied to the different levels and sites should be carried out in order to provide comparable results.