Arvicola Sapidus Research Articles

Activity timing of southern water vole (Arvicola sapidus Miller, 1908) in a Mediterranean river

Knowledge of the alternation between activity and rest during the 24 h daily cycle is important in order to understand how species interact with the environment and can also provide tools for designing appropriate conservation measures. At present, little is known about this alternation in Arvicola sapidus, an endemic rodent restricted to the Iberian Peninsula and France. This study aims to extend our knowledge of this rodent’s hour to hour activity/rest patterns by using radiotelemetry to quantify the distances travelled (associated with activity) by individual southern water voles along a stretch of the Montsant River. The results showed that the southern water vole’s behaviour is cathemeral. The use of data of frequency of activity in one-hour intervals to assess the activity pattern showed a lower resolution than the use of data of the mean distances travelled in one-hour intervals. The individuals occupying a suboptimal habitat travelled a greater mean distance per hour than individuals occupying an optimal habitat, indicating that their activity was related to the habitat conditions. These considerations may help to explain why fragmentation and habitat destruction are emerging as the main cause of the decline of the southern water vole, and underline the importance of habitat conservation to encourage the maintenance of the species.

Evidencias de regresión local del desmán ibérico (Galemys pyrenaicus) en los Pirineos meridionales

We have studied the changes in the distribution and frequency of semiaquatic micromammals in the river network of Alt Pirineu Natural Park (southern Pyrenees, Iberian Peninsula) between 2000 and 2013-2014. The priority of this work has been the Iberian Desman (Galemys pyrenaicus) but we also evaluated the frequency in Water Shrews (Neomys fodiens and Neomys milleri) and Southern Water Vole (Arvicola sapidus), for which 2000 data were incomplete. It is the first time that a diachronic study on the relative frequency of Iberian Desman takes place at regional level and using an identical method in the two surveys. The methodology was the detection of faeces of these species in 66 river sections, prospected in the two periods considered. The most common semiaquatic mammals were Water Shrews, present in almost all river sections (94%), followed by the Desman (45%) and the Water Vole (34%). We found an intense regression of the Desman in a river basin where this species was common in 2000 (Noguera de Cardós) and it is extinct in the upper basin of this river. This local regression is probably attributable to a recent change in the model of hydroelectric management and we started a survey to evaluate this hypotesis.

Factors affecting southern water vole (Arvicola sapidus) detection and occupancy probabilities in Mediterranean farmland

Failure to detect a species at sites where it is present (i.e. imperfect detection) is known to occur frequently, but this is often disregarded in monitoring programs and metapopulation studies. Here we modelled for the first time the probability of patch occupancy by a threatened small mammal, the southern water vole (Arvicola sapidus), while accounting for the probability of detection given occupancy. Based on replicated presence sign surveys conducted in autumn (November–December 2013) and winter (February–March 2014) in a farmland landscape, we used occupancy-detection modelling to test the effects of vegetation, sampling effort, observer experience, and rainfall on detection probability. We then assessed whether occupancy was related to patch size, isolation, vegetation, or presence of water, after correcting for imperfect detection. The mean detection probabilities of water vole signs in autumn (0.71) and winter (0.81) indicated that false absences may be generated in about 20–30% of occupied patches surveyed by a single observer on a single occasion. There was no statistical support for the effects of covariates on detectability. After controlling for imperfect detection, the mean probabilities of occupancy in autumn (0.31) and winter (0.29) were positively related to patch size and presence of water, and negatively so, albeit weakly, to patch isolation. Overall, our study underlined the importance of accounting for imperfect detection in sign surveys of small mammals such as water voles, pointing out the need to use occupancy-detection modelling together with replicate surveys for accurately estimating occupancy and the factors affecting it.

The role of the southern water vole Arvicola sapidus in the diet of predators: a review

Abstract For the recovery and conservation of endangered species such as the southern water vole Arvicola sapidus, it is important to understand the effects of predation on their populations. The impact of a predator on a prey species depends on the dynamics and structure of their populations, the abundance of both species and their relationships with other species. When considering broad geographic areas, the analysis of the trophic dimension can provide an estimate of the effect of predatory pressure on the prey. To determine the potential impact of predators on the southern water vole, we used information provided in 74 studies concerning the diet of predators in the geographical range of the prey species. The trophic spectrum was determined based on faeces, stomach contents or pellets in which the arvicoline was present. Based on the percentage of biomass consumed in each of nine trophic categories, the potential impact posed by predators was linked with dietary profile, trophic diversity, intensity of southern water vole consumption and availability of preferred prey. In the localities studied, southern water voles are not the preferred prey of any of the predators we considered, but represent an alternative prey for some of them, especially when their main prey species are scarce. The predators with the greatest potential impact on southern water vole populations are Lutra lutra and Ardea cinerea; those with a moderate impact are some mesocarnivores (Felis silvestris, Genetta genetta, Neovison vison, Vulpes vulpes and Martes foina), a bird frequenting aquatic environments (Ciconia ciconia), and the raptors Aquila fasciatus and Hieraaetus pennatus. The results obtained may be useful in the planning of measures for the conservation of the southern water vole, such as translocations or reintroductions, and in the design of strategies to reduce predatory pressure with the aim of promoting the success of these programmes.

The habitat of the water vole Arvicola sapidus Miller, 1908 in France: description and conservation

The habitat of the water vole Arvicola sapidus Miller, 1908 in France: description and conservation

Influence of Land Mosaic Composition and Structure on Patchy Populations: The Case of the Water Vole (Arvicola sapidus) in Mediterranean Farmland

The ability of patchy populations to persist in human-dominated landscapes is often assessed using focal patch approaches, in which the local occurrence or abundance of a species is related to the properties of individual patches and the surrounding landscape context. However, useful additional insights could probably be gained through broader, mosaic-level approaches, whereby whole land mosaics with contrasting patch-network and matrix characteristics are the units of investigation. In this study we addressed this issue, analysing how the southern water vole (Arvicola sapidus) responds to variables describing patch-network and matrix properties within replicated Mediterranean farmland mosaics, across a gradient of agricultural intensification. Patch-network characteristics had a dominant effect, with the total amount of habitat positively influencing both the occurrence of water voles and the proportion of area occupied in land mosaics. The proportions of patches and area occupied by the species were positively influenced by mean patch size, and negatively so by patch isolation. Matrix effects were weak, although there was a tendency for a higher proportion of occupied patches in more intensive, irrigated agricultural landscapes, particularly during the dry season. In terms of conservation, results suggest that water voles may be able to cope well with, or even be favoured by, the on-going expansion of irrigated agriculture in Mediterranean dry-lands, provided that a number of patches of wet herbaceous vegetation are maintained within the farmland mosaic. Overall, our study suggests that the mosaic-level approach may provide a useful framework to understand the responses of patchy populations to land use change.

The impact of the American mink (Neovison vison) on native vertebrates in mountainous streams in Central Spain

The American mink (Neovison vison) is responsible for the widespread decline of its prey species in the regions where it is an invasive species. The current expansion of the mink in the Iberian Peninsula has aroused concern among conservationists about its negative impact on the rich native fauna. However, evidence for this is still scarce, although there are several studies establishing a direct causal relationship between declining native species and the presence of the American mink. Thus, it is important to further investigate the responses of native species to the American mink in several habitats and locations to enhance our knowledge about the patterns of the effect of the mink in Spain, as well as to inform conservation actions. A field study of the impact of the American mink on a mountainous vertebrate community in central Spain is presented. We studied six species: two fish, one amphibian, one bird, and two mammals. The general results showed a species-specific sensitivity to mink presence, with the Mediterranean water shrew (Neomys anomalus) and the southern water vole (Arvicola sapidus) being the most affected because their ranges were significantly decreased after the introduction of the mink. Regarding the other species, neither their abundance nor range was apparently affected by the American mink. The predatory behavior of the mink and interactions with other carnivores could account for these results. These data aid in shedding light about the current impact of the mink on invaded areas of the Iberian Peninsula and highlight the variability of its effects, as well as the urgent need to establish a general program of control of the mink to avoid negative effects upon native prey communities. Furthermore, given the different responses of native species, we propose that measures to protect native species should be based on species-specific goals and attributes.

First documented attack of southern water vole Arvicola sapidus Miller, 1908 on a viperine snake Natrix maura (Linnaeus, 1758), on the Montsant river (NE Iberian Peninsula)

. 2002, Flechoso & Alarcos 2009), which mainly occurs in females during pregnancy and lactation, in response to a higher protein requirement (Strachan 1997). The females are territorial (Roman 2007), espe-cially in the breeding season, which is a defence me-chanism for spatial and trophic resources (Ostfeld 1990). Females defend offspring against conspecifics and other species through strategies such as moving pups to other nests when threatened. Presumably, given the references to the aggressiveness shown by some individuals of semi-aquatic species of

Habitat selection by Southern water vole (Arvicola sapidus) in riparian environments of Mediterranean mountain areas: a conservation tool for the species

The Southern water vole, Arvicola sapidus, is endemic to the Iberian Peninsula and France. Despite being catalogued as vulnerable, our current knowledge of this species is not sufficient to establish measures for its conservation and recovery, particularly in riparian zones of Mediterranean mountain areas. The aim of this study was to identify factors related to habitat configuration that determine the presence or absence of the species in the Montsant River. Specifically, we associated the presence/absence of this arvicolid rodent with composition of vegetation, river bank morphology, and watercourse characteristics. The results suggest that, in this area, the most favorable places for the species are those with a high degree of cover of herbaceous plants (mainly helophytes) and moderate to low levels of tree and shrub cover; gently sloping banks and a soft substrate; and the presence of water, with moderate to high stream widths and depths. In addition, we developed a classification method which allowed us to classify and characterize habitat conditions: the optimal scenario (preferential for arvicoline establishment), the suboptimal scenario (whose use is related to opportunities to find best scenarios), and the hostile scenario (not acceptable for use). In such riparian areas, the results revealed that the Southern water vole is a specialist in terms of habitat selection, but behaves as a generalist in terms of occupancy. Its ability to adapt to suboptimal conditions widens the options for managing Southern water vole populations, and indicates that the maintenance and rehabilitation of habitat along continuous stretches of river is the most effective approach to achieving self-sustaining populations.

Prisoners in their habitat? Generalist dispersal by habitat specialists: a case study in southern water vole (Arvicola sapidus).

Habitat specialists inhabiting scarce and scattered habitat patches pose interesting questions related to dispersal such as how specialized terrestrial mammals do to colonize distant patches crossing hostile matrices. We assess dispersal patterns of the southern water vole (Arvicola sapidus), a habitat specialist whose habitat patches are distributed through less than 2% of the study area (overall 600 km2) and whose populations form a dynamic metapopulational network. We predict that individuals will require a high ability to move through the inhospitable matrix in order to avoid genetic and demographic isolations. Genotypes (N = 142) for 10 microsatellites and sequences of the whole mitochondrial Control Region (N = 47) from seven localities revealed a weak but significant genetic structure partially explained by geographic distance. None of the landscape models had a significant effect on genetic structure over that of the Euclidean distance alone and no evidence for efficient barriers to dispersal was found. Contemporary gene flow was not severely limited for A. sapidus as shown by high migration rates estimates (>10%) between non-neighbouring areas. Sex-biased dispersal tests did not support differences in dispersal rates, as shown by similar average axial parent-offspring distances, in close agreement with capture-mark-recapture estimates. As predicted, our results do not support any preferences of the species for specific landscape attributes on their dispersal pathways. Here, we combine field and molecular data to illustrate how a habitat specialist mammal might disperse like a habitat generalist, acquiring specific long-distance dispersal strategies as an adaptation to patchy, naturally fragmented, heterogeneous and unstable habitats.

Circadian activity rhythms in relation to season, sex and interspecific interactions in two Mediterranean voles

Although environmental conditions and biotic interactions are widely recognized as key sources of variation in circadian activity rhythms of a broad array of vertebrates, information on their actual significance outside experimental settings remains scarce. We investigated changes in circadian activity rhythms of free-ranging Cabrera voles, Microtus cabrerae , and water voles, Arvicola sapidus , in highly seasonal Mediterranean environments, and analysed how such changes were further affected by intersexual and interspecific interactions. Cabrera voles were largely diurnal, with a unimodal peak around midday during the wet season, whereas during the dry season activity was reduced during the hot midday period and increased strongly at dawn and dusk. Water voles also had a marked bimodal crepuscular pattern during the dry season, but this was much attenuated during the wet season, when they were comparatively more diurnal. Activity patterns varied little between the sexes, although with a tendency for higher overall activity by male Cabrera voles (dry season only) and water voles, possibly because of intersexual interactions involving seasonal shifts from monogamy to facultative polygyny in Cabrera voles, and year-round polygyny in water vole. Within each season, Cabrera voles appeared to change their activity patterns in the presence of water voles, reducing overall activity and shifting activity peaks towards diurnal (dry season) or crepuscular (wet season) time periods less used by water voles. Overall, this study provides evidence for the strong role of seasonal changes in environmental conditions and interspecific interactions in driving variation in the activity patterns of Mediterranean voles under natural conditions.

Palaeoenvironmental and palaeoclimatic proxies of the Gorham’s cave small mammal sequence, Gibraltar, southern Iberia

Gorham’s cave is located in the British territory of Gibraltar in the southernmost end of the Iberian Peninsula. The cave was discovered in 1907 and first excavated in the 1950s by John Waechter of the Institute of Archaeology in London. New excavations, which started in 1997, have exposed 18 m of human occupation in the cave, spanning the Late Pleistocene, as well as including brief Phoenician, Carthaginian and Neolithic occupations. The Late Pleistocene levels consist of two Upper Palaeolithic occupations, attributed to the Solutrean and Magdalenian technocomplexes (Level III), and which are dated, by AMS radiocarbon, to between 18,000 and 10,000 years ago. The underlying Mousterian layer (Level IV), dated by AMS radiocarbon to between 23,000 and 33,000 years ago, is separated from Level III by an archaeologically sterile layer, which spans some 4000 years. This paper presents previously unpublished palaeoenvironmental and paleoclimatic reconstructions of Gorham’s cave, during these Pleistocene occupations, using the small mammal assemblage. The small mammal assemblage at Gorham’s cave comprises of at least 12 species: 4 insectivores ( Crocidura russula, Sorex gr. coronatus-araneus, Sorex minutus and Talpa occidentalis); 3 chiropters ( Myotis myotis, Myotis nattereri and Miniopterus schreibersii); and 5 rodents ( Microtus ( Iberomys) cabrerae, Microtus ( Terricola) duodecimcostatus, Arvicola sapidus, Apodemus sylvaticus and Eliomys quercinus). The presence of these small mammal species indicates that the landscape surrounding the Rock of Gibraltar was predominantly an open habitat, with the presence of woodland and water stream meadows, as well as the presence of larger bodies of water. These results are then compared with pollen and charcoal analysis as well as other faunal proxies, such as the herpetofauna, bird and large mammal assemblages, providing an accurate reconstruction of the climatic and environmental conditions that prevailed during the Late Pleistocene in the southernmost of the Iberian Peninsula.

Revisión del estatus del topillo de Cabrera Microtus cabrerae Thomas, 1906 y la rata de agua Arvicola sapidus Miller, 1908 en las Sierras Subbéticas cordobesas (Andalucía)

We analyzed the presence of the Cabrera’s vole Microtus cabrerae at the Subbetic mountains of Córdoba (South of Spain). Although the subfossil remains proved that the vole lived at this region in the past, the absence of new founds of extant populations in its tipical habitats suggest that it has disappeared. Simultaneously, we analyzed the situation of the southern water vole Arvicola sapidus, whose populations are clearly threatened.

Loss of water availability and stream biodiversity under land abandonment and climate change in a Mediterranean catchment (Olzinelles, NE Spain)

In the north rim of the Mediterranean region, where forest cover is increasing as a result of land abandonment and temperatures are rising as a result of climate change, there is increasing interest for the effects of such changes on the runoff of water courses. This is a paramount issue for the conservation of many freshwater habitats and species. In this work we studied the effects of both an increase in forest cover after depopulation and land abandonment and an increase in temperature on the runoff of a Mediterranean catchment and on the aquatic and semi-aquatic fauna species of the stream (Olzinelles valley, NE Spain). Although in our simulation no decreasing trend in runoff is detected, the monthly runoff-rainfall ratio is now 15% lower than 30 years ago, a fact that may be attributed to a drier period rather than to the small afforestation experienced by the catchment in the last decades. Other factors such as increasing temperatures, changing rainfall patterns and increasing canopy cover are discussed. The observed decrease in the water flow has caused the disappearance of white-clawed crayfish ( Austropotamobius pallipes), Mediterranean barbel ( Barbus meridionalis), chub ( Squalius cephalus), European eel ( Anguilla anguilla), and southern water vole ( Arvicola sapidus). Our results suggest that in a progressively warmer climate, and especially after land abandonment processes, management of Mediterranean mountain areas should be oriented towards an appropriate distribution of agrarian and forest land-covers in terms of water availability. Down to the stream scale, the pools that keep water throughout the year should be conserved and extended to enhance its potential to maintain aquatic and semi-aquatic species populations.

Palaeoenvironmental and palaeoclimatic reconstruction of the Latest Pleistocene of El Portalón Site, Sierra de Atapuerca, northwestern Spain

The site of El Portalón is the entrance to the Cueva Mayor karst system, located in the Sierra de Atapuerca (Burgos, Spain). This is an important Holocene archaeological site, which was excavated in the 1970s but from which little has been published. New excavations starting in 2000 have highlighted a deep stratigraphical sequence, with human occupations starting at the end of the Late Pleistocene. In this paper, we present for the first time, on the basis of the small-vertebrate assemblage, palaeoenvironmental and palaeoclimatic reconstructions of the Latest Pleistocene of the Sierra de Atapuerca, well known for its Early to Middle Pleistocene human-bearing localities. The small vertebrates of El Portalón comprise at least 25 species: 4 amphibians ( Alytes obstetricans, Bufo bufo, Bufo calamita and Rana temporaria); 3 squamates (an indeterminate small-size lacertid, an indeterminate large colubrine and Vipera sp.); 6 insectivores ( Sorex gr. coronatus-araneus, Sorex minutus, Neomys fodiens, Neomys anomalus, Talpa europaea and Galemys pyrenaicus); 2 bats ( Myotis myotis and Myotis gr. myotis-blythi); 10 rodents ( Microtus arvalis, Microtus agrestis, Microtus oeconomus, Iberomys cabrerae, Chionomys nivalis, Terricola duodecimcostatus, Arvicola sapidus, Arvicola terrestris, Apodemus sylvaticus and Eliomys quercinus). These taxa, many of which are ecothermal (sensitive to temperature) show variations in their taxonomic diversity throughout the sequence. Although, with the exception of M. oeconomus, they do not differ from the extant fauna of the Iberian Peninsula, they do so in the abundance of their taxonomic assemblage. When the small vertebrates are grouped and studied in terms of vertical trends through the sequence, it is possible to follow environmental and climatic changes. Results from the small-vertebrate associations indicate that the landscape had open habitats in the vicinity of the Atapuerca caves throughout the sequence, with wet locales in the surrounding area. Woodland and water stream meadows were more developed during “warm” periods (Is5, Is6/Is7 and Is3/Is4), whereas during “cold” periods (H3 and LGM) the environment was slightly more humid in response to winter precipitation and the opening of the landscape. These results are compared with pollen analysis and marine isotopic curves, giving a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the Latest Pleistocene in the Sierra de Atapuerca.

Structure, organization and nucleotide diversity of the mitochondrial control region and cytochrome b of southern water vole (Arvicola sapidus)

The southern water vole (Arvicola sapidus Miller, 1908) is an endangered rodent whose conservation guidelines should preserve the current genetic variability. We analyze the structure and organization of the mitochondrial control region (CR) in A. sapidus. The CR of this species is characterized by a low guanine-cytosine content, the absence of any repetitive motif within the two hypervariable regions, and the presence of the two extended termination-associated sequences and conserved sequence blocks. Nucleotide diversity comparisons between A. sapidus and the European water vole (Arvicola terrestris) revealed differences in the distribution of genetic variation. Furthermore, we provide primers for the amplification of short and highly polymorphic fragments of CR and cytochrome b especially designed for degraded materials. These markers offer molecular tools to assist in the establishment of future conservation and management guidelines, and will also facilitate studies at different spatial and evolutionary scales of this species.

Spatial segregation of two vole species (Arvicola sapidus and Microtus cabrerae) within habitat patches in a highly fragmented farmland landscape

Spatial segregation is one of the common mechanisms allowing the co-existence of similar interacting species in heterogeneous environments. Analysing spatial segregation requires information on individual home-range sizes and their degree of spatial overlap. In this study, we used radio-tracking to report for the first time the home-range and core-area sizes of sympatric Cabrera and water voles and to analyse intra- and inter-specific space sharing within habitat patches in a highly fragmented landscape. Results indicated that both species exhibited strong fine-scale site fidelity and reduced variation in range size across sexes and seasons. Monogamous mating system seemed to prevail for both species, although water voles may also exhibit polygynous breeding strategies. Mean home-range and core-area sizes of water voles (946.3 and 156.6 m2) were about twice that of Cabrera voles (418.2 and 55.1 m2). Within habitat patches, individuals of both species often overlapped their home ranges, particularly during the dry season (May–September), though intra-specific home-range overlap was generally higher than inter-specific overlap. Inter-specific space sharing was restricted to areas outside the centre of activity of animals, as no core-area overlap was ever recorded between Cabrera and water voles. Taken together, results support the view that co-existence of Cabrera and water voles in Mediterranean patchy habitats may in part result from spatial segregation among individuals, which may reflect competitive displacement or small-scale habitat partitioning. Results highlight the need to account for species interactions when designing conservation management strategies for sympatric Cabrera and water voles in fragmented landscapes.

Dating the divergence between Southern and European water voles using molecular coalescent‐based methods

AbstractInvestigating the evolutionary history of the species is critical for understanding the evolution of biodiversity and for its conservation. Towards this goal, molecular approaches are becoming increasingly powerful with the incorporation of recent theoretical and analytical advances. Here, we apply an isolation‐with‐migration coalescent‐based model to control region and cytochrome b mitochondrial sequences to investigate the evolutionary history of European (Arvicola terrestris) and Southern (Arvicola sapidus) water voles throughout Eurasia. We date the time of the split of the common ancestor of European and Southern water voles around the fourth Mindel glacial (c. 252 000 bp), a date similar to that estimated by classical phylogenetic methods (c. 241 000 bp). Although postglacial expansions brought these species into secondary contact in Iberia and France, our results do not contain evidence of subsequent mitochondrial gene flow between descendant groups or current hybridization. We also estimate the effective population sizes of A. sapidus and Arvicola terrestris scherman on c. 199 000 and 52 000 individuals, respectively. This study illustrates the utility of modern coalescent‐based genetic tools to investigate recent species and population divergences and sheds some light on the evolution of the genus Arvicola in Eurasia.

Phylogeography of Southern Water Vole (Arvicola sapidus): evidence for refugia within the Iberian glacial refugium?

The role of Southern European peninsulas as glacial refugia for temperate species has been widely established, but phylogeographic patterns within refugia are being only recently addressed. Here we describe the phylogeographic patterns for Southern water vole (Arvicola sapidus) in its whole distribution across Iberia and France. Control region and cytochrome b sequences were obtained for 228 samples from 130 localities across Iberia and France. Eighty-five haplotypes were found in total yielding a high overall mitochondrial diversity (pi = 0.027; H = 0.974). Phylogeographic structure was relatively shallow (3.1% average intraspecific divergence) with few supported clades and 95% and 90% maximum parsimony unconnected networks, but significant, as reflected in increased pairwise nucleotide divergences with distance (r = 0.197, P = 0.03) and significant autocorrelation up to approximately 500 km. Spatial analysis of molecular variance analysis detected seven geographical groups explaining 43.73% of the total mitochondrial variation. We detected demographic expansions in three of these groups. A recent colonization of France from Iberia was suggested and estimated around 62 000 years bp by an isolation-with-migration model. Our results suggest the contribution of episodes of isolation in glacial subrefugia in Iberia, but seem to exclude a long-term isolation over successive glacial cycles. Phylogeographic divergence was probably tempered by relatively large population sizes and rapid and extensive mixing among subrefugia during interglacials, that might have eroded the phylogeographic structure accumulated at glacial peaks. Phenotypic differences in A. sapidus do not delineate historically isolated intraspecific divisions and do not warrant subspecific delimitations. Our results do support the existence of subrefugia within Iberia and their role in promoting intraspecific divergences.

Artificial neural networks enable discrimination of taxa using morphological characters: an example with a problematic small mammal, the water vole (genus Arvicola) (Rodentia, Cricetidae)

The aim of this study is to assess the reliability of different artificial neural networks as tools for identifying taxonomic or ecotypic subdivisions in European water voles (genus Arvicola). Self-organizing maps show that taxa at subspecies or species level are organized along morphological gradients correlated with ecotypes (from extreme forms of fossorial Arvicola terrestris to strictly aquatic Arvicola sapidus). An automatic discrimination process based on a multilayer feed-forward network, working with 17 French and one Spanish reference populations, proved able to correctly identify species in test samples from France, but sometimes misidentified specimens from other countries. Three morpho-ecotypes were identified using a self-organizing map with a single-species dataset (Arvicola terrestris only). However, there were no clues as to how these morpho-ecotypes might correlate with the known phylogenetics of the species. Our model can identify species on the basis of a limited range of cranial measurements which are available from vole skull fragments commonly found in owl pellets. This can have very practical risk-assessment applications as it allows easier identification of the more fossorial Arvicola terrestris populations which are a threat to crops.