Jacinto Román

Local and landscape habitat determinants of water vole distribution in a patchy Mediterranean environment

Abstract We studied the distribution of a water-dependent species (southern water vole, Arvicola sapidus) in a Mediterranean region (Doñana National Park, southwest Spain) characterized by a complex array of different-sized ponds (where voles were confined) embedded in a mostly unsuitable landscape. For each surveyed pond (n = 185), a total of 26 variables related to both local (20) and landscape (6) attributes were quantified, and the presence of voles was evaluated by finding their typical signs (latrines). We found signs of water voles in 60% of ponds, despite the fact that most of them (84%) were totally dried out. A generalized linear model analysis showed that water voles were sensitive to both local and landscape attributes of ponds. At a landscape scale, presence of voles was more likely in ponds located outside the national park, close to other ponds holding voles, and far away from areas rich in potential predators and competitors. At a local scale, ponds with water voles were characterized by abundant grasses, banks well covered by brushes, low altitude, and low abundance of rabbits (Oryctolagus cuniculus). We also studied the use of microhabitat by voles within four specific ponds and found that they preferred plots of higher vegetation cover; thus, there was consistency in some cues used by water voles at the population/subpopulation scale (among different ponds) and at the behavioral scale (within ponds). Our study strongly supports the notion that the entire vole population is structured in distinct subpopulations, which are affected by a hierarchy of processes ranging from metapopulation dynamics and influenced by the landscape within which ponds are embedded as well as the local habitat quality.

Road avoidance responses determine the impact of heterogeneous road networks at a regional scale

Summary Barrier effect is a road-related impact affecting several animal populations. It can be caused by behavioural responses towards roads (surface and/or gap avoidance), associated emissions (traffic-emissions avoidance) and/or circulating vehicles (vehicle avoidance). Most studies so far have described road-effect zones along major roads, without determining the actual factor inducing the behavioural response. The purpose of the present study was to assess the factors potentially causing road-effect zones in a heterogeneous road network (with variations in road width, road surface and traffic volume) and eventually to estimate the reduction of habitat quality imposed by roads within a protected area (Donana Biosphere Reserve, Spain). As model species, we used two ungulates, red deer Cervus elaphus and wild boar Sus scrofa. We surveyed the presence of both species along 200-m transects. All transects started and were perpendicular to reference roads (those with a traffic volume above 10 cars per day), often intersecting unpaved minor roads with virtually no traffic. The presence probability of both species was mainly affected by the distance to the nearest road (in most cases unpaved roads without traffic), but also by the proximity to reference roads. Red deer presence was also affected by the traffic volume of the nearest reference road. At a regional scale, the overall road network within the protected area imposes a reduction in presence probability of 40% for red deer and 55% for wild boar. A road network optimization, decommissioning unused and unpaved roads, would re-establish almost entirely the potential habitat quality (91% for both species). Synthesis and applications. We found that both study species avoided roads regardless of their surface or traffic volume, suggesting a response due to gap avoidance which may be based on the association between linear infrastructures and the possibility of vehicles occurring along them. The overall behavioural response can substantially decrease habitat quality over large scales, including the conservation value of protected areas. For this reason, we recommend road network optimization by road decommissioning to mitigate the impact of roads at a regional scale, with potential positive effects at ecosystem level.

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.

Variability in primary productivity determines metapopulation dynamics.

Temporal variability in primary productivity can change habitat quality for consumer species by affecting the energy levels available as food resources. However, it remains unclear how habitat-quality fluctuations may determine the dynamics of spatially structured populations, where the effects of habitat size, quality and isolation have been customarily assessed assuming static habitats. We present the first empirical evaluation on the effects of stochastic fluctuations in primary productivity—a major outcome of ecosystem functions—on the metapopulation dynamics of a primary consumer. A unique 13-year dataset from an herbivore rodent was used to test the hypothesis that inter-annual variations in primary productivity determine spatiotemporal habitat occupancy patterns and colonization and extinction processes. Inter-annual variability in productivity and in the growing season phenology significantly influenced habitat colonization patterns and occupancy dynamics. These effects lead to changes in connectivity to other potentially occupied habitat patches, which then feed back into occupancy dynamics. According to the results, the dynamics of primary productivity accounted for more than 50% of the variation in occupancy probability, depending on patch size and landscape configuration. Evidence connecting primary productivity dynamics and spatiotemporal population processes has broad implications for metapopulation persistence in fluctuating and changing environments.

Heterogeneous road networks have no apparent effect on the genetic structure of small mammal populations

Roads are widely recognized to represent a barrier to individual movements and, conversely, verges can act as potential corridors for the dispersal of many small mammals. Both barrier and corridor effects should generate a clear spatial pattern in genetic structure. Nevertheless, the effect of roads on the genetic structure of small mammal populations still remains unclear. In this study, we examine the barrier effect that different road types (4-lane highway, 2-lane roads and single-lane unpaved roads) may have on the population genetic structure of three species differing in relevant life history traits: southern water vole Arvicola sapidus, the Mediterranean pine vole Microtus duodecimcostatus and the Algerian mouse Mus spretus. We also examine the corridor effect of highway verges on the Mediterranean pine vole and the Algerian mouse. We analysed the population structure through pairwise estimates of FST among subpopulations bisected by roads, identified genetic clusters through Bayesian assignment approaches, and used simple and partial Mantel tests to evaluate the relative barrier or corridor effect of roads. No strong evidences were found for an effect of roads on population structure of these three species. The barrier effect of roads seems to be site-specific and no corridor effect of verges was found for the pine vole and Algerian mouse populations. The lack of consistent results among species and for each road type lead us to believe that the ability of individual dispersers to use those crossing structures or the habitat quality in the highway verges may have a relatively higher influence on gene flow among populations than the presence of crossing structures per se. Further research should include microhabitat analysis and the estimates of species abundance to understand the mechanisms that underlie the genetic structure observed at some sites.

The Near Threatened Eurasian otter Lutra lutra in Morocco: no sign of recovery

Abstract Although the Near Threatened Eurasian otterLutra lutra has been recovering in Europe since the 1980snothing is known about population trends of the species innorthernAfrica.Ninetysiteswassearchedforsignsofottersin northern and western Morocco in 1983 and we repeatedthissurveyin2011.Ateachsitewesearchedforotterspraints(faeces) or clear footprints along a maximum of 600mofriver bank, ending the search when the first sign was found.Overall results were strikingly similar in 1983 and 2011, with36positivesitesandthesamegeneraldistributionpatternofthe species. Healthy otter populations appear to remain inthe foothills of the Middle and High Atlas but the trend ofpopulations disappearing from the relatively flat Atlanticslopehasincreased.Theresultsareinclearcontrastwiththerecovery of otter populations in Europe, probably becauseof differences in the implementation of environmentalpolicies, especially regarding water pollution. Keywords Eurasian otter, Lutra lutra, Morocco, PCB,pollution, recovery, survey

Management-Related Traffic as a Stressor Eliciting Parental Care in a Roadside-Nesting Bird: The European Bee-Eater Merops apiaster

Traffic is often acknowledged as a threat to biodiversity, but its effects have been mostly studied on roads subjected to high traffic intensity. The impact of lower traffic intensity such as those affecting protected areas is generally neglected, but conservation-oriented activities entailing motorized traffic could paradoxically transform suitable habitats into ecological traps. Here we questioned whether roadside-nesting bee-eaters Merops apiaster perceived low traffic intensity as a stressor eliciting risk-avoidance behaviors (alarm calls and flock flushes) and reducing parental care. Comparisons were established within Doñana National Park (Spain), between birds exposed to either negligible traffic (ca. 0–10 vehicles per day) or low traffic intensity (ca. 10–90 vehicles per day) associated to management and research activities. The frequencies of alarm calls and flock flushes were greater in areas of higher traffic intensity, which resulted in direct mortality at moderate vehicle speeds (≤ 40 km/h). Parental feeding rates paralleled changes in traffic intensity, but contrary to our predictions. Indeed, feeding rates were highest in traffic-exposed nests, during working days and traffic rush-hours. Traffic-avoidance responses were systematic and likely involved costs (energy expenditure and mortality), but vehicle transit positively influenced the reproductive performance of bee-eaters through an increase of nestling feeding rates. Because the expected outcome of traffic on individual performance can be opposed when responses are monitored during mating (i.e. negative effect by increase of alarm calls and flock flushes) or nestling-feeding period (i.e. at least short-term positive effect by increase of nestling feeding rates), caution should be taken before inferring fitness consequences only from isolated behaviors or specific life history stages.