Diel variation in movement patterns and habitat use by the near-threatened cabrera vole in mediterranean farmland

As variações circadianas no comportamento animal e o seu impacto nas populações constituem desafios importantes em ecologia e conservação. Nesta tese documentam-se as variações circadianas no uso do habitat e padrões de movimento pelo rato de Cabrera, em habitats Mediterrânicos fragmentados. O estudo baseou-se no radio-seguimento de indivíduos em habitats dominados por herbáceas e arbustos. Os resultados indicaram que a proporção de tempo despendido em deslocações, a distância percorrida, e a selecção do tipo de vegetação, estão fortemente interrelacionados, variando consideravelmente ao longo de diferentes períodos do dia. Os ratos movimentaram-se mais frequentemente e maiores distâncias nos períodos diurnos, durante os quais as áreas dominadas por herbáceas foram usadas mais intensivamente. Durante a estação seca houve alguma tendência para a diminuição dos movimentos durante as horas mais quentes. Estes resultados são discutidos no sentido de mostrar como indicadores comportamentais podem contribuir para melhorar a gestão e conservação da espécie; ABSTRACT: Understanding the circadian variations in species behaviour and its impacts on population is a challenging topic in ecology and conservation. This thesis documents the circadian variations in habitat use and movement patterns by Cabrera voles in fragmented Mediterranean farmland. The study was based on radiotracking data of individuals living in habitat patches dominated by wet grasses and shrubs. Results indicated that the proportion of time animals spent moving, the distance moved and the selection strength of vegetation were closely linked behavioural traits, which varied considerably across the 24 hour cycle. Voles moved more frequently and over larger distances during daytime, which was when wet grasses were used more intensively. During the dry season there was some tendency for a decrease in movement activity during the hottest hours of the day. These results are used to discuss how behavioural indicators may be useful to improve conservation management of the species.

Assessing the conservation status of Mediterranean temporary ponds using biodiversity: a new tool for practitioners

The assessment of the habitat condition is the first step of conservation actions and several tools are available to assess wetlands. However, only a few tools are adapted to the priority habitat Mediterranean temporary ponds. Thus, our objectives were (i) to identify biological indicators associated with the different conservation status of Mediterranean tem- porary ponds and (ii) to create an efficient evaluation tool for non-experts using indicators of conservation status. A total of 87 ponds were sampled in southwest Portugal to assess the presence of plants, large branchiopods, amphibians, threatened voles and bats. Ponds with favourable conservation status showed higher species richness of plants, large branchiopods and amphibians. We identified eighteen indicators for favourable ponds: 15 plants, one large branchiopod and two amphibian taxa. We propose a new tool to assess the conservation status of Mediterranean tem- porary ponds based on the presence of these indicators. This tool is an alternative to other common, but time- consuming, methods and can be readily used by trained practitioners. The replication and adaptation of this tool to other regions and habitats enables the collection of comparable data and the geographical scaling-up of the assessments.

Assessing the conservation status of Mediterranean temporary ponds using biodiversity: a new tool for practitioners

The assessment of the habitat condition is the first step of conservation actions and several tools are available to assess wetlands. However, only a few tools are adapted to the priority habitat Mediterranean temporary ponds. Thus, our objectives were (i) to identify biological indicators associated with the different conservation status of Mediterranean temporary ponds and (ii) to create an efficient evaluation tool for non-experts using indicators of conservation status. A total of 87 ponds were sampled in southwest Portugal to assess the presence of plants, large branchiopods, amphibians, threatened voles and bats. Ponds with favourable conservation status showed higher species richness of plants, large branchiopods and amphibians. We identified eighteen indicators for favourable ponds: 15 plants, one large branchiopod and two amphibian taxa. We propose a new tool to assess the conservation status of Mediterranean temporary ponds based on the presence of these indicators. This tool is an alternative to other common, but time consuming, methods and can be readily used by trained practitioners. The replication and adaptation of this tool to other regions and habitats enables the collection of comparable data and the geographical scaling-up of the assessments.

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.

Hierarchical spatial segregation of two Mediterranean vole species: the role of patch‑network structure and matrix composition

According to ecological theory, the coexistence of competitors in patchy environments may be facilitated by hierarchical spatial segregation along axes of environmental variation, but empirical evidence is limited. Cabrera and water voles show a metapopulation-like structure in Mediterranean farmland, where they are known to segregate along space, habitat, and time axes within habitat patches. Here, we assess whether segregation also occurs among and within landscapes, and how this is influenced by patch-network and matrix composition. We surveyed 75 landscapes, each covering 78 ha, where we mapped all habitat patches potentially suitable for Cabrera and water voles, and the area effectively occupied by each species (extent of occupancy). The relatively large water vole tended to be the sole occupant of landscapes with high habitat amount but relatively low patch density (i.e., with a few large patches), and with a predominantly agricultural matrix, whereas landscapes with high patch density (i.e.,many small patches) and low agricultural cover, tended to be occupied exclusively by the small Cabrera vole. The two species tended to co-occur in landscapes with intermediate patch-network and matrix characteristics, though their extents of occurrence were negatively correlated after controlling for environmental effects. In combination with our previous studies on the Cabrera-water vole system, these findings illustrated empirically the occurrence of hierarchical spatial segregation, ranging from withinpatches to among-landscapes. Overall, our study suggests that recognizing the hierarchical nature of spatial segregation patterns and their major environmental drivers should enhance our understanding of species coexistence in patchy environments.