Assessing landscape functional connectivity in a forest carnivore using path selection functions

Context Understanding connectivity patterns in relation to habitat fragmentation is essential to landscape management. However, connectivity is often judged from expert opinion or species occurrence patterns, with very few studies considering the actual movements of individuals. Path selection functions provide a promising tool to infer functional connectivity from animal movement data, but its practical application remains scanty. Objectives We aimed to describe functional connectivity patterns in a forest carnivore using path-level analysis, and to explore how connectivity is affected by land cover patterns and road networks. Methods We radiotracked 22 common genets in a mixed forest-agricultural landscape of southern Portugal. We developed path selection functions discriminating between observed and random paths in relation to landscape variables. These functions were used together with land cover information to map conductance surfaces. Results Genets moved preferentially within forest patches and close to riparian habitats. Functional connectivity declined with increasing road density, but increased with the proximity of culverts, viaducts and bridges. Functional connectivity was favoured by large forest patches, and by the presence of riparian areas providing corridors within open agricultural land. Roads reduced connectivity by dissecting forest patches, but had less effect on riparian corridors due to the presence of crossing structures. Conclusions Genet movements were jointly affected by the spatial distribution of suitable habitats, and the presence of a road network dissecting such habitats and creating obstacles in areas otherwise permeable to animal movement. Overall, the study showed the value of path-level analysis to assess functional connectivity patterns in human-modified landscapes.

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.

Landscape structure shapes carnivore-mediated seed dispersal kernels

Context Seed dispersal is recognized as having profound effects on the distribution, dynamics and structure of plant populations and communities. However, knowledge of how landscape structure shapes carnivore-mediated seed dispersal patterns is still scarce, thereby limiting our understanding of large-scale plant population processes. Objectives We aim to determine how the amount and spatial configuration of forest cover impacted the relative abundance of carnivorous mammals, and how these effects cascaded through the seed dispersal kernels they generated. Methods Camera traps activated by animal movement were used for carnivore sampling. Colour-coded seed mimics embedded in common figs were used to know the exact origin of the dispersed seed mimics later found in carnivore scats. We applied this procedure in two sites differing in landscape structure. Results We did not find between-site differences in the relative abundance of the principal carnivore species contributing to seed dispersal patterns, Martes foina. Mean dispersal distance and the probability of long dispersal events were higher in the site with spatially continuous and abundant forest cover, compared to the site with spatially aggregated and scarcer forest cover. Seed deposition closely matched the spatial patterning of forest cover in both study sites, suggesting behaviour-based mechanisms underpinning seed dispersal patterns generated by individual frugivore species. Conclusions Our results provide the first empirical evidence of the impact of landscape structure on carnivore-mediated seed dispersal kernels. They also indicate that seed dispersal kernels generated strongly depend on the effect that landscape structure exerts on carnivore populations, particularly on habitat-use preferences.