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- Sett Use, Density and Breeding Phenology of Badgers in Mediterranean Agro-Sylvo-Pastoral SystemsPublication . Silva, Marcelo; Rosalino, L. M.; Alcobia, Sandra; Santos-Reis, MargaridaCarnivores social organization varies widely, from strongly social to solitary predators. European badgers are facultative social carnivores that also shows a geographical variation in social structure. These patterns derive mainly from central/west European regions, with an underrepresentation of Mediterranean populations that face different conservation challenges, especially regarding group composition, sett use patterns and breeding phenology. We addressed these traits topics for a population inhabiting a Portuguese agro-silvo-pastoral system. Based on monthly monitoring of 34 setts and continuous camera-trapping surveys of 12, we showed that setts surrounded by diversified vegetation and located in sandy sites are more used, a pattern probably linked to food availability and ease of sett excavation and maintenance, respectively. Badgers followed a general pattern regarding group size (2–4 adults), but showed an intermediate population density (0.49–0.73 badgers/km2), with values higher than those estimated for other Mediterranean environments, but lower than for central-western populations. This, together with the breeding (November/January) and cub emergence (1.8 cubs/sett; March/April) periods, indicates an ecological adaptation to the landscape context, where human-related resources and mild environmental conditions allow badger to reach higher densities than in many southern populations, and to reproduce earlier than their northern counterparts.
- Comparing the performance of two camera trap-based methods to survey small mustelidsPublication . Barros, Ana Luisa; Marques, Margarida; Alcobia, Sandra; MacKenzie, Darryl I.; Santos-Reis, MargaridaSmall mustelids are an understudied group partly due to the challenges in detecting and monitoring their populations. Despite the classification as Least Concern for several small mustelid species, some studies indicate a population decline in parts of their range. Therefore, efficient and group-specific methods are essential to support monitoring efforts. Camera traps are widely used, particularly to monitor cryptic and nocturnal species such as most carnivores. However, they tend to miss small-sized and fast-moving species due to the sensitivity of the passive infrared sensor. The Mostela is a device which consists of a camera trap and a tracking tunnel inside a wooden box, designed specifically to detect small mustelids. Here, we propose testing the performance of this device and comparing it to a tree-mounted camera trap, using the least weasel (M. nivalis) as a case study. We used multi-scale occupancy models to estimate differences in the detection probability between devices. Although both methods detected the least weasel, the detection probability was higher with the Mostela (0.8, BCI: 0.52–0.97 vs 0.2, BCI: 0.03–0.48). Furthermore, we obtained a higher trapping rate when using a shorter distance between sampling stations (∼350 m). Although the Mostela performed better at detecting the weasel, the number of independent events was low (N = 11). Therefore, we present recommendations in terms of deployment and future research since the development and testing of new methods are essential for the conservation efforts of small mustelids.
- Do Mesocarnivores Respond to the Seasonality in Management Practices in an Agroforestry Landscape?Publication . Barros, Ana Luisa; Raposo, Diogo; Almeida, João David; Alcobia, Sandra; Oliveira, Maria Alexandra; MacKenzie, Darryl I.; Santos-Reis, MargaridaIn the Mediterranean, we find a mosaic of natural and cultural landscapes, where a variety of forest management practices created intermediate disturbance regimes that potentially increased biodiversity values. Nonetheless, it is essential to understand the species’ long-term response to the dynamic management in agroecosystems, since the species tolerance to disturbance can change throughout the life cycle. Mammalian carnivores can be sensitive to human disturbance and are an essential part of ecosystems due to their regulatory and community structuring effects. We investigated the spatial response of five mesocarnivores species to spatially- and temporally- varying management practices in an agroforestry landscape. More specifically, we assessed the mesocarnivores’ temporal changes in space use by implementing multi-season occupancy models in a Bayesian framework, using seasonal camera-trapping surveys for a 2-year period. All species had a weak response of local extinction to forestry management and livestock grazing pressure. For forest-dwelling species, occupancy was higher where productivity of perennial vegetation was high, while colonization between seasons was positively associated with vegetation cover. For habitat generalist species, we found that occupancy in the wet season increased with the distance to cattle exclusion plots. Most of these plots are pine stands which are subject to forestry interventions during winter. During the 2-year period we found seasonal fluctuations in occupancy for all species, with an overall slight decrease for three mesocarnivore species, while for the two forest-dwelling species there was an increase in occupancy between years. The weak species response to management practices supports the importance of traditional management for upholding a diverse mesocarnivore community in agroforestry systems but could also reflect these species’ ecological plasticity and resilience to disturbance.
- Assessment of technological developments for camera‐traps: a wireless transmission system and solar panelsPublication . Barros, Ana Luisa; Alcobia, Sandra; Gonçalves, Paula Isabel; MacKenzie, Darryl I.; Santos-Reis, MargaridaCamera-trapping is considered a cost-efficient method to monitor wildlife, but relevant performance constraints remain. We assessed performance and cost-benefit for 2 recent technological innovations: (i) a wireless transmission system where cameras communicate in a network, and (ii) using solar panels as a camera's sole power supply. The maximum distance between cameras that ensured wireless connection varied between 2 km in open habitats and 335 m in forest habitats with dense tree cover. The cost of using the wireless transmission system was lower for surveys run for >45 days and for >15 sampling units (i.e., camera-trap sites). For surveys longer than 15 days, using the wireless transmission system required, on average, 8 fewer days of fieldwork. We measured the performance of the solar panels in terms of capture probability, and the solar-powered cameras (β = −0.015 ± 0.01 in the log scale) outperformed battery-powered cameras (β = −0.103 ± 0.005) as capture rate decreased more slowly, particularly for nighttime events (difference in capture probability of the solar-powered relative to the battery-powered cameras at night, β = 0.09 ± 0.01). We consider that, although camera-traps with wireless transmission can provide a return on investment for a wide range of survey designs, the constraints on maximum distance for transmission are a limitation. Despite the higher cost, we recommend solar-powered camera-traps as they had improved performance with a higher proportion of species events captured than by battery-powered cameras.