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Increased predation risk or avoidance of wildlife underpasses by small mammals have been highlighted. To overcome this problem and to provide these species with an opportunity to safely cross road-crossing structures, we previously designed an Anti-Predation Tube (APT). The features (shape and size) of this device have been tested under laboratory conditions and its use by captive European hamsters (Cricetus cricetus) has been validated. In this study, we investigate both the enrichment and anti-predation functions of the APT for hamsters in an actual underpass. To do so, we built two small enclosures of 6 m2 at both extremities of an underpass and cross-manipulated the presence of the APT and a predator of hamsters, the European ferret. Our results show that the APT does not act as an enrichment, as it did not increase the crossing frequency of hamsters in the absence of the predator. However, it acts as an anti-predation device, since, in the presence of the ferret, male hamsters crossed more than 10 times as much when the APT was present inside the underpass than when it was not. We therefore recommend implementing the APT as a conservation measure to upgrade wildlife underpasses while conducting surveys to investigate how the presence of the APT influences the crossing of other small mammals and wildlife.

The period of emancipation in seabirds, when juveniles change from a terrestrial existence to a life at sea, is associated with many challenges. Apart from finding favourable foraging sites, they have to develop effective prey search patterns and physiological capacities that enable them to capture sufficient prey to meet their energetic needs. Animals that dive to forage, such as king penguins (Aptenodytes patagonicus), need to acquire an adequate breath-hold capacity, allowing them to locate and capture prey at depth. To investigate the ontogeny of their dive capacity and foraging performance, we implanted juvenile king penguins before their first departure to sea and also adult breeders with a data-logger recording pressure and temperature. We found that juvenile king penguins possess a remarkable dive capacity when leaving their natal colony, enabling them to conduct dives in excess of 100 m within their first week at sea. Despite this, juvenile dive/foraging performance, investigated in relation to dive depth, remained below the adult level throughout their first year at sea, probably reflecting physiological limitations as a result of incomplete maturation. A significantly shallower foraging depth of juveniles, particularly during their first 5 months at sea, could also indicate differences in foraging strategy and targeted prey. The initially greater wiggle rate suggests that juveniles fed opportunistically and also targeted different prey from adults and/or that many of the wiggles of juveniles reflect unsuccessful prey-capture attempts, indicating a lower foraging proficiency. After 5 months, this difference disappeared, suggesting sufficient physical maturation and improvement of juvenile foraging skills.

International audience; Agriculture intensification, marked by the generalization of crop monoculture, by the increase in plot size and by the reduction of plant diversity, has led to huge decline in wildlife in European farmlands. In such habitat, research has long been biased towards birds and invertebrates, while very few studies have investigated the effect on small mammals. Considering the European hamster, Cricetus cricetus, we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals. We suggest that only a multidisciplinary approach will allow exploration of these effects, combining experimental laboratory work on captive-bred animals with the monitoring of wild individuals. In particular, individual energy balance has to be investigated and measured as accurately as possible, through either biochemical or bio-logging techniques. It is, indeed, the most affected physiological trait in a changing environment, as it determines both the reproductive output and the survival of the individual. We also discuss the inconvenience of capture-release approaches for such an endangered species and emphasize the disturbance that experimental protocols could impose on the hamster.