A typical feature in members of the mustelid family is sexual size dimorphism, related to the different reproductive strategies of the sexes. As a consequence sexual divergence in many ecological and behavioural traits is expected, including temporal strategies. In line with this prediction, sex differences in the diel activity pattern of the European polecat Mustela putorius, a dimorphic mustelid, were quantified and tested. Twenty-eight polecats were captured in a rural area of central Italy (Abruzzo region) and 10 males and six females were monitored in the field using radio-telemetry techniques for 81–621 days each. Males and females showed a pronounced dimorphism in size (males/females mass ratio=1.6) within the known range for the species. Multivariate analysis of diel time preference shows that temporal behaviour differed significantly and markedly between the sexes. Males exhibited a regular and constant nocturnal pattern in every season, preferring the time ranging from 20:00 to 06:00; activity was lower at dawn and dusk, and scarce during daylight hours. Females were significantly diurnal and crepuscular but individuals revealed flexibility in activity pattern, including polyphasic or arrhythmic patterns without apparent temporal organization. The constraints of small body size and reproduction on female activity, and the sex segregation in activity timing are discussed in the context of intrasexual territoriality.

Dead specimens provide valuable data for the conservation of threatened species, allowing investigations of mortality, health conditions, and demographic parameters. The Eurasian otter (Lutra lutra) is a semiaquatic carnivore listed as endangered in Italy. In 2009, we started the first post mortem (PM) study of otters in Italy, through collaborative research between mammal ecologists and veterinary pathologists, using standardized protocols. Twenty-eight otters, mostly collected between 2009 and 2017, were examined. Most otters were males (67%), between 1 and 3 years old (64%), and predominantly in good nutritional condition. Adult males were significantly larger than adult females (p < 0.02), as expected for the species, although both sexes appeared to be smaller than otters examined in Central–northern Europe. The youngest sexually mature female was 3 years old. Road traffic collisions were the major cause of death, especially in young individuals, and mainly occurred in autumn–winter, particularly for females. Investigations of the scene of death contributed to revealing factors forcing otters to travel out of the water and move over the road, suggesting appropriate measures to reduce vehicle collision risk. Other causes of death included blunt chest trauma of uncertain origin, dog and conspecific attacks, or diseases of infectious or non-infectious origin, such as ulcerative gastritis, pleuropneumonia and peritonitis. Other diagnosed diseases included lymphoma. Ecto- and endoparasites were rarely detected, although we report the first documentation of heartworm and Ixodes hexagonus infestation in Italian otters. It is important to continue comprehensive, standardized PM investigations of otters in Italy to define baseline health, biometric and demographic parameters, collect biological samples for comparative analyses, and to reduce road-kill mortality. The present study suggests that the timely collection of carcasses and collaborative and coordinated research efforts are essential for obtaining useful data for the conservation of otters.