Size is not everything: differing activity and foraging patterns between the sexes in a monomorphic mammal

Animals balance foraging with other activities, and activity patterns may differ between sexes due to differing physical requirements and reproductive investments. Sex-specific behavioural differences are common in sexually dimorphic mammals, but have received limited research attention in monomorphic mammals where the sexes are similar in body size. Eurasian beavers (Castor fiber) are obligate monogamous and monomorphic mammals and a good model species to study sex-specific differences. As females increase energy expenditure during reproduction, we hypothesized differing seasonal activity budgets, circadian activity rhythms and foraging patterns between male and reproducing female beavers. To test this hypothesis, we equipped adult beavers with VHF transmitters (N=41; 16 female, 25 male) and observed them throughout their active period at night from spring to late summer. Occurrence of their main activities (foraging, travelling and being in lodge) and use of food items (trees/shrubs, aquatic vegetation and herbs/grasses) were modelled to investigate sex-specific seasonal activity budgets and circadian activity rhythms. The sexes did not differ in time spent foraging across the season or night, but during spring, females resided more in the lodge and travelled less. Males and females both foraged on aquatic vegetation during spring, but females used this food source also during late summer, whereas males mostly foraged on trees/shrubs throughout the year. We conclude that seasonal activity budgets and foraging differ subtly between the sexes, which may relate to different energy budgets associated with reproduction and nutritional requirements. Such subtle seasonal behavioural adaptions may be vital for survival and reproduction of monomorphic species.publishedVersio

Endozoochorical plant seed dispersal by red deer (Cervus elaphus)in the Pol'ana Biosphere Reserve, Slovakia

From an evolutionary point of view, endozoochory can be considered as a¿mutualistic process, in which both the plant seed- dispersing animal species and the dispersed plant species benefit. Disperser benefits may be direct, by using the dispersed plant species as a¿food source, and indirect, by promoting the distribution of these food plants. Despite biomass loss involved, plant species may benefit from endozoochory, because it promotes long-distance dispersal and linked advantages. We tested this mutualism hypothesis in the Po¿ana Biosphere Reserve, central Slovakia, with red deer (Cervus elaphus) as disperser. We collected data on distances covered by red deer between seed ingestion and excretion sites, and the corresponding vegetation by VHF telemetry and GIS analysis. We assessed the viable seed content of red deer dung by a¿germination test. Information on forage palatability, habitat and seed longevity of the dispersed species were taken from literature. From a¿total of 400 g¿dry red deer feces, 1766 seedlings emerged, belonging to 43 species. Most of the observed dispersal distances exceeded 100 m, which is commonly considered as a¿minimum for long-distance dispersal. Red deer transported mostly seeds from a¿variety of vegetation types to forests. Our results support the hypothesis that endozoochory is a¿mutualistic process. We conclude that, since landscapes are changing due to global warming and land use changes, it is important for the maintenance of plant species diversity to promote migration and free ranging of large grazers like red deer, by means of infrastructural measure

Size is not everything : differing activity and foraging patterns between the sexes in a monomorphic mammal

Animals balance foraging with other activities, and activity patterns may differ between sexes due to differing physical requirements and reproductive investments. Sex-specific behavioural differences are common in sexually dimorphic mammals, but have received limited research attention in monomorphic mammals where the sexes are similar in body size. Eurasian beavers (Castor fiber) are obligate monogamous and monomorphic mammals and a good model species to study sex-specific differences. As females increase energy expenditure during reproduction, we hypothesized differing seasonal activity budgets, circadian activity rhythms and foraging patterns between male and reproducing female beavers. To test this hypothesis, we equipped adult beavers with VHF transmitters (N=41; 16 female, 25 male) and observed them throughout their active period at night from spring to late summer. Occurrence of their main activities (foraging, travelling and being in lodge) and use of food items (trees/shrubs, aquatic vegetation and herbs/grasses) were modelled to investigate sex-specific seasonal activity budgets and circadian activity rhythms. The sexes did not differ in time spent foraging across the season or night, but during spring, females resided more in the lodge and travelled less. Males and females both foraged on aquatic vegetation during spring, but females used this food source also during late summer, whereas males mostly foraged on trees/shrubs throughout the year. We conclude that seasonal activity budgets and foraging differ subtly between the sexes, which may relate to different energy budgets associated with reproduction and nutritional requirements. Such subtle seasonal behavioural adaptions may be vital for survival and reproduction of monomorphic species

Polar bears ( Ursus maritimus

Polar bears are seasonal breeders and typically mate from late March to early May. Implantation is, however, delayed until autumn, which can allow plasticity in the date of mating. As for other seasonal breeders, a rapid return to estrus after the loss of dependent offspring can be expected, even into the summer. A few earlier observations and dissections of dead animals suggest that polar bears are able to mate in summer. We report on a mating incident on 29 June 2014, the first documented mating this late in the season among wild polar bears. The female had lost her dependent cub during the period prior to the mating event. We speculate that she lost this cub late in the mating season, entered estrus and successfully mated in late June