Browsing by Author "Penteriani, Vincenzo"
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- Evaluating the influence of diet-related variables on breeding performance and home range behaviour of a top predatorPublication . Lourenço, Rui; Delgado, Maria del Mar; Campioni, Letizia; Korpimäki, Erkki; Penteriani, VincenzoDiet composition is linked to reproductive performance directly or indirectly by other life-history traits, including home range behaviour. The relationships between prey abundance, diet and individual fitness have often been explored. However, these relationships are complex and difficult to disentangle, especially in vertebrate top predators. Here, we present the results of a longterm study using multi-model inference procedures to elucidate the influence of diet-related variables on breeding parameters and home range behaviour of a top predator, the eagle owl Bubo bubo. Superpredation, diet diversity, rat biomass and rabbit mean weight were the most important variables when analysing reproductive parameters, suggesting that less diverse diets with greater rabbit biomass percentage may benefit reproductive performance, whereas rat biomass percentage is apparently associated with greater variation of breeding success. Earlier laying dates seem to be associated with the consumption, on average, of smaller rabbits. On the other hand, edge density was the most relevant factor determining the variation in home range behaviour, with individual characteristics, such as age and sex, also being important. Although the relative importance of the diet-related variables was generally low, mean weight of alternative prey, diet diversity and rabbit biomass also helped to explain home range parameters. In an optimal foraging context, centred on the abundance of the main prey species, our results suggest that when rabbits are less available eagle owls may increase home range size in order to obtain alternative prey, increasing at the same time their dietary diversity, which may also require higher movement speed.
- Evaluating the influence of diet-related variables on breeding performance and home range behaviour of a top predatorPublication . Lourenço, Rui; Delgado, Maria del Mar; Campioni, Letizia; Korpimäki, Erkki; Penteriani, VincenzoDiet composition is linked to reproductive performance directly or indirectly by other life-history traits, including home range behaviour. The relationships between prey abundance, diet and individual fitness have often been explored. However, these relationships are complex and difficult to disentangle, especially in vertebrate top predators. Here, we present the results of a longterm study using multi-model inference procedures to elucidate the influence of diet-related variables on breeding parameters and home range behaviour of a top predator, the eagle owl Bubo bubo. Superpredation, diet diversity, rat biomass and rabbit mean weight were the most important variables when analysing reproductive parameters, suggesting that less diverse diets with greater rabbit biomass percentage may benefit reproductive performance, whereas rat biomass percentage is apparently associated with greater variation of breeding success. Earlier laying dates seem to be associated with the consumption, on average, of smaller rabbits. On the other hand, edge density was the most relevant factor determining the variation in home range behaviour, with individual characteristics, such as age and sex, also being important. Although the relative importance of the diet-related variables was generally low, mean weight of alternative prey, diet diversity and rabbit biomass also helped to explain home range parameters. In an optimal foraging context, centred on the abundance of the main prey species, our results suggest that when rabbits are less available eagle owls may increase home range size in order to obtain alternative prey, increasing at the same time their dietary diversity, which may also require higher movement speed.
- Owl dusk chorus is related to the quality of individuals and nest-sitesPublication . Penteriani, Vincenzo; Delgado, Maria del Mar; Stigliano, Renato; Campioni, Letizia; Sanchez, MariaDawn and dusk choruses represent one of the most investigated topics in avian vocal behaviour, but their underlying basis remains unclear. As with the dawn chorus in passerines, dusk chorus in owls seems to support the mate and rival assessment hypothesis and happens during the most constraining period, as individuals have not yet fed and, under the handicap principle, dusk chorus is likely to reveal inter-individual differences in competitive ability, body condition and/or habitat quality. Here, a study of vocal displays at dusk of 14 Eurasian Eagle Owls Bubo bubo revealed a temporal succession in the order in which males began their vocalizations. The vocalization order appeared to be related to both the quality of the nesting territory (based upon mean number of fledged young and proportion of rats in the diet) and the male’s individual quality, as revealed by haematocrit values and the brightness of the white throat patch.
- Pattern of repeatability in the movement behaviour of a long-lived territorial species, the eagle owlPublication . Campioni, Letizia; Delgado, Maria del Mar; Penteriani, VincenzoObserved movement patterns are the response of the interaction between environmental variables and the animal internal state. Therefore, even individuals of the same species experiencing similar environmental conditions can exhibit different behavioural responses, as these responses can be highly repeatable within individuals. Here, we investigated the nocturnal movement behaviour of a territorial species, by radiotracking 26 eagle owls Bubo bubo in order to analyze within and between individual variation with respect to movement parameters and route choice. Owls showed a considerable individual consistency in all movement parameters and made repeated use of similar routes while moving within fixed home ranges. Thus, movement parameters varied much less between repeated nightly trajectories than between different individuals. Furthermore, when we compared different individuals inhabiting the same territory in different years, within-group repeatability was low or non-significant suggesting that the spatial configuration of habitat does not always represents one of the main drivers in animal movement behaviour. Similarly, male individuals appeared to exhibit greater repeatability than females. The overall pattern of repeatability we found seems to identify such consistent movement behaviour not only as the expression of individual response to external/internal inputs but also as an additional trait to include in the broad definition of animal personality.
- Quantifying space use of breeders and floaters of a long-lived species using individual movement dataPublication . Penteriani, Vincenzo; Delgado, Maria del Mar; Campioni, LetiziaTo date, animal movement studies have mostly analysed the movement behaviours of individuals at specific times of their lives, but we lack detailed information on how individual movements may be affected by the various and different changes that individuals experience throughout their life (e.g. life history phases, experience, age). Here, we attempt to identify differences in home range and movement behaviour between two different statuses, disperser vs. breeder, of a long-lived species (the eagle owl Bubo bubo). Information on home range and movement behaviour between different stages of an individual life are crucial for species conservation and management, as well as for basic knowledge on space use and rhythm of activity. Does the transition from an exploratory stage to moving within more familiar surroundings call for changes in the movement behaviour? We observed notable differences during the two stages of the owls’ lives, with individuals having different home range behaviours and rhythms of activity depending on their social status. Significant differences in home range behaviour between the sexes began only with the acquisition of a breeding site. Breeders showed larger home ranges than dispersing individuals, although nightly variation of home ranges size was higher for dispersers than for breeders. Finally, dispersers were active throughout the night, whereas breeders displayed a less active movement phase at both the beginning and end of the night. Our results demonstrate it is important to consider individual variations in space use and movement behaviour due to the different life history phases that they attain during their lifetime. The knowledge of the different needs of a species across life stages may represent an important tool for species conservation because each phase of an individual life may need different requirements.