1,721,021 research outputs found
Ecological sexual segregation in fallow deer (Dama dama): a multi-spatial and multi-temporal approach
No full textWe questioned the different interpretations of ecological sexual segregation from a novel perspective, i.e., by carrying out diverse temporal and spatial scale analyses within a long-term study (1984-2003). Thus we combined spatial (small/large) and temporal (small/large) scale analyses to identify the factors generating sexual segregation in fallow deer in San Rossore, Italy. The study site was divided into an eastern sector characterized by human disturbance (DS) and a western undisturbed sector (US). According to census data, human presence increased in DS from 1984, and while females gradually abandoned it, males remained-thus supporting the predation risk hypothesis (large spatial and temporal scale)-and actually increased their presence in DS, where they seemingly benefited from a lower female density. This supported the indirect competition hypothesis. The analysis of data on a large temporal and small spatial scale confirmed that intersexual competition, in particular for grass, was higher in a crowded pasture in US. Observations by means of radio-telemetry of 23 adult females and 25 adult males (1997-2001, reduced temporal and large spatial scale) showed that large scale segregation was relevant during the day and disappeared at night, when disturbance was absent and also the females reached DS. This also supported the predation risk hypothesis. Moreover, sexes showed different habitat choices inside DS at night, thus supporting the forage selection hypothesis (small spatial and temporal scale). In conclusion, failure to address the whole set of combinations of spatial and temporal scale analyses would have led to monocausal explanations of ecological sexual segregation
Do antlers honestly advertise the phenotypic quality of fallow buck (Dama dama) in a lekking population?
No full textSize and symmetry of secondary sexual traits are supposed to be honest signals of male phenotypic quality in vertebrates. Antler size and symmetry, male quality and mating success have not been fully demonstrated to be correlated in cervids. Such correlations can be particularly intriguing in the case of species adopting costly mating strategies, which imply territorial defence without feeding. In these cases, body condition appears to be crucial at the onset of the rut, and large and symmetrical antlers may be borne by successful males. For these reasons, during four consecutive years, we analysed growth rate, size and symmetry of 26 fallow bucks' antlers in relation to individual mating strategy and success in a lekking population. Territorial (T) males, which gained higher mating success in the lek, showed a faster antler growth (about 10 g/d per antler) than non-territorial (NT) males (3.6-5.2 g/d per antler) during the velvet period, and this was likely because of optimized foraging strategies. At the onset of the rut, when antler growth was completed, T males had larger antlers than NT males. Possibly because of worsened body conditions, NT males showed a pronounced antler directional asymmetry, while T males did not. However, no direct link between antler symmetry and mating success was found, thus confirming the ambiguous role of antler asymmetry as an indicator of fitness. The faster the antler growth, the larger its final size and the higher its beholder's mating success. Our results confirmed that, like groaning and scent marking, antler size reflects social status and dominance in male fallow deer, and therefore represents an honest advertisement of phenotypic quality
Reproductive timing in a lekking mammal: male fallow deer getting ready for female estrus
No full textA lek is an aggregated male display that females attend for the purpose of fertilization. A male needs to climb the relative hierarchy to be available for mating when the peak of female estrus occurs. We analyzed the link between timing of lek use by males in relation to age, phenotype, territoriality, and mating success. For more than a decade, we collected radio-tracking data and behavioral observations of a lekking mammal, the fallow deer (Dama dama). Competitively stronger males (i.e., older and heavier males with larger antlers) moved to the lek before less competitive ones. However, an early arrival did not guarantee the territory defense for a longer period nor higher mating success. The early arrival seemed to be a necessary but not sufficient condition to be a successful male in a lek. In fact, the ability to defend a territory for longer was related to age, body mass, antler length but not arrival time. We accordingly argue that males move to the lek early because they need to engage in male–male interactions and scent-marking activities. Successful males left the lek later than unsuccessful ones. The latter did not attempt to compensate for their low mating success by remaining in the lek, likely adopting alternative strategies outside of it. Adult males seeking for a chance to defend the territory and mate have to move to the lek early and stay there until the end of the rut, though this does not guarantee them a higher mating success
The use of sub-optimal meadows by Alpine chamois (Rupicapra rupicapra) due to the presence of domestic and/or non-native wild ungulates.
No full textEffects of livestock and non-native mouflon on use of high-elevation pastures by Alpine chamois.
No full text"Interspecific interference among livestock, native and non-native large herbivores is a key management and conservation issue, and little is known about its dynamics and implications. We investigated whether native Alpine chamois (Rupicapra r. rupicapra) modify their spatial distribution when non-native mouflon Ovis orientalis musimon and livestock (domestic sheep Ovis aries, and domestic goats Capra hircus) inhabit the same areas in the Alpine meadows of Italian Eastern Alps. We walked 5 hiking trails (5.0 +\/- 0.1 km) at dawn, twice a month during summers 2007 and 2008. During these surveys, we located each group of free-ranging ungulates (chamois, mouflon, and livestock). We also estimated the quality of meadows, finding that forage availability increased linearly as the distance from rocks (i.e., chamois refuges) increased. We predicted that the linear distance between chamois groups and rocks would depend on the co-presence of livestock and mouflon groups. Our results showed that chamois were more likely to be observed in areas with low food availability, but safer (i.e., closer to the rocks), whenever the nearest livestock group was larger and closer, especially if the shepherd's dog was present. Avoidance of the best feeding patches by the wild species is presumably due to spatial interference (e.g. visual and acoustic disturbance) and\/or predation risk perception caused by the presence of shepherd's dogs. Similarly, the larger was the nearest group of mouflon, the closer to rocks was located the chamois group. Interestingly, mouflon group vicinity induced chamois to move closer to rocks only if mouflon rams were within the group. This suggests that physical displacement of the smaller species (i.e. chamois) is likely to occur to avoid direct disturbance of larger mouflon rams. Our study clearly showed how a native herbivorous species adjusts its spatial distribution and decreases the likelihood of using areas with higher food availability when livestock and\/or a non-native species co-occur.
Evaluation of an expandable breakaway radiocollar for subadult cervids
No full textWe designed and field tested an expandable, easy-to-build radiocollar for subadult male fallow deer (Dama dama). This collar is inexpensive (it only costs few euros), and breaks away due to the natural growth of the neck without causing injury. Elastic rubber bands (expandable section) are covered by a leather layer that protects it from pre-mature breakaway. We evaluated the effectiveness of 37 expandable collars deployed on pricket (1-2 y.o.) fallow deer, by using the Kaplan-Meier survival analysis. Average duration of collars from their deployment to their natural drop off was almost 2 years (mean +/- SE, 91.7 +/- 6.4 weeks). This enabled us to monitor subadult fallow deer during maturation and to collect data on their spatial behaviour for the first time. Very little is known on the behavioural ecology and life history of subadult cervids. Accordingly, breakaway radiocollars are important research tools whose use should increase among field biologists
The analysis of sexual segregation in fallow deer (Dama dama) on different time and space scales
No full textLong-term influence of human presence on spatial sexual segregation in fallow deer (Dama dama).
No full textThe present work investigates how a fallow deer (Dama dama) population in central Italy might have been affected from 1984 to 2003 by the increase of human access to the study site, where humans were the main deer predators. By using deer census data, possible correlations were analyzed between the increase in human presence and the response of. each age and sex class. The numbers of different age and sex classes of deer recorded inside and outside the sector affected by human presence throughout the 20-year period of study were compared. A differential response was recorded among classes. Adult females and juveniles left this area (reducing their presence from 37% of all deer observed to 11% for adult females and from 19% to 3% for juveniles) when human pressure became higher, whereas the opposite result was true for males older than 24 months (adult males) that remained inside the disturbed sector (from 27% to 50% of deer observed). Intermediate values were recorded for yearling males, because they can be associated with both groups of females and groups of males. Results Of this long-term study are best explained with the reproductive strategy hypothesis, because the increase of predation risk evoked a marked spatial Sexual segregation in the fallow deer population. Females and juveniles used relatively predator-safe habitats, whereas males used habitats with higher predation risk but better food quality. Furthermore, as females increased their presence outside the disturbed sector, males gradually abandoned the undisturbed area, increased use of the disturbed sector, and maximized foraging opportunities by going to areas where indirect competition with females was probably reduced
Fallow deer lekking and alternative mating strategies in San Rossore, Italy: Insights from a long term study
No full textTrade-offs between predation risk and food quality re-distribute elk across a road network: not all roads are equal
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