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The function of male territoriality in roe deer has been debated for decades. There now seems to be consensus that it is a mating tactic. As such, it is highly untypical though. The reasons being, first, males neither conform to the typical ‘resource defence’ territoriality model nor to the ‘mate defence’ territoriality model; second, territory defence commences several months in advance of the breeding season; and third, the territorial system seems to be very rigid, as practically all studies that have described the social organisation of the species have reported adult males to be territorial. In spite of the general agreement that territoriality is a mating tactic, conclusive evidence on which selective forces are responsible for the prevalent pattern is still lacking. In the present paper, it is suggested that territorial defence serves as a sexual ornament, i.e. ‘cleanness’ of other males on the territory, in combination with size of the ‘clean’ area, and tenure length are parameters used by females to estimate male phenotypic quality. The hypothesis generates at least four predictions, and available data provide support. It is concluded that although a firm test of the hypothesis remains to be undertaken, existing data support this, just as well as any other, explanatory model and therefore it should be taken into consideration.
Patrolling behavior plays an important role in resource defense and in shaping social interactions in territorial species. However, it is not clear whether and how resource deterioration affects patrolling and interactions between territorial males. We addressed this issue by studying the territorial patrolling of damselfly Calopteryx splendens males, which use riverine vegetation patches composed of floating rafts of Potamogeton natans as territories. Males can hold single territories established on one vegetation patch (solitary residents) or hold adjacent territories established on shared vegetation patch (contiguous residents). The study predicted that solitary males engage more in patrolling than contiguous residents and that patrolling intensity is proportional to patch quality. Two types of semi-natural vegetation patches were sunk: of high and low quality measured on the basis of the patch size (range 2–5 m2) and its attractiveness to damselflies (measured as number of residents, non-territorial males and contests observed at a given patch). Changes in number of patrolling flights were monitored for solitary and two contiguous residents: first which hold territory situated closer to the patch centre and secondary holding territory nearer to the edge of a patch. Results indicated that solitary residents patrolled more often than either of the two contiguous residents. Habitat deterioration significantly reduced the patrolling intensity of both single and first contiguous resident, however, their patrolling activity was not resumed at the same intensity after the original patch had been restored. The secondary resident of a contiguous pair did not respond to habitat deterioration, but increased its patrolling activity following restoration. Patch quality was found to have no impact on patrolling, which implies that social context can be more important in predicting changes in patrolling behavior in response to resource deterioration.
Several vole species use scent marked runways radiating from their burrows for foraging and dispersion. These marks are probably used for social communication. This 4-day laboratory study investigated the environmental and social causations of marking inside pre-existing corridors in male and female common volesMicrotus arvalis (Pallas, 1778). Firstly I tested the novelty and the reinforcement hypotheses in isolated voles, predicting respectively a habituation or a continuous increase in mark deposition. I then confronted with each other two same-sex voles for two days to investigate the differences between males and females in the pattern of marks inside three corridors, one of which runs along the common partition with the neighbour. I tested the self-advertisement and territorial-defence hypotheses, respectively predicting in the presence of a neighbour either a similar marking between the three corridors or a greater marking in the corridor close to the neighbour than in the two other corridors. The results showed no habituation in marking, even in a familiar environment, confirming the reinforcement hypothesis. After the addition of a neighbour, only the females left more marks in the corridor that ran alongside the common border than in the two other corridors. The territorial-defence hypothesis was thus confirmed in (territorial) females while the self-advertisement was supported in (non-territorial) males. Finally, I tested the competitive-ability hypothesis in females, stating that the abundance of scent marks of an individual before a social interaction can predict its degree of intolerance in a future social interaction. The results from female pairs physically interacting for four days support the hypothesis.
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