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Density and productivity of Common Buzzard and Goshawks populations were studied over a period of 11 breeding seasons in Central Poland. The mean densities of Buzzards and Goshawks were 1.73 and 1.63 pairs/10 km² of the whole area (105km²), respectively. Both studied species showed little variation of density during the study period. Breeding pairs constituted over 90% of all pairs recorded in the study area. Productivity of the Common Buzzard was greater than that of the Goshawk. Mean number of fledglings per statistical, breeding and successful pair were 1.67,1.78 and 2.34 in Buzzard, and 1.96, 2.08 and 2.76 in Goshawks. Between-year variation in number of fledglings was high in Buzzard population and moderate in Goshawks. Buzzard productivity was related to changes in food composition of this species, whereas in Goshawks no relationship between productivity and diet was found.
Red fox Vulpes vulpes (Linnaeus, 1758) are generally regarded as strictly territorial animals, inhabiting distinct and well-separated ranges. The home ranges of these predators can vary in size from a few dozen hectares to as much as 20-30 km2. Because it seemed impossible that foxes could defend areas so different in size with the same intensity, the published data were analysed in order to see how changes in home range size could affect the following parameters: home range overlap, the area visited daily and the distance travelled by animals during 24 h. It was found that the overlap between fox families (groups) occupying large ranges was much greater than between foxes living in small ranges. The ratio of the area visited daily to the seasonal home range size was greater in small ranges than in large ones. No significant correlation was found between the mean distance moved daily and home range size (r = -0.118, p = 0.75). These results suggest different patterns of the use of space and differences in territorial defence by red foxes inhabiting large and small ranges. The implications of home range overlap and intensity of contacts between foxes occupying neighbouring ranges for the spread of disease are discussed. The significant overlap between large ranges found in this paper is discussed in the light of Andrzejewski's (2002) home range concept.
The densities of three sympatric carnivore species (fox, raccoon dog and badger) were estimated in Suwałki Landscape Park (North Eastern Poland}. The number of predator den was estimated by a double survey of the area; additionally, snow tracking was carried out. Mean spring density (1995-1996) of foxes was estimated on 0.27 individuals per square km of the whole Park territory whereas those of badgers and raccoon dogs were 0.36 and 0.37, respectively. These values are much higher than estimations by the Park Authorities. In comparison with other regions of Poland the densities of both raccoon dogs and badgers were among the highest recorded. Mean number of cubs per family den was 2.3 in badgers, 6.0 in foxes and 5.7 in raccoon dogs.
Both the Buzzard and the Goshawk nested mainly in pines. The mean clutch size in the former was 2.8, in the latter 3.6 eggs per breeding pair. There were statistically significant differences in clutch sizes in the Buzzard in particular breeding seasons. The mean number of hatchlings was 2.3 in the Buzzard and 2.6 in the Goshawk. Brood losses were similar in both raptors —19% in the Goshawk and 24% in the Buzzard. The breeding success (the ratio of the number of fledglings to the clutch size) in the Buzzard was highest in clutches of 3 and 4 eggsy whereas in the Goshawk a similar level of success was achieved with smaller clutches (2 or 3 eggs). Only in the case of the Buzzard there were significant differences in clutch sizes and numbers of fledglings in the various years. In this species the mean number of fledglings was positively correlated with the rodent availability index in a given year. There was no such relationship between the abundance of prey items found in Goshawk nests and the number of fledglings. The correlation between the number of newly-fledged Buzzards and Goshawks in a given year could have been due to diet overlap between the two species.
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