The aim of the present paper was to compare the picture of habitat selection obtained by using 1) different home ranges and core areas and 2) different methods (compositional analysis, Jacobs index and selection ratio), in radio-tracking studies of mammals. The experimental animal was the Eurasian badger Meles meles, radio-tracked in southern Finland in 2006-2007. The total home ranges used in the study, minimum convex polygon (MCP) and 95% fixed kernel home range (K95) differed in size, MCP being larger. Therefore its habitat composition resembled more that of the landscape, and comparison between K95 and the study area revealed better habitat selection within the landscape (second order selection). The proportions of two common habitat types (fields and spruce forests) differed between the core areas used in the study. Comparison between the smallest core area (K50) and MCP revealed best habitat preferences within the home range (third order habitat selection). Comparing the distribution of individual location points in different habitats to the habitat composition of home ranges did not reveal habitat preferences of badgers. The use of compositional analysis together with Jacobs index in habitat selection studies is recommended, because the simple selection ratio was not very sensitive.
The prey of 66 free-ranging urban and rural house cats Felis catus was studied in a mainland area in SW Finland. The data included 1624 home-brought prey animals, of which 92 % could be identified at least to the class level. The mean number of prey brought home was 4.1 per cat per month (excluding winter). Rodents were the most common prey (72 %), 18 % of prey being birds, 5.4 % insectivores, and the rest other mammals (hares, least weasels, pine martens, and a bat), reptiles or amphibians. Six “super predator” cats accounted for 40 % of all prey items captured. There were no differences between the sexes in the number or diversity of prey
brought home. The prey of young cats was more diverse than that of older, more experienced cats. Especially old cats in rural areas benefit humans by killing many rodents. The proportion of birds captured was 24 % in urban areas where cats represent a possible threat to native birds: probably > 1 million prey animals are monthly killed by free-ranging cats in Finland, at least 144000 of these being birds. “Super predator” cats should thus be kept in the house, especially in urban areas, to prevent predation on birds.
A predator removal study was done in Finland to reveal the possible effects of mammalian predators on the breeding success of ducks. Predator removal/protection from hunting was most effective in northern Finland. Also in eastern Finland predator removal had some influence on predator numbers, whereas its impact on predator numbers was not so evident in southern Finland. In southern Finland, no increase in the breeding success of ducks was observed in the predator removal area, whereas in northern Finland the relative reproduction rate of diving ducks increased in the removal area and that of dabbling ducks declined in the control area. In eastern Finland, the breeding success of ducks declined in both areas. There was a positive relationship between the raccoon dog index and the relative reproduction rate of dabbling ducks in southern Finland, indicating that raccoon dog numbers probably are of minor importance for the breeding success of ducks. On the contrary, there was a negative relationship between the fox and marten indices and the breeding success of ducks in some areas. Marten and fox removal may thus have a positive effect on the breeding success of ducks in Finland. The effect of the American mink could not be verified in this study.