Two distinct subpopulations of wood bison Bison bison athabascae inhabit the Mackenzie Bison Sanctuary and adjacent areas: the ML subpopulation which is increasing and inhabits the periphery of the bison range, and the MBS subpopulation which is stabilizing and inhabits the core area of the bison range. This system provided the unique opportunity to examine how the plant community responded to an erupting, indigenous herbivore population. The standing crop of sedges and grasses in willow savanna habitats located in the core area of the range (MBS) was consistently lower than that of willow savannas located at the periphery (ML). The difference in standing crop between areas appears to be a direct result of different grazing pressures between the two areas. Net primary production was similar between MBS and ML indicating that the vegetation in MBS showed at least some partial compensation in response to grazing. The species composition of willow savannas differed between areas. Willow savannas located in MBS showed an increase in more unpalatable or less preferred species compared to willow savannas located in ML. Forages were of similar quality between the areas.

American grey squirrels Sciurus carolinensis introduced to northern Italy in 1948 have caused damage to commercial poplar plantations and have replaced the native red squirrel Sciurus vulgaris from most of the 350 km² of the Piedmont Po-plain they currently occupy. In order to plan a control programme aiming to stop grey squirrels from further spreading and to decrease their numbers, the current distribution and population size in the highly fragmented landscape of the Po-plain were studied. The probability of finding grey squirrels in woodland fragments increased with habitat quality (diversity of trees producing large, consumable seeds), woodlot size and the proportion of poplar. Adding isolation variables did not improve the fit of the logistic regression model that predicted squirrel presence. The density of squirrel dreys, an index of population density, in the large Stupinigi forest also increased with tree species diversity. An estimate of the minimum population size for all woodlots assessed for squirrel presence was 1,260 animals in the summer of 1996. This extrapolates to a total of ca 2,500 grey squirrels in Piedmont. Grey squirrels continue to increase their range and are getting close to the continuous mixed forests of the pre-Alps and to large hazel plantations. Control measures to stop the spread of grey squirrels, and eventually to eradicate them, should be implemented immediately.

In 1996, an epizootic occurred among wintering and breeding common eiders Somateria mollissima in southwest Kattegat, Denmark, causing the death of at least 900 birds during late winter, and of a total of 3,146 females in five local breeding colonies, corresponding to 35–95% of the females present within the single colonies. The cause of death was related to a bacterial infection by Pasteurella multocida isolated from all examined eiders collected on wintering and breeding grounds. This is the first documented incidence of pasteurellosis in Scandinavia. Based on knowledge of the phenology and winter distribution of eiders, the temporal occurrence of the disease suggests that apparently healthy birds acted as carriers of the disease bringing it from the wintering grounds to the breeding colonies.

Wintering waterfowl community structure and their association with lake characteristics were studied in the Cotswold Water Park, a complex of more than 120 gravel pit lakes in southern England. The major distinction in community types was between assemblages dominated by diving waterfowl and those dominated by dabbling waterfowl. The trophic status of lakes was found to be a major determinant of community structure: young lakes in the early stages of a natural process of eutrophication tended to support the most diverse assemblages of diving waterfowl. The abundance of individual species was strongly related to lake size and assemblage type. Some effects of food supply and the recreational use of lakes were also apparent. The relevance of the findings for the sustainable value of the lakes for wintering waterfowl is discussed.

Corpses of red grouse Lagopus lagopus scoticus were collected monthly from 10, 1-km² study areas on managed grouse moorland for a period of 10 years. Six of the study areas were located in Scotland and four in Northern England. A greater number of corpses were found on the Scottish study areas than on the English and compositional analysis identified the relative importance of death through parasitism in England. Stoat Mustela erminea kills were more prevalent in England but fox Vulpes vulpes and large raptors were more important in Scotland. Predators were more abundant in Scotland and frequency of sightings positively correlated with number of kills between study areas. There was a seasonal peak in mortality in spring.

To evaluate hypotheses on why the European badger Meles meles uses more than one underground burrow (‘sett’) as a diurnal resting site, the distribution and utilisation of setts within territories were recorded for nine radio-tagged individuals in four adjacent social groups in the boreal forest of central Norway. The density of setts was low, but the mean number of setts within a territory (12) was higher than found in earlier studies in Europe. Natural setts were small, and though randomly distributed within territories the upper parts of south-west facing slopes were preferred. Between April and September individual badgers used an average of nine different setts. They moved frequently from one sett to another, except for two reproducing females which remained very faithful to one sett in spring. Random utilisation and frequent changes of setts support the hypothesis that badgers use multiple setts to avoid accumulation of ectoparasites. No indications which support the hypothesis that young badgers use multiple setts to avoid harassment from dominant conspecifics were found.

A combination of discriminant function analysis and multiple regression was used to develop a linear model of American marten Martes americana winter habitat use within second-growth boreal forest in northeastern Ontario, Canada. Four structural variables significantly discriminated between sites that were used or not used by martens: the percentage of spruce or fir trees, tree height, the number of downed logs, and canopy closure. The model was tested against a second data set and was not invalidated. The results demonstrated that martens were using second-growth forests in Ontario, and that their response to structural characteristics was similar to responses described previously in uncut forests.