We used logistic models to estimate the risk of moose-train collisions for the Rørosbanen railway in Norway. During 1990–1997, a total of 13,506 train departures were registered along Rørosbanen during the months when the risk of collision was highest (December to March). The statistical model selected to predict the risk of moose-train collisions included train route, time of day, lunar phase and average train speed, as well as two climatic covariables, i.e. snow depth and temperature. Trains running at night, in the morning or in the evening experienced a higher risk of collision with moose Alces alces than day trains. The probability of collision was also higher during nights of full moons than during nights of half or no moons. As observed previously with trains in Norway moose-kills increased with increasing snow depth and decreasing temperatures. To test the predictability of the model, we used a logistic model based on train departures during 1990–1996 to predict the number of moose-train accidents during winter 1996/97. Although the model had a satisfactorily high predictability, the best models would probably be those based on a combination of both temporal and spatial aspects. We discuss how logistic models may be applied to introduce remedial actions on high-risk routes or during high-risk periods.

Experiments with captive wolverines Gulo gulo showed that oils and chemicals gave distinct avoidance reactions. In 1993 and 1994, volatile repellents were tested on lambs in free-ranging flocks and significantly fewer lambs were lost in treated groups than in untreated groups. In 1996, the effects of repellents were tested when wolverines did not have lambs without repellents as alternative prey. The experiment was carried out in four different areas where high losses of lambs due to wolverine predation had been observed in recent years. The flocks were monitored by environmental officers throughout the season. There were relatively few technical problems with the repellents, except that some ear tags were lost during the grazing season. The effect of the repellent was tested on two different time scales, a survival model based on 15 years of data and a model based on a narrow time window, comparing the results of the test year with the losses in the previous year. Losses of lambs increased from 1983 to 1996 and were highest in years in which wolverines reproduced within the areas concerned. Both models showed that the use of volatile repellents on all lambs did not reduce losses in either of the four areas. In one of the areas (Ulvådalen), the losses were higher in 1996 than in 1995. In the other three areas, no difference was found between 1995 and 1996, suggesting that the wolverines had become habituated to a situation where all the lambs in a relatively large area were treated with repellents. Based on the results of former surveys as well as the present survey, we conclude that this particular repellent is only a potential tool which may be used to reduce losses in target groups of sheep and that repellents cannot be recommended as a general tool to reduce wolverine predation on sheep.

In the region of First near Grindelwald in the Swiss Alps, experiments were carried out on the reaction of alpine marmots Marmota marmota when confronted with hikers. Marmots in highly frequented areas showed less reaction to hiking activities than marmots in remote areas. In adult marmots, there was no change in reaction during the season. In young animals the reaction shortly after leaving the burrows in early July, was slight and similar in highly frequented and remote areas. In late summer, the intensity of the reaction of young animals increased significantly in animals in both study groups but to a much larger extent in the remote areas. We conclude that the perception of danger has to be learned or is built up during growth and development. At the same time, young animals in highly frequented areas may adjust to the presence of hikers.

We assessed biases in the techniques used to investigate the cause and rate of mortality in two red grouse Lagopus lagopus scoticus populations in Scotland during 1985–96. Comparison of the field signs left on grouse carcasses by known predators suggested that whilst it was usually possible to distinguish between grouse killed by mammals and by raptors, it was not possible in most cases to further distinguish between grouse killed by peregrine falcons Falco peregrinus and hen harriers Circus cyaneus. Similar estimates of the cause and rate of grouse mortality were derived from systematically counting grouse and searching for carcasses and by radio-tagging. Searching for carcasses may provide a useful technique for identifying major causes of mortality in grouse populations inhabiting open habitats.

Female age and condition as well as nesting schedule may affect clutch size and chick survival, which both are important factors affecting the annual reproductive output. Clutch size and chick survival are often interrelated in altricial birds but in precocial species the interrelation is dubious. To study factors affecting clutch size and the survival of ducklings in the common goldeneye Bucephala clangula, we examined ringing-recovery data, supplied by ringers, from seven intensively studied goldeneye populations from different parts of Finland. Due to large sample sizes it was possible to distinquish the effects of interrelated variables, e.g. female age and hatching date. Clutch size was significantly associated with both female age and hatching date; first-time breeders and late breeders had small clutches. Clutch size was not associated with female condition. The recovery rate of ducklings was associated with hatching date (low in late broods) but not with female age, condition or brood size. The natal brood sizes of recruited female ducklings did not differ from annual averages, but the natal hatching date of recruited females was earlier and their mothers were older than annual averages in the populations into which the recruited females were bom. The timing of nesting was the most important factor affecting the reproductive output of common goldeneye females in a given year.

We analysed the food of eiders Somateria mollissima at Hanko, Finland, in the northern Baltic, by examining the contents of mussels in the faeces and digestive system of eiders. The aim of our study was to determine whether size selection of the main food, blue mussels Mytilus edulis, occurs and if so why. Generally, diving ducks seem to choose mussels smaller than the average found on mussel beds. One hypothesis states that size selection of mussels occurs because eiders choose to minimise the daily intake of shell material. We did not find unambiguous evidence of size selective feeding on blue mussels in our study area. Although eiders selected mussels somewhat smaller than the average found on mussel beds when the entire data set was analysed, this minor discrepancy can probably be attributed to the fact that benthic sampling was conducted in areas which were partly different from the areas in which eider specimens and faeces were collected. Individual differences among eiders were significant. The meat content of northern Baltic mussels was generally higher than that of Atlantic blue mussels, with only a slightly decreasing trend with increasing mussel size. Shell weight increased more than meat weight with increasing mussel size. However, the shell weight that birds have to ingest to obtain their daily requirement of food is many times greater in the Atlantic than in our study area for all size categories of mussels. Thus, shell mass minimisation is probably not of crucial importance to eiders in the northern Baltic.

The present study evaluates dispersal among breeding willow ptarmigan Lagopus lagopus in five closely located subareas in central Norway. During a six-year period, breeding territorial ptarmigan were live-trapped, aged, sexed and genotyped. Since it is believed that female willow ptarmigan are the dispersing sex, and foreign intruders are expected to be more genetically different than birds from the natal subarea, it is predicted that the genetic similarity between breeding birds of a given year (t) and the breeders in the same territories the next year (t+1) would be greater for males than for females. The extent of dispersal is believed to be positively correlated with the intruder pressure. Thus, the genetic similarity outlined above is predicted to be greatest in comparisons where chick production in year l was lowest. Analysis of genetic similarity among territorial birds in two consecutive breeding seasons revealed no significant difference between males and females. However, males showed greater genetic variability between years than females. For both yearling and adult males, the increased variation coincided with changes in the population density. Hence, a significant relationship between genetic similarity and chick production for both yearling and adult males was observed. This may suggest density-dependent dispersal for males, but not for females. The fact that there was a stronger relationship between genetic similarity and natal chick production, than between genetic similarity and mean chick production on all subareas, for both adult sexes, suggests that breeding adults are more often challenged by yearlings from their own subarea than by foreign intruders from neighbouring areas.

In central Norway, the body temperatures of two wild-living badgers Meles meles, one male and one female, were recorded in the morning and evening from early November to late March using an implanted temperature-sensitive radio transmitter. The external ambient and internal sett temperatures were also recorded. Both badgers showed a general decrease in their mean daily body temperature from early November until the second half of December, followed by a general increase until the beginning of March. The reduction in body temperature for both animals was around 2–3 °C. The female spent most of the winter under a building, in a crawl space where the internal temperature varied from +4°C to -11°C, being strongly influenced by the external ambient temperature. The male spent the winter in a natural sett where the temperature was rather constant (+2–5°C), and where the external ambient temperature had little influence on the internal sett temperature. However, the external ambient temperature only accounted for 11 and 12% of the observed body temperature variations in the male and female, respectively. When the length of daylight was compared with the body temperatures, it was found to account for 60 and 30% of the variations in the male and female temperatures, respectively. Thus, the data indicate that the photoperiod, at its minimum at the winter solstice, acted as the primary synchroniser of the body temperature cycle in the badgers during their winter lethargy.