Behavioural observations, measurements of male and female reproductive success, and DNA microsatellite loci were used to investigate parentage of common eider Somateria mollissima clutches and productivity of widowed females in Finland. In an experimental study simulating spring harvest of male eiders, a total of 20 males were shot while attending 16 females (four males after rematings, 16 initial males) during the pre-laying and laying period in 1994. Of the 16 widowed females, 11 nested and five did not. Mean clutch size of breeding widows (4.55) did not differ from that of control females in the same year (4.47; N = 32). However, the hatching success of widows was significantiy lower than that of control females (53 vs 81%) because of a greater proportion of addled eggs and dead embryos (38% vs 11%). Male removal also appeared to change male and female behaviours resulting in higher incidence of intra-specific brood parasitism and mate replacement. Occurrence of foreign eggs averaged 9.5% during the treatment year but was not observed during a year without disturbance during mating and egg laying (1997). Behaviours of widowed females related to remating attempts varied from active seeking of new mates to total rejection of courting males. Rematings did not lead to full clutch fertilisation among widowed females. Neither did we observe evidence of immigration of new males into the hunting area to court the widows. Male removal clearly lowered the fecundity of eider females, reducing nesting success by 35% of long-term averages. The potential for remating appears to be reduced by the female-biased sex ratio caused by simulated male-only harvest.

We assessed the influence of habitat characteristics on nest site selection and nest success of red grouse Lagopus lagopus scoticus in three populations on managed moorland in Scotland during 1998–1999. We measured habitat characteristics at the nests of 148 radio-tagged female grouse and compared them with similar measurements taken at fixed and random points within their home range. Red grouse nested in vegetation that was significantly taller and denser, and with greater canopy cover, than points adjacent to nests or to random points. They nested more in mature heather and less in grass-dominated vegetation than would be expected by chance. Red grouse nest success was high with 77% initial success rising to a minimum of 80% success once re-nesting had occurred. Nest success was weakly related to vegetation height in 1998, but no similar relationship was found in 1999. We suggest that the high nest success of red grouse and the relatively small influence of habitat characteristics on the outcome of nesting attempts is due to predator control on managed grouse moors in Scotland.

Experimental investigations showed that during the first 10 days of their life partridge Perdix perdix chicks grew most vigorously on a high protein value diet composed largely of insects. They grew less quickly on rearing crumbs and were unable to survive when fed entirely on seeds. We determined the daily uptake of food and, from carcass analysis, the proportion assimilated. From this information the average daily food requirement in terms of the dry weight of insects was calculated as 0.80 g on day 2 and 1.95 g on day 9. We calculated the number of individual insects of various groups required daily, if feeding was restricted to one group, and the amount of habitat that would need to be searched if insects were taken randomly. Resistance to chilling was shown to be correlated with weight and not with age. Thus shortage of insect food in the first few days of life would extend the period when the chicks are particularly vulnerable to lower temperatures and rain, effects that have also been demonstrated in other studies.

In this article we describe 77 arctic fox Alopex lagopus dens in Vindelfjällen, northern Sweden, with regard to distribution, morphology and fox use. The density of dens in the area was 1/21 km² and dens were more spaced than random. The dens were situated at a mean altitude (± SD) of 915 m a.s.l. ± 74, were on average 3.5 km ± 1.88 from the nearest tree line, had a mean number of 44 den openings ± 32 and a mean area of 277 m² ± 237. During the 21-year study period, 31 dens were used by arctic foxes and 10 by red foxes Vulpes vulpes. Number of den openings, den area, altitude and distance to the nearest tree line explained 36% of arctic fox den use (P < 0.001) and 21 % of red fox use of arctic fox dens during the study period (P = 0.01). Arctic foxes used dens at higher altitude (P = 0.03) and further away from forest than did red foxes (P = 0.03), and tended to breed in dens with more openings (P = 0.08). Arctic foxes used some breeding dens more frequently than others (P = 0.002). Among the breeding dens, both den use and litter size were positively related to den area (den use: P = 0.04; litter size: P < 0.001). Successful arctic fox breeding dens in Sweden thus appear to be characterised by large size and many openings, and they are situated far away from forest at relatively high altitudes.

In this paper we aim to define whether fish farms or stocked trout streams substantially contribute to the diet of otters Lutra lutra living in freshwater habitats of Mid-Finland. Diet was assessed using spraint analysis. We especially focused on areas with fish farms and stocked trout Salmo trutta streams (salmonid-rich habitat) and used ‘normal’ (salmonid-poor) habitats as control. Frequency of salmonid remains in spraints was significantly higher in salmonid-rich habitats than elsewhere in all seasons, the difference increasing from summer to winter. In salmonid-rich habitats, however, salmonid consumption was not strongly seasonal. Data from spraint collection indicated a shift in activity towards salmonid-rich habitats in winter. Otters therefore seem to switch prey seasonally, due to seasonal variation in the availability of other prey categories, by choosing to forage in particular, predictable habitats. Furthermore, our results suggest that, in salmonid-rich habitats, the increase in salmonid frequency is to a larger extent due to the presence of fish farms than that of trout streams. Fish farms, and to a lesser extent stocked streams, may therefore constitute seasonally important feeding grounds for otters.

We tested non-invasive genetic methods for estimating the abundance of marten Martes americana using baited glue-patch traps to pull hair samples from individual animals. We divided our 800–km² study area into 3 × 3 km cells and put one hair trap in each cell. We trapped 309 sites for an average of 15 days each between 15 January and 14 March 1997. Based on tracks in snow and hair morphology, we captured hair from marten, red squirrels Tamiasciurus hudsonicus, flying squirrels Glaucomys sabrinus, short or long-tailed weasels Mustela erminea and M.frenata, and several unidentified mouse and vole species. Of 309 sites, 58% collected a marten hair sample while 8% of sites removed weasel hair. When roots were embedded in adhesive, a xylene wash was used to remove them before extracting DNA. All marten samples were genotyped at six microsatellite loci to identify individuals. Xylene-washed samples yielded similar genotyping success to samples that had never been exposed to xylene, and genotyping success increased with the number of hairs in the sample. Genetic data allowed 139 samples to be assigned to 88 individual marten, constituting 124 capture events during the four trapping sessions. The population estimate for our study area was 213 (95% Cl: 148–348) and the average capture probability was 0.15. The density of marten in our study area was 0.33/km² when inhospitable habitat was removed from the calculation. We believe hair sampling and genetic analysis could be used to measure population distribution, trend and size for marten, and perhaps also for other carnivores.

Besides red fox Vulpes vulpes predation, mowing is probably the most important mortality factor for roe deer Capreolus capreolus neonates in areas of intensive agriculture. Using radio-transmitters on roe deer neonates in south-central Sweden, I estimated mortality caused by mowing and tested and evaluated a traditional method to decrease this kind of mortality. During 1997–1999 fawn mortality caused by mowing was estimated at 25–44% of the yearly recruitment. Fawns were at risk for at least up to one month of age. The method tested uses scaring devices made of plastic sacks that are set out before mowing. The idea is that this will prevent female roe deer from placing their fawns in the field and make them remove the ones already hiding there. Black plastic sacks were attached to approximately 2-m long poles and placed in hay fields where marked fawns were bedded. During 1998–1999,14 separate experiments were performed. Out of 22 fawns bedded in the vicinity of sacks, 18 were removed the day after the sacks were set out and three were removed on the second day. The fawns were always removed to another field or habitat patch. Fawns in the experiments were removed to a higher degree than fawns used as a control, and they were moved longer distances than both control fawns and the distances moved during the days before the experiment. The results imply that the use of this method is effective in reducing the mortality of roe deer fawns.

Moose Alces alces suffering from Moose Wasting Syndrome (MWS) have been observed in Sweden since 1985. In this study a population characterisation of MWS is done based on moose delivered to the National Veterinary Institute of Sweden during 1985–1989, public reports of non-traumatic moose deaths during 1991–1998, and radio-collared moose in one high- and one low-report frequency area. Moose suffering from MWS have been observed nationwide, but deaths from non-traumatic causes, including MWS, are most frequently reported from the county of Älvsborg. Nationwide reports of non-traumatic deaths peaked in 1992, but no peak was observed in Älvsborg. We suspect that the temporal as well as the spatial patterns observed were largely due to information about the MWS by the media, research activities and local concern. The age-specific mortality pattern of non-traumatic deaths did not differ, in either sex, between one high- and one low-report frequency area. The risk of dying from non-traumatic causes increased with moose age. Reports of female moose either suffering from MWS or having died from other non-traumatic causes largely outnumbered reports of males (1,349 and 387, respectively). Our results of age-specific risks suggest, however, that females are less vulnerable to non-traumatic mortality than males. The discrepancy between report frequencies and death risks is explained by the fact that the population sex ratio is female-biased (by sport harvest), and few males reach the age at which the risk of dying from non-traumatic causes increases. In the area from which most of the reports came the non-age-specific yearly risk of dying from non-traumatic causes, including MWS, was estimated to be 3.5% for females and 3.0% for males. Because there are other non-traumatic causes of death, the risk of dying from MWS exclusively is lower than our risk estimates indicate. There is no immediate risk of local extinction of moose due to MWS, as we estimate that the population would increase if culling was stopped.

In 1999, seven dark-bellied brent geese Branta bernicla bernicla were followed during spring migration from western Europe to Arctic Russia using satellite telemetry. For six of the birds we were also able to monitor their summer stay at the Taymyr Peninsula, and for five birds part of their autumn migration was recorded. In this article, we report on site use during summer and spring/autumn migration. We also describe migration routes and evaluate general migratory performance during autumn migration. All birds spent the summer within areas covered by the Great Arctic Reserve on the Taymyr Peninsula. None of the birds returned to the wintering area with young, so the sites used during summer were most likely used primarily for moulting. The birds remained at the same sites the whole summer until the start of autumn migration, indicating that the build-up of fuel stores for migration took place at the moulting sites. Autumn migration was conducted in a similar way as spring migration regarding routes and general migratory performance. Site use showed both a relatively large variation between individuals and seasons, as well as some degree of site fidelity as all birds returned for a longer stay in autumn to at least one of the areas they had used for more than two days in spring. Thus the migration of brent geese along the Arctic Ocean cannot be considered as a simple migration system with just a few key sites along the route, but instead it is a complex system with several localities used in different ways by different individuals. Most of the areas used by the satellite-tagged birds were previously known stopover areas, but some of them had not been recognised as being of importance for brent geese before. Most of the stopover areas do not have any kind of formal legal protection. It is suggested that further research should be carried out in the areas identified in this study to evaluate their importance and role in the migratory journeys of dark-bellied brent geese.