Conservation of species requires knowledge on population changes in time, but achieving such data in proper spatio-temporal scales can often be difficult for rare and vulnerable species. We used long-term diet data of three avian predators (the nocturnal Ural and eagle owls and the diurnal goshawk) from four landscapes to study population changes of two forest-dwelling species, the Siberian flying squirrel Pteromys volans and the red squirrel Sciurus vulgaris in Finland. We also determined the role of vulnerable flying squirrel in the diet of these predators. Both squirrel species were relatively rare in the diets of the three avian predators, with the exception of red squirrel in the diet of goshawks. The Siberian flying squirrel also appears to be a less important prey for avian predators than flying squirrel species (Glaucomys spp.) are in North American forest communities. Numbers of consumed flying squirrels, but not of red squirrels, increased as the abundances of voles increased in the diets of eagle and Ural owls, that is more flying squirrels were consumed during the good vole years than the poor ones. The declining trends in the diets of three avian predators appeared to be quite similar for both studied squirrel species, possibly indicating that the process behind the decline has been the same.

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.

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24To devise effective conservation actions, it is important to know which factors are associated 25 with the population parameters of a declining population. Using mark-recapture methods, we 26 estimated the annual population size, growth rate and survival probability of an ear-tagged flying 27 squirrel population over a 15-year period in a 4,500 ha study area in western Finland. The species is 28 considered vulnerable, but detailed knowledge concerning population sizes or trends is lacking. The

Long-term studies were carried out in central Finland between 1985 and 2003 to examine the temporal and spatial variation in the density of otter populations. Snow tracking was used to estimate the total population and the number of litters in the study area. In total 52 otters, including 16 cubs in 11 litters, lived in the study area (1,650 km(2)) in 2002-2003. The otter population clearly increased during the study period. The increase in density of the otter population was sigmoid, indicating that the population had reached the local carrying capacity. The density of the population was 0.12 individuals per river ha in 1985 and 0.29 individuals per river ha in 2002. The number of cubs per litter decreased when the density of the population increased. Density-dependent offspring production, together with the auto-correlation function of growth rate, indicates intraspecific competition in otter populations. Otters in a few river systems produced most of the cubs, creating several small source populations in the entire study area. Otters in secondary (sink) habitats had a low reproduction rate. Most otters lived in river systems with large lake surfaces. The number or area of lakes within the river system correlated positively with the total number of otters, litters and cubs in the river system. The six river systems (out of 16) with the largest water area of lakes produced 81.2% of all cubs born in the study area. However, the population growth rate per river hectare or per river kilometre was equal in all kinds of river systems. Thus, among local otter populations in central Finland, a source-sink system between different habitats seems to be prevalent.