Pre- and post-harvest population size and the structural composition of the moose Alces alces population in the Vefsn valley in northern Norway estimated by the use of cohort analysis were compared to population density indices derived from hunter moose observations during 1968–1993. The moose observation index (moose seen per hunter day) was able to predict the same trend in the post-harvest population size in 84% of the cases, and was significantly linearly related both to pre- and post-harvest population size. The moose observation index was more closely related to the post-than to the pre-harvest population size, probably because the main part of the harvest took place during the first week of the hunting season, whereas the observation index was based on aggregated values collected over two weeks. Moreover, the observation index tended to overestimate population size when hunting success was high, indicating that factors influencing hunting success may also affect the probability of detecting moose. The recruitment rate (calves per female) recorded by the hunters was also closely related to the recruitment rate estimated by the cohort analysis, suggesting that the observed recruitment rate may provide a useful index of the recruitment to the population. We suggest that further improvements of moose recordings as a management tool can be obtained if the data are analysed separately for shorter periods (e.g. week, day) of the hunting season because this will probably reduce the impact of annual variation in harvesting rates on the estimates.

Introduced North American beavers Castor canadensis pose a potential threat to the continuing recovery of Eurasian beaver C. fiber populations in several European countries. For management purposes, it is necessary to be able to identify and distinguish the two species. This, however, is difficult because the two species are morphologically, ecologically and behaviourally similar. To find a method for species identification, we examined the possibility of using anal gland secretion (AGS) collected from the two beaver species. We asked 20 inexperienced volunteers to inspect the colour and viscosity of the AGS. When we provided the volunteers with the sex of each beaver and descriptions of the colour and viscosity of AGS from males and females of the two species, all volunteers could 100% correctly identify the two species. We therefore conclude that the colour and viscosity of the AGS can be used for a quick and easy identification of the two beaver species.

This paper describes the results of tests performed to evaluate linear correction of GPS measurements as an alternative to differential correction of GPS positional fixes. Differential correction requires information which is not provided by the existing animal-borne GPS systems for smaller mammals. Therefore, linear correction, by means of a second GPS rover, has been suggested as an alternative to differential correction. To test the accuracy of linearly corrected measurements, we compared the position estimates of raw, linearly corrected and differentially corrected GPS positional fixes with the true (known) geodetic position. The tests indicate that the accuracy of linear correction is highly unstable and is related to differences in the satellite constellation used by the GPS receivers. Linear correction is consequently strongly discouraged. If differential correction is not possible, we recommend the use of raw GPS measurements, of which the error is well known and more predictable.

Administrative, political, and natural history constraints on the design of research studies in ecology often result in small data sets. In this paper, I identify some problems associated with small data sets and describe a contingent process for data analysis. I argue that exploring small data sets is heuristic and can be a valuable first step in the formulation of biologically interesting hypotheses.

From the 1970s to the 1990s, changes in breeding waterfowl populations were monitored at 26 well-vegetated lakes in southern Finland. Extreme total population levels were found to differ by 40%, but between successive years fluctuations did not exceed 20%, the most unstable populations being garganey Anas querquedula, tufted duck Aythya fuligula, coot Fulica atra and pochard Aythya ferina. Multiple regression analysis was used to determine the effects of weather factors during wintering, spring and brood seasons on the variation in breeding waterfowl populations. The following weather factors were statistically significant in explaining fluctuations observed in four species; in garganey: spring temperature; in pintail Anas acuta: brood season temperature, winter severity in France and spring temperature; in goldeneye Bucephala clangula: winter severity in the Baltic and spring temperature; and in mallard Anas platyrhynchos: brood season temperature of the previous year. Mallard, teal Anas crecca, wigeon Anas penelope and goldeneye were shot in larger numbers than would be expected considering their respective proportions of the breeding waterfowl community. Hunting pressure on mallard, tufted duck and goldeneye was clearly higher in our study area than in other parts of Finland. Our results indicate that the level of hunting pressure in our study area may affect population densities of mallard.

Unsprayed cereal crop margins were tested in large-scale field trials during 1991–1994, as part of the Swedish agricultural authorities' nation-wide campaign to reduce pesticide usage. Eleven pairs of farms in central and southern Sweden were chosen. One farm in each pair was sprayed normally (i.e. 90–100% of cereal fields were treated annually with herbicides; insecticides and fungicides were only used after pest and disease thresholds had been exceeded), whilst on the other farm the outer six metres of crop of several cereal fields received no pesticides. In each year, unsprayed crop margins in both autumn- and spring-sown cereals had significantly higher percentages of weed cover. Unsprayed crop margins supported higher densities of nontarget arthropods, particularly the non-pest species which are important in the diet of insect-eating gamebird chicks. Significant positive relationships were observed between the densities of these insects and the degree of weed cover. Mean brood sizes and chick survival rates of both grey partridges Perdix perdix and pheasants Phasianus colchicus were higher on farms with unsprayed crop margins. The effects of omitting herbicide (pesticide) treatments were most dramatic for grey partridges. The treatment, both by itself and mediated through insect density and weed cover, had highly significant effects on brood sizes. There was a significant increase in the mean number of pairs of partridges found in spring on farms with unsprayed cereal crop margins. No similar increase was observed for pheasants. The benefits of unsprayed cereal crop margins to partridges and pheasants are discussed.

Scots pine Pinus sylvestris is a dominant winter food species to moose Alces alces in Fennoscandia but reports of its use during the growing season are limited. Browsing by moose on current-growth, terminal shoots of Scots pine (CGTS) during summer was studied in three areas in southern and central Sweden to quantify this seasonal feeding habit. Dynamics of nutrient content in CGTS were also studied to relate the timing of consumption to the changing qualitative value of this forage. To determine the temporal pattern of browsing by moose, data were taken in young pine stands of two separate areas during the growing seasons of two different years, 1980 and 1995. In the former year use of terminal shoots peaked in mid-June while in the latter year it peaked some two weeks earlier. Nutrient analyses, made only in 1995, showed that peak use of pine terminal shoots coincided with seasonal highs in magnesium (Mg), potassium (K), crude protein (CP), phosphorus (P), starch and total carbohydrates, and seasonal lows in acid detergent fibre (ADF) and acid detergent lignin (ADL). In vitro dry matter disappearance (IVDMD), a measure of digestibility, in terminal shoots in June was found to be significantly higher than in two other important moose browse species, birch Betula spp. and bilberry Vaccinium myrtillus. To determine frequencies of use of CGTS and heights of recently browsed trees, young pine stands in a third area were surveyed in July 1985. All browsed pine trees were between 30 and 230 cm in height, and 14% were browsed on some occasion during the growing season. Our results are discussed with respect to the potential mechanisms underlying summer use of CGTS by moose. Further research on the impact this feeding habit may have on forestry is suggested.