North American boreal nesting waterfowl (and their eggs and ducklings) share a number of generalist predators with small mammals and non-migratory birds that could indirectly link fluctuations in these coexisting prey. We surveyed pairs and broods to determine an index of productivity for lesser scaup Aythya affinis breeding near Yellowknife, Northwest Territories, Canada. We also calculated a mallard Anas platyrhynchos productivity index for birds from northern Saskatchewan, Canada. Small mammal abundance was estimated by snap trapping rodents and by counting pellets of snowshoe hares Lepus americanus in the Yellowknife area. Because small mammal data were not available for the same area as mallard harvest survey data, correlation with an estimate of ruffed grouse Bonasa umbellus harvest was used because small mammal abundance and grouse are known to correlate positively. We found a positive correlation between the abundance of rodents and lesser scaup productivity suggesting a prey switching relationship for predators between their main prey (rodents) and alternative prey (lesser scaup, eggs and ducklings). A negative correlation between snowshoe hare abundance and lesser scaup productivity was also found as well as a negative correlation between ruffed grouse abundance and mallard productivity. Negative correlations suggest a possible shared predation relationship, where changes in main prey abundance (hares) may cause a numerical response in predators that influences predation rates of shared alternative prey (ducks, eggs and ducklings). Although our conclusions are based on correlations, they indicate that a great deal of variation in boreal duck productivity might be explained by the indirect effects of coexisting prey abundance. Further work is needed to determine causal mechanisms contributing to these relationships, the effect of cycles in small mammal populations and the overall importance of top-down predator regulation for regulating duck productivity in boreal forest.

Escape distances (EDs) have been used to study sensitivity of waterbirds to different sources of disturbance, to design reserves for waterbirds, and to define eco-targets for the Wadden Sea management plan. However, the use of ED as an index of sensitivity has been criticised because it can be highly variable. Although some factors affecting variation in the EDs of species have been studied, there is still a need for further analysis of factors that may affect it. In this study, we analysed the EDs of 19 waterbird species (geese, ducks, waders and gulls) exposed to a walking person (N = 1,371) during autumn and spring 1980–1984 under controlled conditions in the Danish Wadden Sea. We analysed how EDs varied between species in relation to body mass and hunting and within species in relation to flock size and weather conditions. EDs increased significantly with species body mass, and quarry species (dabbling ducks, curlew Numenius arquata, golden plover Pluvialis apricaria, common gull Larus canus and black-headed gull L. ridibundus) had longer EDs than non-quarry species when corrected for body mass. EDs increased with flock size in dabbling ducks and nine waterbird species in autumn and two waterbird species in spring. In autumn an inverse relationship was found between visibility and ED for dabbling ducks and five wader species. An inverse relationship was also found between wind force and ED for three wader species, but this relationship was found to be positive for two wader species. Several factors affected EDs, and EDs measured in one region may not apply to other regions. Based on our results it is recommended that reserve borders (core area and buffer zones) are designed to take into account mean EDs as well as variation in EDs, with respect to local disturbance levels, flock size and target species.

Investigations of food digestibility are important in nutritional studies of herbivores, but accurate assessments in the field are usually difficult and time consuming. This study explored the possibility of predicting digestibility and metabolisability of organic matter from the chemical composition and retention time of food in barnacle geese Branta leucopsis. Captive birds were used in indoor trials to allow accurate assessments of digestion in terms of energy, organic matter and nutritional components. Retention times were estimated from dropping rates which were recorded by an electronic device. The regression models that best explained the variation in apparent digestibility and metabolisability of organic matter incorporated the proportion of cell walls in the food (acid detergent fibre had a negative effect) and the retention time (longer retention had a positive effect). To test the predictive power of the regression model, we performed seven field trials with captive barnacle geese on Festuca rubra salt marshes. The regression model proved reliable except when salt concentrations in the food were high following inundation by spring tides. The results obtained from this study further demonstrated its value in estimating the individual digestibility of each plant species in mixed diets. This is illustrated with reference to a study of food selection by brent geese Branta bernicla.

We collected hair samples from bears and used microsatellite genotyping to identify individual bears on three study areas near the Canadian Rocky Mountains. We estimated density of grizzly bears Ursus arctos in eight different ecosystems across five study areas, including the reanalysis of two previously published data sets. We also estimated black bear U. americanus density for two ecosystems in one study area. Grizzly bear density was lowest in boreal and sub-boreal plateau areas, moderate in the Rocky Mountain east slopes and highest in the Rocky Mountain west slopes. Presumably these gross differences are related to ecosystem productivity. In the Rocky Mountain west slopes, grizzly bear density was lower in populations that were partially isolated from the continuous bear population to the north. Presumably, these differences have more to do with human impacts on habitat and survival than ecosystem productivity, because productivity in partially isolated areas was similar to productivity in adjacent continuous populations. We show that large differences in bear density occur down to the ecoregion scale; broader ecosystem classes such as Banci's (1991) grizzly bear zones, ecoprovinces or ecozones would include areas with major differences in density and are therefore too coarse a scale at which to predict grizzly bear density. There appears to be little movement across ecoregion boundaries further suggesting that this may be an appropriate scale at which to extrapolate density. Differences in density across finer-scale ecosystems are likely due to seasonal movements and not population level differences in density. Average bear movements were longer in less productive ecosystems. Female grizzly bears did not appear to leave their home ranges to fish for salmon Oncorhynchus spp., and extra-territorial movements by males appeared to be rare, in both ecosystems which supported spawning salmon.

The binturong Arctictis binturong and yellow-throated marten Martes flavigula are widely distributed through much of Southeast Asia, yet their natural history remains poorly understood. We radio collared and tracked five male binturongs, and five yellow-throated martens (four males and one female) for 4–23 months in Phu Khieo Wildlife Sanctuary, Thailand. For binturongs, mean annual range size (± SD; 95% minimum convex polygon) was 6.2 km² (± 1.0), and mean range overlap was 35%. Wet season ranges were larger for most binturongs. Binturong mean daily distance was 688 m (± 667). A cumulative activity pattern of 47% indicated that binturongs were arrhythmic and crepuscular. Yellow-throated martens showed an annual range of 7.2 km² (± 4.3) and exhibited overlapping ranges of 34%. Yellow-throated martens traveled an average of 966 m/day (± 834) and activity (58%) was characterized as diurnal, but increases in nocturnal activity increased during lunar nights (± 7 days from full moon).

We tested whether snow-urine ratios to creatinine of urea nitrogen (U:C), potassium (K:C), allantoin (A:C) and 3-methylhistidine (M:C) could be used to determine when to initiate an emergency feeding program in white-tailed deer Odocoileus virginianus. Food distribution to 11 experimental adult deer was gradually reduced over 64 days to simulate the conditions occurring for wild deer during winter. At the end of the partial fasting period, experimental deer had lost 19% of body mass on average. The animals were then fed ad libitum during a 13-day recovery period. A control group of four deer was fed ad libitum during the entire study. Control deer lost 6% of body mass during the experiment. Results for U:C and K:C ratios suggest that they were unreliable as indicators of physical condition of white-tailed deer during winter, at least within the physiological range and sample size considered in this study. A:C ratios showed fluctuations that were congruent with current knowledge of fasting physiology. A:C ratios of experimental deer relative to control deer, however, increased significantly only after 64 days of partial fasting, when animals had lost 19% of body mass. At that time it may already be too late to launch an effective feeding program. K:C and A:C ratios also increased during the recovery period, illustrating the potential difficulty of determining whether such an increase results from starvation or from resumed food intake. Concentrations of 3-methyl-histidine in the snow remained too low to be detected, due to dilution. We conclude that, under the limits of this study, none of the creatinine ratios represents an accurate index of body condition to determine when to initiate an emergency feeding program.