Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact email@example.com with any questions.
Nest boxes erected on 75 small lakes near Sudbury, Canada were monitored annually between 1987 and 1996 to measure the response of cavity-nesting waterfowl to changing chemical and biological conditions of their nesting habitat from the effects of acidification. Nest boxes were used mainly by common goldeneyes Bucephala clangula and hooded mergansers Lophodytes cucullatus, although a few were occupied by common mergansers Mergus merganser and wood ducks Aix sponsa. Use by hooded mergansers and wood ducks increased from 1987 to 1996, while use by goldeneyes remained stable. Patterns in nest box use reflected general population trends observed in the area. Interspecific nest parasitism also increased to 33% of all nests in 1996, probably a consequence of more hooded merganser nests. Clutch size, nesting and hatching success of goldeneye and hooded merganser eggs were similar to values reported for conspecifics in other studies. Overall, interspecific nest parasitism did not appear to affect the nesting success of either species. Although goldeneyes nested more often on fishless lakes early in the study, overall, fish presence, pH-value, lake area and connectivity were not related to nesting attempts or measures of nesting success for either species. Therefore, it is believed that for common goldeneyes and hooded mergansers currently breeding in the acid-stressed Sudbury area, habitat characteristics have little influence on nest site selection, particularly when compared to their documented effects on brood-rearing. However, monitoring of nest boxes may prove a less expensive method than aerial surveys to track population responses of cavity-nesting species to chemical improvements.
During 1988–1992, 684 scats were collected throughout the year in the territory of the only reproducing family group (mean five individuals) of wolves Canis lupus in Scandinavia. Moose Alces alces, roe deer Capreolus capreolus, and badger Meles meles constituted the three most important prey species, and hair from them was found in 52%, 50%, and 19% of scats, respectively. When compensating for different area/volume ratios in prey species of different size, these three species were estimated to constitute 97% of the biomass ingested. The proportions of moose, roe deer, and badger were 66%, 27%, and 8% by mass, and 25%, 52%, and 23% by number, respectively. Young-of-the-year dominated two samples of dead moose (51% of 65 killed by wolves; 43% of 155 killed by hunters), but no significant differences between the samples were found in any age class. Wolves killed significantly more female moose (76%) than hunters (53%), and among wolf-predated moose, no male was older than two years. Mean winter density of moose and roe deer in the wolf territory (523 km2), estimated by fecal pellet group counts, was 1.5 moose and 0.4 roe deer/km2. Moose density decreased slightly at the end of the study, but it was estimated that wolves killed only about 5% of the moose population each year and that this could be compensated for by a decrease of about 10–20% in the hunter kill. In spite of a high predation pressure from wolves, in addition to predation from an increasing lynx Lynx lynx population, the density of roe deer increased threefold. It is concluded that the future predation pressure on moose may be more pronounced if the density of wolves increases, and roe deer may be more affected by predation when the present favourable ecological conditions cease.
Roe deer Capreolus capreolus food and feeding habitat selection was studied by snow tracking on transects along an altitudinal gradient in Flatdal, the county of Telemark, south-central Norway, during winter 1979/80. The main food was bilberry Vaccinium myrtillus (36.8%), rowan Sorbus aucuparia (24.4%) and arboreal lichens Alectoria sarmentosa, Bryonia spp., Hypogymnia physodes, Usnea spp. (17.4%), which were also the only preferred food plants. The amount of food removed from the field layer was stable through the winter. Roe deer used the lower part of the study area most heavily. At lower altitudes, older mature stands and edges between medium-aged stands and clear-cuts/plantations were preferred, pole-sized stands and edges between older mature stands and clear-cuts/plantations were used as expected from their availabilities, whereas medium-aged stands, clear-cuts and young plantations were avoided. That snow depth was an important factor determining habitat use by roe deer was evident in three ways: 1) use of areas at higher elevations decreased as winter progressed, 2) use of mature forest stands increased from early to late winter relative to open habitats, and 3) use of mature forest stands was more extensive at higher than at lower elevations compared to open habitats.
Winter den abandonment by brown bears Ursus arctos in south-central Sweden and southeastern Norway was found to occur in 9% of 194 bearwinters, based on 68 radio-marked bears almost two years old and older. There was no statistical difference between the sexes, between adults and subadults, nor did protection from military or timber-harvesting activities reduce the rate of abandonment. Although anecdotal, observations suggest that human disturbance was a major cause of den abandonment. Most abandonment occurred early in the denning period, before mid-winter. Bears moved up to 30 km before denning again. Distance was not related to sex, age, or time of abandonment. Apparently for the first time, a fitness cost of den abandonment is documented: pregnant females that changed dens prior to parturition lost young in or near the den significantly more often than those that did not move.
This paper reports on field tests of an animal-borne GPS telemetry system for moose Alces alces in northern Sweden. Tests involved accuracy of locations (standard mode GPS), percentage of successful location attempts under different canopy conditions, effect of movement, and performance of the GPS telemetry system on free-ranging moose. Locational accuracy was better than 92 and 183 m 95% of the time, and better than 42 and 74 m 50% of the time, respectively, dependent on whether the GPS receiver recorded a 2- or 3-dimensional location (3 or 4 satellites used to calculate the location). Percentage of successful location attempts ranged within 69–100%, and varied inversely with over-storey canopy cover and basal area of stems. Thick canopy cover and high stem basal area reduced locational accuracy and the percentage of successful location attempts. A backpack trial indicated that movement rate of 3–4 km/hour may reduce the percentage of successful location attempts under forest canopy. On moose, approximately 75% of attempts resulted in a location, the success rate being highest during winter/spring and lowest during fall. It is concluded that GPS has a great potential in wildlife telemetry studies, but effects of movement and habitat selection have to be addressed further.
In order to identify inter-dive intervals in diving ducks, i.e. the time spent regaining breath between consecutive feeding dives, the position of the tail, carpal joints and head was recorded in different behavioural categories for eight species on the southwestern coast of Norway in March. Inter-dive intervals are part of the feeding behaviour and are easily confused with the behavioural categories of swimming and loafing. During inter-dive intervals the ducks adopt a more or less hunch-backed position, preparing for the next dive. In this position the tail touches the water surface and the head is held in a more forward position than during loafing and swimming. Some species expose carpal joints in inter-dive intervals, while most of the wings are covered by the flank feathers during non-feeding behaviour. Logistic regressions showed that a near perfect classification was obtained from the position of the wings alone in common eider Somateria mollissima, velvet scoter Melanitta fusca, and long-tailed duck Clangula hyemalis. An almost equally good classification was obtained for the two last mentioned on the position of the tail, for scaup Aythya marila on the position of the head, and for red-breasted merganser Mergus merganser on the position of the head and the stretching of the neck. Less reliable classifications were obtained for goldeneye Bucephala clangula and tufted duck Aythya fuligula, whereas in common scoter Melanitta nigra none of the variables fulfilled the criteria for entering a logistic regression function.