Record Details
Ecology of moose on the Copper River Delta, Alaska
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Ecology of moose on the Copper River Delta, Alaska |
| Names |
MacCracken, James Gray
(creator) |
| Date Issued | 1992 (iso8601) |
| Note | Access restricted to the OSU Community |
| Abstract | Moose (Alces alces gigas) were introduced to the copper River Delta with a series of translocations of 23 calves from 1949-58. The population grew rapidly and a hunting season was initiated in 1960. The great earthquake of 1964 uplifted the delta resulting in changes which, presumably, increased the amount of high quality habitat for moose. The population continued to grow and expand their range to the southeast. The severe winter of 1971-72 resulted in the loss of about 15-20% of the moose population on the west Copper River Delta and since that time, the west and east Delta herds have been maintained at about 250 animals each through a combination of registration and/or limited permit hunts. The ecology of moose on the west Copper River Delta was intensively studied from March 1987-July 1989. Mean home range size was not different among seasons (winter, summer), sex, or areas (west and east deltas). Mean (SE) home range size was 58.8(4.8) km². About 50% of collared females were seasonally migratory with distinct winter and summer home ranges. Only 20% of collared males were migratory. Snow depths influenced moose movements and distribution and varied among years, areas, and habitat types. Calf production averaged >1 calf/female, but survival was low with an average recruitment rate of 30 calves/100 females. Calf mortality was associated with inclement spring weather and predation by brown bears (Ursus arctos). Most adult mortality was due to legal harvest with accidents and starvation (due to severe jaw necrosis) accounting for the rest of adult moose mortality. Antler characteristics of Copper River Delta moose suggested a founder effect of the translocation, and/or a genetic "bottleneck" created when approximately 83% and 63% of breeding males were harvested in 1960 and 1962, respectively. The retention of pedicle bone on some cast antlers suggested a mineral imbalance in the diet associated with foraging in an aquatic habitat. Telemetry studies indicated that 5 habitat types (plant communities) were most important to moose and that use of those habitats varied among years, seasons, and sex. Open tall alder-willow (Alnus sinuata-Salix spp ..), closed tall alder-willow, and low sweetgale-willow (Myrica gale-Salix spp.) habitat types were used the most; woodland spruce (Picea sitchensis) and aquatic (wet forb herbaceous) types were used relatively less. Aquatic and sweetgale-willow habitat types were used primarily for feeding. Closed tall alder-willow and woodland spruce habitats were used primarily for bedding, with open tall alder-willow stands used equally for both activities. Moose calved primarily in closed tall alder-willow and upland low sweetgale-willow habitats with low soil moisture and a closed canopy. Habitat selection by moose was examined at 2 levels. Moose selected areas (home ranges) that contained proportionately more aquatic and low sweetgale-willow habitats than were available on the west Copper River Delta. However, within their home range, moose selected for the open tall alder-willow habitat and used aquatic and low sweetgale-willow habitats significantly less (P < 0.0001) than their availability. An ordination of the 5 habitat types emphasized the importance of moisture regimes and stand age in habitat characteristics. The positioning of woodland spruce stands along the ordination axes was related to their understory composition suggesting that this habitat type was an extension of either low sweetgale-willow or closed tall alder-willow habitat types. Moose food habits were determined by fecal and rumen analyses. Cluster analysis of data from monthly fecal collections resulted in 3 groups representing winter, spring/early-summer, and late-summer/fall diets. Willows (S. barclayi, S. sitchensis) were the primary forage of moose year-round. The addition of sweetgale and alder during winter was significant. spring/early-summer diets included aquatic herbs, while late-summer/fall diets were mostly willow leaves. Digestible protein, digestible dry matter, and ash content were greatest for aquatic herbs, followed by the leaves and current annual growth twigs of browse, then older twigs. The bark of browse was low in digestible protein, but significantly greater in digestible dry matter and ash than browse leaves and twigs. Forage quality was greater in spring and summer than fall and winter. Emergent aquatic herbs had elevated levels of a number of minerals including iron, magnesium, sodium, phosphorous, and fluoride (FI). The bark of browse had the greatest concentrations of calcium and Fl. Current annual growth. twigs of some browse species had the greatest manganese and copper levels. Forage standing crop and production (kg/ha) varied by species and habitat type with use estimates generally below 15% of available mass. Alder was the most productive species, but lightly used by moose. Available mass and production of willows was similar among areas and habitat types on the west Copper River Delta. Excluding the aquatic habitat, alder-willow stands were the most productive and had the greatest available browse mass. Aquatic habitats were 3.5 x more productive than terrestrial habitats with peak use occurring from May-August. Results of this study suggest that managers should consider expanding the closure of the moose winter range to off-road vehicles to an area north of the Copper River highway. However, the assumptions underlying this policy need further consideration. Managers should also consider expanding the boundary of Management unit 6C to include areas currently in 6B that are used during the fall by moose that winter in 6C. The moose population on the west Copper River Delta was below habitat carrying capacity, based on food availability, and could probably be increased. Habitat selection patterns observed in this study were not confounded by density and reflected actual preferences. Increased moose density on the west Copper River Delta could change habitat selection patterns, but habitat types identified as preferred in this study would remain so, and habitat manipulation programs based on the results of this study will remain appropriate at higher densities. |
| Genre | Thesis |
| Topic | Moose -- Ecology -- Alaska -- Copper River Delta |
| Identifier | http://hdl.handle.net/1957/33069 |
