• Ecology of a reestablished population of muskoxen in northeastern Alaska

      Reynolds, Patricia Claire Embry (1998)
      The restoration of muskoxen (Ovibos moschatus) to regions of former range in northeastern Alaska presented an opportunity to study population dynamics, seasonal patterns, and dispersal in an expanding population of ungulates. Muskoxen were returned to the Arctic National Wildlife Refuge (Arctic NWR) in 1969-70 after an absence of $>$100 years. In 1982-97, I used annual censuses, counts by sex and age, radio and satellite telemetry, and data from Landsat-TM maps to determine rates of population growth, changes in production, survival, and group size over time, seasonal habitat use, activity patterns, and dispersal of mixed-sex groups. In 1982-86, mixed-sex groups of muskoxen occupied the same regions as in 1977-81, but annual rates of increase and calf production declined (1977-81: rate = 0.24, 87 calves/100 adult females; 1982-86: rate = 0.14, 61 calves/100 adult females). In 1987-95, numbers of muskoxen in regions first occupied declined and stabilized at $<$300 animals as calf production continued to decline and mixed-sex groups dispersed into unoccupied regions. Survival of calves and yearlings did not decline over time. By 1995, about 800 muskoxen were distributed between the Itkillik River west of Prudhoe Bay, Alaska, and the Babbage River in northwestern Canada. In summer, female muskoxen occupied large core areas $(\bar x=223$ km$\sp2),$ and had high rates of movement $(\bar x=2.6$ km/day) and activity $(\bar x=18.9$ counts/min). In winter muskoxen remained in small core areas (mid-winter $\bar x=25$ km$\sp2)$ and reduced movements (mid-winter $\bar x=1.4$ km/day) and activity (mid-winter $\bar x=11.8$ counts/min.) possibly as a strategy to conserve energy. Muskoxen selected (use $>$ availability) riparian and moist sedge vegetation along rivers in all seasons. Dispersal of mixed-sex groups occurred infrequently through periodic pulses. Population density likely influenced patterns of dispersal through social interactions and habitat change. Weather conditions that affected the length of the growing season and availability of winter forage were major factors in the dynamics, distribution, and dispersal patterns of this reestablished population of muskoxen.