Alexander Archipelago Wolves: Ecology And Population Viability In A Disturbed, Insular Landscape

Abstract

The Alexander Archipelago wolf (Canis lupus ligoni) occupies Southeast Alaska, a region undergoing intensive harvest of timber. Sitka black-tailed deer (Odocoileus hemionus sitkensis) are the primary prey of these wolves. We conducted a telemetry study of 23 wolves on Prince of Wales and adjacent islands in Southeast Alaska between September 1992 and October 1995. We examined home range, habitat use, reproduction, mortality, and dispersal of wolves in logged landscapes and those that were relatively unlogged. We used those data to parameterize a wolf-deer model to predict long-term effects of timber harvest on the wolf-deer system on Prince of Wales and adjacent islands. Home ranges of 7 wolf packs averaged 259 km2 in winter but only 104 km2 during pup-rearing season (15 April--15 August). Home-range size was positively correlated to pack size, and area per individual wolf was inversely related to the proportion of winter habitat for deer within the home range. Radiocollared wolves were classified as residents, extraterritorials, and dispersers. Annual mortality was 64% for extraterritorial and dispersing wolves and 31% for residents. Eighty-two percent of mortality was human caused. Radiocollared wolves were located mostly at low elevations (<250 m) regardless of time of year, and selected for old-growth forest habitat during pup-rearing season. Wolves generally avoided second-growth forests and clearcuts, and their use of those habitats occurred mostly at night. Density of roads was positively correlated with rate of harvest of wolves. Simulations from our wolf-deer model indicated that deer and wolf populations on Prince of Wales and adjacent islands likely have declined since initiation of industrial-scale logging. Nonetheless, risk that the population of wolves will no longer be viable is low. Our predictions indicate that deer will decline disproportionately to decline of carrying capacity (K). Thus, a small change in K may precipitate large, long-term changes in deer numbers. The most important management strategy for the conservation of wolves in Southeast Alaska is to maintain high-quality habitat for deer. We believe that managing human access by closing roads for motorized use and limiting construction of new roads are also measures necessary to conserve wolves.