SELECTIVE HABITAT USE BY MOOSE DURING CRITICAL PERIODS IN THE WINTER TICK LIFE CYCLE

Abstract

High calf mortality attributed to winter tick (Dermacentor albipictus) parasitism occurs in moose (Alces alces) populations along their southern range in the northeastern United States. We analyzed habitat use of cow and calf moose during the critical drop-off and questing periods in the winter tick life cycle to determine a potential relationship between tick density and habitat. We measured habitat use using geospatial analyses of locational data from > 200 radio-marked animals at 3 sites in New Hampshire and Maine. Moose selected for optimal habitat, defined as 4–16 year-old forest openings, regardless of season or site; this was the only land cover type used more than available (1.1–2.1X availability in home range, 1.2–3.1X availability in core range). Further, the proportional availability of optimal habitat within overlapping portions of seasonal home and core ranges exceeded the absolute proportion of optimal habitat within any one range. Temporal use of optimal habitat, which is available in relatively low proportion (15–20%) across the landscape, likely exceeds the geospatial estimates of use because moose spend 30–40% of daily activity foraging. We conclude that disproportionally abundant densities of winter ticks exist in this preferred cover type because of its selective use during the drop-off and questing periods of winter ticks.

Keywords

• Alces alces
• Dermacentor albipictus
• GIS
• home range
• Maine
• New Hampshire
• optimal habitat
• questing