Date of Award
Program or Major
Natural Resources and Environmental Studies
Master of Science
Peter J Pekins
ASSESSING ABUNDANCE AND QUESTING BEHAVIOR OF WINTER TICKS (DERMENCENTOR ALBIPICTUS) IN NORTHERN NEW HAMPSHIRE.
Brent Illig Powers
University of New Hampshire
Recent decline in New Hampshire’s moose (Alces alces) population is attributed to parasitism by winter ticks (Dermacentor albipictus) associated with high calf mortality and reduced adult cow productivity. Research has focused mainly on moose (host) population dynamics with minimal study of abundance and distribution of winter ticks (parasite) on the landscape. Importantly, tick location is dictated by where ticks drop from moose in April, when they principally forage in regenerating forest. This research was designed with 4 primary objectives: 1) measure and compare larval abundance in 2 types of regenerating forest habitat (clear-cuts and partial harvests), 2) measure and compare larval abundance on 2 transects types (random and high-use) within the 2 cut habitat types, 3) estimate the length of the larval questing period, and 4) measure the microclimate within cut habitats to evaluate conditions associated with termination of the larval questing period. Ticks were not evenly distributed within preferred habitat as larvae were collected on 50.5% of all transects combined; proportionally, 57.5% of transects in clear-cuts and 44.3% in partial cuts had larvae. The average abundance (by cut and transect types) ranged from 0.11-0.36 ticks/m2, similar to that measured in 2008-2009 when moose density was 40% higher; however, the maximum values in individual cuts were up to 10x higher than those measured earlier. Abundance was highest on high-use transects and in partial cuts. No difference in abundance was found between cut or transect type when eliminating tickless transects. Abundance or weekly collection rate was stable until the onset of temperatures < 0 0C and multiple days of snow cover, after which abundance decreased in all cut and transect types except high-use transects in partial harvests. Questing slowed during an initial snow of ~15 cm in late October but resumed on these transects during a warmup indicating the relative hardiness of larvae; it terminated permanently at the onset of permanent snow cover and prolonged cold in early November. The higher abundance of winter ticks in partial harvests suggest that moose may prefer or spend proportionally more time in partial harvests than clear-cuts. Predicting the final infestation rate on moose is theoretically possible by relating the stable collection rate, infestation level of moose harvested in late October, and length of the questing period.
Powers, Brent Illig, "Assessing the Relationships of Winter Ticks, Weather and a Declining Moose Population in Northern New Hampshire" (2019). Master's Theses and Capstones. 1330.