Tick development on sexually-active bull moose is more advanced compared to that of cow moose in the winter tick, Dermacentor albipictus

Abstract We performed a complete survey of ticks on 100 cm 2 skin samples collected from 30 moose Alces harvested in 2017 in central and northern Maine, U.S.A. The samples were collected from 15 bulls, 13 cows, and 2 calves in mid-October when moose are breeding and winter ticks Dermacentor albipictus quest for a host moose. We identified only winter ticks with 99.2% in a juvenile stage; 3 adult ticks were found. Unfed nymphs were most common on bulls, whereas most ticks were fed larvae on cows and calves. The average abundance (density) on bull samples was 21 ± 4.4 (range = 0–55) and higher than on cows (8 ± 1.5). Unlike previous surveys, tick abundance was lowest on calves. Tick density was independent of age or weight of adult moose. The higher abundance and more rapid development of winter ticks on adult bulls likely reflects the seasonal influence of increased movements and hormonal cycles associated with reproduction. Specifically, the high density of unfed nymphs on breeding bulls could reflect their high testosterone production, a known attachment stimulant and phagostimulant of ticks.