You Scratch My Back: White-Footed Mouse (Peromyscus leucopus) Sibling Pairs Engage in Allogrooming in Response to Tick Burdens

Grooming behaviors in rodents serve multiple functions, including ectoparasite removal; however, the role of allogrooming in tick management among white-footed mice (Peromyscus leucopus) remains poorly understood. This study investigated whether blacklegged tick (Ixodes scapularis) infestation influences allogrooming behavior in sibling pairs of white-footed mice. Using laboratory-reared siblings housed in pairs, we compared allogrooming frequency and cumulative duration between tick-infested and non-infested groups across both sexes. Results demonstrated that allogrooming occurred in all sibling pairs regardless of treatment; however, infested pairs exhibited significantly higher allogrooming frequencies and spent a significantly greater amount of time allogrooming compared to non-infested pairs. Infested tick load did not significantly predict allogrooming in infested pairs, suggesting that the presence or absence rather than the number of ticks drives the allogrooming response. Tick counts declined significantly from infestation to the end of the trial in male and female mice, and overall tick attachment rates were low (mean approx. 8%). These findings suggest that allogrooming may serve as an effective ectoparasite defense mechanism in white-footed mice. Future work with larger sample sizes is needed to clarify sex-based differences in grooming patterns and their potential contribution to observed differential tick burdens among wild populations of white-footed mice.