According to a new paper mice appear indifferent to larval tick infestations. Moreover, the ticks do not seem to affect the health of a mouse. The study looked at
white-footed mice with hundreds of larval ticks and found that they survived just as long as those with only a few ticks. Surprisingly, male mice with large tick loads were more likely to survive during a given season.
The findings are based on an analysis of 5,587 studies recorded between 1995 and 2011. Every 3-4 weeks, from the peak of
larval tick activity in midsummer until the end of the mouse breeding season in fall, mice were trapped. On their first capture, animals were outfitted with ear tags. Each time a mouse was trapped researchers recorded the number of ticks on the animal, as well as other variables like its tag ID and sex.
As to why the ticks do not make a mouse ill, the authors think that the host-parasite relationship could be ideal. Some ideas are: habitat most conducive to mouse survival (that is dense vegetation) may also favor ticks, dominant mice with large home ranges may encounter more ticks, and mice with heavy tick burdens may exhibit more risk-averse behavior.
The research was carried out by the Cary Institute of Ecosystem Studies in Millbrook, New York. The findings have been
published in the journal
Ecology, in a paper titled “When is a parasite not a parasite? Effects of larval tick burdens on white-footed mouse survival.”
