Mercury Exposure, Fuel Stores and Torpor Use in Silver Haired Bats

Methylmercury (MeHg) is an environmental contaminant that has a high biomagnification potential with potent neurotoxic effects. Insectivorous bats may be readily exposed to MeHg through their diet. To test the effect of exposure on torpor and body composition in silver-haired bats (Lasionycteris noctivagans), I measured total mercury (THg, combination of inorganic and methylmercury) through fur samples and quantitative magnetic resonance analysis, temperature sensitive radio tags, and respirometry data from these bats to quantify body composition and torpor use. THg levels varied 20-fold with heavier and fatter bats having higher levels, suggesting that individuals that routinely eat more accumulate more THg. THg was not related to torpor use at 25 and 17°C, however, at 10°C, bats with higher THg levels used more torpor. This was characterized by fewer but longer torpor bouts. This study provides insight into the tolerance of MeHg in bats, and potential adverse effects that it may elicit.