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In December 1999 a female hoary bat (Lasiurus cinereus) was found in Ontario. The bat, which was kept in captivity from then on, showed signs of distress resembling abortion in late April 2000. Autopsy revealed the presence of two foetuses in the uterus, a male at the latest stage of development and a smaller dead one. The latter stopped development at an earlier stage and was most likely being resorbed, probably due to deficiencies in the female's diet. Mating leading to this pregnancy must have occurred in autumn, likely before the onset of migration.