Pedersen, S.P.: The impact of volcanic eruptions on the bat populations of Montserrat, BWI.

Hurricanes and volcanic eruptions have had significant impacts upon the bat populations of Montserrat, underlined by the loss of 3 of its 10 species:Chiroderma, Sturnira, Noctilio. Seven surveys have documented population decreases following Hurricane Hugo in ’89 and the Soufriere Hills volcano since ’95. Apart from the minor inconvenience of being incinerated by pyroclastic flows (500 C), the fruitbats of Montserrat have contended with acid rain, the deposition of volcanic ash on fruits/flowers (and its subsequent ingestion), and the accumulation of ash on the animals pelage whilst foraging. Volcanic activity has declined during the last two years. and fruitbat populations have rebounded slightly as estimated by bat captures per net-night. There was a focal increase in sub-lethal pathologies associated with ash-fall during peak volcanic activity (95-98). Before the onset of activity, 3/641 (< 1%) fruit bat captures exhibited tooth wear. Since 1995, 35/190 (18%) fruit-bats exhibited abnormal wear and/or dental attrition. Occlusal surfaces of remaining teeth exhibit abnormal wear, advanced dramatically by the incidental ingestion of volcanic ash while feeding and grooming. Idiopathic hair-loss (alopecia) had only been observed once in 638 captures before '95. Alopecia was frequently (30-60%) recorded for all Brachyphylla, Artibeus, and Ardops in ’97-’98. This alopecia is likely related to roost-parasitism, and possible mineral deficiencies associated with ash ingestion. During 2000, alopecia was noted only in female Brachyphylla. Our survey of the adjacent island of Antigua provides an interesting control for the biogeography and natural history of Montserratian bats. Antigua has not been affected by volcanic ash, nor have our survey efforts identified a single case of alopecia or extreme tooth wear.