Significant changes in local climate and correlated changes in non mammalian vertebrate populations have been documented in the Monteverde cloud forest in the Tileran Mountains of northern Costa Rica, leading to the prediction that corroborative changes should occur in bat populations. Habitat changes resulting from development for ecotourism, including a 19% increase in forest, might also be expected to impact bat populations. Analysis of data collected between 1973 and 1999 in Monteverde supports the hypothesis, although changes are less dramatic than those shown for birds, reptiles, and amphibians in earlier studies. Capture rates did not change significantly during the 27 year sample period, but relative species abundance increased, and at least 24 new species (of mostly lowland distribution) were recorded in the study area during the 1980s, 1990s, and through early 2002. These changes are likely a consequence of climatic change following global warming, forest clearing, and an increase in amount of secondary forest. This latter factor is a result of changes in land use due to development for tourism.