This is a list of bat species by global population. While numbers are estimates, they have been made by the experts in their fields. For more information on how these estimates were ascertained, see Wikipedia's articles on population biology and population ecology.
This list is not comprehensive, as not all bats have had their numbers quantified.
Common and widespread until the 1980s. Population here was recorded in January 2009. An immediate capturing project was requested to save the species, and efforts for approval included a personal meeting with then-Australian environment minister Peter Garrett. Due to a potential cost of a few hundred thousand dollars, the government decided against quick action and instead undertook a bureaucratic feasibility study. After its eventual assent in August 2009 a team of experts travelled to Christmas Island to capture the remaining individuals but only one was detected, which managed not to be caught. Its subsequent disappearance may be one of very few times extinction has been witnessed first-hand. Reasons for the bat's decline remain unknown.
^ abcdLumsden, L., Racey, P.A. & Hutson, A.M. (2010). "Pipistrellus murrayi". IUCN Red List of Threatened Species. Version 2012.2. IUCN. Retrieved 2012-11-20.
^Tim, Flannery (17 November 2012). "Unmourned death of a sole survivor". The Sydney Morning Herald. Retrieved 2012-11-21. In an attempt to avert it I met Peter Garrett, then the environment minister, and warned him of the impending loss. I had brought offers of assistance and expertise from the Australian Mammal Society to his attention. The society was confident the species could be saved - at a cost of perhaps only a few hundred thousand dollars. But Garrett was convinced by the orthodoxy that ecosystems rather than species should be the focus of the national conservation effort, and I got the message that nothing would be done.
^ abcdDávalos, L. & Mancina, C. (2008). "Natalus primus". IUCN Red List of Threatened Species. Version 2012.2. IUCN. Retrieved 2012-11-20.
^ abcdGerlach, J., Mickleburgh, S., Hutson, A.M. & Bergmans, W. (2008). "Coleura seychellensis". IUCN Red List of Threatened Species. Version 2012.2. IUCN. Retrieved 2012-11-20.
^ abcdHutson, T., Helgen, K., Flannery, T. & Wright, D. (2008). "Aproteles bulmerae". IUCN Red List of Threatened Species. Version 2012.2. IUCN. Retrieved 2012-11-20.
^ abcdArroyo-Cabrales, J., Álvarez-Castañeda, S.T., S., Cuarón, A.D. & de Grammont, P.C. (2008). "Myotis planiceps". IUCN Red List of Threatened Species. Version 2012.2. IUCN. Retrieved 2012-11-20.