Population Changes in Bats from Central Arizona: 1972 and 1997


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December 1999


Prompted by concern about declining bat populations in the southwestern United States, we surveyed for changes in populations between 1972 and 1997 at a study area in central Arizona. We duplicated earlier searches of ancient Indian dwellings and crevices in surrounding cliffs for diurnally roosting bats during the time of year when maternity colonies should have been present, and repeated mist-netting to capture bats in flight along the cliffs at night. Antrozous pallidus was gone. A maternity colony of Myotis velifer no longer existed. Tadarida brasiliensis was rare in 1997 compared to 1972; aggregations of Myotis yumanensis seen in 1972 were missing in 1997. Breeding Corynorhinus townsendii were found in 1997, but were unknown at this location in 1972. Small numbers of Eptesicus fuscus, Myotis californicus, and Pipistrellus hesperus occupied the site in both 1972 and 1997. Additionally, museum records show that most of the bats we documented at this site also were present in 1931. Surrounding habitat did not appear substantially different between 1972 and 1997, and a reconstruction of possible impacts from bat biologists did not suggest that researchers caused the local extinctions we document. The most obvious change over 25 years was a dramatic increase in recreational use of the area. We believe that disturbances associated with recreationists resulted in the observed population changes, primarily through roost abandonment. /// Por preocupación por la disminución poblacional de los murciélagos en la región suroeste de los Estados Unidos, monitoreamos los cambios poblacionales entre 1972 y 1997 en un área de estudio en Arizona central. Repetimos las búsquedas anteriores en antigüas moradas de indígenas americanos y en cuevas de acantilados aledaños para murciélagos en dormideros durante el tiempo del año cuando las colonias de maternidad deberían haber estado presentes, y repetimos la captura con redes de malla de los murciélagos en vuelo a lo largo de los acantilados durante la noche. Antrozous pallidus no


Bats, Cliffs, Grottos, Mammalogy, Depopulation, Population Ecology, Vegetation Structure, Wildlife Conservation

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The Southwestern Naturalist, Vol. 44, no. 4 (1999-12-01).