Foraging of vampire bats (<i>Desmodus rotundus</i>) in Atlantic wet lowland Costa Rica

Abstract

Extensive observations of the foraging activity of vampire bats (Desmodus rotundus) were conducted for eleven successive months at one locality in Atlantic wet lowland Costa Rica. This study period included parts of two wet seasons and one entire dry season. Data were obtained on nightly departures and returns of individual vampires at two roosting sites in order to estimate the amount of time spent away from roosts during the wet and dry seasons. Several individuals from these roots were marked (using different colored aluminum bands for different roosts) and nightly data were also obtained on their Occurrence, along with many unmarked individuals, attaching themselves to cattle (prey) inhabiting three nearby pastures. From these two series of observations, it was found that (i) vampires exploit local cattle populations for blood; (ii) vampires invariably return to the same roosts every night after foraging; (iii) vampires spend more time attached to their prey animals during the dry season than they do during the wet season, and (iv) presumably more blood is actually ingested during the dry season. A brief study of homing ability demonstrated that vampires can return to their original roosting sites from as far away as 10 to 18 miles.