Natural History of the Vampire Bats of Eastern Mexico

Abstract

Vampire bats of two species range throughout eastern Mexico from the southern limits of the republic northward to approximately 175 miles from the United States boundary. The common vampire, Desmodus rotundus murinus Wagner, is a common to abundant bat almost wherever it is found. The hairy-legged vampire, Diphylla ecaudata centralis Thomas, is one of the rarer North American bats but seems to reach its maximum abundance in eastern Mexico. These disgusting but nevertheless interesting mammals do great damage to livestock and attack human beings on occasions. Domestic animals are weakened and sometimes die from loss of blood from the wounds inflicted by vampires, while the open wound's are a common site of infection by bacteria and parasitic insect larvae such as screw worms. Vampires are potential vectors of disease also. They are known to transmit rabies and some cattle diseases in Panama, Trinidad, and South America, and such communicable diseases as the hoof-and-mouth disease might easily be spread by vampires. In the British West Indies an intensive campaign has been carried out in an effort to rid the island of Trinidad of these da-igerous animals; The writer is convinced that a similar campaign must soon be undertaken in Mexico. The following report, which may assist in such a campaign, is based on several years of field work in eastern Mexico, during which period approximately ten thousand vampires were examined. In the uninhabited jungles of extreme southern Veracruz I found no vampires, although conditions, except for the absence of domestic animals, seemed to be ideal for these bats. Along the Rio Coatzacoalcos, at the northern edge of the uninhabited area, where people, horses, cattle and burros are again found, vampires again were encountered. Large game animals are abundant in the uninhabited area, but none of the many specimens taken showed evidence of vampire predation. Probably vampires were rare to uncommon in eastern Mexico in prehistoric times, but the arrival of domestic animals accompanying the conquest of the country by Europeans presented the existing vampires with a constantly increasing food supply in the relatively helpless burros, horses, and cattle. The common vampire breeds throughout the year, is extremely shy, is probably safe from most predators in the caves, it inhabits, is remarkably hardy, and has now increased in numbers until it is one of the commonest and most widespread mammals in eastern Mexico. It is adaptable enough to live in hollow trees and the structures of man and to live on the arid deserts as well as in the tropics. It is principally, perhaps almost entirely, dependent on domestic animals for food at the present time and may even attack man.