Thursday, February 2, 2017
Researchers highlight link between feral pigs , vampire bats and rabies.
Researchers highlight alarming link between feral pigs and vampire bats,according to results of a study published in the journal Frontiers in Ecology and the Environment. The number of vampire bats, which transmit rabies and are a concern for livestock breeders, may be increasing in Brazil and the Americas along with growth in the populations of invasive feral pigs and wild boars (Sus scrofa). The researchers recently reported an alarming rise in the numbers and distribution of S. scrofa, as well as showing that the common vampire bat Desmodus rotundus is now feeding on the blood of these animals. As numbers of invasive feral pigs increase, so does the damage to crops and native fauna, among other problems. S. scrofa is also a growing source of blood for vampire bats, so the population of D. rotundus is also likely to increase. Only three of the approximately 1,200 known bat species feed exclusively on blood, and all three are found only in the Americas. D. rotundus is the most widely distributed, inhabiting a territory that ranges from Mexico to Argentina. This species feeds mostly on livestock and poultry, but it has also been documented to prey on mammals such as tapirs and deer. In Brazil's Atlantic Forest biome, about 1.4% of vampire bats are infected with rabies. The proportion may be as high as 10% in the Peruvian Amazon. Transmission of rabies by vampire bats is a major concern for ranchers in Brazil, even in areas where cattle are routinely vaccinated. Wild animals, including feral pigs, are not vaccinated and may therefore pose a serious threat by spreading this disease. The researchers have used camera traps to monitor mammals in the Brazilian Pantanal and Atlantic Forest for the past 12 years. These are remotely activated infrared cameras that film at night when triggered by sensors that detect the presence of an animal. After checking 10,529 photos and videos with several examples of vampire bats feeding on feral pigs, cattle, tapirs, and red brocket deer (Mazama americana), the researchers selected 158 independent events in the Pantanal (101 with feral pigs, 38 with deer, and 19 with tapirs), and 87 events in the Atlantic Forest (35 with feral pigs, 29 with deer, and 23 with tapirs). Based on these events, they estimated that the probability of vampire bat attacks on feral pigs was as high as 10% for nights in which recordings were made.