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Much maligned, vultures now missed as Asia populations collapse

June 26, 2012
Courtesy of the Wildlife Conservation Society
and World Science staff

Cam­bo­dia is a last bas­ti­on of vul­tures in Asia as po­pul­ati­ons of the much-mal­igned bird are col­laps­ing, con­serv­ati­on­ists are re­port­ing.

Sci­en­tists blame the deaths on the spread in the en­vi­ron­ment of a vet­er­i­nary drug for cat­tle, di­clo­fe­nac, which is poi­son­ous to vul­tures.

Vultures in Cambodia. (Credit: A. Michaud)


In a new stu­dy, re­search­ers with the Cam­bo­di­an gov­ern­ment, the U.S.-based Wild­life Con­serv­ati­on So­ci­e­ty, and oth­er groups pro­pose meas­ures to pro­tect Cam­bo­di­an vul­tures. These in­clude the cre­ati­on of feed­ing stati­ons, or vul­ture “restau­rants” and restor­ati­on of popul­ati­ons of de­plet­ed prey spe­cies. The pa­per ap­pears in the on­line edi­ti­on of the jour­nal Bird Con­serv­ati­on In­tern­ati­onal.

In and near Cam­bo­dia, “re­sults from vul­ture cen­sus­es from the past sev­er­al years have been en­cour­ag­ing, with new nests recorded and even popul­ati­on in­creas­es,” said the Wild­life Con­serv­ati­on So­ci­e­ty’s Tom Clements, lead au­thor of the new pa­per. “With con­tin­ued in­vest­ment, these crit­i­cal popul­ati­ons can sur­vive and grow.”

With their hab­it of scav­eng­ing dead an­i­mals, their some­times off-put­ting looks, and a name that’s al­most syn­on­y­mous with the idea of prof­it­ing from mis­ery, vul­tures have rarely en­deared them­selves to hu­mans. But they pro­vide an ec­o­log­i­cal and pub­lic serv­ice by help­ing to clean up an­i­mal car­casses.

In the stu­dy, which be­gan in 2004, the au­thors col­lect­ed da­ta from sev­er­al sites in Cam­bo­dia, La­os and Vi­et­nam through a va­ri­e­ty of meth­ods, in­clud­ing mon­i­tor­ing of vul­ture nest­ing sites and feed­ing stati­ons; health as­sess­ments of vul­tures; in­ter­views with gov­ern­ment of­fi­cials, hunters, and wild­life traders to col­lect da­ta on threats; and sat­el­lite trans­mit­ter vests on four birds to as­sess rang­ing pat­terns.

The find­ings: while Cam­bo­di­a’s vul­ture popul­ati­ons re­main ro­bust, the use of poi­son by hunters and fish­ers for cap­tur­ing oth­er spe­cies are lead­ing to un­in­tend­ed vul­ture deaths. Ac­cord­ing to the da­ta, 74 per­cent of the 42 recorded mor­tal­i­ties dur­ing the study pe­ri­od were at­trib­ut­a­ble to poi­son. Di­rect at­tacks against vul­tures ac­counted for 10 per­cent of recorded vul­ture mor­tal­ity.

Vul­tures have faced dis­as­ter across Asia due largely to the vet­er­i­nary drug di­clo­fe­nac, sci­en­tists say. Used as an an­ti-in­flam­ma­tory, di­clo­fe­nac kills the birds that feed on the cat­tle car­casses, caus­ing kidney fail­ure and vis­cer­al gout. It has led to a glob­al popul­ati­on de­clines high­er than 99 per­cent in some vul­ture spe­cies, ac­cord­ing to re­search­ers.

Cam­bo­di­an vul­tures have been spared be­cause di­clo­fe­nac is not used in the ar­ea, but they are still vul­ner­a­ble as they are largely de­pend­ent on do­mes­tic an­i­mals for food; their wild trad­i­tion­al prey, including gaur and Eld’s deer, are thin in num­bers.

“For­tu­nately, the Roy­al Gov­ern­ment of Cam­bo­dia has in­sti­tut­ed meas­ures to ban di­clofenac to en­sure the sur­viv­al of these im­por­tant birds,” said Joe Wal­ston, Di­rector of the society’s Asia Pro­gram. “The chal­lenge now is to re­duce the in­di­rect and di­rect per­se­cu­ti­on of vul­tures, spe­cif­ic­ally from poi­soning and shoot­ing, and longer-term pres­sures from hab­itat loss.”

The slender-billed vul­ture, white-rumped vul­ture, and red-head­ed vul­ture are all list­ed as “Critic­ally En­dan­gered” by the Swiss-based In­tern­ati­onal Un­ion for Con­serv­ati­on of Na­ture.


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Cambodia is a last bastion of vulture populations in Asia as populations of the much-maligned bird are collapsing, conservationists are reporting. Scientists blame the deaths on the spread in the environment of a veterinary drug for cattle, diclofenac, which is poisonous to vultures. In a new study, researchers with the Cambodian government, the U.S.-based Wildlife Conservation Society, and other groups propose measures to protect Cambodian vultures including the creation of new feeding stations, or vulture “restaurants” and restoration of populations of depleted wildlife species. The paper appears in the online edition of the journal Bird Conservation International. In and near Cambodia, “results from vulture censuses from the past several years have been encouraging, with new nests recorded and even population increases,” said the Wildlife Conservation Society’s Tom Clements, lead author of the new paper. “With continued investment, these critical populations can survive and grow.” With their habit of scavenging dead animals, their sometimes off-putting looks, and a name that’s almost synonymous with the idea of profiting from misery, vultures have rarely endeared themselves to humans. But they provide an important ecological and public service by helping to clean up animal carcasses. In the study, which began in 2004, the authors collected data from several sites in Cambodia, Laos and Vietnam through a variety of methods, including monitoring of vulture nesting sites and feeding stations; health assessments of vultures; interviews with government officials, hunters, and wildlife traders to collect data on threats; and satellite transmitter vests on four birds to assess ranging patterns. The findings: while Cambodia’s vulture populations remain robust, the use of poison by hunters and fishers for capturing other species are leading to unintended vulture deaths. According to the data, 74 percent of the 42 recorded mortalities during the study period were attributable to poison. Direct attacks against vultures accounted for 10 percent of recorded vulture mortality. Vultures have faced disaster across Asia due largely to the veterinary drug diclofenac, scientists say. Widely used as an anti-inflammatory drug for cattle in South Asia, diclofenac is toxic to vultures, causing death through renal failure and visceral gout to birds that feed on the cattle carcasses. It has led to a global population declines higher than 99 percent in some vulture species, according to researchers. Cambodian vultures have been spared because diclofenac is not used in the area, but they are still vulnerable as they are largely dependent on domestic animals for food, as populations of wild species such as gaur and Eld’s deer remain low. “Fortunately, the Royal Government of Cambodia has instituted measures to ban diclofenac to ensure the survival of these important birds,” said Joe Walston, Director of WCS’s Asia Program. “The challenge now is to reduce the indirect and direct persecution of vultures, specifically from poisoning and shooting, and longer-term pressures from habitat loss.” The slender-billed vulture, white-rumped vulture, and red-headed vulture are all listed as “Critically Endangered” by the International Union for Conservation of Nature.