New Research Questions Invasive Bird Introduction to Manage Tick Populations in Turkey
As Turkey raises and releases thousands of non-native helmeted guineafowl (Numida meleagris) to eat ticks that carry the deadly Crimean-Congo hemorrhagic fever virus, new research suggests guineafowl actually eat few ticks, carry the parasites on their feathers, and further spread the disease.
"It took me only three hours of literature search and quick scan of the abstracts of some 60 papers in the Web of Science to see that guineafowl hardly ate any ticks in their environment and in fact carried many more," Çağan Şekercioğlu, assistant professor of biology at the University of Utah, told mongabay.com.
In his new paper, the third-most downloaded in the journal Trends in Parasitology, Şekercioğlu explains that the idea guineafowl eat Dermacentor reticulatus ticks and control the disease is based on evidence from a 1992 study suggesting that birds could control ticks that carry Lyme disease in the United States.
Crimean-Congo hemorrhagic fever is a tick-borne virus, which according to statistics compiled by Şekercioğlu has infected 6,392 people and killed 322. With cases of the disease dropping in 2011, some officials proclaimed the guineafowl program a success. However, wild ground-feeding birds serve as hosts for Hyalomma marginatum ticks, the most efficient and common vectors of Crimean-Congo hemorrhagic fever, magnify the virus, and help to transmit the disease.
"They should stop these introductions immediately because there is a risk they may be doing the opposite of what they intended," warned Şekercioğlu in a recent press release. "They want to stop this disease, but they may be helping spread it."
For example, of the 39 bird species examined for ticks in South Africa, guineafowl were the most infested with marginatum ticks infesting 70 percent of the birds examined.
"I had warned the government three times since May 2011 not to introduce these animals, but I was ignored... my opinion was never sought before the releases began. My understanding is that a government employee saw a web site talking about how guineafowl are good at eating ticks", said Şekercioğlu. A conservationist and ecologist actively working in Turkey with local NGO KuzeyDoga, Şekercioğlu's wildlife research has received government support.
Not only are guineafowl unlikely to reduce disease-carrying ticks significantly in rural Turkey, but also introducing an exotic species without detailed studies often has negative ecological consequences, said Şekercioğlu in his forthcoming paper. For example, cane toads were introduced to Australia to eat French's cane beetle and the Greyback cane beetle.
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Helmeted guineafowl image via Shutterstock.