Global parrot trade spreads deadly virus, threatens endangered parrots everywhere
A deadly virus that plagues parrots, destroying their feathers and immune systems, has recently been detected in eight countries where it was previously unknown, raising concerns for the long-term conservation of this threatened group of birds
by GrrlScientist for Forbes | @GrrlScientist
NOTE: originally published under this title: “Global Parrot Trade Threatens All Endangered Parrots By Spreading Deadly Virus”
Parrots are popular pets, but this popularity comes with a steep price. They are amongst the most threatened group of birds (ref), and they are amongst the most frequently traded birds that are listed as threatened by the Convention on International Trade in Endangered Species (CITES) (ref). The pet trade alone has driven international movements of more than 19 million parrots since 1975 (ref). Predictably, some of these parrots escape or are released into the wild, and sometimes, these introduced parrots establish breeding populations, often to the delight of local residents.
One species that has become widely established outside its natural range is the rose-ringed parakeet, Psittacula krameri, a handsome medium-sized parrot that also happens to be highly invasive; having established breeding populations in 35 countries on five continents (PDF and ref), including several regions in the United States.
Like all animals, parrots have their own collection of pathogens to which they are susceptible, but one of the most deadly is the virus that causes psittacine beak and feather disease (PBFD). Infection by beak and feather disease virus (BFDV) often causes feather abnormalities and loss and occasional, but severe, beak and claw deformities combined with immune suppression, rendering infected parrots susceptible to a variety of secondary illnesses to which they would otherwise be resistant. Juvenile parrots are particularly susceptible, often dying suddenly shortly before fledging. Because of its powerful immunosuppressive effects, I think of BFDV/PBFD as “parrot HIV/AIDS”. Basically, BFDV can devastate avicultural and captive breeding programs and cause tremendous distress to new parrot owners, not to mention their young birds.
To date, BFDV or PBFD have been recorded in 78 parrot species and five subspecies (ref) and has been reported in captive parrots in at least 33 countries. Its remarkable spread may have been expedited by the global trade in live parrots as well as its high transmission rate between closely related species and the virus’s exceptional durability in the environment. The virus is most common in captive-bred parrots, particularly cockatoos, whereas it occurs in a very few wild populations outside Oceania, where BFDV is thought to have originated.
At this time, no one was quite sure how far BFDV/PBFD has spread amongst wild parrot populations, particularly in regions where many species of parrots naturally occur, but it does represent an indisputable global biosecurity concern that stems from the pet trade. This prompted Deborah Fogell and her collaborators to investigate. Ms. Fogell has a Masters’ degree from the University of Kent, where she studied how providing supplementary food facilitates transmission of diseases amongst endangered species that depend upon this resource. Supplemental feeding is a widespread conservation tool, and is often used to aid species recovery whilst other factors, such as restoration of damaged habitat, are addressed.
Ms. Fogell and her collaborators’ recently published study was designed to clarify our understanding of where in the world BFDV/PBFD can be found in wild or free-flying parrot populations, and to track how arrived. To do this, they focused their energies specifically on the highly traded and invasive rose-ringed parakeet, commonly known in aviculture as the ring-necked parakeet, an invasive species that continues to spread globally. The researchers collected blood, feather, and tissue samples and genetically screened them for the presence of BFDV (Figure 1).
Ms. Fogell and her collaborators detected BFDV in eight countries where it was previously unrecognized, including Bangladesh, Pakistan, Japan, Nigeria, Seychelles, Vietnam, Senegal and The Gambia, and also they documented the presence of this virus in wild populations of ring-necked parakeets within the species’s natural range in Asia and Africa.
They found that all parrots screened for BFDV from Bangladesh and The Gambia were infected, but they did not detect the virus in the threatened Seychelles black parrot or Praslin parrot, Coracopsis barklyi, in the Seychelles nor in ring-necked parakeets in Germany, South Africa — nor in Kent, U.K. despite its being located right next door to the adjoining Greater London Area, where it was detected.
Ms. Fogell and her collaborators did detect BFDV in both the native (26.1%) and invasive parakeet (16.1%) species on Mauritius, home to the endangered echo parakeet or Mauritius parakeet, Psittacula eques. BFDV was detected in ring-necked parakeets from Pakistan (71.4%), Japan (6.7%), Nigeria (9.1%), and Senegal (50%) and in individuals seized from trade in western Africa (20%). The closely-related grey-headed parakeet, Psittacula finschii, which occurs in Vietnam (66.7%), tested positive for BFDV as did Timneh parrots, Psittacus timneh, seized in western Africa (62.5%).
When BFDV was detected, Ms. Fogell and her collaborators compared and analyzed the viral DNA sequences against all other publicly available BFDV sequences to construct a family tree (Figure 2).
Ms. Fogell and her collaborators inferred that viral variants that were closely related genetically — even when their points of origin were geographically distant — suggested that they originated from recent introductions, likely the result of global trade. These findings indicate that the global trade in live birds and the establishment of invasive populations play a key role in the spread of BFDV, highlighting the necessity for effective regulation of the international trade in live parrots, especially in regions with a lot of naturally-occurring wild parrots or with threatened parrot populations, where the popular ring-necked parakeet could act as a reservoir host.
“The successful establishment of invasive species like Rose-ringed parakeets can be devastating to small island populations or threatened species,” Ms. Fogell said in a press release. “Not only through competition for resources, but by exposing them to a virus like BFDV which may pose an important additional threat to species that are already suffering the pressures of low genetic diversity and habitat loss.”
Deborah J. Fogell, Rowan O. Martin, Nancy Bunbury, Becki Lawson, James Sells, Alison M. McKeand, Vikash Tatayah, Cao Tien Trung, and Jim J. Groombridge (2018). Trade and conservation implications of new beak and feather disease virus detection in native and introduced parrots, Conservation Biology, published online on 28 August 2018 ahead of print | doi:10.1111/cobi.13214
Originally published at Forbes on 21 September 2018.