Cape parrot population Stalked by killer virus

In the Amatola Mountains in the Eastern Cape, Cape parrots are as iconic as the giant yellowwood trees they feed on and nest in. But as Mike Burgess reports, initial fears of a deadly viral disease that had apparently infected Cape parrot populations in the area in 2008 and 2009, is now being confirmed by parrot expert Dr Steve Boyes, who believes the disease can wipe out South Africa’s only endemic parrot.

“In May 2010 we started catching Cape Parrots to take blood and feather samples while recording their body weight and wing/beak dimensions. Alarmingly, 75% of the samples tested positive for Psittacine Beak and Feather Disease (PBFD).”

This is the disturbing reality of the health of Cape parrots (Poicephalus robustus) in the Amatola Mountain range as discovered by researcher Dr Steve Boyes,a postdoctoral fellow of the South African Department of Science and Technology/ National Research Foundation Centre of Excellence, at the Percy FitzPatrick Institute of African Ornithology at the University of Cape Town.

A population at risk

The Amatola Mountain area is home to about half of South Africa’s estimated 1 300 to 1 500 Cape parrots. Dr Boyes, a trustee of the Wild Bird Trust (WBT), is shocked by how the disease is affecting the area’s Cape parrot population. Infected parrots exhibit symptoms that include deep lesions on the bill, darkening of skin around the cere, weight loss and the general deterioration of body and feather condition.

A number of dead birds have also been discovered on the forest floor, and there is an estimated 40% decrease in parrots in the Amatola Mountains since last year, he says. “We’ve reached a tipping point and now PBFD is threatening the Cape parrot population in the Amatola area, and possibly the Transkei and KwaZulu-Natal,” he warns.

Up to 30% of Cape parrots in feeding flocks have yellowing feathers that may be genetically induced by a collapsed population, but is far more likely to be a new manifestation of the PBFD virus. These apparently sick parrots, says Dr Boyes, congregate together in groups and can be seen flying together to feeding sites.

Habitat degradation to blame

Dr Boyes believes that PBFD may have initially entered wild populations in the Amatola Mountains after parrots confiscated from poachers were released back in or near the area in the past decade. By late 2008, Cape parrots with symptoms first surfaced in East London along the coast and then in Hogsback, King William’s Town and Alice in the Amatola Mountains.

The reasons for PBFD’s rapid spread may be complex, he says, but may be sufficiently assisted by a change in the parrots’ diet. Parrots are now eating pine nuts, acorns, plum, cherry kernels, eucalyptus flowers and pecan nuts in the face of habitat destruction.

“I think the disease has been in the Cape parrot population in the Eastern Cape for many years and has just recently reached a tipping point due to poor diet, low breeding success, and increased stress. We have an ageing population that’s eating the wrong food,” he says.

Dr Boyes is currently collecting samples of most of the parrots’ major food items, specifically pecan nuts, for analysis to determine the impact that alien foods are having on the parrots’ susceptibility to PBFD infection.

“Pecan nuts have dangerously high levels of aflotoxins, myotoxins and tannins. When added to a fat content of 68%, this may be very unhealthy for Cape parrots over long periods, causing conditions including liver failure and nutrient deficiencies.”

The way forward

Dr Boyes says the Percy FitzPatrick Institute of African Ornithology and the WBT are investigating solutions to the challenges facing the Cape parrots in the Amatola Mountains. Theses measures may include quarantine, planting trees with a more suitable food source, and vaccinating to create a small disease-free population.

“All South Africans need to engage us on the way forward and look for ways in which they can support the conservation of our only endemic parrot, our ‘Green and Gold’ Cape parrot, that is critically endangered by a disease due to our degradation of their natural habitat,” he said.

“We are their only custodians and we need to step up and assist this proudly South African parrot.”

Contact Dr Steve Boyes on 0728585644 or e-mail
[email protected] or [email protected].