An outbreak of avian cholera has hit the seabird breeding colony on Dyer Island, off Gansbaai on the southern Cape coast, killing more than 4 000 birds in the past two weeks.
Conservation staff from several agencies have pooled resources to try to contain the killer disease, which has swept through the breeding colony three times since winter last year.
Several times a day, staff walk through the colony to pick up dead birds and burn their carcasses in bonfires in an attempt to halt the spread of the virus. They wring the necks of ill or dying birds, whose carcasses are also burned.
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The disease has affected the cormorant population in particular, which is already classified as "near-threatened".
In the past two weeks, 4 115 birds, mainly cormorants, have died on the island, which is a Cape Nature Conservation reserve.
Gail Cleaver, Cape Nature Conservation's manager for the Overberg region, said yesterday: "The previous outbreaks of cholera affected adults, but coming at this time of year, this outbreak is affecting the fledglings as well.
"We are trying to get the dead out of the colony as quickly as possible and are burning them on the island to try to stop the spread of the disease."
Cleaver said this was the third year in a row that had seen avian cholera outbreaks on Dyer Island. In the 2002 epidemic, 7 800 birds died.
There was an outbreak on the island in winter last year and another smaller outbreak in October.
She said a joint operations team had been set up to deal with the cholera outbreak and comprised staff from Cape Nature Conservation, the Department of Environment Affairs' Marine and Coastal Management, and Overstrand Municipality's nature conservation department.
Kevine Shaw, ornithologist for Cape Nature Conservation, said avian cholera was spread through the birds' faeces and mucous.
Shaw said: "Obviously bird colonies are more susceptible to the rapid spread of the disease because the birds are so close together.
"The only way to fight it is to go through the colony a couple of times a day and collect the dead birds and burn them.
"I don't think an inoculation exists against avian cholera, but even if it did it would be impossible to inoculate thousands of birds.
"Avian cholera is a natural thing and it's been around for years, but because both the Cape cormorant and crowned cormorant populations have been steadily decreasing over the years, every outbreak of the disease has more of an effect than it would normally have."
Cormorant populations have been in decline because of a variety of factors, he said, including human disturbance and declining fish stocks. - Environment Writer
- This article was originally published on page 3 of Cape Times on January 06, 2004
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