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Avian Botulism of International Concern 
OAK HAMMOCK MARSH, MAN., Aug. 6 - Avian botulism has been a major problem in western North America during the 1990s and, this summer, incidents of botulism are once more killing birds on Prairie wetlands. In an attempt to better manage recurring botulism outbreaks, Canadian and American wildlife and conservation specialists have joined forces to conduct research on wetlands where great numbers of birds die from botulism.
"In Canada, we estimate that probably a million birds died last year because of botulism,'' said Brian Gray, chief biologist for Ducks Unlimited Canada. Waterfowl species compose the greatest proportion of bird mortality, the remainder of the birds that die are shorebirds and gulls.
Avian botulism outbreaks occur worldwide. In Canada, botulism mortality occurs primarily on three large wetlands in southern Prairie Canada: Pakowki Lake, Alta., Old Wives Lake, Sask.; and Whitewater Lake, Man. These lakes are the focus of coordinated botulism research in the Prairies.
"All of the agencies concerned with botulism have joined together and one of the first things we have done is set up a working group on botulism,'' said Gary Wobeser, codirector of the Canadian Cooperative Wildlife Health Centre and chairperson of the international working group on avian botulism. "We have brought together expertise from agencies, universities and people in both the United States and Canada to address the problem.'' The working group on avian botulism was formed under the Prairie Habitat Joint Venture responsible for delivering programs of the North American Waterfowl Management Plan.
The objectives of the working group are to identify the impact of botulism outbreaks on waterfowl populations, to identify the factors that create outbreaks and to evaluate various management procedures.
"The management technique most frequently used is to respond to outbreaks in a reactive way and to try and pick up carcasses,'' Wobeser said, ``But we really don't know how effective that is in preventing the disease from spreading to additional birds.'' Studies have shown that as the size of a wetland increases, the effectiveness of carcass pick up decreases, a factor that must be considered on large wetlands like Old Wives Lake that is 350 km(2) (86,450 acres).
Kevin Cash, a research biologist with Environment Canada, is involved in the research on the Prairie wetlands. Researchers know the basics of botulism outbreaks, but there are still questions to be answered. "We need three things to cause botulism: the botulism bacteria that occur in many wetlands in large numbers; a carcass or substrate for the bacteria to develop; and appropriate environmental conditions.''
Insects, like maggots, ingest the botulism toxin when they feed on decaying organic material where botulism bacteria occur. Botulism is then transmitted to birds when they eat the insects.
To increase understanding of the environmental conditions necessary for a botulism outbreak, Cash said researchers are investigating water quality and sediment quality. Additional research on waterfowl involves banding, tracking birds with transmitters and vaccinating birds. Researchers will also fly over the three wetlands routinely to count the number of birds on the lakes.
Wobeser said the research collected through the working group will ultimately aid in developing new management techniques for botulism. "We've never really been able to prevent botulism from occurring but, hopefully, we can begin to manage outbreaks to minimize the impact on bird species.''
Members of the public who see large groups of birds exhibiting the following symptoms should contact their local natural resources representative or conservation officer: paralysis of the inner eyelid so eyes appear to be half closed; and an inability to support the neck, the reason why botulism has also been called "limberneck''.
The working group on avian botulism brings together: Ducks Unlimited and its research arm the Institute for Wetland and Waterfowl Research; the Canadian Cooperative Wildlife Health Centre; the Canada Centre for Inland Waters; the Canadian Wildlife Service; Manitoba Natural Resources, Alberta Environmental Protection; the U.S. National Wildlife Health Centre; the U.S. Fish and Wildlife Service; and Utah State University.
