Thousands of waterfowl were successfully diverted from Smith and Bybee Wetlands Natural Area in late September to protect them from a disease outbreak.
An estimated 2,000 to 10,000 ducks were successfully diverted daily for 12 days to control an outbreak of avian botulism. About 200 ducks died from the disease, which affects pond ducks and geese, not fish-eating birds such as herons, egrets and pelicans.
Avian botulism is a natural but fatal disease that is common in wetlands, particularly as warm, dry summers extend into late September. Recent rains and cooler temperatures helped reduce the effects of this year’s outbreak.
The type of avian botulism at Smith and Bybee does not affect people, through the wetlands were closed to paddlers as a precaution during the diversion efforts.
Crews used about 7,000 pyrotechnic noisemakers to divert the birds during dawn and dusk. Metro coordinated the diversion efforts in partnership with the U.S. Department of Agriculture-Wildlife Services, the Oregon Department of Fish and Wildlife, the Port of Portland and the Audubon Society of Portland.
In the past year, Metro has also worked to restore the natural seasonal draining of Smith Lake, which discourages ducks that prefer deeper water and attracts birds immune to that type of botulism, such as herons, egrets and pelicans.
Unfortunately, nutria and beavers have built dams of mud and branches that prevent the flow of water from the lake. In order to ensure water drains properly, some hazing of invasive nutria is expected to start in the next few weeks.
At nearly 2,000 acres, Smith and Bybee Wetlands Natural Area is one of the largest protected wetlands within an American city -- hiding in a part of Portland surrounded by port terminals, warehouses and other commercial developments.