The Parks Canada agency has proposed holding annual April culls to reduce the number of cormorant nests on Middle Island in Point Pelee National Park from 4,026 to between 438 and 876 by 2012.
Animal Alliance of Canada and Zoocheck Canada filed a federal injunction in Toronto to block the plan, the Windsor Star reported.
Parks Canada claims the guano from the fish-eating cormorant colony is killing nest trees, chemically altering the soil and killing vegetation, and said 41 percent of the forest on the 45-acre island was killed between 1995 and 2006.
Online federal documents say nesting double-crested cormorants would be shot before chicks have hatched early in the nesting season for several days, the newspaper said.
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