Golden Lake is one of many lakes in Ontario that have seen an increase in the number of nesting cormorants over the past few years. These birds are not really an invasive species in the normal sense because they are indigenous to our region. However, toxic contamination in the lakes caused egg shell thinning and just about eliminated the birds from the province. In some ways the return of the cormorant is a sign of improved water quality.
However, the populations have increased so fast that their status as an endangered species is being challenged. Bill 62, regarding this change to the Fish and Wildlife Conservation Amendment Act (Double-Crested Cormorants), 2008 has had its first reading and is scheduled to be debated in the Ontario Legislature on December 3rd, 2009.
Here is some background information on cormorants: Cormorant Fact Sheet