From Bird Studies Canada:
18 August 2006 – Military officials at the armed forces base in Petawawa, Ontario, have revealed that at least two Kirtland’s Warblers spent the summer in the extensive jack pine forests found on the base. This is the first record for the Ottawa area since 1985 and the first territorial birds for the Petawawa base since a singing male spent the summer there in 1977. This endangered species is one of the world’s rarest birds; as recently as the late 1980s, it numbered less than 400 individuals.
Through careful management of its very specific habitat and control of the Brown-headed Cowbird (a nest parasite), the population has increased to more than 3000 birds in recent years. While the bulk of the population breeds in Michigan, there are historical breeding records in Wisconsin and Ontario. Indeed, ornithologists considered the species to be “not uncommon” in the Petawawa area until the early 1900s.
The return of the Kirtland’s Warbler to Ontario would be welcome news as a breeding population outside of Michigan would further ensure the species’ continued recovery.