Biologists who searched for endangered Kirtland’s Warblers at Garrison Petawawa in Ontario last year detected three males and one female but, for the second time since 2007, found no nest.
According to an overview published in a recent issue of the journal Ontario Birds, four to six different females and seven different males have been detected at the base since 2006.
Most of the males returned to Garrison Petawawa in at least one subsequent year, writes Tammy Richard, a wildlife biologist at the base. One bird, a male banded on the property in July 2006, returned for six consecutive years.
Richard last saw the bird on July 31, 2012. She estimates that, at the time, the warbler was nine years old. Most males, she points out, live to be only about 4.0 years old on average. The lifespan of a typical female is even less, 2.5 years.
Nests were found at Garrison Petawawa, which is adjacent to Algonquin Provincial Park, about 110 miles northwest of Ottawa, in 2007, 2008, 2009, 2010, and 2012. According to Richard, they have produced at least 27 fledglings.
The 2007 nest was the first in Canada in 62 years.
Between 1900 and 2005, observers documented 18 occurrences of the warbler in potential breeding habitat in Canada. Five of the instances — males discovered in 1916, 1939, 1946, 1977, and 1978 — were at Garrison Petawawa, but no nesting was detected.
Then, in June 2006, three males were discovered at the base. (The warbler that returned year after year was one of them.) Annual surveying and monitoring began the following season, the same year a history-making Kirtland’s Warbler nest was also discovered in Wisconsin. Until then, the species was known to breed only in Michigan.
Kirtland’s Warblers typically arrive on their breeding grounds at the beginning of May, usually between May 3 and May 12. Males sing loudly and persistently to defend territories, making them great candidates for annual surveying.
Counters in Michigan found 2,004 singing males during the 2013 census period, June 6-20. Observers outside Michigan tallied 21 additional males: 18 in Wisconsin and 3 in Ontario.
Ontario Birds is the journal of the Ontario Field Ornithologists. Published three times a year, it documents new information on the birds of the province and includes notes about their status, distribution, identification, and behavior as well as the annual report of the Ontario Bird Records Committee.
Read the paper:
Tammy Richard, 2013, Seven Years Later: Kirtland’s Warbler at Garrison Petawawa, 2006-2013, Ontario Birds, Volume 31, Number 3 (December 2013), page 148.