BC Purple Martin Stewardship and Recovery Program
Purple Martins are the largest swallow in North America. The western subspecies (Progne subis arboricola) is threatened in British Columbia. Historically, Purple Martins nested in woodpecker holes in old trees or snags in open woodland areas or near freshwater and likely made extensive use of fire-killed stands. Due to logging, fire prevention, snag removal, burned timber salvage and agricultural and urban development throughout their original breeding range around the Georgia Basin, this habitat has been destroyed. Increasing populations of non-native European Starlings and House Sparrows also provide strong competition for any remaining nest cavities. By the early 1980s the BC population of western Purple Martins was reduced to less than 10 breeding pairs.
Since then, the British Columbia population of Purple Martins has rebounded to over 200 pairs by 2002 and ~650 pairs by 2007. This is largely due to the volunteer-based nest box program begun in the Georgia Basin area in 1986, as well as a similar program begun a decade earlier in Puget Sound, Washington, in 1975.
The BC population increased dramatically between 2003 and 2006, due in part to good weather conditions throughout the breeding season, resulting in an ample food supply of flying insects for both adults and nestlings. As for other swallows, the nesting success of Purple Martins is highly sensitive to adverse weather-induced reduction in food supply availability. An article about the history of the recovery of Purple Martins in BC, up to and including 2004, was printed in BirdWatch Canada (winter 2005 No. 30, p.21-22), a publication of Bird Studies Canada and is available here in .PDF format.Since 2002, GBEARS has provided overall co-coordination and scientific direction, monitoring and management of the BC Purple Martin Stewardship and Recovery Program. As part of this program, nest boxes are being put up at potential new colony sites as well as existing ones. Each box is numbered with a unique number that includes the year of installation. Abundance, nesting success and production at each colony site are monitored and recorded.
Also, Purple Martin nestlings from each colony are banded with numbered bands which allow us to track their migratory routes, dispersal and recruitment and colony and nest box selection throughout their lives, without further capture or disturbance. Bands read with spotting scopes in later years indicate that martins fledged from any one colony return to nest at many different colonies throughout the Strait of Georgia and Puget Sound, providing extensive genetic mixing within at least the BC and Puget Sound, WA, population, with occasional dispersal to Oregon and possibly California.
In 2007 a 10-year old adult male banded in 1997 and a 9-year old adult female banded in 1998 were both identified from their band numbers and nested successfully. The female returned and nested successfully again in 2008 as a 10-year old bird. These are believed to be western longevity records for males and females in the wild. Most martins that survive their first winter live only 2-3 years and very few exceed 5 years of age.
In addition, the long term banding study is now providing valuable information on the population dynamics and variable age composition of the BC population, which is important for understanding changes in the rate of growth or decline of the population due to variations in nesting success, fledgling production and recruitment of new subadult birds, and thus the progress and overall success of the recovery program. Some of these results may be applicable generally to other equally weather-dependent but less closely monitored swallow populations as well.
In 2005 and 2006 a survey of remaining historic and potential new freshwater nesting sites was conducted in preparation for re-introducing Purple Martins into naturally occurring nesting cavity situations in the wild. In general, suitable freshwater sites with snags for mounting a few "starter" nest boxes and containing natural cavities for new colonies to expand into as they grow were very scarce, particularly on south Vancouver Is. and in the Lower Mainland. Many former nesting sites in the wild have been lost to various forms of development, the snags have fallen or been removed and very little suitable 'traditional' nesting habitat remains in the Georgia Basin. So far 15 freshwater nest box sites have been established in the Lower Mainland and lower Fraser Valley and 10 have been initiated on the east coast of Vancouver Island and the Gulf Islands, some on pilings.
There are currently active colonies established at the locations shown in the following map (2010):
Purple Martin Recovery Sponsor Spotlights
Gold ($20,000 & over)
Silver ($10,000 – 19,999)
Bronze ($5,000 – 9,999)
Western Purple Martin genetic relationships - comparison of populations using mitochondrial DNA analysis
Baker, A. J., A. D. Greenslade, L. M. Darling and J. C. Finlay. 2008. High genetic diversity in the Blue-listed British Columbia population of the Purple Martin maintained by multiple sources of immigrants. Conservation Genetics, Vol. 9, Num. 3, June 2008.
Puget Sound Georgia Basin Research Conference, March 2007 - Knowledge for the Salish Sea: Toward Collaborative Transboundary Solutions
B. Cousens et al. 2007. A Simple Population Forecast Model for Purple Martins in British Columbia. (Oral presentation)
J. C. Lee et al. 2007.Update on Purple Martin Stewardship and Recovery in British Columbia, 2006. (Poster)
B. Cousens and F. Schrock. 2007.
Searching for Barn Swallow Fall Premigratory Roosts with Doppler Weather Radar
in western North America. (Poster)
Puget Sound Georgia Basin Research Conference, March 2005 - Science for the Salish Sea: A Sense of Place, a Sense of Change
B. Cousens et al. 2005.
Recovery of the Western Purple Martin bordering the 'Salish Sea' - the Georgia Basin of British Columbia and Puget Sound, Washington. (Science
B. Cousens et al. 2005.
Two Decades of Purple Martin Stewardship and Recovery in British Columbia - Successes and Challenges. (Poster)
BirdWatch Canada 2005
B. Cousens. 2005. A Purple Martin Success Story. BirdWatch Canada (Bird Studies Canada), No. 30, pp. 21-22.
BC Species At Risk Conference, March 2004: Pathways to Recovery
L. M. Darling et al. 2004.
Recovery of the Purple Martin in British Columbia: More Than a Nest Box Program. (Oral presentation)
Western Purple Martin Working Group (WPMWG) Publications
The WPMWG has served since 1998 as an international coordinating body for researchers, government agency management personnel, non-profit groups, bird banders and volunteers working toward the study, conservation and recovery of the western subspecies populations of Purple Martin breeding west of the Rocky Mountains in Canada and the USA. Members of the group meet annually (usually at Vancouver, Washington) to share research and monitoring results, plan further studies and coordinate leg banding, conservation and recovery efforts. Secretary: Stan Kostka
WPMWG - Interim Western Purple Martin Population Objectives
Title: Interim Population Objectives for the Pacific Population of the Western Purple Martin - Western Purple Martin Working Group, 2005 (written in conjunction with Partners In Flight).
WPMWG – Western Purple Martin Nest Site Use Assessment Protocols
These are preliminary general protocols developed by the WPMWG to provide consistent and reliable methods of assessment of western Purple Martin nest site use, nesting success and productivity at inaccessible cavities. They are provided as working documents for application, evaluation and modification to specific cavity nesting situations as needed. If you apply either of these protocols and find them useful, discover a need for modifications or additions, or require further information, please contact us and let us know, so we can track usage and provide updates and other Purple Martin monitoring and recovery workers may benefit from your experience.”
Original web site design by Carley Colclough. Send mail to
GBEARS with questions or comments about