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BC Purple Martin Stewardship and Recovery Program

Recent BC recovery status and population trend - 2010  Summary - 2009  Summary - 2008

NEW 2013! - Status Report on the Western Purple Martin in BC  -  see Recent Publications section below for citation

Purple Martins are the largest swallow in North America. The western subspecies (Progne subis arboricola) is threatened in British Columbia. Historically, Western 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 urbanA summer student checking a box. development throughout their original breeding range around the Georgia Basin, this habitat has been lost. Resident populations of non-native European Starlings and House Sparrows also provide strong competition for any remaining nest cavities.

As other suitable habitat was lost, martins shifted to nesting in woodpecker cavities in abundant old and decaying untreated wooden pilings remaining from early industrial development around the Strait of Georgia (as well as in Puget Sound, WA, and along the lower Columbia River), and as these old pilings fell or were replaced with creosote-treated pilings (and later steel and concrete pilings), in which woodpeckers cannot excavate nest cavities, their numbers steadily declined due to lack of usable nest cavity sites. By the early 1980s the BC population of Western Purple Martins was reduced to less than 10 breeding pairs.

A pair of Purple Martins perched on their nest box.

Since then, the British Columbia population of Purple Martins has rebounded to over 200 pairs by 2002 and ~650 pairs by 2007. This is 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.

After stalling for several years at 500-650 pairs (2006-10) due to low fledgling production and subadult (yearling) recruitment as a result of 4-5 nesting seasons with long cool wet periods that limited food availability and reduced nestling survival, the BC population again began to increase, reaching 950 pairs in 2013 and likely to exceed 1,000 pairs in 2014.

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, Western 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. This female and a second previously unseen female returned and nested as 11-year old birds in 2009, but neither nest was successful and neither of these birds has been seen again since. These are believed to be western longevity records to date 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, this 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. This long-term population dynamics and age composition study is unique for Purple Martins in Canada and for Western Purple Martins in western North America, and has been supported in part by the Canadian Wildlife Service, The Baillie Fund of Bird Studies Canada, The Canadian Wildlife Foundation and Timber West..

In 2005 and 2006 a survey of remaining historic and potential new freshwater nesting sites was conducted in preparation for re-introducing Western 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 and others on flooded snags (at right, Crofton Lake). Three of these sites were first occupied by Western Purple Martins in 2013, at Westwood Lake in Nanaimo and Comox Lake near Courtenay on east Vancouver Island, and at Burnaby lake in Vancouver on the BC Lower Mainland. We hope to see this trend continue in the next few years.

There are currently active colonies established at the locations shown in the following map (2012):


* Shaded area indicates historic breeding range of Purple Martin in BC; colonies in Puget Sound, WA, (dark grey) not shown. New nesting sites in the lower Fraser River valley east of Vancouver at Dewdney (2006) and Mission (2007) and in Johnstone Strait at Port Neville (2013) also not shown.

Nest Box Construction and Mounting Plans

If you would like to build your own Western Purple Martin nest boxes, click here for the nest box plans and here for instructions on how to mount them. If you want copies of these document files, save them to a file on your computer and print them from that file. (Tip: If the drawings appear difficult to read, click on them to increase screen zoom magnification.) Please contact us before putting up nest boxes, so we can keep track of where they are and also provide any help or further information you might need.

When choosing suitable nest box locations for attracting Western Purple Martins, it's important to keep in mind that they like to nest in clusters of single boxes placed in open spaces beside or over water (rather than the familiar multi-compartment "condos" placed over land for the eastern subspecies). In BC eastern martin apartment houses are NOT accepted by western martins and tend to be taken over by non-native European Starlings and House Sparrows, which then exclude martins and become part of the problem. They show a strong preference for open coastal locations and do not accept nest boxes placed in typical upland "back yard" situations, but are beginning to show interest in sites over or bordering fresh water.

As of 2013, almost all occupied Western Purple Martin colonies in BC are located on pilings along the marine coastal foreshore in bays, estuaries, and marinas, within or beyond the intertidal zone within the Georgia Basin. They are also at least 50-100m away from trees and other tall structures on the foreshore that might provide hunting perches and approach cover for ambush predators, mainly small hawks.

Apart from 1-2 early site colonizations along the lower Fraser River, east of Vancouver (after a 40+ year absence!) in 2006-07, and more recent colonization (2013) at several lakes near the coast (Westwood Lake in Nanaimo, Comox Lake near Courtenay and Burnaby Lake in Vancouver), there are no nest box sites in use inland of the marine coast in the Georgia Basin. Purple Martins in BC historically used fresh water sites for nesting here and results of monitoring during the 2013 nesting season indicate we are beginning to have some success re-introducing them to similar suitable nest sites without House Sparrow populations or large numbers of Starlings. For this reason we encourage placement of nest box clusters on snags, pilings, and other offshore structures at fresh water sites on lakes and marshes. It may take a few more years for them to adapt to this situation, but if they do take a liking to your fresh water colony site please let us know.

It's also important to note that, unlike other native cavity-nesting members of the swallow family that nest in both the wild and in human-supplied nest boxes, Western Purple Martins in BC are currently completely dependant on human-provided nest boxes and would not be nesting in the province at all without them. (The nearest known snag-nesting site is at Fort Lewis in southern Puget Sound, Washington.) One long term objective and major challenge of the Stewardship and Recovery Program in BC is to re-introduce martins to nest sites in their original habitat (or a reasonable modern equivalent) where they may become self-sustaining, rather than develop a population of semi-domesticated birds entirely dependant on ongoing human provision and maintenance of nest sites. Recovery results so far suggest this goal is very likely achievable in time, given a continued strong stewardship effort, continued population growth and the existence of sufficient natural cavities in snags in suitable habitat in the wild. Recent documentation of Western Purple Martins nesting successfully in woodpecker cavities in mechanical harvester-topped and killed "created snags" in central Oregon (M. Hane, unpub. data) provides additional promise in this regard.
 

B.C. Purple Martin Recovery Program Sponsor Spotlights

Gold ($20,000 & over)

2007 - VanCity enviroFund

Silver ($10,000 19,999)

2006 - Environment Canada EcoAction                      2005 - VanCity enviroFund

Bronze ($5,000 9,999)

2013 - HSRDC Canada Summer Jobs                        2013 - Western Purple Martin Foundation
2012 - Western Purple Martin Foundation                  2011 - HRSDC Canada Summer Jobs                       
2009 - HRSDC Canada Summer Jobs                        2008 - HRSDC Canada Summer Jobs                       
2008 - BC Transmission Corporation                          2007 - HRSDC Canada Summer Jobs                       
2006 - HRSDC Summer Career Placement              2005 - Environment Canada EcoAction                      
2005 - HRSDC Summer Career Placement

For more information, see our Recent Publications below, visit our Purple Martin Links, or find out about our Adopt-a-Purple-Martin Program

Recent Publications

NEW 2013! - Status Report on the Western Purple Martin in BC, with previously unpublished results of biological research and population monitoring

Cousens, N. B. F., and J. C. Lee. 2012. Status Report on the Western Purple Martin (Progne subis arboricola) in British Columbia. Prepared for the British Columbia Ministry of Environment, Victoria, BC. 117 pp. (Electronic resource).

Western Purple Martin genetic relationships - comparison of eastern and western 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) 
[Locations where abundant, eastern Purple Martins also form similar large roosts in eastern N. America following the breeding season. (PMCA Project Martin Roost)]

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 conference  paper)

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)
B. Cousens et al. 2004. Purple Martin Stewardship and Recovery in British Columbia - Two Decades of Successes and Challenges. (Poster)

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

Title: Western Purple Martin Nest Site Type Identification and Site Use Classification Protocol

Title: Western Purple Martin Colony Population Size and Reproductive Success Evaluation Protocol

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.

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Last modified: 02/02/09