Western Purple Martin Foundation
Western Purple Martin Recovery
Purple Martins (Progne subis) are the largest swallow in North America. Western Purple Martins (Progne subis arboricola) breed along the West Coast of North America from California to British Columbia and are genetically distinct from their eastern cousins, Progne subis subis. Western martins are a Species of Concern from California to Washington and a provincial Species At Risk (Blue-listed, Vulnerable) in BC.
In BC, they once nested in loose colonies in cavities in old trees and snags as far north as Campbell River, the historic northern limit of their range. Their colony sites were either in open treed areas with little undergrowth such as recently burned areas or bordering freshwater.
Purple Martins numbers decreased due to loss of nesting habitat from logging, agricultural land clearing, fire suppression, urban development and severe competition for remaining natural nest cavities from introduced bird species.
By 1949, Purple Martins had disappeared from the BC Lower Mainland and by 1985 there were only about 5 breeding pairs remaining on Vancouver Island.
Goals and Objectives of the Program
The current long-term goals of the recovery program are:
A Nest Box Program Begins in BC
A volunteer nest box program to rebuild the martin population was started in 1985 with the installation of nest boxes at Cowichan Bay when martins were seen nesting in piling cavities at this estuary. These boxes and others located around Esquimalt Harbour probably rescued the BC Purple Martins from extirpation (local extinction).
Purple Martins numbers increased slowly but steadily, primarily as a result of nest boxes built, installed and maintained by volunteers at marine coastal locations around the Strait of Georgia (right). As martins numbered increased, nest boxes were installed at more potentially suitable marine locations.
By 1989, 14 nesting pairs were located at 3 nest box sites and 1 piling location on southern Vancouver Island and by 2000 these numbers had grown to about 200 pairs at 16 colonies.
Active (square) and inactive (circle) colony sites in 1989 (above) and in 2006 (right).
A New Era Begins
In 2002 the nest box program was renamed the BC Purple Martin Stewardship and Recovery Program when Georgia Basin Ecological Assessment and Restoration Society (GBEARS) assumed responsibility for the program. The scientific assessment and monitoring program implemented with provincial government support in 1998 was retained and enhanced to sustain the scientific credibility required for funding support.
As the BC martin population increased and colonization of adjacent unoccupied marine sites occurred in increasing numbers, freshwater nest box sites were started in the Lower Mainland/Fraser Valley area in 2005 and on the east coast of Vancouver Island in 2006. Two freshwater sites were occupied in the Fraser Valley area for the first time in almost 40 years – one each in 2006 and 2007. There are currently 1500 nest boxes distributed among 70 marine and 20 freshwater locations. No other Purple Martin conservation program in North America is attempting to move martins back into natural nest cavities or has an identified strategy to do so.
There are now 145+ volunteers actively involved in this recovery program, including many individuals, First Nation groups, naturalist/conservation groups, corporations, federal, provincial, regional and municipal government departments, and universities.
For information regarding nest box construction, please visit the Purple Martin page of the GBEARS' website at http://georgiabasin.ca/puma.htm
Weather Affects Recovery Success
Weather has a major effect on the growth of the BC Purple Martin population. Between 2003-2006 when the spring and summer weather was warm and sunny, flying insects for food were plentiful and nesting success was high, the population tripled and many new colony sites were established (see map for 2006 above). In years when there were periods of cold wet weather during the breeding season and subsequently fewer flying insects, the population grew more slowly or declined. The worst weather effects seen in the 24-year history of the recovery program occurred in 2008. A combination of a long cold spring, a week of rain at the end of July and resulting lack of food at both these times saw the loss of about 100 adult martins and about 40% of the nestlings. This led to a subsequent decline in the number of breeding pairs that returned in 2009. However, the extremely good weather conditions in the following two summers are proving not only to offset the 2009 decline but potentially bring the population up to its highest levels yet recorded.
Sustainable Funding Needed
As the martin population has grown and the number of occupied nesting colony sites has increased in recent years, increased volunteer involvement has been required. The coordination and management of this volunteer effort has become both essential and challenging. The nest box recovery program has now grown too large to be self-sustaining without a structured coordination effort. The Western Purple Martin Foundation needs your financial support so we can ensure that the goals of BC Purple Martin Recovery Program are accomplished with stable ongoing funding.
Website funded in part by the Ladysmith Maritime Society
Original website design by Danielle Morrison
Last modified 1 Oct 2010