Purple Martins (Progne subis)
are the largest swallow found in North America. Western Purple Martins (Progne
subis arboricola) breed along the western coast of North America from
California to British Columbia and are genetically distinct from their eastern
cousins, Progne subis subis. Western Purple Martins are a Species of
Concern from California to Washington and a provincial Species at Risk
(Blue-listed, Vulnerable) here in BC.
Purple Martins are neotropical
migrants, like other members of the swallow family. They migrate from their wintering
grounds in north and central South America to the United States and southern
Canada each spring to breed during the summer months, returning south in the
fall.
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. Now their numbers have steadily increased to
over 1000 pairs, primarily as a result of nest boxes being built, installed,
and maintained by volunteers at marine coastal locations around the Strait of
Georgia.
Purple Martin Nesting Habits
Our western Purple Martins use
individual nest boxes in loose clusters, while eastern Purple Martins prefer
hanging gourds or condo-style apartment blocks.
Here in BC, they once nested in loose
colonies in the cavities of old trees. Their numbers decreased due to loss of
nesting habitat as well as severe competition for remaining natural nest
cavities, particularly from introduced bird species such as House Sparrows and
European Starlings.
Now Purple Martins mainly use nest
boxes provided by people. They make very rustic nest structures using
clamshells and large sticks lined with cottonwood leaves. These nest boxes are
usually clustered together on groups of marine pilings near or on the water.
Purple Martins develop strong site
fidelity to a particular location, especially if the sites are well maintained
and the birds experience reproductive success.
BC Purple Martin Stewardship and Recovery Program
In 1985 a volunteer nest box program to
rebuild the Purple Martin population on Vancouver Island was established,
beginning with the installation of nest boxes at Cowichan Bay. These boxes at
Cowichan Bay and others subsequently located around Esquimalt Harbour likely
rescued the BC Purple Martins from extirpation. As their numbers slowly
increased, more nest boxes were installed at various suitable locations around
the Strait of Georgia.
In 2002 the Georgia Basin Ecological
Assessment and Restoration Society (GBEARS) assumed responsibility for the nest
box program and it was named the BC Purple Martin Stewardship and Recovery
Program. GBEARS has provided overall co-coordination and scientific direction,
monitoring and management of the program.
There are currently around 1,500 nest
boxes located in the Lower Mainland/Fraser Valley area and on the eastern coast
of Vancouver Island. Approximately 150 volunteers are now actively involved in
this recovery program, including many individuals, First Nation groups,
naturalist and conservation groups, corporations, universities, as well as federal,
provincial, regional and municipal government departments.
Each year nestlings that are 10-days
old and older are banded at most of the BC colonies with a coloured, alpha-numeric
band on one leg and an aluminum US Fish and Wildlife band on the other. The Purple
Martins experience a fledge rate of 2-3 young per nest.
When martins return from South America
in the spring a spotting scope is used to read the bands on about 300 previously
banbirds. This provides a representative random sample of 20-30% of the BC population.
This unique, long term banding study provides valuable information about the BC
Purple Martin population. This is important to understand the changes taking
place in the species due to variations in nesting success, fledgling
production, and the overall progress of the recovery program.
Greater
Victoria’s Purple Martin colonies are monitored as part of the BC Purple Martin
Stewardship and Recovery Program which is coordinated by Bruce Cousens and
Charlene Lee in Nanaimo.
RPBO and Purple Martins
In 2014 a
number of RPBO members assumed responsibility for the Purple Martin nest box colonies
in the Greater Victoria area. Prior to that Tom Gillespie, a long time RPBO
member, had worked in the recovery program in Victoria on an informal basis, in
affiliation with GBEARS. Tom was
devoted to this project until his final days, banding almost 400 Purple Martin
nestlings in the summer of 2013.
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| Tom Gillespie banding a nestling |
Wallis
Moore Reid is now the Regional Coordinator for the South Island population of
Purple Martins. John Costello is in charge of nest box building and
maintenance. Daniel Donnecke has taken on the task of reading and recording the
band numbers of returning adult birds. These are just a few of the people who
are involved in Greater Victoria.
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| John and Wallis preparing the nest boxes for 2015 |
2014 Results
The BC Purple Martin population continues to grow.
In 2014 a total of 1060 pairs nested at 74 marine and 6 freshwater sites – 110 more
pairs than last year! There are 13 active Purple Martin colonies in the South
Island region. Last summer Wallis Moore Reid banded 467 nestlings. Some of the
more active sites in this area were: Tod Inlet (122 nestlings banded), West Bay
Marina (95 nestlings banded), and the Institute of Ocean Sciences on Patricia
Bay (89 nestlings banded).
It is encouraging to see how a species can recover
thanks to the dedicated effort and cooperation of both individuals and groups.
The Purple Martin, once near extirpation in this region, now has a strong
“wing”-hold. There is every reason to hope that these birds will continue to
flourish, thanks to everyone who has helped, and continues to help, make this such
a successful project.
There is much more information about the
Purple Martin program on the GBEARS website.
Purple Martin Conservation Association
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