Mayne Island’s Purple Martins

International Travellers

If being a human feels challenging these days, take a moment to consider the awe-inspiring purple martins who are now on their epic journey to southeastern Brazil – an extraordinary round trip migration of 22,000 km. These large swallows have spent their summers on the Pacific Northwest coast for thousands of years, and some birds make this trip eleven times during their lifetimes. The beautiful liquid notes of their song is truly a signature sound of Mayne Island summer. Click below to listen. (Sound file by John Neville)

In 2005, Bruce Cousens and Charlene Lee of the BC Purple Martin Stewardship and Recovery Program (PUMA) oversaw the installation of two sets of nesting boxes here on Mayne, one in Bennett Bay beside the Mayne Island Resort pier, and the other in Miners Bay. Herbie and Bernard Rochet were the stewards of this project for over a decade, and after my recent conversation with Herbie I felt very moved by their commitment and love for these amazing creatures. With the help of Jon Hoff who built all the nest boxes, and Ron Willick and Bob Tucker who installed them, the boxes attracted their first occupants in the summer of 2006. Parks Canada supported the new project by supplying a boat to access the boxes for banding birds and to remove them for cleaning, and our local Trust Committee provided funding for several project accessories. These days the boxes are left up and plugged for the winter, and only a few birds are banded each year. 

A Challenging Life

Purple martins live for about five years, and the survival rate of the chicks on migration is only 40-60%. Predators such as gulls, ravens and herons can steal chicks from the nest box porches, so wire covers have been installed to deter them. Herbie and Bernard found the summer of 2008 particularly heartbreaking. They had just banded 49 chicks when heavy rains arrived preventing the adults from finding food for their young. Some adult birds appeared to be foraging on the shoreline in search of sandfleas, but at the end of this short untimely spell of cold wet weather, half the chicks and two adult birds were dead.

Predators of the Air

Purple martins are North America’s largest swallow measuring about half as large again as other swallows in this region. Adult males are a dark iridescent purple, and females are brownish/grey with a few iridescent purple feathers on their backs. Martins are extremely vocal birds making them easy to locate when in flight, even from a considerable distance. Purple martins are aerial insectivores feeding on dragonflies, moths, and beetles, as well as many smaller insects. A dragonfly makes a particularly good feast for their hungry nestlings as it is high in protein and fat.  

Adult males arrive back first and often return to previous nest sites. They can be heard singing a glorious dawn song which attracts other incoming migrants to join them. A large number of birds ensures healthy numbers of chicks and also diminishes the risk from predators. Purple martin nests are made of grasses, twigs, leaves, wood chips, and sometimes shells. Females lay 4-7 eggs and are largely responsible for the 17-20 day incubation until the young hatch. The nestlings will stay in the nest for another four weeks until they can finally fly on their own. Birds can remain in the nest into August or even early September. When the chicks are fledged, they practice flying from their boxes to roost in trees before facing the gruelling journey south. In September, colonies of Western purple martins flock together before migrating to South America for the winter. 

The Road to Recovery

Western martins are a Species at Risk (Blue-listed, Vulnerable) in BC as they are still recovering from a severe population decline in the 1900s. Historically, these birds nested in cavities in old trees near fresh or salt water or in open woodlands. With habitat use due to human development, changes in building design, fire suppression, and the introduction of invasive bird species, the reduction in available natural nesting sites meant there were just a few remaining breeding pairs by the 1980s. The PUMA program has installed more than 1500 nest boxes near or over water, and now there are over 1200 pairs of birds in 120 colonies. The largest BC colony is located in Ladysmith Harbour with 30 active nests, and Campbell River is the northwestern limit of their range in BC. Sadly though, Western purple martins now rely almost entirely on human-made nest boxes. If you have a freshwater pond, some open habitat or foreshore areas/structures where nest boxes could be installed, visit www.georgiabasin.ca and click “Projects” to find out more.

This year I had my last glimpse of these amazing birds on September 7th and listened to their mellifluous song as they flew higher and higher in the sky until they were out of sight. I always shed a few tears thinking about them on their arduous journey and look forward all winter to hearing them return in the spring.

More Reading

Purple Martins

Western Purple Martin Foundation