Purple Martin father feeding large green darner dragonfly to baby - photo by Marian Brickner

Becoming a Purple Martin host

 "Wherever he comes, he finds some hospitable retreat fitted up for his accommodation and that of his young, either in the projecting wooden cornice—on the top of the roof, or sign post—in the box appropriated to the Blue-bird; or, if all these be wanting, in the dove-house among the pigeons… Some people have large conveniences formed for the Martins, with many apartments, which are usually fully tenanted, and occupied regularly every spring."
Alexander Wilson, American Ornithology (1828)

How many Purple Martins once lived in North America? Reports by early naturalists like Mark Catsby, Alexander Wilson and John James Audubon suggest they were once far more common than they are today. In Kingston, a former Purple Martin host told me that 40 years ago, there were 25 Purple Martin colonies in Collins Bay alone. 

purple martin population trend chart shows gradual decline from the 1970s to around 2005, but then a significant increase since 2015, resulting in a current level 66% higher than in 1970

Purple Martin, The State of Canada's Birds 2024

State of Canada's Birds reports that from the 1970s to around 2005, Purple Martin populations declined significantly but that beginning in 2015 populations climbed steadily across most of Canada. Southern Ontario, with a decline of about 90%. 

map displaying purple martin breeding trend, in Ontario showing declineeBird trends map, Purple Martin illustration by Hilary Burn

The eBird Trends map for Purple Martin shows steeply declining breeding populations in the South (red dots), with some steady or slightly increasing populations (blue dots) elsewhere. If you zoom in to the Kingston area, you'll notice a decline despite an increase in most of Canada. This could simply be due to the lack of Purple Martin houses in our area. 

"While a common approach to wildlife conservation promotes the continued existence of appropriate habitats, the conservation of Eastern Purple Martin may hinge upon the continued existence of a specific human behaviour."
(Jervis et al., 2019)

Humans and Purple Martins have a longstanding relationship

art by John James Audubon of two purple martin couples with two hanging gourds
Courtesy of the John James Audubon Center at Mill Grove, Montgomery County Audubon Collection, and Zebra Publishing 

“They breed like Pigeons in Lockers prepared for them against Houses, and in Gourds hung on Poles for them to build in, they being of great Use about Hoses and Yards for pursuing and chasing away Crows, Hawks and other Vermin from the Poultry." 
Mark Catesby, The Natural History of Carolina, Florida and Bahama Islands (1731)

Humans have been enticing Purple Martins to nest near their homes for centuries. In his book American Ornithology (1808), Alexander Wilson observed that:

"The Chactaws and Chickasaws cut off all the top branches from a sapling their their cabins, leaving the prongs a foot or two in length, on each of which they hang a gourd, or calabash, properly hollowed out for their convenience... Wherever I have travelled in this country, I have seen with pleasure the hospitality of the inhabitants to this favourite bird."

In reciprocity, it's thought that Purple Martins served as security system, sounding the alarm if animals or birds of prey showed up to raid the food supply. Purple Martins, partly due to habitat destruction, are now reliant on humans their housing.

Supporting Purple Martins by becoming hosts

In the Kingston area, the Kingston Field Naturalists (KFN) have been working to increase the Purple Martin population by providing housing on Amherst Island and Wolfe Island. How might more people hosting Purple Martin colonies help? In Missouri, Kathy Freeze grew a the host community from 20 hosts, 97 pairs and 296 fledged in 2010 to 176 hosts, approximately 4,284 pairs and 16,093 fledged—a 5436% increase!  

On the left, a picture of two people from KFN standing in front of an aluminum purple martin box. On the right, a picture of a newly installed T-14 purple martin box in a field.

With the support of the KFN, we now we have two Purple Martin houses in the City of Kingston! At Lakeside Community Garden, KFN installed a recycled aluminum Purple Martin house, modified from the original 8 compartments to 4 to give the babies lots of room to grow and offering better protection from birds of prey. In the spring, we'll add a second pole with 8 Troyer horizontal gourds. At Invista in the new naturalized meadow visible from Sunny Acres Road, KFN installed a beautiful new T-14 Purple Martin house built by Dale Christensen. 

time progression with six images of a purple martin nest under construction then babies at different agesDr. Anna M. Forsman/Wild Symbioses Lab

In 2025, the first sighting of Purple Martins in our area was April 8. Once the first Purple Martins arrive, we'll add pine needles to each compartment (a favourite nesting material), raise the boxes and play dawnsong — sung by male Purple Martins during the pre-dawn hours — to let newly arrived Purple Martins know there's new housing available. Fingers crossed that the new houses will attract some first year parents. 

Wondering what happens inside a Purple Martin nest? Watch this fabulous Purple Martin nest story. At 7:37, check out the size of the dragonfly dad is feeding to one of the babies. 

Purple Martins love flying insects, meadows and water

Purple Martins, like other swallows, are aerial insectivores. They eat flying insects — beetles, flies, dragonflies, damselflies, leafhoppers, grasshoppers, crickets, butterflies, moths, wasps, bees, caddisflies, spiders, cicadas, termites and mayflies. They hunt as high as 150 metres and, when breeding, up to around 3 km of their nest. They also eat gravel, oyster shells, eggshells and pigeon grit to help digest insect exoskeletons. 

Marian Brickner, Facebook
In this picture a Purple Martin is feeding a Green Darner dragonfly to one of their babies. According to Ami Thompson, who did her PhD on Green Darners, Green Darners are an important early food source for Purple Martins as they migrate in early spring, arriving before many of our overwintering insects emerge. Spring cold snaps or snow storms sometimes interrupt Green Darner migration.

More Purple Martins die from starvation due to lack of insects during colds snaps and extended spells of windy or rainy weather than all other sources combined. Many Purple Martin hosts help Purple Martins survive tough times with supplemental feeding. 

Dr. Anna M. Forsman/Wild Symbioses Lab
While dragonflies, along with flies and Lepidoptera, are favourite Purple Martin prey, pooper snooper Dr. Anna Forsman from the Wild Symbioses Lab discovered a total of 71 different prey species in fecal samples. 

New research also indicates that for baby Swallows, what they eat is important as how much they eat. Swallows get their omega-3 fatty acids from flying insects — mayflies, caddisflies, and dragonflies — who, as larvae, live in water and are composed of more fatty acids than terrestrial insects. Our streams and wetlands are critically important in ensuring Purple Martins have the nutritious insects they need to raise healthy young!

Gratitude to everyone who supported this project

Deep gratitude to Jack Staszak and Dale Christensen from the Kingston Field Naturalists for their expertise and support in building and installing the Purple Martin houses at Lakeside and Invista. Thank you to City of Kingston Climate Champion Program, Trailhead Kingston and Nature Canada for supporting this project. And thank you to the team at Dupont, Invista and Qnity for inviting Purple Martins to their property.

Learn more about Purple Martins

References

Local efforts to support Purple Martins