Biodiversity, Conservator, Partnerships, Science, Wetlands

Lessons in habitat and hope

Why wetlands may just be the swell solution that help swallows succeed

By Suzanne Joyce with Leigh Patterson June 19, 2025

Two dusty tracks wind like a tan snake, gradually climbing to a high point before disappearing over a small knoll. In the low spots, the truck shakes, rattles and rolls as its tires drop in and out of ruts and potholes, remnant clues of recent rain.

It’s slow-going navigating the lane onto Ducks Unlimited Canada’s (DUC) Rink Project, 70 kilometres southeast of Saskatoon, Sask. But it’s worth it — tree swallows abound here and it’s magical.

Flashes of blue and white dart through the air above. Up close, each tiny swallow is like a microcosm of a summer sky, backs deep cerulean, cottony cloud tummies, and remarkable iridescent feathers like the shimmer of sunlight itself.

The antenna of a Motus station stands on a hill nearby and the swallows have adopted its steel arms and cables as their own, just as easily as they’ve taken to the dozen or so nest boxes that line the lane. Tree swallows are an adaptable species alright. But population declines over the past 50 years suggest that may not be enough to guarantee the survival of this charismatic species — or that of its swallow cousins.

Aerial insectivores — birds that hunt for insects in flight — include swifts, swallows, flycatchers and nightjars. The group overall has declined by 43 per cent since 1970, but for three North American swallow species — the trees, the banks and the barns—the drop has been more precipitous.

Scientists point to declining insect populations as a major cause, with habitat loss, increased perils during migration and climate change all likely co-conspirators.

This is a story of possibilities, though, thanks to the efforts of people in three Canadian provinces striving to boost swallow populations. We’re holding out hope for Hirundininae.

Project leader Christy Morrissey inspects a nest box for tree swallows at DUC’s Rink Project. © DUC

^“

As long as we can maintain a mosaic of habitat types that includes wetlands and patches of grassland, we actually can sustain a working landscape with room for biodiversity.

Christy Morrissey

Bug buffets: Why wetlands matter to tree swallows

At DUC’s Rink Project, a powerful prairie wind whips tall grasses one way then the next, creating undulating waves on a verdant sea. Little brown birds chip and buzz from the cover, a bumblebee whizzes by, and a turkey vulture floats high up in the thermals. And of course, there are the swoon-worthy swallows.

Scenes of biodiversity like this are becoming rarer. Even in this area, much of the hummocky land has now succumbed to the plough; decrepit fences alongside annual cropland hint at past farming practices centred more around cows than canola.

Increasingly, intensive agriculture dominates this landscape, relying on crop varieties, fertilizers, irrigation and pesticides to boost food production per acre. It’s an approach that — unfortunately — often leads to the loss of wetlands and grasslands, and declining biodiversity. But this pattern doesn’t always hold.

Christy Morrissey is associate professor in the Department of Biology and School of Environment and Sustainability at the University of Saskatchewan. An ecotoxicologist, Morrissey studies environmental contaminants and their impact on birds and aquatic ecosystems. “We should have the lowest biodiversity of any agricultural landscape,” Morrissey notes, “but we don’t. Swallows seem to be doing better on the Prairies, despite this being the most agriculturally intensive region in Canada.”

Together with colleagues and students, Morrissey is leading research efforts at Rink Project and other Saskatchewan study sites, seeking to explain the relationship between agriculture and biodiversity, and what it could mean for the future of swallows.

Morrissey and her team looked at how breeding tree swallows respond to the spectrum of agricultural practices, comparing sites ranging from intensive annual cropping to pasture, and from few wetlands to many.

The fitness of tree swallows hatched at cropland sites with wetlands nearly matched those hatched at grassland sites, with eggs laid earlier and nestling body condition that would make moms proud. Morrissey explains, “Several studies suggest that birds do as well on cropped sites in areas of intensive agriculture, if there are wetlands close by.”

A hefty body of research on tree swallows has linked wetland-derived nutrition to healthier nestlings and more successful fledglings, and much of it is due to long-chain fatty acids. These all-important nutrients are specific to aquatic food chains that begin with algae and lead to high-quality insect prey.

For tree swallows, water bugs are good vittles, and they’re worth covering extra distance to procure. Morrissey explains, “We found that even though wetlands cover a small per cent of land, tree swallows strongly preferred feeding over these water bodies. It wasn’t uncommon for birds to be found two kilometres from their nest in search of aquatic insects.”

According to Morrissey’s research, prairie pothole wetlands punch above their weight in providing critical support for biodiversity in agricultural landscapes. If we hope to provide a wing up for tree swallows and other aerial insectivores, retaining wetlands will be an essential part of the equation.

“As long as we can maintain a mosaic of habitat types that includes wetlands and patches of grassland, we actually can sustain a working landscape with room for biodiversity,” Morrissey says.

Rachel Darvill scans the banks of the Columbia River in B.C. for bank swallow nests. She was contracted to lead the Upper Columbia Swallow Habitat Enhancement Project to help area populations recover. © DUC

^“

With the naturalization taking place over the next few years, water will return to Moberly and bring even more insect food for the swallows and their young.

Rachel Darvill

Banking on recovery in B.C.’s Columbia Valley

Rachel Darvill has over two decades’ experience in species-at-risk conservation in Canada and abroad and has worked with everything from elephants to whales. These days, Darvill’s sweet on swallows, leading a unique approach in B.C.’s Columbia River Valley to help populations of at-risk bank swallows recover.

Once numerous and widespread, bank swallow numbers have been dwindling over the last 40 years, amounting to a loss of 98 per cent of their Canadian population. In May 2013, the species was listed as threatened by the Committee on the Status of Endangered Wildlife in Canada.

Recovery efforts emphasize restoring and protecting the places where bank swallows nest, forage and roost. And in B.C., the Ramsar-designated Columbia Wetlands Wildlife Management Area (WMA) has been identified as a hot spot.

Wildsight Golden is an organization that works to protect the uniquely rich and diverse Columbia River Valley, home to abundant amphibians, reptiles, mammals, birds, fish and invertebrates, including rare species like bank swallows.

In 2021, they launched the Upper Columbia Swallow Habitat Enhancement Project to help bank swallow populations recover. Biologist Darvill was contracted to develop and lead the program’s scientific and educational efforts.

Bank swallows nest in burrows that they dig in banks and sandy cliffs using their feet, wings and bill. Darvill’s initial inventory of potential nesting areas found that those banks and sandy cliffs were in short supply.

“We identified 128 bank swallow colonies along the Columbia River,” Darvill explains. “But we also found a gap in available nesting habitat along the northern stretch of the valley. We hoped to build nest structures where natural nest sites were lacking and enhance the suitability of these areas for swallows.”

The location Darvill selected for the nest structure was an area of floodplain wetlands along the Columbia River known as Moberly Marsh. Thanks to the combined efforts of DUC and BC Parks, the natural areas at Moberly Marsh — more than 692 acres (280 hectares) — had already been protected.

To construct the bank swallow nest structure, the Wildsight team gained insight from a design piloted in Quebec. Resembling a giant pegboard, a cement wall with small, perforated openings provides the vertical surface desired by the swallows. The material behind the wall is just as important.

“We knew we needed the right type of substrate for the swallows to burrow into,” Darvill explains. “Sandy material was taken from a nearby gravel pit where swallows had been trying to nest, so we knew they would use it.”

For the swallows and other area wildlife, life at Moberly Marsh is going to get even better. Fifty-year-old water control structures DUC operated under an agreement with BC Parks are slated to be removed over the next five years. The infrastructure is nearing the end of its useful life. In consultation with biologists, BC Parks staff, Indigenous communities and other area stakeholders, plans are to restore Burges James Gadsden Provincial Park back to natural and dynamic floodplain habitat that will provide the greatest benefit to species diversity within the park and connect the project to the adjacent Columbia Wetlands WMA.

For Darvill, that made Moberly Marsh an optimal location for nesting swallows. “With the naturalization taking place over the next few years, water will return to Moberly and bring even more insect food for the swallows and their young.”

Aerial insectivores, such as tree swallows, have declined by 43 per cent since 1970. © Eli Ouimet

Prairie Wings: A swallow conservation journey in Manitoba

It’s early May 2025, and Patrick Lang and Mark Lussier are freshly back home in Winnipeg after two days spent cleaning nest boxes in the St. Ambroise area. They report sightings of bluebirds, tree swallows, tundra swans, marbled godwit, common snipe, meadowlarks, blackbirds, gulls, kestrels and garter snakes.

“Glorious sunshine and fresh air. Talk about bathing in nature,” enthuses Lang.

Lang and Lussier get hefty doses of nature, in all seasons. They load Lang’s trusty red Ranger to the roof with boxes, bikes and other equipment and head out to crisscross the countryside with the sole purpose of giving the birds safe homes.

For 10 years, the friends have been devoted to the conservation of birds under the name “Prairie Wings,” building and installing nest boxes for tree and barn swallows, bluebirds, cavity-nesting ducks and great horned owls. With an estimated 70 per cent success rate under those proverbial wings, they’ve left an impressive legacy in their wake. It’s a labour of love that quite literally flies under the radar.

Lang, a retired DUC staffer, and Lussier conduct their field work quietly and with purpose, keeping meticulous records of nest box locations, approximate number of fledglings, dates and discoveries. For tree swallows and Eastern bluebirds alone, they’ve built and put up 500 compact Peterson nest boxes at various southern Manitoba locales (which they clean out in early spring or late fall). Along with numerous nest cups and experimental nest structures for barn swallows at the Oak Hammock Marsh Wildlife Management Area, Lang figures 1,750 insectivores fledge successfully each year courtesy of their volunteerism.

Patrick Lang (left) and Mark Lussier (right) are devoted to the conservation of birds under the name “Prairie Wings,” constructing nest boxes in Manitoba for tree and barn swallows, among other birds. © Patrick Lang

^“

The birds will tell us what they need.

Patrick Lang

(No longer) born in a barn

At Oak Hammock Marsh, the dynamic duo has been putting much of their effort into building homes for barn swallows. Like other aerial insectivores, habitat loss and insecticides are believed to be among the leading causes of their decline. Barn swallows also require nest sites protected from rain and avian predators like crows and many of the old barns they once used are being torn down or decaying — like the one just up the road from Oak Hammock that’s been slowly sinking, beam by beam, into the ground.

Their approach includes various experimental nest structures for barn swallows, like horizontal and vertical “condos” with special nest cups, all designed and built by Lussier, who had been doing this solo since the early 1990s before being joined by Lang. They place structures in different locations around the marsh — on dikes, under bridges, and eaves — places that might mimic what swallows find attractive in barns, to test their effectiveness. Some are enthusiastically accepted by the birds, while others need relocation. It’s all part of the process: observing, adapting and trying again, learning from each breeding season.

“The birds will tell us what they need,” says Lang.

In their own way, the birds are doing just that. While swooping and darting above their preferred wetlands, gulping insects mid-flight and making use of nearby nest structures, swallows are dropping hints about what they need for habitat and homes.

And thanks to the people helping these winged acrobats by listening and innovating, we can better understand how, and why, wetlands may just be the swell solution that help swallows succeed.