Skip to content

Second endangered black swift nesting site discovered

“We had three breeding pairs and chicks that successfully fledged this year, as well as a fourth nest that we think was probably being used as a roost by a sub-adult."

BANFF – A second nesting site of an endangered bird species has been discovered in Banff National Park.

Up until now, the only known nesting site of black swifts in the park was Johnston Canyon; however, researchers found another spot last summer in Banff’s backcountry in the Egypt Lake area.

“Through our expanded survey efforts, we’ve been able to confirm a second nesting site in the Egypt Lake lake area, which is super exciting,” said Jennifer Reimer, a resource manager officer in Banff National Park who has led the black swift monitoring program since 2015.

Black swifts, the largest of swift species in North America, are graceful and agile aerial insectivores that spend most of their lives on the wing, and choose mostly inaccessible waterfalls and cliffs to nest on.

They were listed as endangered under the Species at Risk Act (SARA) in May 2019 based on a 50 per cent decline in the Canadian population over the past 40 years – much of which happened in the last 10 to 15 years alone.

Work on a recovery strategy, including identification of critical habitat, is underway.

The black swift nesting colony in Johnston Canyon, about 25 kilometres west of the Banff townsite, was discovered in 1919 and was the first confirmed inland nesting site in North America.

“Johnston Canyon is a great example of a colony that’s been active for at least 100 years,” said Reimer, who gave a presentation to the Bow Valley Naturalists in October.

“From the records we have, it appears that until 1992, the colony was relatively stable with a maximum recorded number of nests at 12,” she added.

“After that year, it abruptly drops off; it does fluctuate over time, but with a mean of two nests per year over the last 37 years.”

In 2020, there were four active nests in Johnston Canyon compared to two in 2019.

“We had three breeding pairs and chicks that successfully fledged this year, as well as a fourth nest that we think was probably being used as a roost by a sub-adult,” Reimer said.

“We’re not sure what next year holds, but we’re hopeful that we’ll have a similar level of activity, and I am also hopeful that next year we can identify even more nest sites in Banff National Park.”

Work continues at Johnston Canyon to educate people about the importance of abiding by restrictions on off-trail use from May 1 to Nov. 15 to protect the sensitive black swifts.

Despite ongoing education, onsite interpretation and extensive signage at Johnston Canyon, Parks Canada law enforcement wardens laid 89 charges in 2019 and 25 in 2020.

However, Reimer said the canyon only had about 10 per cent of visitors in 2020 due to COVID-19 restrictions, compared to 2019 when close to one million people visited, anywhere between 3,000 and 8,000 a day.

“Our law enforcement team has put in a ton of effort into increasing surveillance and improving compliance,” she said.

“They have been so responsive and really gotten the message out that respecting that seasonal trail restriction is absolutely necessary.”

Canada has the largest concentration of black swifts in North America, with most nesting sites occurring in British Columbia and only a few sites in Alberta. There are about 10 U.S. states where the birds also breed.

“We have up to 86 per cent of the breeding pairs in North America,” Reimer said, adding that the breeding season runs between May and September.

With long pointed wings and a slight notch in their tail, Reimer said black swifts are “one of the most aerodynamically efficient birds we’ve seen.”

She said they spend most of their lives flying, foraging for insects, particularly flying ants, which are their main source of prey.

They also fly extremely high, she noted, having been recorded flying in Colorado as high as 4,300 metres.

“I’ve seen them locally at Marble Canyon foraging at about 2,000 metres after they leave their nesting site in the morning, and likely flying at higher elevations throughout the day,” Reimer said.

“They also forage quite far from nesting sites, up to 120 kilometres away. They make really good use of that air space.”

In 2012, it was first discovered that black swifts fly to South America to winter.

Reimer said three birds were tagged with tracking devices and later recaptured, indicating the wintering grounds were in western Brazil.

She said research has also indicated black swifts are aerial roosters, which means they remain in the air 24 hours a day in their wintering grounds.

“That’s quite an exciting find, and even more interesting is the discovery that during a full moon, black swifts will fly at even higher elevations,” Reimer said.

“It’s not exactly known why, but it is suspected that this might be an adaptation to avoid greater risk of predation under the brightness of a full moon.”

Research has indicated black swifts prefer higher elevation and along rivers for nesting sites, likely because there’s more insects.

“Essentially, their range is limited by where they nest – along canyons, beside waterfalls and occasionally in caves,” Reimer said.

“They‘re using pockets and ledges along steep walls and cliffs.”

Black swifts also only lay one egg a season, which is usually laid by the end of June. With a lengthy rearing period, the chicks don’t fledge until near the end of September.

“The chicks are progressively attended to less frequently during the rearing period,” Reimer said.

“They might spend up to 12 hours alone before being fed by the adult, and both adults share responsibility during all phases of nesting.”

Habitat needed for black swifts to survive is very specific: consistent water flow through summer, nest niches or ledges, moss to build and repair nests, shading, and at a height safe from ground predators.

Reimer said consistent water flow is very important, noting it helps maintain a micro-climate around the nest.

“Because chicks are being left alone for such a long period of time, having that cool, consistent environment they think may actually help reduce the chick’s metabolic rate, so those chicks can endure long periods without provisioning,” she said.

“You’ll also find nests are mainly inaccessible to terrestrial predators, and only occasionally they are are predated by corvids like ravens, but that is not frequently reported.”

Some of the main threats to black swifts include airborne pollutants.

“We know black swifts are a long-lived species with low reproductive rates, and food availability is likely a driver in population regulation,” Reimer said. “We know, in general, aerial insectivores are being hit pretty hard.”

Reimer said the second biggest threat to black swifts is climate change.

“We’re experiencing that through a decrease in snowpack, earlier run-off altering stream flow, which is both affecting the micro-climate right at the nest sites and likely insect availability,” she said.

“As well, we know black swifts are already limited by suitable nesting habitat. With climate change, there is and will continue to be less suitable habitat and we may start to see some of those range contractions.”

Parks Canada continues to conduct research on these endangered birds using many tools, including drones in winter when the birds have flown south, remote cameras and "cover" infrared cameras that use a no-glow for nighttime images.

With an infrared camera during a search for possible nesting locations, researchers were able to get a positive heat signature of a chick in a nest in Kootenay National Park.

“We were then able to confirm a second active nesting site in Kootenay National Park,” Reimer said, which is an addition to the Marble Canyon site.

Cameras have also helped divulge other previously unknown information in Johnston Canyon.

Looking at the camera images, Reimer was able to narrow down the timing of chicks fledging from the nest to within an hour.

“I collected timing of shift changes between both adults, daily arrival and departure times; they were usually leaving between 6 and 7 in morning and returning mid-summer between 10 and 11 at night,” she added.

“We do know from one of these cameras that one of the chicks successfully left the nest early in morning on Sept. 10 and another one on Sept 18.”

This winter, Reimer hopes to head out with the visitor safety team to place temperature and humidity loggers beside the nests before the black swifts return in spring.

She said a stable micro-climate at the nest is important for black swifts in determining which sites to select for nesting, again mentioning it may also play a role in chick metabolic rates.

This type of research, she said, was done during one study in New Mexico, Colorado and California in 2010, which found temperature varied very little and humidity remained high.

“With climate change, we may see a reduction in humidity over time and increase in temperature of these nests sites,” Reimer said.

“These nest sites that occur right on the edge of their range in drier locations are likely at greater risk of becoming unsuitable over time. Collecting this data will contribute to understanding those future range shifts and potential contractions.”

Reimer is also hoping to collect feathers this winter from the vacant nests for genetic analysis, though she is unsure how viable that may be, or even if she will find any.

“But if we do, then perhaps we can answer questions like how much turnover do we have of individuals in this colony; do we have the same breeding pairs returning to the same nests and are birds that fledged from here returning to breed?”