Irregular Weather Disrupts Early Golden Eagle Migration Counts in Kananaskis

Erratic weather has disrupted early counts of golden eagle migration at Mount Lorette in Kananaskis, after an unusually strong start to the 2026 season along the eastern slopes of the Rockies.

The spring migration count, which runs from March 1 to April 22, began with 53 migrating golden eagles in the first five days, nearly double the highest total recorded for that period in the past 20 years.

Counts then slowed as conditions shifted from unseasonable warmth to snow, low cloud cover, and extreme winds.

“The migration seems to have been turned upside down by the weather,” said the Rocky Mountain Eagle Research Foundation. “Unusually warm weather in the first week brought far more migrants north than we usually have during that week. Then winter came back and the migration came to a halt.”

The apparent slowdown may not reflect fewer birds, but rather reduced visibility and changing flight behaviour.

“With low clouds hanging over the mountains and snow falling, we can’t see any eagles that might be flying by,” the foundation said, noting the birds can alter their routes. “They have lots of choices.”

Recent high winds along mountain ridgelines, the high points of mountain ranges, have further complicated counts.

“This week we are experiencing extremely high winds, above hurricane force on the ridges,” the foundation said. “That makes it tough for the eagles to fly, and those that are braving the wind are going so high they are hard to spot.”

After the early surge, counts have dropped below average.

“Our numbers, which started out high, have now fallen to about ⅔ of the average of the last 16 years,” the foundation said.

The fluctuation highlights the extent to which weather conditions influence migration counts rather than population alone.

“The weather is the single most important factor,” the foundation said. “That’s why it’s important to make these observations over many seasons, since the numbers for any one season can be very negatively influenced by poor weather.”

Though more information is needed, this year may also point to a possible shift in timing.

“This is the first year we’ve noticed that the migration might have started earlier than usual,” the foundation said. “We don’t have enough volunteers to be out looking earlier in the season or at different locations to be able to know if the migration timing is changing, or whether the eagles are taking different routes.”

Golden eagles migrate along the eastern slopes of the Rockies, where long, unbroken ridges generate rising air currents, or updrafts, that help the birds glide over long distances without expending much energy.

“The front ranges are thrust faults that result in continuous ridges, providing long stretches of continuous uplift,” said the foundation.

Mount Lorette in Kananaskis remains one of the most accessible and consistently monitored sites for observing the migration in western North America, though other areas, including Crowsnest Pass near Frank Slide, can act as concentration points.

The count is conducted daily by volunteer teams, typically consisting of a principal observer who identifies and records all passing raptors and an assistant who helps spot birds. The organization has eight principal observers, some of whom are at the site several times a week.

Data collected at the site is uploaded to Hawkcount, a database managed by the Hawk Migration Association, where it is also included in the association’s periodic Raptor Population Index analysis. With few hawk watch sites in western North America and a high volume of migrating golden eagles recorded at Mount Lorette, the dataset plays an important role in understanding population trends. The organization is also beginning to conduct analysis locally.

“Since there are few hawk watches in the west of the continent, and because we have by far the highest number of migrant Golden Eagles passing our site, our data is very important in understanding population trends,” the foundation said.

For Bow Valley wildlife enthusiasts, the migration remains a seasonal spectacle, though viewing conditions vary. The Mount Lorette site is located about one kilometre from the Troll Falls parking area in Evan-Thomas Provincial Recreation Area in Kananaskis Country. Viewing is typically best in the afternoon, when winds increase.

“The best time to visit is mid to late afternoon on days when there are strong, but not too strong, southwest winds,” said the foundation.

It is too early to determine what the 2026 season will ultimately show, as lower counts may reflect observation challenges rather than a true decline in migration.