This year’s Vaux’s Swift counts are in. While numbers were the lowest they have ever been in Monroe, volunteers observed the largest migration yet.

Vaux’s Happening project coordinator and researcher Larry Schwitters speculates all the smoke from regional forest fires that lingered in the area may have had something to do with the unexpected statistics.

“This year was a very unusual migration,” he said.

There are only four sites in Western Washington that are designed as a Partners In Flight Important Bird Area, Schwitters said. The decommissioned Frank Wagner Elementary School chimney is one of them.

For nine years, the Sky Valley has honored the well-used roost during Swift Night Out. In 2016, the Vaux’s Swift was named Monroe’s official bird. In January, Sultan artist Kevin Pettelle’s “Wagner Swifts” sculpture was set up in the downtown corridor. In August, Mayor Geoffrey Thomas signed an official proclamation declaring Sept. 9 as this year’s Swift Night Out.

Up to 25,000 Vaux’s Swifts have flown into the chimney, the interior of which only has enough room for 12,000 of the birds to cling to the rough surface, in one night during their annual trek from Canada to Central America.

Vaux’s Swifts come up the West Coast. They raise their young as far north as the Yukon in the summer and head back down to southern Mexico and Costa Rica in the fall.

In 2008 — the first year Swift Night Out was scheduled — about 14,000 of the birds flew in through the 31-inch-wide entrance. That is the highest count for the occasion so far.

The IBA designation is recognized on a global level but does not ensure protection, Schwitters clarified. That is why local Audubons and other organizations partner with cities to promote preserving the sites, he said.

Schwitters has said the world Vaux’s Swift population is believed to decrease by about 2 percent each year. Some estimates are that between 200,000 and 250,000 are alive today; the official PIF statistic says about 340,000, he said.

The bird is closely related to the North American Chimney Swift, of which there are about eight million in existence — their population is concentrated on the East Coast. It is believed the swifts roosted on snags — dead or dying trees — before they used chimneys.

Vaux’s Swifts don’t seem to be good at fluffing up to keep warm, which is the tactic used by other varieties. Instead, they share each other’s body heat and choose roosting and nesting locations that have been baking in the sun all day, he said.

The swifts have been flying into Monroe for about 30 years, according to some of the city’s old-timers, Schwitters said previously. In 2007, the Audubon societies were able to convince the Monroe School District not to tear down the Frank Wagner chimney.

Instead, $100,000 was secured so the school district could earthquake-proof the structure. Schwitters also put predator deterrents around the entrance to protect the swifts from crows and hawks.

The three other designated sites for the swifts are in Sedro-Woolley, Selleck and at Joint Base Lewis-McChord near DuPont, Schwitters said. This year, Schwitters and his partners tried to get as many volunteer observers at the four roosts as possible.

Schwitters said the birds showed up every night at Frank Wagner, almost every night in Selleck and at the base, but next to none stopped in Sedro-Woolley. He suspects predation has factored in to why the swifts don’t use the Northern State Hospital — an old psychiatric facility — anymore.

Birds were sighted in Chehalis and in Rainier, Oregon for the first time this year, he said.

Selleck also had its lowest migration counts so far, Schwitters said. Lewis-McChord saw its largest yet. The site is west of Monroe, Schwitters said.

He guesses that easterly winds and an abundance of smoke pushed the swifts west this year. In all, 164 observers, who went out 675 times in 69 suspected sites, counted nearly 1.24 million birds. He said it may have been a good reproductive year for the swifts. Participation may also impact the final numbers. He is still trying to recruit more volunteer observers in Mexico.

“We are getting better at counting them,” he said. “We’ve got more people being excited about it.”