MONROE — Predatory merlins have frightened away the Vaux’s swifts from their popular roosting spot in Frank Wagner Elementary’s chimney.
Now the question is whether the birds will ever come back.
Their practical no-show this year is evident in observers’ nightly logs: Zero. Zero. Zero.
No swifts entered the chimney starting from Aug. 26 through most of September. The numbers plummeted after the first night’s count on Aug. 21.
Usually, a few thousand swifts would dive in each night. Last fall’s cumulative count at Wagner surpassed 140,000.
The Vaux’s swifts are winging down the West Coast, moving from Canada to Mexico. They’ll do the reverse in the spring. The little birds cover 150 or more miles in a day before collectively swooping into select chimneys and trees for nighttime rest.
“The swifts have abandoned the chimney. This is serious,” said Larry Schwitters, the nation’s pre-eminent Vaux’s swifts expert, with clear disappointment.
How serious? The 80-year-old Wagner chimney is seen as one of Washington state’s four most important roosting spots for swifts.
What happened?
Observers say two merlins — possibly a male and a female pair — created an outpost near the site.
The swifts surveyed the Wagner chimney, detected the merlins’ presence, and simply flew over and kept pushing south on their annual migration.
Chimneys at Joint Base Lewis-McChord as well as one in Chehalis and one in Rainier, Oregon saw great upticks in swift activity this year. Those stand 70 to 160 miles south of Monroe.
It’s unclear how the swifts detect the merlin. One theory is scent alerted the swifts. The other theory is that a swift from an early flock stayed behind to warn incoming flock groups to avoid this chimney. The first night on Aug. 21 saw 4,851 swifts enter the chimney, but the numbers dropped precipitously each following night.
It’s believed the Wagner swifts use the Chapman School chimney in Portland as their next stop.
Merlins are falcons. They chase in the air to catch their prey, unlike Cooper’s hawks, which lay in wait to ambush whatever unlucky swift it can get.
A strong swift can outrun a merlin. A weak swift is a meal.
A merlin eats up to 900 birds a year, feeding on “the most abundant and vulnerable prey available,” from the website of Hawk Mountain Sanctuary, a raptor-bird conservation organization.
Schwitters acknowledges the merlins are utilizing natural selection to feed; he despises the hawks’ random ambush tactics as unfair.
Have the swifts abandoned Wagner altogether? That’s unpredictable right now, Schwitters said.
What is known is that the flock did not adjust to nearby chimneys such as the one at the Monroe School District’s headquarters downtown at Fremont and Ferry streets.
History says once the swift migration abandons a place, it’s not necessarily permanent.
An abandonment case is when the swifts began skipping over a chimney near the Canadian border to take up roost at the former mental institution in Sedro-Woolley.
But the swifts also temporarily abandoned a chimney in Eugene, Oregon only to return three years later.
A problem with crows at the Wagner chimney was solved with netting. Schwitters, today 78, climbed up and installed it himself.
What can abate the merlins? He hasn’t figured it out yet.
Owls are the merlin’s predators.
Schwitters is saddened by the whole thing. He’s tracked swifts for 18 years, specializing in Vaux’s swifts for the past 13.
“It would be a shame if the city with the swifts as its official bird has no swifts.”
