Index Town Wall is large enough to accommodate two kinds of visitors: climbers and peregrine falcons.

The Town Wall has been a destination for climbers for decades. It’s also the site of a falcon nest built high on the granite cliff, inaccessible to predators but vulnerable to disturbance from climbers. Thus the closure of several climbing routes each spring to protect the eyrie with its eggs, and later the chicks.

The closure of a section of the Town Wall is in effect until July 1, said Thomas Cyrus, wildlife biologist for the state Fish and Wildlife Department.

“Closures for peregrine falcons and golden eagles around the state are initiated whenever necessary,” said Ruth Milner, district wildlife biologist.

“The climbing community recognizes it’s in its best interest to cooperate with managers to protect the birds. And they’re great about putting up information on their website,” Milner said.

The peregrines are still a species of concern in Washington, but at that level, the the Fish and Wildlife Department doesn’t keep track of them but does protect their nesting area from disturbances that would interfere with the egg-to-fledgling window.

“They nest on a scrape on a ledge and will use the same one over and over, or move back and forth in a number of different sites (on the Town Wall),” Cyrus said.

Only one pair will control the area.

“Peregrines are highly territorial. They will set up housekeeping and defend their scrape from all comers,” Milner said.

The steepness of the face cliff is more important than height, Milner said, to protect the family from mammal predators such as raccoons and weasels.

“The more isolated to mammals, the better the nesting site,” she said.

The female nearly always lays eggs in a scrape, a depression in a ledge. To create one, the female (usually) gets down on her breast and pushes her feet backward to create a small depression just deep enough to keep eggs from rolling off and smashing on rocks hundreds of feet below.

Index Town Wall is off U.S. 2 west of Stevens Pass. It has some of the state’s best crack climbs, and offers more than 600 climbing routes.

Birdathon: Ken Longley’s great gray owl was the winning photograph during Pilchuck Audubon Society’s 2014 Birdathon. It’s worth the trip to www.pilchuckaudubon.org.

The birdathon raised $4,340.

Rock and Tina Taylor (a?k?a Heron Addicts) spotted 211 species for the largest Big Month total, and their Big Day of 113 species topped the list.

They also won the Art Wait Award (most coots) with five.

The Blackbird/Nightingale Award for the best team name went to the Counting Crows (Terry Nightingale, Jonathan Blubaugh and Doug Resnick).

Susie Schaefer won the Best Mentor Award, and Yasi Kopplel took the Rookie Award.

The Best Bird awards went to the Egvedts (Monthly) for a great gray owl; and a red-necked phalarope for the Big Day by the Counting Crows.

Chow down: Research that tracked movement and behavior of seabirds using GPS devices has shown that fishing vessels have a far bigger ecological footprint than previously thought.

A science team led by the University of Exeter (England) discovered that north gannets changed their behavior in response to large fishing trawlers, suggesting boats could influence distribution and foraging patterns.

Researchers discovered that the gannets could be influenced by vessels at distances up to 11 kilometers. The team discovered that the gannets’ behavior depended on whether the boat was fishing or not, and what type of fishing gear it carried.

The findings were published in the journal “Current Biology.”

Pretty simple. A striking lack of diversity has been found in the earliest known birds that lived in the same habitat at the same time.

“There were no swans, no swallows, no herons, nothing like that. They were pretty much all between a sparrow and a crow,” said researcher Jonathan Mitchell, lead author in a paper published in the Proceedings of the Royal Society B last month.

Columnist Sharon Wootton can be reached at 360-468-3964 or www.songandword.com.