MONTICELLO – The bluebird pair watched from a highline as Dorene Scriven waded into the tall bromegrass, freed PVC nestbox No. 14 from its post, reached in and gently extracted one of the days-old nestlings.
Separating one from the mass of five intertwined fuzzy gray bodies and tiny wings was no small task. But Scriven has had a lot of practice.
Her careful monitoring has helped to bring about 4,000 bluebirds to the fledgling stage in the 40 years since she established this 5-mile, 62-box trail encircling Lake Maria State Park.
While the young appeared healthy on this June 4 check, bluebirds face all manner of perils — from late snows that bury insects they eat to house sparrows that peck females to death and destroy the young, to improper nestbox positioning that overheats and kills occupants.
That's why Scriven's No. 1 piece of advice for those who consider starting a bluebird trail is this: Don't do it unless you're going to do it right.
"There are a lot of goodhearted people that put up boxes and don't ever look in them and take care of them," Scriven said.
When seeing a bluebird was rare in Minnesota, Scriven was among a handful of volunteers behind initial efforts to bring them back.
It started in the early 1970s with Dick Peterson, who designed the wooden nestbox named for him. When a newspaper story about his efforts prompted more requests than he could handle, he approached the National Audubon Society's Minneapolis chapter for help. Scriven was on the conservation committee.
She later became chairwoman of the Bluebird Recovery Program, a position she held for 25 years.
"Dorene is one of our conservation pioneers in Minnesota," said Carrol Henderson, the Minnesota Department of Natural Resources' nongame wildlife program supervisor who met her when the nongame program was established in the mid-1970s. "Dorene was one of the original spark plugs that made all this happen."
The first year, 11 people reported results to the Bluebird Recovery Program. At its peak, Henderson said about 15,000 people from Minnesota and surrounding states reported in.
On average, year-to-year Eastern bluebird populations increased 3.2 percent from 1972 to 2012, according to John Sauer of the U.S. Geologic Survey. A research wildlife biologist with Maryland's Patuxent Wildlife Research Center, his specialty is estimating bird populations.
"It created one of the most successful bluebird recovery programs in the nation," Henderson said. He attributed part of that success to Scriven, whose handwritten notes accompanying every annual report made each participant feel as if he or she were an important part of the effort.
Scriven, a soft-spoken woman who wears a straw hat into the field to ward off protective, dive-bombing male bluebirds, keeps a couple of toolboxes in her truck in case a box requires repairs. In the carpenter's apron her daughter appliqued with a vivid bluebird, she tucks away small notebooks for recording the status of each box, an assortment of double-headed nails, two screwdrivers and mosquito repellant.
Her arsenal also includes a pair of pliers. Sometimes for fixing. Sometimes for dispatching invading house sparrows.
On this late afternoon, Scriven points out an osprey nest and the spot where a kingfisher usually nested. On a recent check, she saw a sandhill crane disappearing into the tall grass, three chicks in tow. Those are among the perks of bluebird trail monitoring.
But after four decades, bluebirds still hold an allure.
"You can open up the boxes. You can, at some point in the nesting cycle, you can take out babies, show them, let little kids hold the babies and show the eggs and the whole process," Scriven said.
"It's sort of like Christmas. You go from box to box, and you don't know what you're going to find, what the surprise might be. Sometimes it's not very nice," she said.
One year, after seeing two successive batches of 9-day-old bluebirds killed by house sparrows, Scriven said she learned how to close the sparrows' windpipe with a pair of pliers.
"They don't suffer, but it's not a pleasant thing," Scriven said.
Once a week, Scriven drives from her Minneapolis home to check the houses. The checks begin before the birds nest — on March 30 this year, with help from her son because deep snow made navigation difficult. Early checks are necessary because wasps or mice may take over a box.
She'll continue the weekly visits through the nesting season —probably into September this year, as the birds didn't show signs of nesting until early May.
Last year, for the first time, she got some regular help. A couple of neighbor boys check 14 of her houses.
The houses are arranged in pairs. Ideally, a pair of tree swallows will take up residence in one of the two boxes. The swallows don't compete for food but may defend both boxes against wrens and non-native house sparrows.
This spring, Monticello High School freshman Emily Romine joined Scriven on her Saturday rounds.
While she's hoping to glean knowledge from Scriven and realizes the activity might look good on a college application, Romine seems most motivated by the birds.
"The first time I opened the box, I was using one of those PVC boxes where I had to lift the whole box off," Romine said. "The bluebird was still in there, so I was technically holding the bluebird."
Interested in starting a bluebird trail? In Bluebird Trails: A Guide to Success,Dorene Scriven covers different types of nestboxes, placement and monitoring. A trail is defined as five or more pairs. Among the suggestions:
• Space nestbox pairs at least 300 feet apart in an open area at least 200 feet from woods, with perching readily available.
• Minnesota bluebirds tend to prefer east-facing openings.
• Metal posts with boxes at least 5 feet from the ground dissuade predators.
• Peterson nestboxes and PVC models have proven effective in this region.
Want to build it yourself? Carrol Henderson's Woodworking for Wildlife: Homes for Birds and Animals includes plans for bluebird houses.