The Frederick News-Post
SHARPSBURG, Md. (AP) — They pop up with amazing regularity along the park roads of Antietam National Battlefield — little shoebox-sized cedar boxes hanging vertically on fence posts, metal signs and tree stumps.
For bluebirds, these boxes are a lifeline.
They are perched at 100-yard intervals along the roads, fields and open spaces of Antietam. Because of these boxes, visitors can see bluebirds, sometimes one or two, sometimes dozens, at any time of year.
The boxes are there, 100 in all, because of the efforts of one couple, Mark and Jean Raabe. The Raabes maintain the boxes, checking them once a week from March to November. They painstakingly clean them out at the end of each season and get them ready for the next season. Mark replaces the boxes every five to six years.
Because of these boxes, more than 9,000 bluebirds have successfully fledged, which is bird-speak for an egg which hatches into a bird that flies away from the nest.
“The bluebird is now a thriving species because of all these trails,” said Judy Lilga, a bluebird enthusiast from Sharpsburg who recently spoke to the Potomac Valley Audubon Society about the Antietam Bluebird Trail, as it’s called. Lilga and her husband, John, help the Raabes maintain the boxes.
“You can see bluebirds any day of the year at Antietam,” she said.
The Raabes live in Alexandria, Va., but have owned a weekend cabin in the Horseshoe Bend development on Burnside Bridge Road, directly across Snavely’s Ford from Antietam Battlefield, since 1970.
Through a fortunate series of events, the Raabes became charter members of the North American Bluebird Society in 1978, and started the Antietam Bluebird Trail a year later.
They weren’t bird experts. They did little more than feed birds when they came upon that cabin near Sharpsburg. Both Mark and Jean had grown up in rural Minnesota, however, and loved the outdoors. They loved the sound of the bobwhite, and the sight of the meadowlark.
They weren’t familiar with bluebirds until Jean saw one, a brilliant male in all his plumage, outside their cabin window in 1973. At the time, the population of bluebirds was falling, because of habitat loss and invasive European birds.
“They were 90 percent gone,” Mark said by phone. But the farm habitat that surrounded Antietam Creek, with its open fields, was perfect for bluebirds.
Bluebirds, as the Raabes would learn, are cavity nesters, and need a special kind of house. They live in the hollow spaces of dead trees, usually 3 to 5 feet high, or old wooden fence posts. In the mid-20th century, farmers began replacing wooden fence posts with metal, and dead trees were often removed rather than left to crumble.
That, plus the competition for nesting space with starlings and English sparrows, caused bluebird numbers to drop precipitously.
The Raabes wanted to know more about this striking bird. In the pre-Internet days of 1973, they did some research and found Dr. Larry Zeleny, a retired government scientist living in College Park. Zeleny spent years studying and writing about the declining bluebird populations. He became a bluebird mentor to the Raabes, and the Raabes became part of a growing movement of citizen scientists.
Zeleny sought help to build boxes that would replace the bluebird’s natural habitat. Each box has a hole, an inch and a half around, located near the top. The size of the hole is crucial. Any bigger, and it would allow European starlings to take over the box and kill the bluebird eggs.
Mark built several boxes according to Zeleny’s guidelines. He put them up in a meadow near the cabin. Within five years, the couple’s boxes helped more than 100 bluebirds fledge.
The Raabes also followed the plight of the bluebird. Starlings and English sparrows, also called house sparrows, are major threats. Neither bird is native to the United States, and both have reproduced in large numbers and become major pests to native birds. Sparrows can get into bluebird boxes, kill the bluebird eggs, and lay their own eggs. House wrens also try to take over bluebird nests.
The Raabes answered Zeleny’s call for more bluebird boxes, and built a few to be put up at Antietam. With the help of two park rangers, Ed Wenchoff, who has since moved on, and the late Ed Mazzer, they put up 40 boxes. Eventually, the bluebird trail came to have 100 boxes. Each box has air vents and drainage holes.
The Raabes check the boxes at least once a week throughout the nesting season. If sparrows or wrens have laid eggs, they remove the eggs. The Raabes repeat this until the female abandons the nest in frustration.
This attention to detail has allowed the bluebirds to flourish.
There’s still another detail that the Raabes scrupulously adhere to. The boxes, mostly made of cedar to blend in with the park’s natural surroundings, are rough on the inside, which allows the birds to climb in and out of the box. Bluebird babies will not survive in boxes with smooth interior walls.
The Raabes monitor the boxes weekly, taking notes on each box and comparing the findings from week to week. These pen and paper records help show patterns.
“Mark takes meticulous records,” Lilga said.
The Raabes do some traveling, and each summer they return home to Minnesota for several months. For the past 10 years, Lilga, a retired Montgomery County schoolteacher, and her husband John have taken over Antietam bluebird duty in May, July, August and September. Bluebirds typically nest two or three times a year.
Mark, a lawyer and consultant, and Jean, a retired high school teacher, are still active, even though Mark just celebrated his 83rd birthday.
“We’re not viewed among people who know us as anywhere near our age,” Mark said. “We’ve been blessed with good genes.”
Judy Lilga spoke at her recent presentation about the Raabes and their fortuitous meeting with Zeleny.
“He started the movement to save the bluebirds,” she said. “These trails have owners who are aging. They are starting a discussion of who will maintain them in the future.”
While the Raabes were busy building their bluebird trail in the east, Al Larson built a trail with 300 nest boxes in the wide open spaces of Idaho. There, mountain bluebirds and western bluebirds live in similar habitat to the Eastern bluebird. Larson is now 92, and bluebird advocates there are hoping to carry on his legacy.
“We’re trying to get younger people involved in these efforts,” Lilga said.
A half-hour documentary on Larson, “Bluebird Man” is now in production.
Bluebirds make very neat nests, which help caretakers identify them. The nests consist of dried grass, pine needles or similar material, with each piece nearly the same size. To prevent cats and raccoons from robbing the nest, the Raabes attached Noel guards, metal cages a few inches square, over the nest box entrance.
After each nesting, the Raabes or the Lilgas clean each box with bluebird house protector, a spray they get from the North American Bluebird Society. It repels parasites that can infect bluebird young.
Last year brought 111 successful nests, with 451 birds fledged. Bluebirds have other predators besides other birds, cats and raccoons. Snakes can crawl through the hole.
The Noel guard doesn’t entirely prevent this. Black snakes will eat bluebird eggs, and they sometimes nap in the boxes.
The Raabes’ records showed that 2012 was an especially good year, because of an early spring and a hot, somewhat dry summer. Bluebirds love hot, dry weather, Lilga said.
Lilga recalled finding a nest box, with bluebird babies, that had fallen on the ground. She and her husband re-attached the box to the fence post.
“They seem tolerant of people,” she said. There’s no truth to the myth that touching a bluebird egg will prevent the mother from returning to the nest, she added.
Bluebird eggs need 12 to 15 days to hatch, and the young birds need another 16 to 18 days before they leave the nest.
In colder winters, like the current winter, bluebirds will often take shelter in nest boxes to keep warm. Overnight, they roost in the boxes and fluff up their feathers to trap air, which warms them.
Putting up a bluebird box in your backyard helps the bluebirds. It must be monitored weekly, however, just as the Raabes monitor the Antietam boxes.
“That way, you’re helping the birds to be successful,” Lilga said. “Bluebirds have come to depend on these boxes.”
“We’ve got the habitat and they’ve got the drive,” said park ranger Debbie Cohen. “Their efforts have paid off handsomely.”
Information from: The Frederick (Md.) News-Post, http://www.fredericknewspost.com
(Copyright 2013 by The Associated Press. All Rights Reserved.)