A pair of rare peregrine falcons that have chosen the Route 30 bridge across the Susquehanna as a base were given an extreme-makeover home this morning in hopes that they can pull off the first successful nesting in Lancaster County in 60 years.

A PennDOT "snooper crane" carefully lowered a prefabbed nesting box and two workers in climbing gear onto a concrete pier on the bridge after closing one of the two eastbound lanes of rush-hour traffic around 9 a.m.

The world's fastest-flying birds, whose species last nested in the county on nearby Chickies Rock in 1947, laid at least three eggs under the bridge last year, but none hatched.

A team of Pennsylvania Game Commission falcon specialists who found the eggs last June said the exposed location of the eggs may well have caused them to fail.

This morning, PennDOT workers lowered onto a downriver-facing pier a wooden structure that contains all the key ingredients needed by nesting falcons.

Enclosed on three sides for protection from the elements, it's 20 to 22 inches high, 22 inches deep and 34 inches wide. It comes fully equipped with a roof, gravel so eggs don't roll anywhere and a couple of perches. The perches would be used for mom and dad to sit and guard the nest, as well as for future young to use to exercise their wings as they learn to fly.

"We'd prefer they find a nice, natural cliff. That's where they naturally belong," said Art McMorris, the Game Commission's peregrine falcon coordinator.

But "the birds have clearly chosen the bridge as their nesting site. In this case, there is no good flat area for them to nest on. We don't know why the eggs failed but a good possibility is inadequate protection from the weather.

"This nest box will satisfy all those concerns," McMorris said.

The falcons have been sighted recently by birdwatchers. If they move in, the public would be able to watch the comings and goings with binoculars or spotting scopes from such spots as the park at the John Wright Store and Restaurant on Front Street in Wrightsville or the Route 462 bridge between Columbia and Wrightsville.

The pier, number 17 if counting from the York County side, is on the southern side of the bridge that supports eastbound lanes. It is about one-third of the way across the river from the York side.

The nesting box is being pointed to look downriver, pointing southeast, to block the predominant northwest winds.

The box itself was built by PennDOT using specifications provided by Pennsylvania Game Commission. It was bolted onto the pier.

Of the 24 breeding pairs of peregrine falcons in Pennsylvania last year — up from 16 the previous year — only three were on cliffs, despite their abundance around the state.

The remainder chose bridges, high ledges of tall buildings or smokestacks.

The Game Commission's policy now is to avoid placement of artificial nesting structures unless a pair of falcons has already picked a manmade structure, or the natural nest is unsafe for the birds, McMorris noted.

The artificial nest on the Route 30 bridge would be the 10th used in Pennsylvania.

A pair of falcons — probably the same pair as least year — have been spotted in recent days in the Columbia-Chickies Rock area.

In February, as hormones kick in, both the male and female may start trying to show off their hunting and flying skills to impress their mate, McMorris said.

Often during this courting period, the male catches prey and presents it to the female as a gift. Peregrines kill their prey — other birds — only in flight.

Eggs could be laid in March with hatching in late April or early May. Fledglings would be expected to fly away from the nest in late May or June.

Falcons disappeared from Pennsylvania in 1965 due to DDT egg-thinning. The Game Commission began a reintroduction program in the 1970s and the birds have made a remarkable comeback.

Nationally, peregrine falcons were taken off the endangered species list in 1999, but are still classified as endangered in Pennsylvania.

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