CAPE CHARLES, Va. -- Screenwriters and cartoonists often cast bird-watchers as timid eccentrics in funny hats with Sibley guides sticking out from their safari jackets and binoculars around their necks. The perfect disguise for a terrorist, perhaps?

But serious ornithologists tend to have a bit of Indiana Jones in them. Ned Brinkley, for one, has driven into hurricanes looking for birds blown off course to unusual places. He has floated through swamps searching for evidence that the ivory-billed woodpecker is not extinct. And he was not about to knuckle under meekly when he learned that officials worried about terrorism were about to ban visitors from the Chesapeake Bay Bridge-Tunnel, one of the best birding spots on the East Coast.

Ever since the attacks of Sept. 11, 2001, Americans have grown accustomed to probes into their private lives and a great many new restrictions. From full-body searches at airport boarding gates to barricades around the Capitol, the nation has accepted many intrusive and prohibitive security measures as the price of safety.

Bird-watchers are oddly vulnerable to the new scrutiny. They carry binoculars, scopes and cameras. They like to go to such places as buffer zones around military bases and nuclear power plants, where lots of birds roost. They are sometimes turned in to police by suspicious passers-by.

This time, Brinkley and a few cohorts were prepared to fight back. Their successful effort to regain access to the bridge islands illustrates how it is possible to continue their activities, even in a security-conscious age. But it requires concessions that once would have been considered extreme. It is a predicament many Americans are facing.

Tuesday, the commission overseeing the span voted to accept a compromise negotiated with the bridge's executive director and head of security. Under the plan, scientists and researchers will be allowed to go on the islands that connect the bridge once they get a pass, renewed annually. Amateur bird-watchers will have to submit to a security check several weeks in advance and pay $50 an hour for a police escort.

"Why allow people whose intentions we don't know [to] dictate how our lives as Americans, our lives as Virginians, our lives as bird-watchers, are restricted?" asked Brinkley, who runs a bed-and-breakfast in Cape Charles when he is not leading bird-watching tours.

The Chesapeake Bay Bridge-Tunnel, a 17.6-mile span that costs $17 round-trip for a passenger car, connects Virginia's Eastern Shore with the mainland at Virginia Beach. The entrance and exit of two tunnels in the middle of the bay are secured by small, man-made islands of granite boulders. At the southernmost island, there is a restaurant and a fishing pier open to the public.

The three northern islands are popular with bird-watchers.

Until this year, visitor passes were handed out almost casually. A mailed or faxed request routinely secured a letter of permission granting access to the islands for a year.

That changed after a risk analysis by the state Department of Transportation. It warned that the air-intake buildings providing ventilation to the tunnels were prone to sabotage. Homeland Security authorized a $1.3 million grant to secure the ventilation.

The report triggered a rethinking of the entire approach to security. Last year, 800 letters of permission were handed out to birders who provided little more identification than a driver's license. The authority concluded that it had not screened visitors well or kept tabs on their movements.

No one questioned the need for more security on the bridge, located just north of the largest Navy base on the East Coast.

Short of a specific threat, however, many wondered if the ban accomplished its intended purpose. Why keep the southernmost island, with its restaurant and pier, open to the public? Why allow fishing boats to approach? And would a fence around the ventilation buildings really keep out a determined terrorist?

The birders pronounced themselves grateful for even the limited access.

Brinkley's only regret is that he could not convince anyone of the merits of training bird-watchers to be on the lookout for terrorists.