ACADIA NATIONAL PARK – Peregrine falcons, an endangered species that has been spotted at Maine’s only national park since 1991, have returned, prompting rangers to close parts of the park immediately.

Acadia Superintendent Sheridan Steele announced late last week that the area around Precipice Cliff will be closed until further notice to all visitor and operational activities.

Falcons were observed last week defending their nesting territory and engaging in breeding behavior. To protect the birds from disturbance, the popular Precipice and East Face trails on the east side of Champlain Mountain were posted.

Those trails have been closed since last October because of damage from a series of small earthquakes off Mount Desert Island.

In previous years, the trails have been reopened about five weeks after the falcon fledglings take their first flights, which is usually late July or early August.

This year, however, the trails likely will be closed much longer while rangers and volunteers rebuild the damaged trails, meaning the two trails could be closed for nearly the entire season.

Rangers have been observing other cliffs in the park, and if other falcons are found, additional closures likely will follow.

A dispatcher at the Acadia Ranger station on Sunday said the park was busy over the weekend and some people had inquired about the closed trails.

The first pair of peregrine falcons successfully nested on Champlain Mountain in 1991. Another pair followed at Beech Cliff in 1995 and at Jordan Cliffs in 1996.

The species become endangered in the early 1970s after pesticides such as DDT caused the population to decline.

As part of Maine’s recovery program, more than 80 chicks have hatched during the last 16 years at the park.