It's a good sign of spring, and a great sign that a once-endangered species is doing well: the return of nesting peregrine falcons to Acadia National Park has led to the temporary closures of the Precipice and Valley Cove Cliffs areas of the park.

Park officials say the birds are once again defending nesting territories in those areas. Staff has observed these adults engaging in courtship and pre-nesting behavior that signals their intentions to nest and raise chicks during the spring and early summer. Peregrine falcons were extirpated several decades ago and remain listed as a Maine Endangered Species to help in their recovery and conservation.

To protect the nesting birds from inadvertent disturbance or harassment, the Precipice Cliff area and trails closed on March 15, while the cliff trails at Valley Cove will be closed on Tuesday.  The closure at the Precipice includes the popular Precipice Trail on the east face of Champlain Mountain and the equally popular Orange & Black Path (formerly the East Face Trail).

Along with closing the trails, the closure applies to the surrounding cliff face area. The closure at Valley Cove includes the Valley Cove Trail and the entire cliff area directly west of Valley Cove and below St. Sauveur and Valley Peak.  The closed trails are clearly marked with signs that identify the reason for the closure, the dates, and include a map that delineates the area of the closure.  

These trails will remain closed until approximately five weeks after the chicks take their first flights, or fledge, from their nests.  The opening of the trails and cliffs is usually in early August. Additional notices about the closures will be posted at all appropriate parking areas, trail heads and junctions with more detailed information available at the park’s visitor center, contact stations, and at park headquarters.

If the park biologist determines that the nesting attempt has failed later this spring or early in the summer, the park’s management team will be informed and decide when to open the trails and surrounding cliff areas. 

The park staff has been observing other possible nesting cliffs in the park this spring in hopes of documenting other falcon nesting behavior or activity.  To date, no falcons or indications that the birds are present (i.e., territorial defense or breeding behavior) have been observed. If falcons are observed engaging in pre-nesting or courtship activities at other sites, the park management team will consider the new information and identify if closures are needed for these areas.

Research has shown that nesting falcons are particularly vulnerable to human disturbance in the immediate vicinity of the nest or directed at the nest site.  Continued disturbances can lead to chick mortality or complete nest failure, which further slows the recovery of the species in Maine.

Back in 1991, the first pair of peregrine falcons nested successfully on the east face of Champlain Mountain.  A second pair of falcons established a nest site on Beech Cliffs above Echo Lake in 1995, and a third pair of falcons established a nesting territory at Jordan Cliffs in 1996. In 2009, park staff found a new territory on Ironbound Island in Frenchman Bay, marking the fifth site in the park’s legislative area that has been the used by falcons for nesting.  

Mount Desert Island's nesting falcons have become a mainstay in the recovery of peregrine falcons in Maine with more than 100 chicks fledged during the last 20 plus years. 

The peregrine falcon was placed on the endangered species list in the early 1970s because pesticides such as DDT were found to be causing reproductive failures in nesting attempts, which exaggerated problems the birds had been experiencing for decades from habitat loss and other human activities (hunting).  The peregrine population declined throughout North America and the species common to the northeastern United States and Canada disappeared before the 1960s.  

The federal listing protected any remaining birds and essential habitat while initiating an international captive breeding and reintroduction program.  Acadia National Park was selected to be one of the reintroduction field sites in Maine and for the Northeast. The reintroduction program began in 1984 using a method known as hacking.  This method places and rears young captive-bred peregrines on suitable cliffs with the hope that the cliff and area is “imprinted” upon the young birds and that they return to the area as adults and establish a breeding population.

Jordan Cliff on Penobscot Mountain overlooking Jordan Pond was selected as the hack site and served in this role for three springs beginning in 1984.  In 1999, the peregrine falcon was removed from the list of species receiving federal protection under the Federal Endangered Species Act.  At that time populations in most recovery regions of the United States had attained or surpassed most of the objectives identified in Regional Recovery Plans developed by states in concert with the Fish and Wildlife Service.  

Recovered populations are being monitored through a national delisted species monitoring program that began in 2001, which will be continued until 2015 to ensure that recovered populations remain stable or increase.

The park will announce the reopening of the closed areas and trails upon learning that the park wildlife biologist and Maine’s Department of Inland Fisheries & Wildlife Endangered Species biologist have determined that human activities will not disturb the young birds.