Peregrines are cliff nesters and can be sensitive to human disturbance, especially during their nesting period. Falcons are quite territorial and will often abandon nests to defend their territory, which leads to nest failure and low reproductive success. Nest failures can also result from inclement weather, such as cold temperatures and snowy or prolonged wet conditions. There is no evidence that human interference played a role in either the Baxter’s Pinnacle or Blacktail Butte failures this year.
The Baxter’s nest area was first discovered in 2010. The mated peregrine pair successfully produced one chick in 2010, 2011 and 2013, and fledged four young in 2014. According to park records, those four chicks were the most birds ever fledged from a single falcon nest in Grand Teton National Park. A total of eight peregrine chicks fledged from five nest sites in 2014.
The first successful peregrine breeding in Grand Teton National Park was documented in 1988, eight years after the reintroduction of peregrines was initiated across the Greater Yellowstone Ecosystem (GYE) in 1980. The number of successful nesting pairs in the park has risen from just one in 1988 to five pairs in 2014.
Decimated by the harmful effects of the pesticide DDT, it is believed that peregrine falcons were virtually eliminated from the GYE by the 1960s. In 1980, efforts to reintroduce peregrine falcons to Grand Teton were initiated in conjunction with similar efforts elsewhere in the GYE and western United States. Between 1980 and 1986, 52 fledgling falcons were released at several sites in the Teton Range. After sufficient recovery was achieved, peregrines were delisted from the endangered species list in 1999. Peregrine falcons remain a species of interest at Grand Teton National Park, however.
While in place, the public closure served a second purpose: to also protect climbers from the peregrines as they will defend their nest site by dive-bombing perceived intruders. The peregrine falcon is among the world’s fastest birds, flying at 40-55 mph and diving at more than 200 mph while defending a territory or striking prey. This posed a safety risk to climbers who may have been knocked off their rock ‘perch’ and injured.
Seasonal and temporary closures for wildlife protection are common in Grand Teton to protect both wildlife and park users. Entering a posted wildlife closure is a violation that can result in a citation and fine under the code of federal regulations.