Biologists at Devils Tower have determined that the pair of peregrine falcons at the tower did not have a successful nesting season for the first time in seven years, the National Park Service announced June 26.
Although the falcons in the area showed behavior consistent with courtship and breeding, the weather may have had an effect on the nesting situation, the announcement said.
“Falcons nest on rock ledges high on the tower in areas with very limited shelter,” Rene Ohms, chief of resource management said in the announcement. “This year’s late-season snow, colder than normal temperatures and frequent hard rains have made it very difficult for them.”
Ohms says it’s very obvious when and where the nest is located based on the falcon’s vocalization and where they’re taking their food. The nest would have had to have been constructed in May or early June.
The species was listed as an endangered in 1970, but had a remarkable recovery, being removed from the list in 1999. Devils Tower had the falcon return in 2013, seeing successful nesting for the last six years.
Ohms says that nests sometimes fail, but the population as a whole won’t be impacted.
Peregrine falcons are birds of prey and fill an important niche in the ecosystem of the tower. They help the monument control the population of pigeons, which are an invasive species, Ohms said.
The falcons’ nesting locations affect rock climbing routes that are available for the season. If climbers are near a nest site, the falcons can become distressed, aggressively diving toward climbers.
The closures are an annual occurrence established under the 1995 climbing management plan. Since the falcon pair didn’t successfully nest, all climbing routes are open, the announcement said.
Park staff are continuing to track the pair but ask climbers to report any defensive behavior. Closures can be implemented at any point for the protection of the falcons.
Aside from closures occurring for the falcons, Devils Tower has a voluntary climbing closure for June. The month is important for Native American ceremonies that occur around the summer solstice.
Climbers are asked to respect the cultural significance of the closures.