Biology

Nesting Chronology

Peregrine Falcons return to Montana during March and April and nest on cliffs. They prefer nesting cliffs over major waterways and small streams. However, they will occasionally nest several miles from water. Generally, they prefer the large faces on cliffs over 150 feet in height. Peregrine lay 1-5 eggs in late April and early May. Incubation lasts approximately 34 days and the young spend another 5-6 weeks in the eyrie before they fledge from the nesting ledge.

Peregrines are attracted to the higher cliffs.
Peregrines are attracted to the higher cliffs.
We have several eyries located in abandoned stick nests.
We have several eyries located in abandoned stick nests.



Peregrine Reproduction

Peregrine falcons can breed in their second year. The average number of young in Montana is 2.0 young per active eyrie. Peregrine falcons continue to breed throughout their life, although productivity declines as the peregrines get older. Peregrines can live up to 20 years of age.


Prairie Falcons also nest on cliffs and make scrapes to lay their eggs. Note the light brown color of the egg compared to the chocolate brown color of the peregrine eggs. Prairie falcons nest within 1/3 mile of active Peregrine Falcon eyries. Prairie Falcons nest along rivers as well as the more xeric habitats away from waterways.


Peregrine falcons choose horizontal ledges to build their scrape, usually in the upper 1/3 of the cliff. They prefer to nest on ledges with overhangs. Potholes are also a favorite location. The female hollows out a shallow indentation (scrape) to lay her eggs. Both the male and female incubate the eggs, but the majority of incubation falls on the female.



Prairie Falcons also nest on cliffs and make scrapes to lay their eggs. Note the light brown color of the egg compared to the chocolate brown color of the peregrine eggs. Prairie falcons nest within 1/3 mile of active Peregrine Falcon eyries. Prairie Falcons nest along rivers as well as the more xeric habitats away from waterways.


Food Habits

Peregrines feed almost exclusively on small and medium sized birds. Favorite prey include pigeons (rock doves), shore birds, medium sized passerines, swallows, White-throated Swifts, Clark’s Nutcrackers, Starlings, and blackbirds. Peregrines also kill game species—pheasants, ducks, grouse, chuckars, and GrayPartridge. Occasionally, the peregrine will even take insects. We observed the Blackfoot peregrine (adjacent) and his mate taking salmonflies over the Blackfoot River.

Female Peregrine Falcon on a Chuckar (Photo: Don MacCarter)
Female adult peregrine catching a salmonfly (Photo: Kate Davis)


Migration

Peregrines are known to migrate south to various locations from Texas south to South American. One young peregrine was radio and wintered in central Mexico, however, more formation on the migration of Montana peregrines is needed. We do not know when they begin migration and to where our birds migrate. One of the primary objectives of the Montana Peregrine Institute is to learn about migration of our Montana birds through satellite tracking. We study the peregrine in Montana for only six months (March-August). The remainder of the time, our peregrines are lost in a shroud of mystery.


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