Monitoring Shows Wonderfully Normal Start to Pinnacles’ 2025 Falcon Nesting Season

By Wildlife Biologist Gavin Emmons and Science Communication Specialist Jessica Weinberg McClosky, San Francisco Bay Area Inventory & Monitoring Network

Female peregrine falcon watching over a breeding territory in Pinnacles in 2022. This year, four peregrine pairs claimed territories in the park.

NPS / Gavin Emmons

May 2025 - Since their remarkable recovery from the effects of DDT, peregrine falcons have delighted Bay Area residents and visitors with their aerial acrobatics. But many of these top avian predators have been vanishing nationwide, especially from more coastal areas. So the San Francisco Bay Area Network falcon monitoring team was relieved to see the usual number of pairs nesting this season at Pinnacles National Park. Prairie falcons and other raptors at the park are also nesting as usual and appear to be doing well. Raptor advisories are in effect to help visitors avoid disturbing these magnificent raptors.

This male prairie falcon arrived just after the female flew from the nest. He proceeded to settle and continue incubation of the five eggs behind him.

NPS / Gavin Emmons

Adult male prairie falcon in flight near its nest site. Prairie and peregrine falcons are actively defending territories and will alarm call or dive at intruders (including people!) that get too close to their nests.

NPS / Gavin Emmons

Biologists suspect highly pathogenic avian influenza (HPAI, or H5 bird flu) has been killing peregrine falcons. The pair that nested for years on Alcatraz Island, for example, is nowhere to be found. Their nest camera now offers a rare, up-close view of nesting Brandt’s cormorants. The long-time residents of the Berkeley Campanile are also missing and presumed dead.

Coastal peregrines may be most affected by bird flu because their prey includes waterfowl, shorebirds, and seabirds. These shorebirds are common carriers of the virus—they can have it without getting sick. Meanwhile, this bird flu strain can kill up to 90 percent of more susceptible species that get infected—like peregrines.

Yet the falcons at Pinnacles are still there, at least for now. Four pairs of peregrines claimed territories and attempted nesting, and three of those pairs are still actively nesting. That total nesting pair count has been the same since 2020. Prairie falcon pair counts are also similar to recent years. Nine pairs staked out territories and eight pairs attempted to nest. Six pairs are still actively nesting.

Four peregrine pairs attempted nesting this year. That total nesting pair count has been the same since 2020. Prairie falcon pair counts are more variable but also similar to recent years. Eight pairs attempted to nest this year.

Many more raptor species are also nesting in Pinnacles this year, including some usual and less-usual suspects. In the usual suspects category, we have nesting American kestrels, red-tailed and red-shouldered hawks, great horned owls, and long-eared owls (a California species of concern). These species nest in the park most years. Golden eagles and white-tailed kites, on the other hand, are this season’s less common breeding residents.

Some raptor species—like this small-yet-fierce merlin feasting on a sparrow—pass through the park on spring migration but don't stick around to nest.

NPS / Gavin Emmons

Long-eared owls do not build their own nests; instead they make use of old raptor nest sites. This beautiful owl is trying to hide from view as it incubates eggs at an old Cooper's hawk stick nest.

NPS / Gavin Emmons

Adult golden eagle in flight. Like cliff-cavity nesting falcons, golden eagles are quite sensitive to disturbance, from humans as well as potential nest predators.

NPS / Gavin Emmons

Two golden eagle pairs have attempted to nest at historic territories in the park this year. One nest attempt failed but the other pair is still nesting. Like cliff-cavity nesting falcons, golden eagles are quite sensitive to disturbance from humans and potential nest predators.

A white-tailed kite pair is occupying an oak / willow grove in the bottomlands, and appears to be preparing to nest soon. Here is one of the kite adults flying with vole prey.

NPS / Gavin Emmons

White-tailed kites are very elegant-looking—and very specialized—predators. They mainly eat California voles in our region, and in recent years they haven’t been active at Pinnacles. However, California vole numbers have surged in the park this year and a pair of kites appears to be taking advantage. They are occupying an oak / willow grove in the bottomlands, seemingly preparing to nest.

Stay tuned for further updates once the 2025 breeding season is further along!

For more information

• Pinnacles Raptor Advisories and Raptors webpages
• San Francisco Bay Area Network Falcon Monitoring webpage
• Pacific Coast Science & Learning Center Prairie & Peregrine Falcons webpage
  • Prairie & Peregrine Falcons Blog
• Contact Wildlife Biologist Gavin Emmons

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