The city’s beloved Peregrine Falcons have mysteriously vanished from their longtime nesting spot atop the downtown jail. Could avian flu be to blame—or is there still hope for their return?
The November edition of Naturally Riverside featured Riverside’s famous bird couple, the Peregrine Falcons known as the city’s “Jail Birds.” For years, they’ve nested on the southeast corner of Ninth and Orange, perched on the face of the Robert Presley Detention Center—better known as the Riverside County jail.
In that article, I challenged readers to be the first to report their return. And since then, I’ve been swinging by the jail regularly to see whether they’ve shown up.
But there’s just one problem: the Jail Birds have not returned.
By now, they should’ve come home, cleaned house, prepped a new nest, and gotten down to the business of populating it with a few eggs. But the site remains empty.
So—where did they go?
One possibility is that they’re still in Riverside but nesting somewhere new. If that were the case, Riverside’s active community of birders likely would’ve noticed and reported them. To check, I looked at Cornell’s eBird database, which contains more than a billion data points. There have been no recent sightings of Peregrines anywhere in our vicinity.
Given that downtown Riverside is a dining paradise for Peregrine Falcons (pigeons, anyone?), it seems unlikely they’d trade their winter home for somewhere less bountiful.
If they haven’t relocated, did they meet with fowl play?
Peregrine Falcons can be preyed upon by Great Horned Owls, Bald Eagles, or Golden Eagles—but it’s highly improbable that both birds would be taken out by a predator. The same logic applies to human-caused deaths or capture: it’s rare for both members of a mated pair to disappear simultaneously.
Another possibility comes from recent news out of the Bay Area, where Annie and Archie—another pair of famed Peregrines—have gone missing. These two have nested on UC Berkeley’s Campanile (bell tower) for years, and Annie has been laying eggs there for eight seasons. They’re so well-known, they even have their own livestream: Webcams | Cal Falcons.
If you tune in now, you’ll see nothing but a patch of gravel. Annie and Archie should’ve started their nest by now, but they disappeared in early January.
The Bay Area birding community believes the pair likely succumbed to a particularly bad season for avian flu. In 2024, outbreaks of Highly Pathogenic Avian Influenza (HPAI), caused by the H5N1 virus, hit hard. A recent study from the Netherlands confirms that Peregrine Falcons are especially vulnerable. Their diet consists almost entirely of other birds—and sick birds, weakened by illness, are easier to catch. When the virus is widespread, exposure becomes nearly inevitable.
Could the same fate have befallen Riverside’s Jail Birds?
We rarely think of wild animals dying from infectious diseases. Even our pets, we expect to lose to old age. But in truth, disease is a major factor in wildlife survival and mortality. HPAI has long been recognized as a communicable disease affecting most, if not all, bird species. Its impacts extend beyond the wild—affecting the poultry industry so severely that egg prices have spiked in recent years as flocks are euthanized to curb the spread.
Although bird-to-human transmission of HPAI is exceedingly rare, the virus has recently made a concerning jump to dairy cattle. It now spreads both from bird to bird and from cow to cow. A few cases have even involved cow-to-human transmission in dairy workers. According to the U.S. Centers for Disease Control and Prevention (CDC), 70 cases of HPAI from the H5N1 virus have been documented in humans in the U.S., resulting in one death. So far, there has been no known human-to-human transmission in the country.
Thanks to the CDC and other public health agencies, such diseases are closely monitored, and mitigation strategies are in place. We’re fortunate to have these safeguards in an interconnected world.
Although the Jail Birds’ nest sits empty, this need not be the end of their story.
The good news is that Peregrine Falcons are resilient. They’ve made an extraordinary comeback since nearly going extinct due to DDT-related eggshell thinning in the 20th century. And despite the recent setbacks, not all hope is lost. The Berkeley webcam recently caught a glimpse of a lone Peregrine scoping out the Campanile nesting site. The Riverside site, too, remains a piece of prime falcon real estate.
With the spread of bird flu beginning to wane, we should keep our fingers crossed—and our eyes peeled—for new residents at both sites.
This article benefited from the input of UCR scientist Professor Chris Clark.
Selected References
Caliendo, V. et al. (2024). Highly Pathogenic Avian Influenza Contributes to the Population Decline of the Peregrine Falcon (Falco peregrinus) in The Netherlands.Viruses, 17.
Hall, J. et al. (2009). Experimental Infection of a North American Raptor, American Kestrel (Falco sparverius), with Highly Pathogenic Avian Influenza Virus (H5N1).PLOS One.
Norm Ellstrand is an emeritus Distinguished Professor of Genetics and former Director of the California Agriculture and Food Enterprise at the University of California Riverside.
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