Once thriving, now threatened

• White-tailed kites live on the UC Irvine campus in small numbers.
• The birds once flourished across Orange County but are now down to fewer than 10 nesting pairs.
• Campus environmental scientists and volunteers are helping to monitor the birds and protect their habitat.

As Orange County's oak tree-dotted rolling hills have given way to housing subdivisions, business parks, shopping centers and college campuses, the white-tailed kite has felt the squeeze. This airborne predator, a species of hawk, has seen its numbers drop significantly in the region in recent decades, but one place where you can still find them is at UC Irvine.

Bird scientist and campus reserves manager Julie Coffey has been monitoring the kites and forging a program to protect them, enlisting the help of people around the university and beyond.

She says white-tailed kites seem to be telling us something. They're not happy to settle just anywhere. Orange County has set aside more than 30,000 acres of protected land, which would seem to be a comfortable home for the avians, but they're no longer using the space to build nests, breed and hunt.

"It appears to be a combination of climate change, invasive species and increased wildfires that are changing the landscape in ways that no longer work for the birds, and they're adapting to use the urban edge instead," Coffey says.

White-tailed kites perform aerial acrobatics in the skies near UC Irvine. A close look reveals raised feathers on the back of the lower bird, a female, from a transmitter apparatus that helps researchers track avian movements. The male kite is conducting a midair handoff of a rodent, something the birds do when the female is close to laying eggs. UC Irvine avian scientists and volunteers have been helping to monitor the birds and protect their habitat. Milton Saavedra

UC Irvine is part of that wildland-urban interface that the kites are still willing to inhabit. They like to settle in trees with ample leaf coverage, and they're finding them around campus and in University Hills, a residential area for many UC Irvine faculty and staff.

A fully protected species in California, the birds are easy to identify due to their light-colored plumage with black markings. A raptor biologist who works with Coffey's group estimates that in the 1970s, hundreds of the birds used to cover trees in white at the nearby San Joaquin Marsh Reserve, managed by the University of California. When they are not paired off and nesting, kites roost communally for protection against predators. Coffey says her team learned within the last year that one of the reasons for the birds' population decline is that there are not enough of them gathering together to ward off great horned owls that attack under cover of darkness.

"One or two birds in a tree are easy to catch versus a chaotic roost of 100 birds," Coffey notes. "We've lost two adult birds and one juvenile to suspected owl predators in the past two years alone."

At one point, there were 70 kite territories around Orange County, 20 of which were occupied by birds in any given year. Now there are only five to seven active territories in the county.

"That's why UC Irvine is so important," Coffey says. "We have two nesting pairs that are consistently coming to our campus and successfully raising their young. This is key because they are attempting to nest in a handful of other places in Orange County, but the nests seem to fail a lot, including at the UC Irvine marsh. That's why we have argued that now it's our responsibility to make sure they stay here and have the habitat and whatever they need."

Nathalie Treminio (left) and Ashley Anderson, students in UC Irvine's master's degree program in conservation and restoration science, set up rodent camera trap locations at the San Joaquin Marsh Reserve as part of a project to identify which rodents are available as a food source for white-tailed kites in the university-adjacent habitat. They ran the cameras throughout their capstone thesis year and used machine learning to analyze the images to better understand rodent abundance and distribution in the reserve. Julie Coffey / UC Irvine

Student volunteers

The campaign Coffey is conducting with her student volunteers and community partners is centered on trying to figure out exactly what the white-tailed kites want and need to flourish. With funding from UC Irvine's Campus Planning & Sustainability unit and the expertise of contracted raptor biologist Pete Bloom, the avian researchers have been able to mount transmitters on birds to track their movements. So far, four have been equipped with lightweight electronic backpacks that allow freedom of travel. The transmitters send data to servers wirelessly every five minutes. The team tracked one kite all the way down to Tijuana and back to campus.

Transmitters can also help the volunteers locate birds in distress. In June, Coffey found a dead kite in the San Joaquin Marsh Reserve. It had been eaten by an owl or coyote. Such carcasses can be brought to a lab to test brain tissue for evidence of West Nile virus, rodenticides or other possible causes of death.

"We're witnessing pretty bad mortality for these birds," Coffey says. "It doesn't bode well for the future of the species in the county, but we're hoping we can get to the bottom of it before they disappear."

White-tailed kites are frequently in conflict with crows - in the air, in trees and on the ground. With their limited diet of small rodents, kites are sensitive to changes in their habitat. Crows are much more capable of living side by side with humans, so their numbers are little affected by urbanization. UC Irvine bird scientists are working with members of the community on projects to control crow populations, such as better trash management in parks and other public places. Milton Saavedra

Help from the campus community

Coffey is seeking assistance from members of the University Hills homeowners association in keeping an eye on the birds and protecting them from dangers. These include crows, who have a nasty habit of ganging up on juvenile white-tailed kites, even holding them down and plucking out their feathers.

University Hills residents have been asked to help by policing outdoor recreation areas, removing food after parties, for example. Trash cans overflowing with leftover pizza attract scavenging crows, which quickly find kite nests.

"The University Hills community members have been really good at working with us on this," Coffey says. "They have shown that we can adjust our behavior in these urban edges to welcome a threatened species like the white-tailed kite and help them thrive."

Rodents, which are a much-desired meal for white-tailed kites, pose another problem. Humans are often repulsed by the critters and take measures to keep their numbers down. Coffey says she fears that the kites may be eating mice or voles that have ingested poison bait intended for rats. Toxins can go up the food chain, ultimately killing the vulnerable birds. So Coffey has been encouraging organizations to follow the advice of the UC Cooperative Extension and use snap traps and birth control instead of poison to manage rodent populations.

Humans have greatly modified the white-tailed kites' habitat through landscaping. This can be beneficial to the birds, as they seem to favor the large, leafy trees that have been planted. On the other hand, manicured landscapes and misguided attempts at rodent control have hurt their ability to hunt.

Julie Coffey, bird scientist and UC Irvine campus reserves manager, works with contracted raptor biologist Pete Bloom to put a transmitter backpack onto a female white-tailed kite that lives in a nest in University Hills. The hood, often seen when falconry is being practiced, is meant to keep the bird calm; raptors are much more easygoing when they can't see, Coffey says. Clementine Bostock / UC Irvine

Unexpected findings

Coffey says that one day she got a call from a University Hills resident who had found a kite chick on the ground being attacked by crows. She went to the spot, picked up the bird with her sweatshirt and brought it to the Orange County Bird of Prey Center. After a period of rehabilitation, officials decided to try to return not only the original fledgling but also an orphaned kite at the center in hopes that the adult kites would adopt it.

"The parents began feeding both young birds, so it was definitely a success story, but then something interesting happened," Coffey says. "The female just left the nest. We had put a transmitter on her, so we could see that she went cruising around Orange County, and it was the male parent that started doing all the training."

She says the episode demonstrates that there's a lot more to learn about white-tailed kites besides their biology and that the transmitters are helping to fill the gaps in our knowledge: "With each bird we track, we learn more about their habits, their space use and their interactions with each other."

Bird scientists can track the movements of white-tailed kites that have been fitted with transmitters. The map shows the comings and goings of two birds, a female that nests in University Hills and another female from the San Joaquin Marsh Reserve, beginning in May. The University Hills kite (blue line) concentrated her movements around UC Irvine and Orange County, while the marsh bird (yellow line) traveled as far as the U.S.-Mexico border. Sadly, according to UC Irvine bird scientist and campus reserves manager Julie Coffey, that kite was found dead this summer. Julie Coffey / UC Irvine

Changing habits

In addition to learning the social characteristics of white-tailed kites, Coffey says, she hopes to encourage shifts in the behavior of humans who have moved into the birds' habitat.

"I think it would be a good idea for us to start some educational campaigns around campus to get people thinking about how they can landscape more sustainably to help this species. Deciding when to trim trees or not based on habitat considerations or managing trash more mindfully - these are all things we can do to help," she says.

"White-tailed kites are such a beautiful, iconic species that we're all a little bit poorer if we don't have them around," Coffey adds. "I think if more people got to know them and really see them, they would probably want to do what they could to help the birds thrive. These birds have ridden the waves with Orange County through its history. They are an indicator telling us what's wrong with our own systems or what we could be paying more attention to."