Striking kite calls San Joaquin Marsh home

white-tailed kite
The white-tailed kite has bright white body plumage and has the distinctive habit of hovering in place while hunting. Image: Sandrine Biziaux Scherson

By Julie Coffey, UC Irvine

With its tree-laden campus and adjacent protected natural reserves, UCI enjoys being home to a great variety of bird species. One particular raptor continues to capture the attention of the many avid birders in Orange County: the white-tailed kite.

This iconic bird of Orange County—named for its ability to hover in the air while hunting—nearly went extinct throughout California in the early 1900s due to human-related threats.

However, thanks to the agriculture-prompted expansion of their prey base, as well as educational campaigns and state protections for raptors, white-tailed kites had begun to bounce back. Now the eye-catching species is again facing declines, because the habitats these birds rely upon in Orange County and elsewhere in California are being converted for urban land uses.

Kites are voracious consumers of small rodents, which they hunt by hovering above open areas such as grasslands and marshes. As with most birds of prey, these avians require big trees in which to nest. Prior to the large-scale conversion of natural lands for agriculture or development, white-tailed kites would nest in native oak or willow trees.

white-tailed kite
White-tailed kites are frequently seen at the NRS’s San Joaquin Marsh Reserve. Image: Sandrine Biziaux Scherson

The birds have been observed hunting, roosting and breeding at the NRS’s San Joaquin Marsh Reserve and UCI Ecological Preserve for several decades through monthly surveys, according to surveys conducted in partnership with Sea & Sage Audubon Society.

They can be found nesting in trees with sufficient height and foliage, such as the stately eucalyptus that form the border between the University Hills community and the UC Irvine Ecological Preserve.

Despite their striking appearance, white-tailed kites are a difficult species to study, and not much is known about their habitat preferences or the relative quality of different landscapes for supporting breeding.

I started to study this archetypal and slightly mysterious bird to better understand its habitat needs on campus. With the help of Barbara Kipreos and Olivia Jenkins—students in UC Irvine’s Masters in Conservation and Restoration Science program—and volunteer birders they recruited, we devised a study to observe kite behavior in the UC Irvine reserves and determine the relative importance and productivity of available habitats. Launched in January and expected to continue for two or three years, our project addresses two key questions:

  • How do white-tailed kites use available habitats in the reserves? Do they spend an outsized percentage of their time utilizing specific habitat types?
  • How does hunting success vary across different habitats in the reserves? And how does this correlate with the vegetation characteristics of these habitats?

This partnership among students, land managers and community volunteers will help us understand where the kites hunt, which trees they select for nesting, and whether certain vegetation management approaches can improve hunting and nesting success for this iconic species.

It’s a fun project—one that can lift the veil off this elusive bird. And if you make it to UC Irvine anytime soon, look up into the trees to see if you can spot a white-tailed kite. You’ll never forget it if you do.

Julie Coffey, M.Sc., is a field research and land management specialist with UCI Nature.

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