This Anna's Hummingbird has leucism, a pigment disorder that gives it its brilliant white color. Photo: Brad R. Lewis

In the Australian Gardens at the University of California, Santa Cruz Arboretum, a dozen Anna’s Hummingbirds dart between golden banksia flowers and various pink and white blooming shrubs. Their feathers are bright, iridescent shades of emerald, pink and gray. The grove is awash with color.

Except for one strange bird that’s sitting in a cypress tree, watching the flurry of feeding and fluttering. It’s an Anna’s Hummingbird—and it’s almost entirely white.

Not much is known about the mysterious white hummingbird that’s been there since May except that it has leucism, a developmental condition resulting in the loss of pigmentation. Unlike albino birds, which can’t produce the pigment melanin, leucistic birds produce melanin but can’t deposit it into their feathers. Albino birds also have red or pink eyes, but this hummingbird’s eyes are black, along with its bill and feet.

What makes this bird extremely rare is that it is almost entirely white, says Steve Gerow, bird records keeper for the Santa Cruz Bird Club. Most leucistic birds are only partially affected, and have white patches of feathers amid colored plumage.

Some of its feathers are darker than others, giving clues to its sex and age. The bird is definitely male and likely hatched in the last six months, Gerow says. “That’s all I know and I don’t really know if there’s much more possible to be known at this point.”

Mostly, the bird has stuck to the Australian Gardens since May, chirping, sipping nectar and flitting between banksia bushes and cypress trees.

The bird also performs the courtship display typical of male Anna’s Hummingbirds—climbing 100 feet into the air and bombing straight down. November is the start of breeding season for the species, which peaks in January through March. Though the bird doesn’t have its adult plumage yet, it’s possible it could breed, Gerow says. It’s still unclear whether the bird’s leucism will make it less attractive to females, since feather color plays a role in courtship.

Its lack of camouflage also may make it more susceptible to predators such as hawks and feral cats. Melanin makes feathers strong and durable, so this bird’s extensive leucism probably means that its feathers are weak, making flight and insulation more difficult.

Todd Newberry, a retired University of California, Santa Cruz biology professor, says that in his 70 years of birding, he’s never seen a bird like it. He’s visited the Anna’s Hummingbird close to 100 times, and he usually finds it close to the arboretum’s Hummingbird Trail.

“The way to find it—the way it is with any rare bird—is to look for people looking at it,” Newberry says.

Roughly 1,000 people have stopped by to see the hummingbird since May, according to the arboretum. The bird was still there as of October 12, and visitors are welcome.

Like this story? See more stunning bird photographs in our recent photoessay, featuring close-up shots of birds in the U.S. and Central America.