February 17, 1995 Contact: Pamela Donegan or Robert Irion (408/459-2495)

UC SANTA CRUZ ARBORETUM IS HUMMINGBIRD HAVEN

FOR IMMEDIATE RELEASE

SANTA CRUZ, CA--The air is abuzz--literally--as scores of tiny iridescent hummingbirds alight in the Arboretum at the University of California, Santa Cruz, just in time for the annual Hummingbird Festival. The birds don't know about the festival, of course. They just come to sample the Arboretum's plentiful nectar-rich blooms.

Scheduled for Saturday, March 18, this event will feature free guided walks starting at10 a.m., 12 noon, and 2 p.m., plus a large assortment of hummingbird plants and paraphernalia at Norrie's Gift Shop, which will stay open until 4 p.m. The walks will be led by local wildlife biologist and environmental consultant David Suddjian and Arboretum staff member Stephen McCabe.

At least two species, the Anna's and the Allen's hummingbirds, will attend the festivities, says Suddjian. For most of the year, the Anna's have the place to themselves, but in January the Allen's hummingbirds come to town. These tiny migrants buzz up from wintering grounds in Mexico and stay around feeding and breeding until June. Although slightly smaller than the Anna's, the Allen's tend to dominate the area once they arrive. "They're pretty pugnacious," says Suddjian.

Despite the competition, both species hum freely about the Arboretum throughout the spring because there is enough food for everyone. According to curator McCabe, hundreds of hummingbird- attracting shrubs and trees line the winding paths.

What really brings them in, says McCabe, is the Grevillea. Originally from Australia, this group of bushy plants comes in so many shapes and sizes that it's hard to tell they are all related. Some have spiky waxy leaves like a live oak, others sport long needlelike foliage, and still others have stiff, antler-shaped vegetation. But most have one thing in common: red tube-shaped flowers about as long as a pushpin. Granted, some of the flowers have straight dangling petals, others curl like spider legs, and a third type bristles like rows on a toothbrush, but even so, they are just the right size and shape for tiny bird bills. Also, they brim with the sweet nectar that hummingbirds depend on to keep up their frenetic pace. At the height of the season, it's not surprising to see fifteen hummingbirds zooming simultaneously from bloom to bloom on the same sprawling bush.

Plants like Grevillea are perfectly suited to the tastes of nectar-feeding birds like hummingbirds for one reason: pollination. In Australia, Grevillea depend on the pollination services of local honeyeaters and sunbirds. But here in California, where there are no honeyeaters, hummingbirds take over. "Some of these species can't set seed without them," says McCabe. That is why the flowers are so similar, whereas the leaves come in every shape under the sun. In a new environment, plants may develop modified leaves to compensate for changes in light or water, but the flowers need to attract bird pollinators regardless. "It's easier to change things that don't have to do with reproduction," McCabe explains.

But hummingbirds have more than plant pollination on their minds during the spring. Many are looking for mates. To attract females, males of both the Allen's and Anna's species put on intriguing courtship displays--but the Anna's really go at it. They perform maneuvers that would make a Blue Angel blanch. To impress his prospective partner, the flashy emerald-and-fuchsia male zips straight into the air, chirping as he goes. At an elevation of about 120 feet, when he is a mere dust mote against the sky, he hovers briefly, then plummets straight down at the perched female. A heartbeat away from crashing headlong into his intended, he veers back up in a midair U-turn. As he swoops, he emits a startlingly loud squeak, caused by compressed air against his tail feathers--the hummingbird equivalent of a sonic boom. Such aerial acrobatics go on constantly at the Arboretum, says Suddjian, because males use the same display to defend their favorite Grevillea bushes from hungry competitors.

Hummingbird enthusiasts who can't make it to the March 18 event can still enjoy the show during the week. The UCSC Arboretum is open to the public every day from 9 a.m. to 5 p.m. for self-guided tours. Docents staff the gift shop Tuesday through Saturday from 10 a.m. to 4 p.m. and Sunday from 1 to 4 p.m. The Arboretum entrance is located on Empire Grade in Santa Cruz, between the main and west entrances to the UCSC campus.

Editor's note: You may reach Stephen McCabe at (408) 427-2998.

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