Anna's hummingbird and the spring bloom

The California buckeye towers above Lafayette Park, its cream-colored flower spikes catching the morning light. Each bloom cluster holds hundreds of tiny flowers, and the air around them hums with activity. Step closer to any flowering shrub here in late spring and you'll hear it: the sharp territorial calls of Anna's Hummingbirds (Calypte anna) defending their feeding routes.

The male Anna's hummingbird weighs less than a nickel, but his voice carries across the entire hillside. His metallic chip notes punctuate the air as he patrols from the buckeye blossoms to the black elderberry (Sambucus nigra) clusters below, then up to the common snowberry (Symphoricarpos albus) flowers scattered through the understory. This is nesting season, and his energy demands have doubled. He burns through his body weight in nectar every day, visiting over a thousand flowers to fuel his metabolism and defend his territory from other males.

The timing is no accident. California's native shrubs bloom in waves through late spring, creating a nectar highway that sustains the hummingbirds through their most demanding season. The buckeye flowers first, its pale spikes offering concentrated sugar water in the cool morning hours. As the sun climbs higher, the elderberry clusters open their small white flowers, each one a tiny cup of fuel. The snowberry follows, its pink-tinged blooms hidden among the leaves but rich in the proteins and sugars that nesting hummingbirds require. Each species flowers for weeks, overlapping to create an unbroken chain of food sources.

The female Anna's hummingbird follows her own rhythm through this flowering landscape. She builds her walnut-sized nest from spider silk and lichen, camouflaged against a branch fork. While the male defends territory with aerial displays and aggressive chases, she makes quiet foraging flights between the blooming shrubs. Her visits are methodical: probe each tubular flower, extract the nectar, move to the next. She needs protein too, so she catches gnats and aphids from the flower clusters, feeding them to her two rice-grain-sized chicks. The same plants that provide nectar also harbor the insects that complete her diet. The buckeye flowers attract thrips and small beetles. The elderberry blooms draw hover flies and tiny parasitic wasps. Each flowering shrub becomes a hunting ground as well as a filling station.

The hummingbird's foraging creates connections across the entire plant community. As she moves between flowers, pollen grains stick to her forehead and throat feathers. She carries genetic material from one buckeye tree to another, one elderberry shrub to the next. Her feeding flights map the reproductive networks of the native plants, linking individuals separated by hundreds of yards of urban landscape. The plants time their flowering to the hummingbird's nesting cycle, and the hummingbird times her breeding to the plants' blooming schedule. Neither could sustain this intensity without the other.

Listen now for that sharp chip call echoing off the hillside. Somewhere in the canopy above, an Anna's hummingbird is defending his patch of flowering buckeye, each call marking the invisible boundaries of territory and the visible abundance of late spring nectar.