No other local habitat is richer in nesting song birds than a stream canyon like the one occupied by Strawberry Creek. In dry coastal California, stream canyons support abundant vegetation with canopy trees like willow, alders, bays, bigleaf maples, and live oaks which shelter a dense understory of currants, poison oak, thimble berries, dogwood, and western sword fern. The presence of water and moist vegetation favors myriads of insects. An abundance of food, nesting sites for every preference, and shelter all add up to make an avian paradise.
With May winding down, nests have been built and nestlings are being fledged. It’s a perilous time for nesting birds. Newly-hatched song birds, almost naked and briefly sightless, are completely dependent on the parents for food and for the warmth of their bodies at night. Even fledglings, often the size of the adults when they leave the nest, are at first unable to fend for themselves. They continue to be vulnerable to predators, particularly avian ones like jays and ravens. But a fair number do survive into adulthood and if they are year-round resident birds, the adults most likely will produce a second brood.
Many birds are year-round residents in temperate coastal California, but each spring bird populations swell with the arrival of migrants from the south who come to build their nests and raise their young before making the return journey in late summer.
Earliest to arrive and begin singing is often the Orange-crowned Warbler whose sweet trill is heard along stream canyons in early March. Soon Wilson’s Warblers arrive; and the beautiful pale singer, the Warbling Vireo who sings up and down the Canyon, but especially in the live oaks in the UC Botanical Garden. By early April, Black-headed Grosbeak have arrived, adding their rich, contralto song to the mix.
Hooded Oriole
For exotic flamboyance, nothing compares to the dazzling Hooded Oriole who each spring nests in the Botanical Garden. Once mostly restricted to the native desert palm groves, Hooded Orioles have spread throughout the state attracted by planted palms. At the Botanical Garden, the orioles have again built their nest in a Sonoran fan palm using palm fibers to weave their hanging basket nest.
Resident birds are also singing and nesting – both species of towhee, Bewick’s Wrens, Lesser Goldfinches and perhaps the most abundant and endearing, the American Robin. Robins, who require only a patch of grass for ‘worming’ and a tree for a nest, are truely egalitarian, singing their cheery songs between skyscrapers, in urban neighborhoods -- rich or poor - in farm yards and, by mid-summer, in the alpine meadows of the High Sierra. At the Botanical Garden their song laces the Garden together. It seems like every other tree has one of their mud nests.
Olive-sided flycatcher
The Olive-sided flycatcher is usually last to arrive in the spring coming from its winter home as far south as Venezuela. Officially listed as a species “of special concern” their numbers are declining. It’s always a happy moment when their cheery “quick three beers” rings out over the Canyon. Choosing the highest trees for perching and nesting, the flycatcher makes frequent dashes out to snag a passing insect before returning to its perch.
--Phila Rogers
The photos were taken by Bob Lewis. Bob is a retired chemist who has taught birding classes for more than 25 years at Albany Adult School, the Oakland Museum, and for Golden Gate Audubon. Since his retirement he has devoted more time to bird photography. For lists of classes and field trips he offers check www.wingbeats.org and for his photographs go to http://www.flickr.com/photos/boblewis.
Phila Rogers
Phila Rogers is a Lawrence Hall of Science neighbor who has lived on the hill for 58 years. Until retiring, she was a science writer at Lawrence Berkeley National Laboratory where she also wrote “Nature Note” for the weekly publication. As a volunteer with the UC Botanical Garden she co-leads quarterly bird walks. She is also one of the founding members of Save Strawberry Canyon.
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