When you are out birding in the Silicon Valley, one of the physical features on a bird that helps you to identify them is the beak, or bill, of the bird. Bills reveal a lot about the habitat and feeding characteristics of a bird. For example, long, slender bills are perfect for probing into flowers or mud, while stout, conical bills are ideal for cracking seeds. Curved bills, whether downward or upward, allow birds to access food sources that are otherwise out of reach, such as nectar deep within flowers or insects hiding under bark.
The role of curved bills in birds
A curved bill, also known as a decurved or recurved bill depending on its shape, is an adaptation for feeding. Birds with these bill types often specialize in certain diets, such as probing flowers for nectar, picking insects from tree bark, or foraging in mudflats.
Birds with curved bills commonly seen in Silicon Valley
Here are a few birds with curved bills commonly found in the Silicon Valley area.
1. California thrasher (Toxostoma redivivum)
A resident of chaparral and scrubby habitats, the California thrasher is known for its long, down-curved bill. This bird uses its bill to dig through leaf litter and soil in search of insects, seeds, and berries. Its foraging behavior often involves flipping over leaves and debris, making it a lively sight in the underbrush.
The California thrasher is medium-sized, with a body length of around 12 inches. Its most distinctive feature is its long, decurved bill, which it uses expertly to dig through leaf litter in search of food. The bird’s plumage is muted but attractive, with a warm brown back, buff-colored belly, and a slightly darker head and wings. These earth tones help it blend seamlessly into its surroundings.
Thrashers are known for their methodical foraging habits. Using their curved bill, they sift through soil, leaf litter, and debris to find insects, seeds, and small fruits. This ground-foraging behavior is often accompanied by energetic movements, such as flipping over leaves or scratching at the ground, making it a dynamic bird to observe.
One of the most delightful aspects of encountering the California thrasher is its song. This bird is a gifted mimic and can produce a variety of notes and phrases that resemble other bird species. The California thrasher is also known for its strong territorial instincts. Males are particularly vocal during the breeding season, using their repertoire to attract mates and mark their territory.
The California thrasher (Toxostoma redivivum) can be found in several chaparral-rich areas of Silicon Valley. These birds favor dense shrubs and rugged terrain, making the region’s open spaces and preserves ideal habitats. Here are some of the best locations to observe this elusive species:
- Rancho San Antonio Open Space Preserve
- Guadalupe Oak Grove Park in the hill above the old quarry
- Edgewood Park and Natural Preserve
- Alum Rock Park
- Los Trancos Open Space Preserve
- Monte Bello Open Space Preserve
2. Long-billed curlew (Numenius americanus)
The long-billed curlew (Numenius americanus), North America’s largest shorebird, is a striking sight during its seasonal visits to Silicon Valley. These birds migrate south from their breeding grounds on the Great Plains and intermountain regions of North America.
Adult curlews are large birds, standing up to 26 inches tall, with a wingspan of nearly 3 feet. Their cinnamon-buff plumage provides excellent camouflage in their preferred habitats, blending seamlessly into the dry grasses and muddy wetlands they frequent.
The bird’s defining feature is its elongated, down-curved bill, which can be up to 8 inches long in females, slightly longer than in males. This specialized bill is an adaptation for probing deep into mud and sand, allowing the bird to extract burrowing prey like worms and crustaceans.
During the winter, long-billed curlews can be spotted in several parts of Silicon Valley, particularly in open fields, wetlands, and along the shores of salt ponds.
If you’re interested in observing long-billed curlews in Silicon Valley, visit wetlands and open spaces during the winter months, particularly between November and February. Look for them in areas with shallow water or fields, often in mixed flocks with other shorebirds like willets, godwits, and avocets.
Key locations to observe them include:
- Don Edwards San Francisco Bay National Wildlife Refuge
- Alviso Marina County Park
- Shoreline at Mountain View
3. American avocet (Recurvirostra americana)
The American avocet features a slender, upward-curving bill. These elegant waders are often seen in shallow wetlands and salt ponds in Silicon Valley. They use their recurved bills to sweep through water, catching small aquatic invertebrates.
The American avocet is a medium-sized shorebird with a long, slender body and a unique, upward-curving bill. Adults have a black-and-white pattern on their wings, a rusty orange or cinnamon-colored head and neck during the breeding season, and a more subdued grayish tone during the winter. Their long, bluish-gray legs are another defining feature, often seen wading gracefully through shallow water.
Avocets are known for their elegant foraging technique, sweeping their curved bills side to side in shallow water to capture aquatic insects, small crustaceans, and other invertebrates. They also occasionally dabble, much like ducks, to access food below the water’s surface.
American avocets are commonly seen in Silicon Valley’s wetlands throughout much of the year. While some populations migrate to breeding grounds in the interior of the western United States, many remain in the region during the winter, taking advantage of the rich feeding opportunities in local salt ponds and marshes.
During migration periods in spring and fall, their numbers often increase as they stop to rest and refuel on their journeys.
Where to spot American avocets in Silicon Valley
- Don Edwards San Francisco Bay National Wildlife Refuge
- Shoreline at Mountain View
- Charleston Slough
- Alviso Marina County Park
