Behold, the beaks!

We have been stopping along the California coast at various sites from San Diego to the Santa Cruz area to check out the shorebirds there. What a wealth of diversity of birds, and what a diversity of adaptations they exhibit, especially in their beaks.

Of course the beak is the primary tool for extracting food in shorebirds, so you would expect to find specialized structures to do that. For example:

Beaks come in different lengths, different curvatures, different thicknesses — all designed to find and extract prey from different locations in the shore environment. (Illustration of beaks in Western Australian birds by Peter Dann)

Even closely related species (e.g., in the same genus) exhibit particular beak structures that allow them to specialize on certain food resources. Few species exhibit the extreme specialization of the Curlews, whose very long and decurved bill is designed to extract crabs and other soft-bodied invertebrates embedded deep in the wet sand or mud.

Long-billed Curlews are the largest of the Sandpiper group of shorebirds, and almost seems oversized for the bird’s small head. Its sensitive tip can locate prey buried far below the surface.
The closely related Whimbrel is half the size of the Long-billed Curlew, but it, too, uses its long, decurved bill to seek out prey buried deep in sand and mud. Where both species are present together, they would be foraging at different depths and thus avoid competing directly with each other.
Willets are common on the ocean shoreline as well as inland, and seem to be more generalist feeders. They probe for crabs and other invertebrates in the sand and mud, but forage for insects, and even plant material away from the shore.
Another member of the same genus as Willets, the Greater Yellowlegs, is about the same size, but weighs half as much as a Willet. This bird is more of a specialist on aquatic invertebrates and fish, using its beak to stir up the water and dislodge its prey from the bottom.
Marbled Godwits use their long, slightly upturned bill to sift the wet sand for tiny invertebrates. Here, they are probing shallow surfaces out of the water, but they also stand belly deep in the water with their heads and necks fully immersed to hunt for prey.
Avocets use their sword-like, upturned bill to sieve the shallow water for small invertebrates. They sweep their bill side to side in the water, picking up minute crustaceans, worms, and even tiny fish.

This has been a subject of interest every time I visit the California shore, and there is more information about this (and a video) in a previous post: “sharing the resources”

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