Coastal Watch, Part 2 - Shorebird Bills

In an era past, when the local newspaper was able to support a weekend magazine, feature writers explored topics about the world around us. Recently I came across these interesting observations on shorebirds in the microfilmed archives of the Gloucester Daily Times at the Sawyer Free Library.

Ralph Scott illustration from "Getting Along between the Tides"
North Shore Magazine, September 3, 1977

Coastal watchers may be curious that a variety of birds somewhat similar in appearance can coexist in the same area. Naturalist Ralph Scott called attention to subtle bill differences evolved by the long-legged shorebirds that give them specialized feeding advantages and somewhat separate interests in the narrow zone between the tide lines. I compared his fine drawings with my own photographic images of birds on the Halibut Point shores.

Least sandpipers with slim, slightly decurved bills

Least sandpipers can be found probing into narrow spaces among barnacles and seaweed, on rocky surfaces.

Greater yellowlegs with long, slightly recurved bill

Greater yellowlegs are rare at Halibut Point because of their preference for soft-bottomed habitat where they can use their long bills to advantage in searching for subterranean prey. This one was exploring the sandy low tide margin of Folly Cove.

Semipalmated plover with short, stout bill

Diminutive Semipalmated plovers search with their short, stout bills for small crustaceans on the surface of rock outcroppings.

Black-bellied plover with long, stout bill

Their larger relative the Black-bellied plover has the size and strength to probe deeper into pebbled or vegetated areas with its similarly shaped but more massive bill.

Ruddy turnstones with stout, slightly recurved bills

The flatter, recurved bills of Ruddy turnstones enhance their ability to push aside or flip over beach pebbles and debris in search of food.

Oystercatchers with long, stout, recurved bills

Oystercatchers have strong versatile bills proportionate to their chunky bodies. They use them to swish laterally, probe deeply, and hammer open small shells as well as to reach inside bivalves to snip the adductor muscles.

This great variety of bill shapes and lengths allows diverse shorebird species to congregate harmoniously and even travel in mixed flocks, each picking, probing with a distinctive feeding behavior. Their tendency to pass through Halibut Point at staggered arrival dates further reduces competition. Were the bird's feeding habits identical, the stronger, more dominant species would soon drive out the weaker species through competition. These variations in bill structure are among the many interrelated features that trace, enable, and define each species' existence in the biological world.