What’s for Dinner?
Story by Jane Ellis;
photographs by Pamela Cohen
I
ntertidal zones and wetlands are areas containing
some of the greatest variety of plant and animal life
on earth with tremendous biological productivity,
and shorebirds are uniquely adapted to locating
and capturing prey in these ever changing and challenging
environments. Such environments must have the biomass
available to sustain the onslaught of thousands—or hundreds
of thousands—of migrating birds descending at one time on a
small spit of sand, mudflat, or marsh looking for energy rich
food sources. These environments must also be able to sustain
populations of birds who do not migrate. One researcher
stated that each shorebird could take in a third of its own
weight in food per day. So what are they eating and how do
they find the morsels hidden in the sand and water?
Legs Are Made for Walking, Running,
Wading—And Dancing?
Shorebirds generally have long legs and toes that aid in
stability and continuous walking, running, and wading in
the surf—but also in locating prey. A number of these birds,
including gulls, understand the physics of stomping up and
down (“Riverdance” as one source calls it) or toe tapping
and “foot-stirring” in about a half inch to one inch of water.
This motion liquefies the hard sand around their feet forcing
surprised shellfish to rise to the surface to be consumed.
Another interesting use of toes can be found in certain
plovers, especially piping plovers, who will run, stop quickly,
and raise one foot, trembling the toes slightly on the surface
of shallow water causing prey to scatter and be snatched
quickly. Innate or learned behavior? Some researchers think
elder gulls teach “rain dancing” or paddling to their young.
curvature, flexibility, sensitivity, and other features of the
bill that determine feeding habits and foraging methods.
The differences in bill length alone allow for a variety of
bird species to feed in the same area and not deplete food
resources found in the sand and mud.
Long Bills
Long-billed shorebirds such as the avocets, stilts, greater
yellowlegs, and others use their bills in different ways. Many
of these are members of the sandpiper family and have very
sensitive bills and can use tactile cues to find prey. You can
often see certain sandpiper species feeding with their heads
underwater. The black-necked stilt uses its needle-like bill
to capture insects, shrimp, small fish, and other very small
invertebrates near the surface of the water. Avocets and
greater yellowlegs prefer to stroll or run through shallow
water skimming food from the surface or sweeping their
bills back and forth like a scythe stirring the bottom to snare
insects, crustaceans, and other invertebrates.
Dowitchers and godwits use their long straight sensitive
bills to probe deeply and sometimes rapidly into the sand or
mud, like a sewing machine, feeling, and then grasping, in
a tweezers-like motion, marine worms, small crabs, or tiny
clams using the bill’s specialized moveable tip. Willets also
have sensitive bills and will take aquatic insects from the
It’s Really about the Bills
Species of shorebirds have highly adapted bills for detecting
and capturing prey. Differences in diet depend on the bird’s
body size, but most importantly it is the shape, length,
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Naturally Kiawah