Beyond their need to replenish lost body weight, these
visitors need to regroup, take a breather, and enjoy significant
down time before taking back to the sky. But how exactly
does a shorebird rest? It’s not like they string up a hammock
and sleep for three days before moving on. It takes weeks and
months to regain their strength. Often arriving on our beach
in March and staying into May, these visitors seek peace and
quiet. But rest for a shorebird can prove elusive, partly due
to their own habits and partly due to human interference in
their natural habitat.
The very nature of a shorebird’s feeding is counter to
their need for respite. Shorebirds feed on the open sand,
in full view of dive-bombing raptors looking for their own
dinner. As they hunt for food, they must be constantly
aware of becoming the hunted. In addition to the risks from
above, shorebirds must be cognizant of intruders on the
ground. Running dogs and approaching people are beyond
bothersome; they rob the shorebirds of rest. Anytime a dog
or person gets too close, shorebirds will scatter to avoid
the perceived danger. While they can easily dodge such
ground-based trespassers, they must expend energy to do
so. Unfortunately, for a bird that needs to rest, any added or
unnecessary flight is counterproductive.
Do these remarkable birds actually ever sleep? Well, yes,
although it is likely a light sleep, easily interrupted by sound
or motion. Beyond the traditional closing of both eyes and
drifting off to a semi-conscious slumber, many shorebirds
have a unique ability to close only one eye at a time, while
keeping their other eye open. Unihemispheric slow-wave
sleep (USWS) allows birds to shut down one-half of their
brain, putting it into a deep sleep, while the other hemisphere
of their brain remains awake. Many animals possess this
ability, including bottlenose dolphins, beluga whales, ducks,
and even crocodiles. Humans do not have this ability, as
evidenced when we try this trick during commercial breaks
while watching late-night television, only to wake up several
hours later to an infomercial for the most powerful blender
ever created.
For shorebirds, USWS provides them the rest they need
while allowing them to be aware of predators and other
threats to their well-being. When resting on the shore, the
birds will remain still with their open eye facing the direction
most likely to hold danger. When done in mass unison,
this phenomenon is referred to as “group edge effect”. The
study of USWS continues to evolve, and not every aspect of
it is understood today, but this ability possessed by many
shorebirds helps them tremendously in their quest for rest.
With fattened bodies and strong wings, these amazing little
fliers will leave as a group, continuing north to their Arctic
nesting grounds. Stopovers further up the coast, such as the
Delaware shore, are common before they complete their
journey. In the cold they nest and welcome their offspring,
then travel south again to start the cycle anew. A typical
shorebird will make this trip a dozen or more times during its
life. These annual flights are a remarkable accomplishment for
such small animals, a tribute to their energy and strength. NK
How can we help shorebirds
get the rest they need?
Some simple rules:
• • Do not let pets or children approach
Least tern.
SUMMER/FALL 2017 • VOLUME 38
the birds as they are resting. A
shorebird who flies away is not
resting.
• • Stay away from feeding areas and any
designated nesting zones.
• • If you hear the birds s creaming or
making loud noises, leave the area.
They are trying to tell you that you
are too close.
• • Stay away from the tips of the island
and any remote sections of the beach.
• • Pick up your trash.
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