Species at Risk: Clark's Nutcracker
By Mary Nelesen
CLICK HERE FOR .PDF VERSION
|
Hear the Clark's Nutcracker sing!
CLICK
HERE (.wav file) |
The Clark’s nutcracker, named after the
famed Lewis and Clark explorer, Captain William
Clark, was mistaken for a woodpecker when first
sighted by The Corps of Discovery while they camped
with the Shoshone Indians near Idaho’s Lemhi River,
on August 22, 1805. This jay-sized gray bird with
glossy black wings with a large white patch and a
black tail with white edges is often heard before it is
seen. Its throaty squawk announces its presence
while perched on treetops.
Clark’s nutcrackers inhabit the
high montane regions of the western
United States and Canada, preferring coniferous
forest dominated by one or more
species of large-seeded pines. Its yearround
diet consists primarily of fresh and
stored pine seeds.
This past summer I participated in
a High Country Citizen Science project in
Glacier National Park that monitored
mountain goats, pikas and Clark’s nutcrackers.
The project is headed by Jami
Belt, a wildlife biologist, who works in the
Crown of the Continent Research Learning Center in
West Glacier.
The Clark’s nutcracker is of particular concern
because of its dependence on the high-energy seeds
of the Whitebark pine. At one time, Whitebark pine
stands covered 15-20% of Glacier National Park. Today,
over 50% of the trees are dead or dying due to
white pine blister rust.
A hoarder of Whitebark pine seeds, the nutcracker
can locate as many as 2,000 different caches
up to eight months after it buried them. Luckily, it
misses some, which germinate and grow.
The nutcrackers – members of the genus
Nucifraga – have a sublingual pouch, an opening in
the floor of the bird’s mouth beneath its tongue. This
pouch can hold about 100 Whitebark pine seeds. According
to Ronald M. Lanner, who taught in the Department
of Forest Resource at Utah State University,
the nutcracker brings up the pouched seeds in its bill,
one by one, and thrusts them into the soil, about an
inch below the surface. Seeds may be cached within a
hundred yards of the tree they came from or up to 20
miles away. Seeds are often buried in open areas,
such as treeless slopes and ridges, and in recently
burned-over forests. Many caches are made where
wind keeps the snow swept clear and winter access is
assured, but nutcrackers will retrieve seeds from beneath
the snow if they must.
So how does the Clark’s nutcracker
find its numerous caches? Experiments
have shown that nutcrackers find
their caches by relying on memory – they
actually remember where most seeds are
buried, by angles between their caches
and certain nearby landmarks, like boulders,
trees, stumps, and logs. In other
words, they triangulate.
Professor Lanner estimated that
48,000 Whitebark pine seeds would be
needed by a nutcracker wintering in the
high country of Wyoming or Montana, and
that each bird would have to memorize the whereabouts
of about 12,000 separate caches. At least two
angles would have to be remembered to locate each
cache. A bird raising a brood would also have to unearth
many additional seeds to feed its young, because
they are fed a diet of almost nothing bu
t pine
seeds, for many weeks after fledging.
Can the Clark’s nutcracker survive without the
Whitebark pine? The bird does eat other wingless
seeds, such as limber pine seed, but this food source
does not contain the high-fat content of the Whitebark
pine, the nutcracker’s primary food source. In addition,
the limber pine is also susceptible to blister rust.
What does the future hold in store for Captain
Clark’s namesake? There is no easy answer…much
research remains to be done. I do know, however,
that I take great joy whenever I catch a glimpse of this
smart bird as I wander through Glacier National Park.
|
