clark's nutcracker (nucifraga columbiana), sometimes referred to as clark's crow or woodpecker crow , is a passerine bird in the family corvidae .
it is slightly smaller than its eurasian relative the spotted nutcracker (n .
caryocatactes) .
it is ashy-grey all over except for the black-and-white wings and central tail feathers (the outer ones are white) .
the bill , legs and feet are also black .
this bird derives its name from the explorer william clark .
it can be seen in western north america from british columbia and western alberta in the north to baja california and western new mexico in the south .
there is also a small isolated population on the peak of cerro potos , elevation 3,700 metres (12,200 ft), in nuevo len , northeast mexico .
it is mainly found in mountains at altitudes of 9003,900 metres (3,00012,900 ft) in pine forest .
outside the breeding season , it may wander extensively to lower altitudes and also further east as far as illinois (and exceptionally , pennsylvania), particularly following any cone crop failure in its normal areas .
the most important food resources for this species are the seeds of pines (pinus sp .
), principally the two cold-climate (high altitude) species of white pine (pinus subgenus strobus) with large seeds p .
albicaulis and p .
flexilis , but also using other high-altitude species like p .
balfouriana , p .
longaeva and p .
monticola .
during migrations to lower altitudes , it also extensively uses the seeds of pinyon pines .
the isolated cerro potos population is strongly associated with the local endemic potosi pinyon pinus culminicola .
all clark's nutcrackers have a sublingual pouch capable of holding around 50-150 seeds , depending on the size of the seeds; the pouch greatly enhances the birds' ability to transport and store seeds .
clark's nutcrackers store seeds , usually in the ground for later consumption , in caches of 1-15 seeds (average of 3-4 seeds) .
depending on the cone crop as well as the tree species , a single clark's nutcracker can cache as many as 98,000 seeds per season .
the birds regularly store more than they actually need as an insurance against seed theft by other animals (squirrels , etc .
), as well as low availability of alternative foods; this surplus seed is left in the cache , and may be able to germinate and grow into new trees , if the conditions are right .
through this activity of caching and over-storing , the bird is perpetuating its own habitat .
closely tied in with this storage behavior is the bird's remarkable long-term spatial memory; they are able to relocate caches of seeds with remarkable accuracy , even nine months later , and even when the cache sites are buried under up to a meter (3 ft) of snow .
the diet also includes a wide range of insect prey , berries and other fruits , small mammals and occasionally flesh from carcasses .
eggs and nestlings are sometimes devoured , and peanuts and suet have become a favorite at bird tables .
food is taken both from the ground and from trees , where the nutcrackers are very agile among the branches .
the birds are able to extract food by clasping pine cones in such a way that the cones are held between one or both feet .
the birds then hack the cones open with their strong bills .
rotten logs are also hacked into in order to locate large beetle grubs , and animal dung may be flipped over in search of insects .
clark's nutcrackers can also be opportunistic feeders in developed areas , and are know to some as "camp robbers" .
the species usually nests in pines or other types of conifers during early spring .
nests are built on the leeward side of the tree , wind protection being a larger concern than sunlight .
two to four eggs are laid , incubation usually occurring in 1618 days .
incubation is performed by both the male and female parents , and the young are typically fledged by around the 22nd day .
the fledglings follow their parents around for several months in order to learn the complex seed storage behavior .
clark's nutcracker is the primary seed disperser for whitebark pine (pinus albicaulis) .
whitebark pine is in decline throughout its range , due to infection by white pine blister rust (cronartium ribicola), widespread outbreaks of mountain pine beetle , and the long term effects of fire suppression .
the clark's nutcracker is an integral part of the whitebark pine restoration process: the clark's nutcracker must remain in whitebark pine forests and cache the seeds in excess , so that healthy whitebark pine will continue to grow .
if whitebark pine declines into extinction , the clark's nutcracker will lose an important source of food and may no longer be seen in areas where whitebark pine is the primary source of seed , such as glacier national park .
the voice of this bird is extremely varied and produces many different sounds .
however , the most frequent call is commonly described as ''khraaaa-khraaaa" .
