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The
Clark's Nutcracker (Nucifraga columbiana), is a large
passerine bird, in the family Corvidae. It is slightly
smaller than its Eurasian relative 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. It occurs 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 Potosí
(3,700 m) in Nuevo León, northeast Mexico. It is
mainly found in mountains at altitudes of 900-3900 m 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. |
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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 eruptions to lower
altitudes, it also extensively uses the seeds of pinyon
pines. The isolated Cerro Potosí population is
strongly associated with the local endemic Potosi Pinyon
Pinus culminicola. Surplus Pine seed is stored, usually
in the ground for later consumption, in numerous caches
of 5-10 seeds each spread over a wide area (up to 20 ×
20 km). The birds regularly store more than their actual
needs (up to 100,000 seeds per bird!) as an insurance
against seed theft by other animals (squirrels, etc.);
this surplus seed is able to germinate and grow into new
trees, thus the bird is perpetuating its own habitat. |
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