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Field
Guide IDs: BREEDING:
Wide variety of
habitats, often mountainous or hilly areas. 1
brood. DISPLAYS:
Male performs
acrobatic aerial display of soaring, wheeling, and
tumbling; pair often soar together, wingtips
touching, male above female; perch together, preen,
and bill. NEST:
Occ in decid tree
(to 100 feet), on human-built structure; of
branches, twigs (occ wire), lined with shreds of
bark, hair. Often repaired and used perennially.
Built over several weeks. Old nests often used by
hawks and owls. EGGS:
Greenish, marked
with browns, olive. 2.0" (50 mm). DIET:
Primarily carrion,
also small vertebrates, bird eggs and nestlings
(esp in seabird colonies), insects, other
invertebrates; garbage, seeds, fruit. Eject
pellets. CONSERVATION:
Winter resident.
Alleged damage to domestic animals and wild game
led to intensive trapping in past. NOTES:
Never retrieve
building materials that fall from nest; large
accumulations of sticks, etc., may occur below nest
site. Long-term pair bond. If initial clutch is
lost, a second smaller clutch occ produced in same
nest. Male feeds incubating female. Female broods.
Cache food temporarily, often burying it. Break
mollusk shells by dropping onto rocks from above.
Occ hunt cooperatively in groups. Aerial acrobatics
and spectacular dives said to be play. Winter
communal roosts in trees, occ in marsh, in flocks
of up to several hundred, often perennial. Largest
passerine. Increasingly common
visitor to campus. Most often seen in fall and
winter, when flocks flying between bayside foraging
areas and foothill roost sites can be seen flying
over campus. This species' local populations have
increased dramatically in recent years, and nesting
on campus occurred for the first time in 1999, when
a pair nested on Green Library. ESSAYS: REFERENCES:
Goodwin, 1976;
Harlow et al., 1975; Stiehl, 1985. |
