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Field
Guide IDs: BREEDING:
Riparian forest,
wooded swamp. 1 brood. DISPLAYS:
1-4 birds soar,
flap, swoop and dive while calling over
territories. May rise in wide spirals 1,500'-2,000'
over nest, flap, dive, descend to original spot in
series of dives and side-slips. NEST:
Usu by trunk, occ
in conif in w; of sticks, twigs, inner bark strips,
dry leaves, moss, lichen, conif needles. Lined with
fine materials, green leaves (replenished from
incubation on). Perennial. EGGS:
White/bluish-white,
oft nest-stained, marked with brown. 2.1" (53
mm). DIET:
Includes rodents,
snakes, lizards, insects, also occ snails. Old nest
often becomes eating platform. CONSERVATION:
Winters within U.S.
Blue List 1972-86; declining or now stabilized at
low numbers; known to accumulate organochlorine
pesticides and PCBs, but habitat loss is the major
threat. NOTES:
Pair or kin may use
same territory for many years. Usu first breed at 2
years. Can tolerate human disturbance if mature
trees/high canopy maintained. Young hatch
asynchronously, differ in size. Hunt in forest edge
and open woodland near meadows and
fields. Resident virtually
throughout campus, foraging for small vertebrates
in fields and occasionally on lawns. The number of
breeding pairs is only 5-10 due to large territory
size and the paucity of trees large enough for
nesting. Most pairs of this highly vocal raptor
nest in eucalyptus trees, which provide sturdy
support for nests and protection from predators
(see Red-tailed Hawk). ESSAYS: Blue
List;
Hawk-Eyed;
Metallic
Poisons;
Raptor
Hunting;
DDT;
Nest
Sanitation;
Brood
Reduction REFERENCES:
Bednarz and
Dinsmore, 1981; Brown and Amadon, 1968; Henny et
al., 1973; Wiley, 1975. |
