BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Grus americana | Whooping Crane 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Courtship - Mate selection occurs on the wintering grounds or during
migration [11].  Whooping cranes are monogamous and normally pair for
life; they will remate following the death of a mate.  Each pair returns
to the previous year's breeding territory but constructs a new nest
[7,11].

Migration - Whooping cranes generally arrive on the breeding grounds
during late April [10].  The southward migration begins anywhere from
mid-September to mid-October and normally all cranes are on their
wintering grounds by mid-November [4,10].  Occasional stragglers may
arrive in late December [10].

Age of first reproduction - Whooping cranes become sexually mature
between 4 and 6 years of age [3,7,11].

Egg laying and incubation - Whooping cranes generally lay two eggs, 2
days apart, in late April or early May.  Both sexes incubate [7].
Incubation period is between 29 and 34 days [3,7,10,11].

Fledging - Whooping cranes fledge between 78 and 90 days [3].  Young
whooping cranes are fed by both parents for an extended time during
their first fall and winter of life and are not independent until they
are gradually adandoned by their parents the following spring [7].
Usually only one chick survives [11].

Life span - Whooping cranes live an average of 22 to 24 years [11].


PREFERRED HABITAT : 
Nesting habitat - Whooping cranes breed and nest along lake margins or
among rushes and sedges in marshes and meadows [1,3,7,10,11]. The water
in these wetlands is anywhere from 8 to 10 inches (20-25 cm) to as much
as 18 inches (46 cm) deep.  Many of the ponds have border growths of
bulrushes and cattails, which occasionally cover entire bays and arms of
the larger lakes.  Nesting has also been reported on muskrat houses and
on damp prairie sites [7].  Whooping cranes prefer sites with minimal
human disturbance [3].

Winter habitat - Whooping cranes winter on estuarine marshes, shallow
bays, and tidal salt flats [11].  The salt flats vary under differing
tidal conditions from dry sandy flats to pools of salt water up to 3
feet (1 m) deep [7].  Whooping cranes stop on wetlands, river bottoms,
and agricultural lands along their migration route [11].


COVER REQUIREMENTS : 
Wetlands provide the whooping crane with protection from terrestrial
predators [10].


FOOD HABITS : 
Whooping cranes are omnivorous feeders.  Some of the more common food
items taken are crabs, clams, shrimp, snails, frogs, snakes,
grasshoppers, larval and nymph forms of flies, beetles, water bugs,
birds and small mammals [1,3,10].  They eat over 58 species of fish [1].

During the fall, whooping cranes eat blue crabs (Callinectes sapiden)
almost exclusively.  In December and January the tidal flats and sloughs
drain and the birds move into shallow bays and channels to forage.  In
these areas whooping cranes feed primarily on clams of at least six
species.  Clams are important food items during periods of low water and
cold temperatures, and during drought when high salinities reduce the
blue crab population [10].  Plants commonly eaten include saltgrass
(Distichlis spp.), three-square rush, beaked spikerush (Eleocharis
rostellata), marsh onion, saltwort, and the acorns of live oak, pin oak
(Quercus palustris), and blackjack oak (Q. marilandica) [1].


PREDATORS : 
Potential predators of the whooping crane include the black bear (Ursus
americanus), wolverine (Gulo luscus), gray wolf (Canis lupus), red fox
(Vulpes fulva), lynx (Lynx canadensis), and raven (Corvus corax) [1,10].


MANAGEMENT CONSIDERATIONS : 
Whooping cranes can tolerate very little human disturbance, especially
during nesting, brood rearing, and during flightless molt (May to
mid-August).  Slight human disturbance is often sufficient to cause
adults to desert nests [3].  On wintering grounds, whooping cranes will
tolerate human disturbance if it is not associated with obvious threats
[10].

Potential hazards to whooping cranes increase as human use of crane
habitat increases.  Barges carrying chemicals occupy the Gulf
Intracoastal Waterway through the whooping cranes' wintering habitat
every day.  A spill or leak of these chemicals could contaminate the
cranes' food supply, or poison or injure the cranes directly.
Additionally, numerous oil and gas wells and connecting pipelines are
located in the bays surrounding the cranes' habitat.  Commercial fishing
activities with nets is another potential hazard to whooping cranes
[10].

Some causes of whooping crane mortality are illegal shooting, powerline
collisions, collisions or entangelment in barbed wire fences, and
diseases, especially avian tuberculosis and coccidia [3,10].  Fecal
accumulations and concentrations of coccidia oocysts at breeding sites
on the nesting grounds may infect whooping crane chicks.  When planning
new powerline construction, wetlands and immediate adjacent areas
frequented by whooping cranes should be avoided [3].

Cross-fostering using greater sandhill cranes at Grays Lake National
Wildlife Refuge, in southeastern Idaho, began in 1975.  Whooping crane
eggs from the wild or from captive breeders are placed in greater
sandhill crane nests, and the sandhill cranes incubate, hatch, and rear
whooping crane chicks [10,12].  To date no whooping cranes
cross-fostered by sandhill cranes have successfully paired and nested
[3].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Grus americana | Whooping Crane