A portion
of three distinct populations of sandhill
cranes winter in Arizona. Cranes from both
the Rocky Mountain (RM) and mid-Continent
(M-C) populations winter in the Sulphur Springs
and Gila River valleys of southeastern Arizona.
Sandhills from the Lower Colorado River Valley
(LCRV) population winter along the lower
Colorado River, primarily on the Colorado
River Indian Reservation and Cibola National
Wildlife Refuge, and below Gillespie dam
on the Gila River. RM cranes nest primarily
in Idaho, Montana, Wyoming, and Utah. LCRV
cranes nest primarily in northeastern Nevada.
The nesting range of the M-C encompasses
most of Canada and Alaska. The M-C population
migrates through the central plains, staging
on the Platte River both spring and fall,
to wintering grounds in Texas, Oklahoma,
New Mexico, Arizona, and Mexico.
Life History
Wintering areas selected by sandhills feature shallow water roosting areas
with low or no vegetation; playa lakes and sandbars along shallow/braided
rivers are preferred. Cranes winter in close proximity to harvested grain
fields, corn is preferred. In mid to late February cranes begin their return
migration to nesting areas.
Cranes leave roosting areas in early morning, usually about sunrise, to
fly to feeding areas, where they spend three to four hours. During midday
the cranes return to the roost, or go to nearby loafing areas, which can
be grasslands or wetlands. In the late afternoon cranes sometimes make
short visits to feeding areas before returning to the roosts.
Behavior
Sandhill cranes in the western United States nest in high elevation shallow
marshes and wet meadows. Sandhills do not nest until they are four to five
years old and typically have very poor success the first couple of years.
Typically, cranes lay two eggs, but only about 1/3 of the successful nesters
are able to raise two young. In dry years, when wetlands shrink, predators,
especially coyotes, take a heavy toll on the flightless young. During recent
dry years the proportion of young-of-the-year birds in the fall population
has been around 4 percent. Even in good production years young-of-the-year
birds rarely comprise more than 12 percent of the fall population.
Depending on habitat conditions sandhills begin to congregate in local
agricultural areas, called pre-migration staging areas, in late August.
Migration to wintering areas begins in September. Cranes typically migrate
in a few long, high altitude flights stopping at traditional stopover areas.
For cranes of the three populations that winter in Arizona the major stopovers
are the Platte River in Nebraska for the M-C, San Luis Valley in Colorado
for the RM, and wetlands near Lund, Nevada for the LCRV. Cranes begin arriving
on wintering areas in late September.
Habitat