Sandhill Crane - Behavior

Behavior

Sandhill cranes are fairly social birds that are usually encountered in pairs or family groups through the year. During migration and winter, non-related cranes come together to form "survival groups" which forage and roost together. Such groups often congregate at migration and winter sites, sometimes resulting in thousands of cranes being found together.

Sandhill Cranes are quite catholic in diet but are mainly herbivorous, often eating various types of food based on availability. They often feed with their bills down to the ground as they root around for seeds and other foods in shallow wetlands with vegetation or various upland habitats. Cultivated foods such as corn, wheat and sorghum are readily eaten and may support large numbers of cranes. For example, waste corn is useful to the cranes in preparing for their migrations, providing them with nutrients for the long journey. Among northern races of Sandhill cranes, the diet is most varied especially among breeding birds. Northern cranes and their offspring may variously feed on berries, small mammals, insects, snails, reptiles and amphibians.

Sandhill cranes raise one brood per year. In non-migratory populations, egg-laying can begin as early as December or as late as August. In migratory populations, egg-laying usually begins between early April and late May. Both members of a breeding pair build the nest using plant material from the surrounding areas. Nest sites are usually in marshes, bogs, or swales, though cranes will occasionally nest on dry land. The female lays 1 to 3 (usually 2) eggs that are oval-shaped and dull brown with reddish brown markings. Both parents participate in incubation, which lasts 29 to 32 (though usually 30) days. Incubation begins with the laying of the first egg and continues until the second egg has hatched. The chicks are precocial; they hatch covered in down, with their eyes open and are able to leave the nest within 24 hours of hatching. The parents brood the chicks for up to 3 weeks after hatching. They feed the young intensively for the first few weeks, and with decreasing frequency until they reach independence at 9 or 10 months old.

The chicks remain with their parents until 1 or 2 months before the parents begin laying the next clutch of eggs. After leaving their parents, the chicks form nomadic flocks with other subadults and non-breeders. They remain with these flocks until they form breeding pairs and begin breeding between the ages of 2 and 7 years old. Sandhill cranes provide extended biparental care to their young. Both members of a breeding pair build the nest, incubate the eggs and feed and protect the chicks for up to 10 months after hatching. Sandhill cranes that reach independence are expected to live around 7 years. Sandhill cranes can live to at least 21 years of age.

As a conspicuous and ground-dwelling species, Sandhill Cranes may face a variety of predators. Mammalian predators such as foxes, raccoons, coyotes, wolves, bobcats and lynxes readily predate cranes of any age, although they are a greater threat to young cranes. Birds that may predate young cranes or crane nests include corvids such as ravens and crows and smaller raptors, including hawks. Cranes of all ages may be predated by eagles, large owls and even Peregrine Falcons. Sandhill cranes often vigorously defend themselves from predators, especially when defending offspring which are not able to avoid ambushes as easily as their parents. When attacking potential avian predators they fly up at the predator and kick with their feet. When facing mammalian predators, they move toward the predator with their wings open and their bill pointed towards it. If the predator persists, the often hissing crane will attack, stabbing with their bill (which is powerful enough to pierce the skull of a small carnivore) and kicking with their feet.