Adult whooping cranes are large white birds with long legs and long necks. They are 130 to 160 cm long, and their wingspan is 200 to 230 cm. Their long legs and biggest wing feathers are black, and their toes are grayish-pink. Their face and the top of their head are bright red to black and covered in short, black feathers like bristles. Their eyes are yellow and their bill is gray with a little bit of pink. Males and females have the same color feathers, but males are a little bigger. Males weigh about 7.3 kg and females weigh about 6.4 kg. Young whooping cranes are the color of cinnamon or brown on their back, and gray or brown underneath. They have white feathers on their heads with cinnamon or brown splotches. The top of their head has short, gray feathers instead of being bare. Whooping cranes look a lot like sandhill cranes, but those are gray and smaller. Wood storks look like whooping cranes when flying, but have black feathers on their wings, yellow feet, and a short, dark neck. ("Cranes", 2003; Hughes, 2008; Johnsgard, 1983; Lewis, 1995)
Whooping cranes live in North America, where they travel between summer and winter locations. They used to breed throughout the central United States and Canada, as well as in parts of northern Mexico. However, there are not many wild whooping cranes today. One group breeds in the Wood Buffalo National Park in the Northwest Territories of Canada and spends the winter along the coast of the Gulf of Mexico in the Aransas National Wildlife Refuge of Texas. A small separate group of them lives in the Rocky Mountains. They spend the summers in Idaho, Wyoming and Montana, and travel to the Rio Grande Valley of New Mexico for the winter. They are native to these areas, and can be spotted traveling through North Dakota, South Dakota, Kansas, Nebraska, Oklahoma, Montana, and Saskatchewan. A third group was introduced to the Kissimmee Prairie in Florida, but they don't migrate. (Allen, 1952; Armbruster, 1990; Doughty, 1989; Hayes, et al., 2007; Hughes, 2008; Johnsgard, 1983; Kuyt, 1993; Lewis, 1995)
Whooping cranes prefer open areas near large amounts of water and lots of plants, especially when they are nesting. If the area doesn't have a lot of trees, they are better able to spot possible predators. Whooping cranes nest in wetlands and marsh areas or close to shallow ponds or lakes. They avoid bogs, which are a type of wetland with lots of dead plants. They are often found where there are willow trees, sedge meadows, mudflats, and bulrush and cattail marshes. These kinds of habitat have protection from predators and food sources. While traveling between summer and winter locations, they stop in wetlands, underwater sandbars, and farm fields. In the winter, they live in wet habitats like bays with slow-moving water and marshes along the coast. They live at elevations of 0 to 945 m. ("Elevation Map Texas Gulf Coast", 2008; Armbruster, 1990; Hughes, 2008; Lewis, 1995; Timoney, 1999; Timoney, et al., 1997; United Nations Environment Programme-Wo, 2008)
Whooping cranes form a pair of one male and one female that stay together for the whole breeding season. They form pairs when they are 2 to 3 years old. Their courtship involves walks, calls, and courtship dances. It usually starts with dancing, which is bowing, hopping, and wing flapping. Either the male or female starts it and then the other joins in. Then, they jump into the air with stiff legs until they are jumping at the same time. Sometimes, a male jumps over a female while she bows her head toward her body. They keep up their relationship by calling together and performing a duet. After pairs are formed, they breed once year. At age 4, they begin nesting. Whooping cranes keep their partners for life, but will find a new one if theirs dies. (Allen, 1952; Hughes, 2008; Johnsgard, 1983; Lewis, 1995)
Whooping cranes breed once a year between late April and May. Males and females build a flat nest on the ground, usually on top of plants and surrounded by water. Females usually lay 2 eggs and keep them warm for 30 to 35 days until they hatch. If something happens and they abandon the nest, they start over if it is within the first 15 days. Young chicks begin to fly when they are 80 to 100 days old. They usually stay with their parents until they are 9 months old. Parents feed and care for their chicks until they are independent, which takes 9 months. Young whooping cranes are old enough to have their own young when they are 4 or 5 years old. (Hughes, 2008; Kuyt, 1980; Lewis, 1995; Spalding, et al., 2009)
Male and female whooping cranes take turns sitting on the nest to keep the eggs warm. While one parent is keeping the eggs warm, the other guards the nest from predators. Parents cover and keep the chicks warm at night or during bad weather after they hatch. When a chick begs for food, parents hold food out from their bills for the chicks to peck at. Females feed the chicks more often than males do. The chicks eat worms and insects at first, and bigger ones as they grow. Slowly, they begin to eat independently, but still beg for food until they are 6 to 9 months old. Most of the young leave their parents in spring of the next year. (Hughes, 2008; Lewis, 1995)
In the wild, whooping cranes live 22 to 30 years old or more. In captivity, they live to be 35 to 40 years old. About 27% of them die in the first year, but females are twice as likely to survive the first year. Diseases like avian tuberculosis, avian cholera, and intestinal coccidia parasites can kill them. Drought in the summer breeding season can contribute to deaths of young whooping cranes, because they have to travel farther for food and might be attacked by land predators. (Forrester, et al., 1978; Lewis, 1995)
Whooping cranes are active during the day and rest or sleep on the ground at night. In the past, all whooping cranes migrated, traveling between a summer and winter location. Now, only 2 out of 3 groups of them migrate. Whooping cranes are not very social, but live in breeding pairs or small family groups. To get around, they usually walk or fly. They flap their wings, soar, or glide, depending on where they are flying. On long flights, they are more likely to soar or glide. Whooping cranes bob their heads while walking. They distract or try to scare away predators with different kinds of body language. Whooping cranes don't swim much, but their chicks do. (Cronin, et al., 2005; Cronin, et al., 2007; Johnsgard, 1983; Lewis, 1995)
The most important way whooping cranes communicate is vocally, which is why they are called whooping cranes. Each of their calls has a name. They are called: contact calls, stress calls, distress calls, food-begging calls, flight-intention calls, alarm calls, hissing, flight calls, guard calls, location calls, pre-copulation calls, unison calls, and nesting calls. They defend their territory with unison and guard calls. Unison calls are also used to form mating pairs. Their calls scare away predators, warn others of attack, help protect and care for the young, and are used to find other whooping cranes. (Cronin, et al., 2005; Cronin, et al., 2007; Lewis, 1995)
Whooping cranes are omnivores, so they eat both plants and animals. In the winter, they eat mostly blue crabs and wolfberry fruits. They also eat clams, acorns, snails, grasshoppers, mice, voles, and snakes. When they are migrating, they often eat potatoes and other tubers as well as grain that was left in farm fields. In summer breeding areas, they eat minnows, insects, frogs, snakes, mice, berries, crayfish, clams and snails. Young whooping cranes eat a lot of worms, and gradually eat bigger food as chicks grow. (Butzler and Davis, 2006; Hughes, 2008; Lewis, 1995; Nelson, et al., 1996)
Whooping cranes are eaten by predators on land and in the air. On land, they are eaten by black bears, wolverines, gray wolves, red foxes, lynx, bobcats, coyotes, and raccoons. From the air, they are eaten by bald eagles, northern ravens, and golden eagles. Golden eagles attack them in the air and are a big threat during migration. Whooping cranes travel at very high altitudes during migration, which may help them avoid predators in the air. (Cole, et al., 2009; Ellis, et al., 1999; Hughes, 2008; Lewis, 1995)
Whooping cranes are the most vulnerable to predators in the first year and especially before they can fly. In years when it is very dry, nests are very easy for predators to get to and young are more likely to be eaten. Whooping cranes use alarm calls or distractions to fend off large predators. The most common is called a slow-walk strut, which is where they walk with their body turned sideways and lift their feet up high, which makes them seem bigger. If that doesn't work, they lower their bill to the ground and growl. Finally, they face the predator, spread their wings, and droop them while they stick out their neck. When a big predator comes close to the nest, the parent sitting on the nest may leave the nest and try to distract the predator dragging its wing. (Cole, et al., 2009; Ellis, et al., 1999; Hughes, 2008; Lewis, 1995)
Whooping cranes are both predators and prey. Because they are endangered and there aren't very many of them, they probably couldn't be a main food for another species. Whooping cranes in the wild and in captivity can get Coccidia parasites, which are passed in feces. These parasites are called Eimeria gruis and E. reichenowi. They are more likely to get infected in captivity because they are all closer together. (Forrester, et al., 1978; Lewis, 1995)
There are no adverse effects of whooping cranes on humans.
Whooping cranes are a great example of successful wildlife conservation. Thousands of people visit the Aransas National Wildlife Refuge every year to see them.
Whooping cranes are endangered, but almost became extinct in the 1940's and 1950's. In the winter of 1954, there were only 21 whooping cranes alive, but there were about 260 in 2009. They have been the focus of many conservation projects. They were bred in captivity and re-introduced into the wild. Sometimes, eggs produced in captivity are actually taken care of by humans dressed in whooping crane costumes. The re-introduced whooping cranes don't migrate like the others too. This means that young whooping cranes learn migration routes from their parents. Now, small, white planes are used as "parent" birds and guide juveniles on their first journey to their wintering grounds. This doesn't always work, but their numbers are still increasing. ("Birds Protected by the Migratory Bird Treaty Act", 2009; Cole, et al., 2009; Doughty, 1989)
Julia Esch (author), University of Alberta, Augustana Campus, Doris Audet (editor), University of Alberta, Augustana Campus, Rachelle Sterling (editor), Special Projects.
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