Critter of the Month: sandhill crane
Living on the Lake report
The sandhill crane is a large migratory bird that spends its winters in Florida but can be found from March to November in Wisconsin. Its features could be described as almost prehistoric, and for good reason. A crane fossil discovered in Nebraska from the Pliocene Period (between 5 and 2 million years ago) was found to be structurally identical to today’s sandhill crane, making it one the world’s oldest known species of bird.
What does this bird look like?
Sandhill cranes are very large, standing 4- to 5-foot tall and weighing anywhere from 10 to 14 pounds. They have a wingspan of six to seven feet and can be easily identified in the air by their outstretched neck and legs. Their bodies are covered with grey or brown plumage and have black legs, feet, and bills. Their eyes are yellow, and they have a bright red patch on their forehead. They have very distinctive calls and can often be heard for several miles on quiet mornings and evenings.
Where do sandhill cranes live?
There are five subspecies of sandhill cranes: three non-migratory species that live in the southern part of the United States and Cuba, and two migratory species. Of the two migratory species, only one (the greater sandhill crane) breeds in the northern United States. These sandhill cranes return to the upper Midwest during spring migration from their wintering grounds in Florida, usually arriving in Wisconsin in March. They prefer wetlands, shallow waters, and bogs to nest and to roost at night, traveling to open fields during the day to feed. They can be found in all 90 Wisconsin counties and generally stay in family groups. In late fall, sandhill cranes stage in large groups, often numbering a thousand or more, where they will fly together to fields for feeding and roost together at night. When they determine it is time to begin their migration south, the group takes off, circling up to as high as 5,000 feet to catch prevailing winds.
What do they eat?
Sandhill cranes will eat seeds and grains such as corn or wheat. However, they are omnivorous so they will also eat insects and small mammals, like mice, as well as frogs and snakes. It is the grain that gets them into trouble with Wisconsin’s farmers though. Sandhill cranes traveling in large numbers can easily decimate a corn field in the spring as they will eat germinating corn seed.
What is the lifecycle of a sandhill crane?
Adult sandhill cranes will not take a mate until about 4 years of age, but then they mate for life. Their mating rituals include dancing and singing, with both the males and females participating in this display. Nests are located on the ground and are built near open water. These large nests (about 5-foot in diameter) will house 1-2 eggs for about 30 days. Both parents are active caretakers of the nest and eggs. Chicks are born in Wisconsin in mid-May and are a fluffy dark yellow. Chicks will leave the nest within one day of hatching to begin learning how to feed themselves, and they will fledge (take their first flight) in 45-60 days, usually around mid-July in Wisconsin. Chicks stay with their parents until their first migration in the fall. Sandhill cranes can live to be 25-30 years old.
What threats do they face?
There are 15 different species of cranes, and 11 of those species are endangered. Sandhill cranes are not endangered, and though there are about 700.000 sandhill cranes in North America, there are still threats to their existence. Conflicts with farmers are a problem, but it is their loss of habitat, especially to those critical migration staging areas, that is most worrisome to scientists. Draining wetlands to create more agriculture space and overall development threaten the species. In addition, strikes with aircraft as well as power lines, wind turbines, and solar arrays are a concern as well. To further complicate matters, sandhill cranes are slow reproducers. Of the possible two eggs per year to a breeding pair, generally only one chick will survive to fledging.
Conservationists, scientists, and the general public are doing what they can to help the sandhill cranes from becoming endangered like their other Crane cousins. Sandhill cranes are protected under the Migratory Bird Treaty Act of 1918, so they cannot be hunted (though permits are sometimes given for individual birds causing a nuisance or danger in places like airports). In addition, the Annual Crane Count, which takes place every April with hundreds of volunteers helping to count sandhill cranes all across the upper Midwest, supplies data for important ongoing research. These efforts create awareness and help to maintain a healthy sandhill crane population.