Bird Watcher's General Store

Some Cranes Migrate, Some Cranes Don't
03/25/11


Dear Bird Folks,

About a month ago I watched a nature show on migrating Sandhill Cranes. The program talked about massive flocks of them pushing north each spring. However, I’ve just recently returned from a birding trip in Florida where I was told that Sandhill Cranes don’t migrate. What gives?

–James, Falmouth, MA

Here’s what gives, Jim,

The nature show you watched was correct. Sandhill Cranes do migrate. However, what you heard in Florida was also correct. Many of those cranes don’t ever leave the state. The reason they don’t migrate has to do with the fact that the Floridian Sandhill Cranes tend to be older, retired and set in their ways. They don’t want to go anywhere anymore. In addition, many of these older cranes pull their pants up so high above their waists they have trouble flying. And according to a recent study, many of the Florida cranes simply miss the annual migration because when it’s time for them to fly off they are in the den, napping.

You aren’t the only person who saw that show about cranes, James. Recently, I’ve had several folks ask me why some cranes migrate, while others are sedentary. As with most things in the bird world, nothing is simple. Sandhill Cranes consist of six different subspecies. Three of those subspecies don’t ever migrate. The populations of non-migratory cranes are rather small and are found in Mississippi, Florida and Cuba (although I doubt the Cuban cranes would be allowed to leave even if they wanted to). The migratory populations, however, make up the vast majority of the cranes. They spend the winter in the southern half of the U.S. and in northern Mexico. (Note: some migrants spend the winter in Florida, but the migrant birds should not be confused with the resident cranes.) Each spring these birds fly north to their breeding grounds in Canada and Alaska. Additionally, cranes can be found breeding in Michigan, Minnesota and also in Wisconsin, where the governor is trying to hire them to replace the teachers.

Each spring an estimated 500,000 northbound Sandhill Cranes, or 80% of their population, stop off along a seventy-five mile stretch of Nebraska’s Platte River. Think about that for a minute. Half a million of these huge birds jam themselves into an area not much larger than Cape Cod. Can you imagine if we had all of those jumbo cranes around here? (That would certainly put a stop the Blue Jay and grackle complaining for a while.) Anyone who is tech savvy should check out “Sandhill Crane migration” on YouTube. It’s amazing. (If you are a non-techie, just sit in front of the television until that special comes on again.)

Unlike many migrating birds, Sandhill Crane couples remain together year-round, even when they are in a huge flock. The advantage of staying together means that the birds are ready to get down to business the minute they reach their breeding grounds. But before mating, they first must perform their wacky “crane dance,” which helps solidify their pair bond. (While you are looking at their migration on YouTube, check out their dance, too. It’s totally nuts.) During the dance, the pair will rear their heads back and give off a series of raucous calls, which can be heard up to two miles away. They will then proceed to bounce, twirl, leap, flap and bow, all in uneven, spastic motions, looking like marionettes that are being controlled by a puppeteer on acid, or me trying to do the Hustle at a wedding.

When the dancing is over, the birds begin building their nest, which is another process that is rather goofy. With their backs to the nest site, they repeatedly toss nesting material over their heads, like someone frantically looking for something in a crowded closet. Once they’ve accumulated enough material, the female puts an end to all of the silliness and starts to form a nest. Eventually, she lays two eggs and both adults share in the incubation duties. Just before hatching, the baby birds begin to chirp…while they are still inside of the egg. Oh, how cute! The cuteness doesn’t last very long, however. Sandhill Crane siblings hate each other from day one. They squabble over everything, but especially over food and which channel to watch on TV. And unless there’s an abundance of food, only one chick will survive. On a brighter note, if both chicks can hold on for about a month, they’ll slowly learn to live with each other and will eventually get along peacefully. I’m still waiting for that day with my siblings.

The young cranes will remain with their parents for the next year. The adults show them the migration routes, the best places to find food and how to behave like a proper crane. It takes several years before young cranes are old enough to start their own family, but by the end of the first year their parents have had enough of them. Before the next breeding season begins the adults forcefully drive the kids away. It seems a little cruel, but it’s all for the best. The young birds shouldn’t have to witness all that freaky dancing. No kids want to see their parents doing that.

One last thing about Sandhill Cranes, James. They may be the oldest bird species alive today. An exact fossil, dating back ten million years, has been discovered. I’m not sure where they found this old fossil, but I’d be willing to bet it was in Florida, slowly driving down Rt. 1, looking for the nearest bingo hall.




Artwork by Catherine Clark


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