Blue and Crabby: Whooping Crane Winter Diet
How would you like to eat the same thing every day for 5 or 6 months every year of your life? That's what whooping cranes do on their wintering grounds, in Texas and florida. Cranes can eat crabs, clams, eels, shrimp, crayfish, acorns, snails, mice, voles, grasshoppers, minnows, dead fish, marsh onions and snakes. But their clear favorite is blue crabs. An adult crane can eat up to 80 blue crabs in a day!
Most Important Crane Food in Winter
What's so great about blue crabs? One large blue crab has about 85 grams (g) of meat. This provides 87 calories, with 17 g of protein, 1.5 g of fat, and 0 g of carbohydrate. But it isn't just the protein and calories in blue crabs that is important for cranes. Each crab is also rich in calcium (necessary for strong bones and also for forming egg shells). It has iron, magnesium, phosphorus, zinc, copper, other minerals, and lots of vitamins. And this is just the actual meat in the crab. Cranes pick off the biggest claw and some of the hard parts of the shell on the largest crabs, but they swallow smaller crabs whole. They eat most of the shell even on large crabs. The shell is extremely rich in calcium and other minerals. A crane would have to eat a LOT of acorns or worms to get the nourishing vitamins, minerals, and calories of just one blue crab!
Harder Than It Looks
Biologist Tom Stehn tells us that the parents have to teach the baby cranes how to eat crabs: "Whooper chicks are fed most of the winter at Aransas by their parents, with feeding tapering off as the young get older and spring approaches. With vegetable matter such as wolfberries or acorns, the young cranes quickly feed on their own. When an adult catches a blue crab, Junior runs over and begs for an easy meal. Small crabs are swallowed whole. With a big crab, the adult usually carries it to the edge of a pond and pulverizes it on the muddy marsh soil rather than in the open water ponds. Once the crab is stunned and on marsh soil, Junior is usually pecking at the crab and trying to eat underfoot of the adult crane. The crab legs are pulled off and often swallowed whole. When crabs get inactive from cold temperatures (below 18 degrees C), adults stand in one spot and probe the mud until they hit a crab. I assume the youngsters also do this.
"George Archibald (ICF) has suggested that the beaks
of 6-month old cranes are still growing and may not be strong enough
crabs, but Felipe Chavez has observed young whoopers catching crabs. Dr.
Chavez writes, 'The cranes I observed catching
crabs generally took the crab to the edge, an open spot to tear
up. Occasionally, particularly with larger crabs, the crane would break
off one of the claws before it took the crab to the edge of the
A free claw is dangerous, it appears. I saw crabs cling to the cranes
beak after the crane had let go of it. Once on the edge, the second
remaining claw was generally broken off first. Then the crane generally
flipped the crab over and proceeded to peck it repeatedly. I am
sure if it was trying to kill it, or break it up regardless of whether
it was alive or not. I'm not sure whether cranes kill the crab first
then tear it up or tear and kill along the way. This generally left
only the carapace of larger crabs, since the undersides, inside,
all extremities were consumed except for very large claws.'"
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