Horseshoe Crabs: Free Lunch To Birds

music
ambience: shorebirds and waves, horseshoe crabs

Every spring, horseshoe crabs lay their eggs on the beach of Delaware Bay in a mass spawning event. At the same time, tens of thousands of shore birds show up to feed on the crabs’ eggs. I’m Jim Metzner, and this is the Pulse of the Planet. The shore birds are migrating from South America all the way up to the Arctic Circle, where they’ll breed. Michael Haramis is a wildlife biologist with the U.S. Geological Survey.

“This is a, a tremendous journey, and the biggest span of it of course is cross the ocean from Brazil to Delaware Bay, a distance of somewhere around 5000 miles, which many birds apparently do in one, one leap. Now they show up just in time in Delaware Bay to feed on crab eggs, which are extremely abundant. The very interesting relationship here is that the crabs themselves, being such crude, fundamental animals, are spawning in this mass event on the beach, they actually plow up their own eggs, because so many crabs come ashore and dig into the beach head in the same places, they actually are breaking up clusters of eggs that were spawned earlier. And the birds just simply sit there and have a free lunch on crab eggs, which of course would never hatch. So in essence the shorebirds are feeding on excess eggs and in no way are affecting the status of, of the spawning success of the horseshoe crab.”

Feasting on crab eggs helps the birds store enough fat in their bodies to continue their migratory journey to the Arctic Circle.

Pulse of the Planet is presented with support provided by the National Science Foundation. I’m Jim Metzner.

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Horseshoe Crabs: Free Lunch To Birds

The breeding grounds for horseshoe crabs is a vital stopover for thousands of migrating birds.
Air Date:05/01/2008
Scientist:
Transcript:

music
ambience: shorebirds and waves, horseshoe crabs

Every spring, horseshoe crabs lay their eggs on the beach of Delaware Bay in a mass spawning event. At the same time, tens of thousands of shore birds show up to feed on the crabs' eggs. I'm Jim Metzner, and this is the Pulse of the Planet. The shore birds are migrating from South America all the way up to the Arctic Circle, where they'll breed. Michael Haramis is a wildlife biologist with the U.S. Geological Survey.

"This is a, a tremendous journey, and the biggest span of it of course is cross the ocean from Brazil to Delaware Bay, a distance of somewhere around 5000 miles, which many birds apparently do in one, one leap. Now they show up just in time in Delaware Bay to feed on crab eggs, which are extremely abundant. The very interesting relationship here is that the crabs themselves, being such crude, fundamental animals, are spawning in this mass event on the beach, they actually plow up their own eggs, because so many crabs come ashore and dig into the beach head in the same places, they actually are breaking up clusters of eggs that were spawned earlier. And the birds just simply sit there and have a free lunch on crab eggs, which of course would never hatch. So in essence the shorebirds are feeding on excess eggs and in no way are affecting the status of, of the spawning success of the horseshoe crab."

Feasting on crab eggs helps the birds store enough fat in their bodies to continue their migratory journey to the Arctic Circle.

Pulse of the Planet is presented with support provided by the National Science Foundation. I'm Jim Metzner.

music