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Sunday, May 6, 2012

The harsh challenge of crossing open water

Migrating birds often have to cross large expanses of open water with no place to stop and rest. No place to re-supply food either. Most Hummingbirds do this twice a year (although some fly along the coast). Some die trying to cross the Gulf, and the ones that make it are much skinnier and are starving when they arrive.

Purple Martin
Purple Martin is another north Texas species that crosses the Gulf during migration. They need to fly non-stop for 72 hours, travelling around 660 miles a day. That's equivalent to a human running at a 4-minute-mile pace for 80 hours straight.

American Robin
Robins are eating machines. Researchers estimate that each brood of  nestling American Robins eats about 3.2 pounds of food. Since they're "insectivores" that means eating only insects (and worms). While in the nest (an average of 13 days) each one grows from 5.5 grams to 56 grams - over 1000 percent! On its last day in the nest, a nestling may eat 14 feet of worms, or whatever else the territory produces.

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