The feeding frenzy that powers the migration

Much about the spring and fall migrations are cloaked in mystery, from how birds know when to leave to what helps them  determine exactly where they’re going.

But there’s no question about one element of their twice-a-year extreme feats of travel: the moment the birds stop for breaks, they go to work eating seeds, beetles, worms, flies, moths, bees, lizards, caterpillars, fruit, nuts, nectar, fish, spiders, snakes, suet, mice, and sometimes other birds.

The migration is a feeding frenzy.

A Yellow-rumped Warbler wrestles with an inch worm.

Dining is a vital part of the day – and a fascinating element of the journeys that four to five billion birds are in the midst of about now across the U.S. They need to eat meals that for us would be pretty much impossible.

The hummingbird, for instance, has to consume its entire weight in nectar every day. For a normal sized human, that’s the equivalent of drinking 18 gallons of milk, according to the Audubon Society.

The Chickadee has to eat about a third of its weight in seeds, berries, insects and worms daily. For us, Audubon says, that would translate into eating 600 granola bars every day.


Much about their meals are easy to watch, particularly during migration when birds seem to be in a very public and frantic search for food. But, in fact, a lot about bird diets are mere guesses.

A Roseate Spoonbill scoops up a shell while fishing in a mangrove swamp.

As efforts to protect birds are expanding, scientists are studying their specific dining needs to determine whether birds can, in fact,  find the insects, plants, fish and small mammals they need.

At the University of Delaware, staff and students are in the midst of a long-range study on what birds eat. They encourage people to send in pictures when they catch birds eating. They’ve set up a website where you can file photos, and a Facebook page where you can post them.

Professor Doug Tallamy, who leads the project, explains that birds often rely on different diets during migration, during breeding season, and at other times.

A Blue Jay plucks a berry.

“Why should we care what birds eat?’’ Tallamy wrote in a piece explaining the project.  “There are many reasons, but my primary motivation is the conservation and restoration of viable bird habitat.’’

You can find a full explanation of the University of Delaware project here. Meanwhile, here’s an Audubon guide on feeding birds, and here’s one from the Humane Society.  And here’s an sampling of what various birds eat, compiled by the Wild Birds Forever store. It’s fascinating, but not the most appetizing reading. 

Finally, here’s our gallery of birds hard at work downing their meals. Not all of these species join in the migration, but many are in the midst of the feeding frenzy that fuels their journeys and also their busiest times of year. (Run your cursor over the photo for info.)




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