WHAT DO BIRDS EAT? The answer isn’t “birdseed,” despite those flying feathered pigs devouring feeder contents extra-fast this extra-cold winter. Our BirdNote correspondent Ellen Blackstone shares some surprises about hummingbirds (it isn’t all about finding red flowers, and yes, they eat bugs); who eats ants for dinner (and who uses them as a grooming aid); why almost nobody likes monarch butterflies; why birds get drunk on one too many fermented fruit, and more.
In the Q&A that follows, Ellen’s answers contain green links to audio files from BirdNote’s archive that you won’t want to miss. A recap of earlier stories in our ongoing series is at the bottom of the page, along with information on how to get BirdNote daily–and if you want to give thanks to nonprofit BirdNote for all their wonderful avian “aha’s,” you can do so at this link.
A. What on earth does the lowly house finch have in common with the elegant, long-legged flamingo? They are what they eat. In color, that is. The carotenoids in their diets affect what color they are. Carotenoids are the same pigments that give oranges and carrots–and brine shrimp–their color. Male house finches will develop brighter plumage when they’re growing in new feathers, if they eat more fruits containing carotenoids. If you see a house finch that looks more yellow than red, like the one above left, it simply hasn’t been getting enough carotenoids (more on that)!
Q. Are any birds strict vegetarians, meaning no insects eaten?
A. House finches eat almost exclusively seeds and other plant matter. Their cousins, American goldfinches, are–according to Cornell’s All About Birds–”among the strictest vegetarians in the bird world.”
Most songbirds, though, eat insects as at least part of their diet. Even the birds that are vegetarians as adults generally feed some insects to their young. And many migrate southward in late summer or autumn, when insects are on the wane.
A. Actually, hummingbirds are meat-eaters, too—meaning they do include insects in their diet.
We generally think of hummingbirds hovering among beautiful red flowers. But baby birds in the nest need protein to grow, just as humans do. So their mamas feed them insects in addition to nectar.
Many hummingbirds also take advantage of sapsucker wells, dining on both the sap and the insects attracted to the sap.
Oh, and although we’ve been led to believe that hummingbirds prefer red flowers, the fact is that they prefer flowers with the most nectar. Although hummingbirds’ eyes have a heightened sensitivity to colors in the red to yellow range, given the choice, they’ll ignore color and head for the most nectar-rich flowers, like this.
Q. Of course, hummingbirds have specially designed beaks so that they can sip from flowers, especially tubular ones. I love how some species’ beaks give you a hint of what they can manage to eat, such as grosbeaks and crossbills.
A. True! Grosbeaks’ beaks like the one below hint at their ability to crack open tough seeds. So do crossbills’ beaks, which are built for feasting on seeds of cones. More on specialized beaks or bills, including of shorebirds.
Q. So what won’t birds eat in the insect world? I know that some species of caterpillars, for instance, have co-evolved with avian predators to develop unappealing colorations and other defenses—fascinating stuff!
A. Monarch butterflies taste so bad that most birds shun them, for one important example. (In fact, viceroy butterflies look so much like monarchs that birds shun them, too.) But black-headed grosbeaks (above) find monarchs quite tasty, thank you.
Cuckoos, both yellow-billed (top photo) and black-billed, like to feast on another tasty morsel that many birds find distasteful: tent caterpillars. Ugh! While other birds may pick a caterpillar apart, cuckoos actually eat the whole thing, fuzz and all. When the fuzz in a cuckoo’s stomach finally reaches critical mass, the bird throws up the entire stomach lining and grows a new one. The story.
A. Ants are both food and a grooming aid for many birds, especially woodpeckers. While we may think of woodpeckers on tree trunks, Northern flickers (above) are most often found on the ground, scooting along, picking up ants. (John James Audubon noted that the flicker tastes “very disagreeable, it having a strong flavour of ants,” but that’s a story for another day…)
Watch for a crow to pick up an ant and use it to stroke its feathers, an act birders smilingly call “formication.” The formic acid in the fluid released by some ants must serve to repel pests.
Q. We have to mention it, though everyone screams in horror: Some birds prey on other birds.
A. Yes, some people find it downright distressing that certain birds, raptors in particular, eat mostly other birds. Except for the tiny American kestrel, which favors mice, voles, insects, and such, birds of the falcon family capture almost all their prey in mid-air. And for those larger falcons, from the sleek merlin to the majestic gyrfalcon, that means birds.
Q. At this time of year or even later winter, flocks of robins and waxwings (like the cedar waxwings in the photo above) visit and seem to get drunk on rotten fruit still hanging on my crabapples and apple trees. Why are they attracted to it?
A. You may picture an American robin, bob-bob-bobbin’ along on your lawn, searching for worms. But that robin appreciates a ripe cherry or berry, too, as any gardener knows. Now, it seems that robins can’t smell, so they wouldn’t know if a berry had spoiled – or fermented. So it’s no surprise that robins–and waxwings, too!–may eat until they nearly fall over, when feasting on fermented berries.
Orioles, too, are fruit-eaters. Baltimore orioles and their cousins, orchard orioles and Altamira orioles, are especially drawn to orange slices and even jelly. Serve ’em up!
how to get birdnote
Meantime, listen to BirdNote’s latest podcast anytime on the player below, or by visiting their website. Subscribe to the podcast or RSS, free. More than 100 public radio stations playing BirdNote are listed here; if you like what you hear, why not ask your local station if they’ll carry it.
The BirdNote backstory: In 2002, the then-executive director of Seattle Audubon heard a short public-radio show called StarDate. “We could do that with birds,” she thought. In 2005 the idea became a two-minute daily public-radio show. Lucky for all of us!
past installments of our series
IN CASE YOU MISSED anything from my ongoing series with the daily public-radio show BirdNote:
- Week 1: How do birds make themselves at home—even in winter?
- Week 2: hummingbird migration, and on flying in formation.
- Week 3: on daring behavior, such as when a mob of small birds chase after a bigger one, or a woodpecker drums on a house.
- Week 4: whether birds mate for life, and how long they live.
- Week 5: What senses birds of prey use to hunt.
- Week 6: Bird houses, or nest boxes.
- Week 7: Bird songs and calls! What you’re hearing.
- Week 8: The complex nests of songbirds.
- Week 9: Crow, or raven?
- Week 10: The biggest bird nests of all.
- Week 11: Fledging, when young leave the nest.
- Week 12: Why the “dawn chorus” quiets in midsummer
- Week 13: Hummingbird migration.
- Week 14: Fall chores (nestbox and feeder care and more).
- Week 15: What “our” birds do in winter.
- Week 16: Wild turkeys.
- Week 17: The indefatigable brown creeper.
(Photos used with permission: Cuckoo copyright Phil Brown; Black-headed grosbeak, Anna’s hummingbird and waxwing with fruit copyright Tom Grey; house finches copyright Gilbert & Henderson; flicker copyright Mike Deal.)