birdnote q&a: what birds eat

Yellow-billed Cuckoo © Phil Brown-600WHAT 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.

House Finches © Gilbert & HendersonQ. I’ve read that flamingoes’ plumage may be more or less colorful depending on their diet, but is this true of other bird species, too?

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.

Anna's hummingbird by Tom GreyQ. Aren’t hummingbirds vegetarian—in that they feast on nectar?

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.

Black headed grosbeak, by Tom GreyQ. 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.

"Northern Flicker"Q. What about ants?

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.

Cedar waxwing by Tom GreyQ. 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!

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FIND ANSWERS to other bird questions in the BirdNote show archives, or on their FieldNotes blog.

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past installments of our series

IN CASE YOU MISSED anything from my ongoing series with the daily public-radio show BirdNote:

(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.)

7 comments
January 30, 2014

comments

    • margaret says

      Hi, Marty. Some will — such as orioles, tanagers, and others, and you can read a bit about that here. They eat my apples on the trees here like mad — but the trees have been here a long time, so the birds are accustomed to them. Sometimes when you start offering fruit at a feeder, such as half-oranges, it’s not immediately understood by the birds…plus many of the birds who like fruit aren’t “feeder birds” who eat seed at actual feeders, so they aren’t looking there for dinner. Make sense?

      • says

        Thank you, Margaret, you just answered the long-standing puzzling question for me, as to why the birds did not eat the half-oranges. Here’s another: I usually give them black-oil sunflower seeds, in the shell. Then I heard you say that you used the seed hearts, to prevent the mess and other problems the husks cause. Good idea. But I mistakenly got a bag of seed containing some black oil in the shell and some shelled – and the birds have only been eating the black ones in the shell and leaving the white hearts. Have I accustomed them to thinking only the black ones are food?? Meanwhile, I bought more black ones – don’t want my friends to go hungry. But do you understand this phenomenon?
        Your post is beautiful, by the way, and so funny – flying pigs – how true! But beloved!

        • margaret says

          Hi, Marian. I don’t know. But it does make me think how with seed mixes (including that awful “wild bird mix” that’s full of useless things like millet and so on, that fewer of the birds eat), more seed seems to go flying out of the port than into birds’ beaks, as they try to grab onto the most desired or familiar or biggest thing.
          My experience is that ground feeders such as mourning doves and birds who’ll feed on perches or the ground (juncos, cardinals…) will eat what falls to the floor (as will my local squirrels!). So nothing seems to go to waste. But I do feed one ingredient per feeder, either the sunflower hearts/kernels/chips (the pieces vary in size a bit, as does the price…I get one or the other), or thistle in some feeders, so I can’t say I’ve had that experience first-hand.
          I’d scatter the leftover chips a little at a time beneath your feeders and see who enjoys them.

          • says

            Good advice, I will try this. Thanks so much. Yesterday I heard more bird music than the day before – then I thought, of course, it’s February – coming closer and closer to the real new year – in its “tender majesty” – I look forward to meeting you at your next open garden day.
            Be well and happy.

  1. Joeth says

    I saw a small hawk on a perch near our feeders yesterday — not to eat the seed, I learned in a reference book, but to see if he could suss out the local bird population for some good eatin’.
    The population seemed to his presence; no one arrived for lunch, and he flew off before we could grab a camera.

    • margaret says

      Hi, Joeth. A very famous bird expert and author said to me once: People think feeders make it easy for hawks to eat smaller birds, but in fact it’s just that you’re getting to witness it since it’s at the feeder — they do it anyhow! Living rurally, I have gotten mostly accustomed to the reality that everyone eats something (and often someone!). :)

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