Unlike other birds, the American goldfinch builds its nests in summer

Goldfinches didn't get the nesting memo. The other birds did. They know to build their nests and start laying eggs in spring. The American goldfinch (Spinus tristis) waits until summer is in full swing before it starts reproducing. Why? First, let's go back to winter.

Winter plumage

If you feed birds, you've seen goldfinches coming for the sunflower and nyjer seeds. Admittedly, they don't look very gold. Instead, both sexes are a dreary brownish-yellow. Interestingly, the goldfinch is the only finch to molt its body feathers twice a year.

Aren't all feathers on the body, you ask? Well, yes, but “body feathers” refers to the feathers that cover the body as opposed to the flight feathers found on the wings and tail.

Like many bird species, the goldfinches sport brighter feathers as the temperatures warm. While goldfinches, especially the males, do grow brighter body feathers in spring, they don't grow new flight feathers. They had those last winter, but they were hiding behind the dull-brown feather edges.

As spring progresses, the drab, flight feather edges fade and wear off, revealing the more vivid feathers underneath.

Potato chip bird

The male goldfinch is definitely a summer celebrity. It is the only small finch that is bright yellow with a black cap and wings. The yellow is so bright that the bird is sometimes called a wild canary. Is it any wonder that it is the state bird of New Jersey, Iowa and Washington?

Besides its distinctive colors, the goldfinch has an easily identifiable call and flight pattern.

With apologies to Frito-Lay, the goldfinch will always be the potato chip bird to me. In particular, it is a Ruffles potato chip bird.

When the male takes wing across a weedy field, it makes a “perchicoree” call as it flies in an undulating pattern. “Perchicoree” can easily be transformed into “potato chip.” For the record, I have never found a goldfinch in my French onion dip.

Summer Stock

Before bringing in the star of our midsummer (re) production, we need to introduce some of the organisms that play supporting roles.

First, the villain: the Eastern cowbird. This species really isn't that bad, it's just misunderstood. You see, female cowbirds lay their eggs in other birds' nests. The cowbird then leaves the care of her offspring with the original female.

The cowbird nestling hatches first. It grabs most of the food that the mother bird brings and often shoves out or starves the nestlings that were intended to be raised in the nest. Sounds pretty bad, eh?

Well, there is a reason for this behavior. As the bird's name suggests, it used to hang around large animals like cattle. Before there were domestic cows, wild bison roamed the grasslands.

Cowbirds gobbled up the insects disturbed by or attracted to bison. Bison didn't stay in one place, they migrated across the prairies.

If your meal ticket is on the move, how can you be a stay-at-home mom? Build a nest between the bison's horns? No, you just drop the kids, I mean eggs, off at the nearest birdie day care.

Unfortunately, free-ranging bison are gone, but the “buffalo birds” remain.

Live From Europe

Speaking of cows and bulls, this brings us to our other important cast members, thistles. While some thistles are native, the most commonly seen one, bull thistle, is a nonnative and, boy, do goldfinches love them.

One can't help but wonder how such a prickly weed got across the Atlantic Ocean. When the thistle seed head ripens, the tiny seeds ride the wind on a soft plume, similar to milkweed, known as thistledown.

OK, picture yourself in the 19th century at a dock in England. You will soon be boarding a ship for America. Nearby shops are selling supplies for emigrants, including thistledown bedding. Nothing could be softer! So, you buy it.

As the decades pass and the mattresses wear out, thistledown (with some seeds) is released into North America. An unintended immigrant soon takes root.

Goldfinch Dance Number

Now, it is time for our leading bird, so to speak. The goldfinch welcomes all thistles to the show. Conveniently, thistle ripens in summer when the goldfinches start nesting. Watching goldfinches select a nest site is quite entertaining. They prefer shrubs with a clearing on at least one side.

Both sexes dance through the bushes, scanning, squatting, twirling and twitching.

Not surprisingly, final nest site selection is apparently done by the female. While preferring deciduous shrubs, goldfinches will also use conifers and herbaceous plants.

They start by attaching spider silk to supporting twigs. Next, rootlets and other plant fibers are used to form a compact cup. Finally, a fluffy lining is added using, you guessed it, thistledown. Milkweed parachutes and almost any other similar material such as cotton and dog fur will also be utilized.

Vanquishing the Villain

Besides providing important props to our nest production, thistle plants also provide food. Goldfinches eat a variety of seeds, whether they come from grasses or trees. They are especially fond of daisies, asters, and thistles. Even the briefest internet search will turn up a photo of a goldfinch on a bull thistle.

Most seed-eating birds feed their young some insects to add a little protein to their nestlings' diet. Such is not the case with goldfinches. Their diet puts the vegetable in vegetarian. Obviously, there are more seeds in midsummer than in spring.

Their diet is bad news for the cowbird. When a cowbird lays an egg in a goldfinch nest, it will hatch under the incubating female finch. However, it usually dies within three days. The cowbird nestling cannot survive on a goldfinch's all-seed diet.

Ogden Nash on Birding

All of this reminds me of a marvelous poem by Ogden Nash about bird watching titled “Up from the Egg: The Confessions of a Nuthatch Avoider.” The closing lines read as follows:

“But a bird in the open never looks

Like its picture in the birdie books -

Or if it once did, it has changed its plumage,

And plunges you back into ignorant gloomage.

That is why I sit here growing old by inches,

Watching a clock instead of finches,

But I sometimes visualize in my gin

The Audubon that I audubin.