The challenge lately, it seems, is to find a field or meadow without goldfinches in it.

Mid to late summer is the time for goldfinches to shine and take the spotlight in the birding world. While most birds have completed or are winding down their nesting seasons, American goldfinches are just getting started.

There are several theories on why goldfinches nest so late compared to other birds, but it is abundantly clear that their nesting season coincides with the availability of seeds and certain nesting materials in nature.

Seeds are more plentiful in July and August than they are in April or May, and goldfinches use the fluff from thistle and other plants to line their nests. Goldfinches are almost exclusively seed eaters and rarely supplement their diet with insects. That goes for the babies as well, as they are fed regurgitated seeds. Nearly all other songbirds feed their young a mix of insects and seeds, or just insects, which are higher in protein.

An interesting tidbit that shows up on many bird internet sites is that brown-headed cowbird babies rarely survive being raised by goldfinches because of the all-seed diet. Cowbirds, as you recall, are nest parasites and lay their eggs in the nests of other birds, allowing the host bird to do the arduous task of raising the young. Cowbird hatchlings need a more protein-rich diet and most perish within a few days of hatching from a goldfinch nest. I’ll look at this more closely in an upcoming For the Birds column.

As an aside, it’s too bad that many people regard thistle as a weed. Sure, it grows prolifically and is toxic and prickly, but it has so many uses in the natural world, not to mention its attractive pink and purple flowers. As mentioned above, goldfinches use thistle plants for their seeds and fluff. I’ve also seen numerous types of butterflies feeding from those pink flowers.

Anyway, back to goldfinches. American goldfinches are year-round birds in New England. They look slightly different during each month of the year as they molt twice a year, and each molt takes several weeks or even months to complete. New birders are often surprised that the dull yellow birds at their Nyjer feeder in January are the same brilliant yellow birds they see in July.

Since it is nesting season for these much-adored birds, here is a little more information about their nesting habits: male and female birds construct the nests and help raise the young, nests are about three inches across and high, females lay four to six pale blue eggs, and each egg is about half an inch long and takes about two weeks to hatch.

I’m lucky enough to live by and work near several fields and meadows. It’s always a thrill to see goldfinches perched on a bent flower or weed or to flush a dozen or more previously unseen goldfinches from the tall grasses as they sing their sweet, undulating song in flight. Goldfinches are a treat year-round, but summer is when they really shine.