As I was surfing the Internet, trying to learn as much as possible about the goldfinches that have swarmed our back yard feeders for almost two months, I discovered that the thistle seed they’ve been gobbling isn’t thistle seed.

It’s really nyjer seed, from a plant native to Ethiopia. Now I know why we’ve never had sprouts of the obnoxious-looking thistle plants popping up in our back yard under and near the finch feeders. You know the plant I’m talking about. It has spines on its leaves and tall stems. I have to admit there is one thing pretty about it — the purple bloom that appears at the top of long stem. Despite that spot of beauty, you recognize it as a weed and immediately get to urge to remove it if it appears in your yard.

The nyjer seeds resemble small grains of wild rice. Birds love them for their high content of protein and fat. They are known to attract house finches, purple finches, towhees, pine siskins, juncos, mourning doves and different kinds of sparrows. I guess it’s a good thing a friend clued me in about the little mesh pouches that most of those birds leave to the goldfinches. We can’t afford to furnish all the birds with nyjer seeds.

I learned that the nyjer seeds are sterilized and imported. Now I know why those little bags are so expensive. We pay around $10 for a five-pound bag, so I fully understand why they are sometimes referred to as “black gold.”

Of course, our goldfinch visitors don’t limit themselves to the four little pouches in our back yard. I guess there are so many of them that they get discouraged waiting around for a spot on the pouches. Many times they fly down from trees in the yard and visit the other feeders. Currently they have lots of competition at the regular feeders from the cowbirds that swoop in and devour the grain in record time.

The cardinal families that we feed year-round also take their turns at the regular feeders, so it keeps my husband busy restocking them.

I’ve noticed a number of chickadees and titmice hanging on the two tube feeders we fill with sunflower seeds. When they aren’t around, the goldfinches cling to those and satisfy themselves with a different treat.

When we refill the feeders, we often just toss handfuls of grain on the ground. Both the mourning doves and those large silvery grey doves with a black streak on their necks wing their way in to get their fill. They join various sparrows and yes, even some of the goldfinches pick their way among them.

Those goldfinches are so accustomed to my husband’s presence that some of them don’t bother to fly off until he reaches to refill the pouches they hang on. We’ll miss them when they depart.