Goldfinches are sociable birds found throughout the United States. Three primary species are known to inhabit the United States, including the American goldfinch, the Lesser goldfinch and Lawrence's goldfinch. They are often seen foraging in woodlands or fields that provide them with the main portion of their diet of seeds. Feeding goldfinches during fall and winter can bring large flocks of the birds to your backyard, especially if you provide them with their favorite meal: thistle and sunflower seeds.
There are various types of wild bird seeds that are used to attract goldfinches. The seed names are often used interchangeably, but in fact they are different. The most popular seeds for feeding goldfinches during fall and winter include NyjerR seed (generic name: niger seed) and thistle. Wild Birds Forever recommends black oil sunflower seeds along with Nyjer seed.
Nyjer seed is often referred to as thistle seed, but it doesn't contain seeds from the American thistle weed, which can sprout and overtake a yard. Nancy Castillo from The Zen Birdfeeder explains that "the USDA requires that all niger seed imported to this country be heat-treated to sterilize the seed." This prevents the birdseed from germinating and growing in and around your yard.
Along with choosing the right food for wild goldfinches, you also need to consider the right feeder. Niger seed is very tiny, and the feeders can become flocked with birds at any given time. Specially designed finch feeders are made to hold the tiny seeds and multiple birds. You may prefer to use a prefilled and refillable thistle sock made from mesh material that conveniently hangs on tree branches.
It is important to use fresh seed when feeding goldfinches during fall and winter. Niger seed tends to spoil quickly when not stored properly, which can harm birds. Seed can be stored for a short period in a dry place. Bird seed in feeders should be kept dry and discarded if any mold is present.