These feeders can be filled with sunflower seeds or, better yet, the commercially available thistle, or Niger, seed imported from Africa. The birds will also come to window trays and bird tables, where they will eat sorghum, millet, canary seed, cracked nutmeats, and sunflower seeds. Before a storm the birds will feed in a frenzied manner at feeders and show a significant gain in weight before and during the storm. This behaviour may increase the American Goldfinch's chance of survival under adverse conditions. Enemies American Goldfinches and their eggs fall prey to a variety of predators including cats, weasels, snakes, squirrels, jays, and Sharp-shinned and Cooper's hawks.
Accidental deaths can occur when the birds entangle themselves in a spider's web or in burdock.
The Brown-headed Cowbird lays its eggs in the nests of smaller songbirds such as the American Goldfinch. But the songbirds' seed diet is insufficient to meet the demands of the growing cowbird young, most of which die as a result. However, the presence of the cowbird does disrupt successful nesting. Population The Breeding Bird Survey of Canada provides us with indices of the population of most of the common species of birds. Although the Breeding Bird Survey designates the American Goldfinch as common, results of the survey showed a decline in the breeding populations of American Goldfinches in the Maritimes, central and southern Ontario and Quebec, and the central Prairies from 1966 to 1983.