These American Goldfinch are eating "nyger" seed from a mesh feeder.
This seed bears a volatile oil that is much prized by birds, especially finches. This seed is grown primarily in Ethiopia, but also in other parts of the world including India and the USA. See Wikipedia description for more information on nyger seed.
The oil evaporates out of the seed and consequently it does not keep more than a few months. It should be kept in a sealed container.
The American Goldfinch is a migratory species, but their summer and winter ranges overlap. We, in Madison County, are fortunate to have both a summer cohort and a winter cohort. These birds are part of our winter flock. In the spring they will migrate northward leaving us without Goldfinch for a few days to a few weeks. Then the summer cohort will appear, having wintered in the southern USA. Both cohorts will grow new feather of a bright yellow color in the spring, replacing them with the duller colors, seen here, in the fall.
