It is mid-summer in the mountains. Berry picking season. Cicadas begin to call during the day, katydids at night. Older leaves on Tulip Poplar turn yellow as butter. The first asters and goldenrods bloom. Black Bears are on the move on the Oak ridges. And Goldfinches begin building their nests.

The American Goldfinch is the last bird to begin nesting in the Southern Appalachian Mountains. The long nesting season, which began the breeding calls of the Great Horned Owl back in January, is drawing to a close.

Male Goldfinches, which have been wearing their bright yellow breeding coats since mid-April, finally establish and defend nesting territories while the females silently build exquisite nests of moss and bark strips, finely woven and lined with plant down.

The females will lay five eggs in the nest, one egg per day, beginning a few days after construction is finished. Meanwhile the male is protecting the nesting territory from other males by singing vigorously from exposed perches at the edges of the territory. If another male dares to approach, the singing male will pause and fly directly at the intruder, taking its perch. If the intruder does not leave immediately, he will be chased and driven away.

If the singing and chasing behavior of the male does not alert you to any nests in your area, you may notice another territorial signal which involves high, looping flights of the male above the boundary of the nesting territory. During this display the bird appears to ride an invisible aerial roller-coaster as it alternately tucks its wings and dives steeply, then spreads its wings while gliding smoothly upward.

Territorial displays of the male cease when incubation begins, usually after the second or third egg is laid. Incubation continues for twelve to fourteen days, and is performed exclusively by the female.

While incubating, the female rarely leaves the nest, and is frequently fed by the male. The male makes regular flights above the nest, and if called by the female will drop down to a branch near the nest and feed the female a meal of partly digested seeds. The male then leaves and the female returns to the nest.

Both parents feed the young a diet of regurgitated seeds. When the birds fledge, the male will continue to feed them while the female begins construction of a second nest. The second brood of Goldfinches hatches in late August or even September. Following nesting, Goldfinches associate in small flocks and feed together, a favorite food being the seeds of various types of thistle. They are still clothed in their plumage and are conspicuous in the fields. The thistles seem to bloom a second time, with blossoms of yellow and black feathers, giving rise to a second common name for the American Goldfinch.

Thistlebirds will in small flocks throughout the winter, the males losing their breeding plumage during the October molt. They may be recognized year round by their undulating flight, which is suggestive of the roller coaster territorial display of the male, given during the late summer breeding season of the Thistlebird, the last bird to begin breeding in the Southern Appalachian Mountains.