Goldfinches live double lives. In winter, they often escape notice thanks to their drab olive plumage. But in April and May, males molt into the vivid yellow, black, and white birds many call wild canaries. That's what my dad called them. But to ornithologists, they are American goldfinches. The seasonal change in appearance is so dramatic, some backyard birders assume they are two different species
Throughout late spring and early summer, the goldfinches that fail to move north to breed appear only as undulating lemon drops crossing the landscape. Their distinctive up-and-down flight pattern is easy to recognize.
Resident goldfinches visit my feeders all summer long where they devour nyjer and black-oil sunflower seeds. But I see at least a few goldfinches every day at my feeders. I'm thinking of goldfinches now because they're just beginning their nesting season.
Goldfinches nest late compared to most other song birds. They usually don't begin until early July, and if they raise two broods, they may not finish until September. The timing of the nesting season is tied, at least in part, to the life cycles of wild thistle and milkweed. Goldfinches feast on true thistle seeds and use thistle and milkweed down to line their nests.
About this tine a few years ago, I noticed a drably colored female goldfinch fly along the edge of the yard. Not recognizing her at first, and thinking female warbler, I grabbed my binoculars for a closer look. The bird landed in a small sassafras, and I identified her immediately. What caught my eye was her bill stuffed with downy material. She was building a nest in the fork of the sapling about six feet above the ground.
For the next three days, I watched as the female built her nest. The male earned his keep defending their territory by singing and occasionally chasing away intruding males.
Then the pair disappeared for a few days. At first, I thought they had abandoned the nest. In their absence, a thunderstorm filled the tightly woven nest with rain water. By the next morning, it had drained.
When the adults returned three days later, the female laid the first of her five white eggs. Perhaps goldfinches leave a newly built nest to divert the attention of predators away from what was a hub of activity during nest building.
For 12 days, the female incubated her clutch faithfully. When it rained, she used her body as a feathered umbrella to keep the nest dry.
The male visited regularly and fed his mate mouthfuls of partly digested seeds. Unlike many birds, which switch to insect foods during the breeding season, goldfinches stick almost exclusively to a granivorous diet. They even feed their nestlings regurgitated seeds. This is one biological justification for maintaining at least one nyjer or sunflower seed feeder during the summer. Nesting late in the season may also be an adaptation to insure that there will be plenty of seeds to feed nestlings.
For the first few days after hatching, mom brooded the helpless chicks, and dad provided meals. After the chicks were large enough to generate some body heat, the female began feeding them too.
Ten days after hatching, the nestlings were recognizable as goldfinches. Thanks to their parents' attentiveness, they had outgrown the nest. It literally bulged with goldfinches. They must have taken turns sitting on top of each other so that all could still fit in the nest.
In just a few more days, the young finches left the nest. A crust of whitewash soiled the rim of the abandoned nest. The male continued to feed the fledglings until they could fend for themselves. When the juveniles began competing aggressively for perches on the nyjer tubes, I knew they were on the verge of independence. By late September, if they survived the threat of hawks by day and owls by night, they no doubt joined the fall flocks of goldfinches that returned to the feeders.