Goldfinches here now, they seem to like the dandelion seeds in my messy lawn and garden.
Goldfinches are among the few songbirds completely adapted to a herbivorous diet. They even feed their young seeds and don't breed until later in the summer after the seed crop has matured. Cowbirds try to parasitize goldfinch nests (heck, they try to parasitize everything, a female cowbird can lay 50 eggs in the spring). Young cowbirds in a goldfinch nest invariably starve, they cannot survive on seeds, the only downside is the female cowbird generally removes an egg from every nest she hits, she needs the protein, fats and calcium to be able to lay all those eggs.
Speaking of which, Mike do you know if they rob nests? We have some swallows (Tree or Violet Green) using a bluebird box and the kingbirds have been hanging around it in the mornings. This morning one of the swallows was grabbed on to the box covering the opening with his back exposed Kingbirds were flitting around and sometimes landing 8'-10' away on the barbwire. Never saw that behavior last year.
Birds are best thought of as the little feathered dinosaurs that they are, generally speaking a bird will eat anything it can fit down its tough and leathery gullet. Once I seen a purple martin fledgling, about as big as a cardinal fully grown but unable to fly, leave the nest and fall to the ground. A flock of about fifty grackles immediately lifted up off of a nearby lawn, landed all around it and commenced to peck it to death.
IIRC Kingbirds aren't known for robbing nests, but I'm sure they would if given the opportunity.
