The American Goldfinch, Spinus tristis, is one of North America’s last birds to get started building a family. In July, when other bird families include fledglings aplenty, the thistles are just starting to bloom. This signals the conspicuous bright yellow male goldfinch and his olive colored mate to start building a nest, constructed mostly of thistle down. When the eggs finally hatch, the thistles have gone to seed — the perfect time to start feeding chicks! Parent goldfinches serve their nestlings a milky cereal-like substance made of thistle seed — the bird world’s closest thing to mammal milk!