On June 10, 2002, I discovered a female Yellow-throated Vireo (a vagrant in Colorado) paired up with a male Plumbeous Vireo (common breeder in the foothills)in the Cache Le Poudre River canyon of Larimer County, in north-central Colorado, USA. The pair attempted to nest, laying 3 eggs, of which at least one hatched. I do not know whether the nestling survived, or whether the nestling was truly a hybrid (perhaps a female Plumbeous Vireo deposited the egg in the nest). These photos of the nest were taken on June 28, 2002.