During fall migration here in northern Colorado, many immature female-type hummers turn up and are a b%&*$# to identify. Most are Selasphorus species (the local breeder Broad-tailed, and the common western migrant Rufous, and the uncommon migrant Calliope). Archilochus species also occur, with Black-chinned a local but uncommon breeder, and Ruby-throated a very rare eastern migrant. Even Calypte species occur accidentally - Anna's and Costa's. Allen's Hummingbird (genus Selasphorus) has never been reported in the state, but could easily be overlooked, and are kknown to migrate from the Pacific Coast to the Gulf Coast in Texas. Some particularly confusing individuals are featured in the galleries here.