Ruby-throated hummingbird (juvenile male)

The Ruby-throated Hummingbird is 7–9 cm long with an 8–11 cm wingspan, and weighs about 3 g. Adults are metallic green above and greyish white below, with near-black wings. Their bill is long, straight and very slender.
The species is dimorphic. The adult male has a ruby red throat patch which may appear black in some lighting, and a dark forked tail. The female has a dark rounded tail with white tips and generally no throat patch. A young male Ruby-throated Hummingbird also may have a white throat like a female, but more often it is streaked to a greater or lesser degree with black or green; this gives the appearance of a "five o'clock shadow."