That is either a female or a juvenile Ruby Throated Hummingbird. Only males get the distinctive red throat, and only after their first winter. This time of year you may see one or two red feathers starting on their necks.
Here's a shot of a male I took on my deck earlier this year, with my 70-300. It's a tight crop. Shot at 300 mm using f6.3 1/800 and ISO 720.