Tail

• Tail feather differences distinguish between male and female hummingbirds of almost every species. Most adult males' tails are solid colored, while most adult females and juveniles' tail feathers have white tips. Both genders of blue-throated hummingbirds have white-tipped tails, however, and some species of hummingbirds never have white-tipped tails, says Texas Parks and Wildlife.
  
  

Size

• Female hummingbirds are generally larger than male hummingbirds. For example, female ruby-throated hummingbirds are usually 15 to 20 percent bigger than their male counterparts. However, according to the Operation RubyThroat, small females and large males defy this method of distinguishing genders.
  
  

Plumage

• Male and female hummingbirds usually have obvious plumage differences. For example, male ruby-throated hummingbirds have ruby or bronze throats and brown-gray bellies, while females have white throats and bellies, thus appearing to be lighter in color overall, reports Operation RubyThroat.
  
  

Migration

• If you track hummingbirds through the seasons and observe their migration patterns, you will note that adult males migrate up to three weeks earlier than females and juveniles in both spring and fall, states Hummingbirds.net.
  
  

Fun Facts

• The fastest recorded hummingbird heartbeat measured 1,260 beats per minute, and the fastest recorded wing beat measured 80 beats per second, according to Hummingbirds.net.