Hummingbirds are tiny and delicate, but don’t be fooled: They are among the most aggressive birds in the avian kingdom. Their territorial fury is especially aimed at other hummingbirds. Competition ...

Small but speedy. Tiny but aggressive. Little bodies, big appetites. Hummingbirds are a study in extremes. They are the lightest North American birds. Most weigh less than two pennies at 3 to 4 grams.