Measuring a mere 3 inches long and weighing one-tenth of an ounce, roughly the same as a table tennis ball, the Calliope hummingbird is incredibly tiny. In fact, Eric Rasmussen, avian scientist at ...

In his research, Halter looked at two species of migrating hummingbirds, Calliope (Selasphorus calliope) and Rufous hummingbirds (Selasphorus rufus), at a site along the Mimbres River in New Mexico.