The smallest of the migrating Minnesota birds are expected back, beginning Friday.

Ruby-throated hummingbirds are a summer resident and typically show up first in the southern part of the state. By about May 12, the birds should start to appear in northern Minnesota, particularly in the Itasca State Park area near Walker. The birds leave by mid-September.

Weighing an average of 3.4 grams and only 3 inches long from the tip of the bill to tip of the tail, the bird has distinctive plumage: metallic green above and white below. Only the adult males have the iridescent ruby-red throat.

Most of the 330 species of hummingbirds live in the American tropics. The hot spot for hummingbird diversity is Ecuador, with more than 100 species. Of the 16 species found north of the Mexican border, it's the ruby-throated hummingbird that nests east of the Rocky Mountains and flies to Minnesota for the summer.

Ruby-throated hummingbirds spend winter in a region that spans from far-south Texas to Costa Rica.

If you want to hear the humming of their rapid wing beats and see them, landscape with a variety of red, purple and orange tubular flowers, and put out sugar-and-water feeders. I recommend dissolving one part white sugar in four parts of water. Do not use food coloring or honey. A red feeder will help attract the hummers. Their natural food is small insects, flower pollen and nectar, and tree sap.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.