Ruby-throated hummingbirds will soon be back. Their tiny size, acrobatic flying ability, and eagerness to use nectar feeders make hummingbirds one of America's favorite backyard birds. This fascination always triggers a flurry of mail, so let me anticipate the most common hummer questions I will get over the next month.Q: How many species of hummingbirds live in the East?A: Only the ruby-throated hummingbird nests regularly east of the Mississippi River. The female lacks the male's bright red throat, so some people mistakenly believe two species visit their feeders.Q: When should I put up my hummingbird feeder?A: My earliest record for hummers is April 22, but I put up a feeder on April 15, just in case. To track the ruby-throat's northward journey, visit http://www.hummingbirds.net/map.html. The first ruby-throats of the year arrived on U.S. soil on Feb. 20 in Louisiana. Last week, there were hummers reported as far north as Maryland, Kentucky, and Missouri.Q: What's the recipe for nectar?A: Add one part table sugar to four parts hot or boiling water. Hot water simply allows the sugar to dissolve faster. Stir, cool to room temperature, and store in the refrigerator. Red dye is unnecessary. And never use honey as a sweetener. Honey promotes a fungal disease that can kill hummers.Q: How can hummingbirds survive if they just sip sugar water?A: If they ate just sugar water, they would not survive. Sugar is nutritionally empty, but rich in calories. Hummers drink nectar for the calories -- the energy. They obtain nutrition by eating soft-bodied invertebrates such as spiders, flies, aphids, and gnats. Nectar probably makes up less than half their total diet.Q: Is there a "best" nectar feeder?A: Any red nectar feeder will catch the attention of hummingbirds, but it must be easy to clean. Rinse the feeder and change the nectar every three days, and wash it with hot soapy water once a week. Aspects and Droll Yankees are two manufacturers that make quality nectar feeders.Q: What else I can do to attract hummingbirds?A: Plant red, tubular, nectar-bearing flowers. Trumpet honeysuckle, trumpet creeper, cardinal flower, jewelweed, and bee balm are all hummingbird favorites.Another way to provide food is to offer overripe bananas. Hummers have a field day feasting on the fruit flies that inevitably appear.Q: How can I keep ants out of my hummingbird feeders?A: An ant guard is an inexpensive moat-like saucer from which you hang the feeder. Fill the moat with salad oil or dish detergent, and ants get trapped in the liquid when they try to cross the moat. Some nectar feeders come with built-in ant guards.Q: Can you briefly the outline a hummingbird's nesting season?A: Males return before females in the spring and establish feeding territories. Fiercely protective of their nectar sources, males seem to spend more time chasing competitors away from "their" food supplies than actually feeding.When females arrive a few days to a week later, courtship begins. The male performs aerial displays while the female watches from a nearby perch. He flies back and forth in a wide semicircle. After mating, the promiscuous male goes on to find another female.The female builds a tiny nest on a small horizontal branch five to 20 feet above a stream or other open spot. She begins by using sticky spider silk to fasten bits of leaves or bud scales to the branch. Over a span of days, she builds an elastic cup about the size of a walnut. She lines the nest with soft plant fibers and camouflages the outside with bits of lichens.After laying two tiny eggs, the female incubates them for about 16 days. Because the female tends the nest alone, she must leave it periodically to eat. When she leaves, the eggs cool a bit. One price of single parenthood is an extended incubation period. Young hummingbirds leave the nest about three weeks after hatching, which is usually in mid-July.To watch an active Allen's hummingbird nest in southern California, visit www.phoebeallens.com. Though this is a western species, the nesting biology is similar. This nest's first egg was laid on April 3rd.Send questions and comments to Dr. Scott Shalaway, 2222 Fish Ridge Road, Cameron, WV 26033 or email firstname.lastname@example.org.