Hummingbirds expected to return any day now
Any day now, ruby-throated hummingbirds will begin trickling in from winter homes in Mexico and Central America for their summer nesting season in Georgia and other points north.
By month’s end, as spring migration revs up, scores of the tiny birds will be arriving and will continue to do so through April and early May. Bird lovers across Georgia look forward to the return of the ruby-throat — one of our most beloved birds and the state’s only nesting hummingbird species.
Only in recent decades have scientists cleared up some of the mysteries surrounding the ruby-throated hummingbird’s migration and nesting habits, although several unknowns remain.
After decades of speculation, we now know that most ruby-throats fly nonstop more than 500 miles over the Gulf of Mexico to reach the shores of North America during spring migration — an incredible journey. In the fall, when the birds return to their winter haunts, the reverse is true. (Some ruby-throats take an overland route through Mexico.)
Scientists, though, are still uncertain about the birds’ flying habits over water. Observations from oil rigs and ships at sea indicate that the birds fly across the Gulf just above the wave tops. They do not, however, “hitchhike” on other, larger birds, as folklorists suggest.
The idea that a tiny hummingbird, weighing on average about as much as a nickel, could fly 18-22 hours without rest over hundreds of miles of open water once met with ridicule. Where would they get enough energy for such a grueling trek?
Scientists cleared up the mystery when they showed that the little birds, before they depart on their arduous migrations, nearly double their body mass by gorging on nectar and insects. The extra heft provides the energy for the long journeys.
It’s also known that male ruby throats arrive at their summer breeding grounds some two weeks before the females. The male’s only role in reproduction, apparently, is to impregnate the female. She does everything else — nest building, egg laying, tending and feeding babies. Presumably, the male’s earlier arrival allows him to establish territory to impress a female when she arrives.
In the sky: From David Dundee, Tellus Science Museum astronomer: The moon will be first-quarter Tuesday. Mercury is low in the east at dawn. Venus rises out of the east about an hour before dawn. Mars, Jupiter and Saturn rise out of the east just after dark.
