I wondered why it is that the Hummingbirds seem to settle down and feed fairly peaceably together once the day came to an end. From early in the morning I hear their buzzing and all day they display and dive-bomb each other, each bird intent on claiming a feeder, or at least a feeder-port it seems, to himself. But at night I regularly find as many as eight or ten birds at every feeder.
I’m reading Dan True’s book Hummingbirds of North America (Thanks again BosqueBill!) and it’s all clear now. Mr True, meteorologist, pilot and bird expert, has been studying the little birds for nearly a lifetime. He tells of how a team at the Rocky Mountain Biological Laboratory, near Gothic, CO, rigged scales with a perch; scales accurate to 1/100 of a gram. All day long, the scrappy little birds were weighed each time they landed on the perch. What was discovered was that, while the hens at normally all day, the males weight increased only 1-2% during the day, but in the evenings their weights went up as much as 40% in just a few feedings!
The author, who flew a Spitfire 1 fighter plane in his military career, compares the logic of fueling planes with just enough fuel for an hour and a half of air-time, including 15 minutes of dogfight time, to exactly what the Hummingbirds are doing. Fuel is heavy and burdensome; keeping lightweight means faster acceleration and more nimble aerial combat sorties…even for birds.
During courtship a Hummingbird’s high-speed dives reach 64 MPH; the yo-yo patterned dives and pendulum swings (done facing the sun to enhance gorget colors), and zooms upward again some 20-50 feet need an athletic bird, one capable of spectacular ‘combat moves’…a light-weight bird not carrying the burden of extra fuel. The males feed only lightly following each flight to chase a rival and left serious re-fueling to the evenings. Lightness equals aerial superiority…even for the birds.
So, that’s why as evening comes the bickering quiets, the zooming settles down and everybody seems to call a truce. It’s time to eat.
- Hummingbirds of North America: Attracting, Feeding & Photographing by Dan True/University of New Mexico Press
- Bill Calder, 1991/Rocky Mountain Biological Laboratory, Gothic, CO