"Hummingbirds live most of their lives within hours of starvation."
That's what Sheri Williamson told me. She's the author of "A Field Guide to Hummingbirds of North America," one of the Peterson field guide series.
I e-mailed her earlier this fall after I witnessed a hummingbird brawl.
The fight took place at a hummingbird feeder, a place where you often see hummers confronting one another for feeding rights. But what I saw didn't seem like a run-of-the-mill territory dispute. One ruby-throated hummingbird attacked another so viciously I thought one bird was going to be killed.
E-mailing with Williamson made me feel a bit better.
"As savage as this no-holds-barred brawling seems, fatalities are extremely rare," she wrote.
She should know. She's been banding hummingbirds at the Southeastern Arizona Bird Observatory in Bisbee (www.sabo.org) for 18 years. Among the more than 5,000 hummers she's banded, she's seen hundreds with patches of missing or regrowing feathers, but fewer than 10 with injuries that looked like stab wounds.
According to Williamson, bill breakage is a more common injury than stab wounds, which she said "suggests that use of the bill as a stabbing weapon would put the stabber at almost as much risk of serious injury as the stabbee."
She added that the fragility of the bill could explain why hummers defending a territory usually opt for less risky feather pulling, grappling and chest-bumping.
That isn't to say the fight for food isn't important.
"A hummingbird's willingness and ability to drive off rivals from a reliable nectar source may be its key to long-term survival," said Williamson. "It seems silly when the energy source is a bottle of sugar water big enough to fill the energy needs of dozens of hummingbirds, but their evolutionary past hasn't equipped them to deal with an essentially unlimited resource."
Hummingbirds don't live on nectar alone. They add insects -- mosquitoes, spiders, gnats, fruit flies, even small bees -- to their diet.
These little birds can claim a world record: They have the fastest metabolism of any animal. And this is what places them so close to the edge of starvation. They have to consume their weight in food each day to support the rapid beating of their wings, as many as 500 beats per minute.
That makes a reliable source of food worth the fight.
Most of our hummers are long gone, but there may be a few stragglers. So go ahead and leave your hummingbird feeder full until the nectar freezes and doesn't thaw. Offering nectar will not keep birds from migrating.
Come spring, if you notice that your hummingbird feeder is dominated by a single bird, avoid brawls by adding a few more feeders to your yard. Just keep them far enough apart so the dominant little devil that thinks he owns the place won't try to guard them all.
Jim Williams, a lifelong birder, serves as a member of the U.S. National Wildlife Refuge Birding Initiative Committee. He also is a member of the American Birding Association, Ducks Unlimited, Pheasants Forever and Delta Waterfowl. Join his conversation about birds at www.startribune.com/wingnut. He can be reached by e-mail at email@example.com.