Sunday, June 21, 2015

Attack of the Hummingbirds

Long-billed hermit - Dennis Skogsbergh
On our recent birding trip to Honduras, Janice Reynolds told the story of an acquaintance who had heard that hummingbirds could kill a human by stabbing their beaks into the center of the throat.  This led to an ongoing string of jokes about wearing a neck scarf for protection, reaching a peak at the final stop where we sat amidst large numbers of hummers including the Long-billed Hermit.  While we mammals are safe, there is a tiny grain of truth in a hummingbird "going for the throat."

Hummingbirds are aggressive by nature and most are not very communal.  Males will attempt to drive away competition, whether at a feeder or in fights over females.  Most of these are aerial battles with bluffs and "chest bumps" but occasionally a few feathers fly.  Usually there is no serious damage except to their chances to mate with a particularly hot female.

If you recall that the largest hummingbird weighs less than a nickle (5 grams), it obviously hasn't enough mass to penetrate your skin, no matter how fast it flew into you.  Watching hummingbirds fight, they hover at close range, banging against their adversary.  Their beak is just for sucking nectar..... right?

Hermit - Robert Gallardo
According to recent research, the long-billed hermit hummingbirds that we saw in Honduras will "go for the throat" during mating season, using specialized beaks that have evolved for mating disputes.  Research led by Alejandro Rico-Guevara from the University of Connecticut showed that their elongated decurved beaks (curving downward) are the "the first evidence of weapons in male bills."

They had observed that unlike our ruby-throats who battle with close encounters and chest bumps, the hermit male hummingbirds used their beaks in territorial fights with rival males during mating season. Rico-Guevara and co-author
"Marcelo Araya-Salas, a Ph.D. candidate at New Mexico State University, measured the size and puncture capability of beak tips in juvenile and adult hummingbirds.  The researchers found that during the birds’ transition to adulthood – puberty, if you will – males developed elongated beak tips that were sharper than those of females.

They also observed male birds using their bills to stab one another in the throat during fights, and found that, not surprisingly, males with longer, pointier bills were more likely to win these battles and therefore defend the best territories."
Rico-Guevara has observed the use of beaks as weapons in other hummingbirds and plans more studies.  He "hopes people realize that despite their tininess, hummingbirds are strong and aggressive animals."

At Rio Santiago in Honduras we were surrounded by hummers, a total of 12 species in all at over 100 feeders, most only a few feet apart.  The air was filled with buzzing and diving but no direct confrontations because the number of feeders reduced the need to compete for one.  You too can reduce most of the hummingbird combat by putting up multiple feeders separated by several feet.

An article in Audubon magazine discusses this and other interesting bird behaviors in the name of "love."  Go to Love in the Air: Even in the bird world, romance can get messy.

No comments:

Post a Comment