Ruby-throat Combat is Serious Business

These are the final days of Ruby-throat migration.  The last of the juveniles and late female breeders will be gone from my area in east Tennessee in a little over a week, as they move southward and eventually arrive in their wintering areas in southern Mexico and Central America.

We often attribute Ruby-throated aggression to high testosterone levels during breeding season, but clearly some of that aggression is pure Ruby-throat personality. In fact, this young bird makes it appear they are born with this aggression and have a timing-mechanism that stimulates its expression by the time they migrate.

On most mornings recently, the hummers drink hurriedly and move on to feed on insects, paying little attention to each other, sometimes even settling on the same feeder to drink.  This morning was different, however, with two juveniles keeping up a relentless dispute over territory that lasted at least fifteen minutes, if not longer.  

Their combat included face to face flight moving high into the air and dropping low into foliage.  Once I saw them land on twigs in close proximity, each seeming to expect the other to leave before they finally tangled in defiance.  Sometimes they directed high speed dives at each other and many times I heard wing buzzing and in-flight "splats" like those you hear at the feeders, but neither would give up dominance.

Eventually, they ended up on the ground. Having seen this before, I expected a brief skirmish with both birds eager to return to the air.  What I saw surprised me.

One bird succeeded in pinning the other to the ground and seemed quite content to keep him there. His posture as he held the bird down gave every indication of victory, with wings spread, neck stretched, looking slowly from side-to-side, as if proud, giving the appearance of dominance posturing.  You can see the top bird's foot in the above image and some of the others. He appears to have the bird pinned by the shoulder and right wing.  It is also likely that his other foot is on the bird's beak since the pinned bird did not raise his head while on the ground.

While holding the downed bird firmly in place, the top hummer proceeded to alternately lift his feet up and down in a "kneading" pattern, his body rocking with the movement. The pace would be similar to the steady rhythm of kneading dough.  A hummer's version of stomping?  This movement and pin-down lasted approximately a full minute and I became concerned that the downed bird might not survive.

As you scroll through the images below, you will see that the bird on the bottom is trying to move, curving his back to struggle free and moving his left wing.

I can't be sure if the top bird was ready to leave and simply lifted off, or if the bird on the bottom wiggled free.  Since I couldn't see the bottom bird clearly while watching, after the top bird flew, I walked over to look at the ground and fully expected to see a dead hummingbird.  Much to my relief, he had flown too.

It is pretty amazing how quickly a hummingbird's life changes from timid fledgling to sword-carrying militant. Clearly this young male is wired for survival!

More about hummingbird aggression 
Bob Sargent on Ruby-throated Hummingbirds
Hummingbird Study Group
Other posts on Hummingbird migration