Thanks Lanny, 
I used to be able to hear them and still can with my SongFinder headset. I have seen the courtship display many times outside my house. 

A few years ago we set up a multi-partner bird banding training session for our Partners in Flight colleagues in Central America (CA) at a meeting in El Salvador. Bill Hilton from North Carolina, you probably know him, came down and did a wonderful mist-netting, banding demonstration for ab6out 25 representative from the seven CA countries. He demonstrated how to cut the little banding strips of off a sheet and talked about the extra training needed to get certified to do it.

Bill was ecstatic because he said he was the first to band RTHUs on the wintering ground and had just done a few in El Salvador and several other countries. He departed for Guatemala and banded the first 10 or so RTHUs at a feeder there.   

Thanks for the info.


Brad Jacobs
Missouri Department of Conservation
P.O. Box 180
Jefferson City, MO 65102
573-522-4115 ext. 3648

-----Original Message-----
From: Missouri Wild Bird Forum [mailto:[log in to unmask]] On Behalf Of Lanny Chambers
Sent: Tuesday, August 04, 2015 8:44 AM
To: [log in to unmask]
Subject: Re: Ruby-throat as a mobber?

Brad and MOBIRDers,

The giant U is called the pendulum arc, for obvious reasons, and it is indeed agonistic. The bottom of the U is typically inches in front of the intruder, which the display is intended to roust. The courtship display is called the mating shuttle, and is a rapid lateral movement typically around 18-24" wide, centered on the hen. Both displays are accompanied by a loud buzzing sound, which I think is made by the wings. Once your ear is tuned to the sound, you'll start to hear it all the time, especially as summer progresses and numbers build toward migration peak, around Labor Day.

The above applies to Ruby-throats; other species may use similar displays for different purposes.

Just to crow a bit: we're in a New Mexico motel as I type this, returning from the Sedona Hummingbird Festival, where I was fortunate to band six species of hummers. I expect my feet to touch the ground again by, oh, maybe Thursday... :)

Lanny Chambers
St. Louis, MO
[log in to unmask] 

> On Aug 4, 2015, at 07:22, Brad Jacobs <[log in to unmask]> wrote:
> About two days ago I observed a ruby-throated hummingbird doing a giant U in my old field; scattered plums, honey locust and persimmons. The top of the one side I could see was 30-40 feet up and it rapidly dropped out of sight behind some shrubs, then I assume back up on the other side.

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