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Old Thursday 15th September 2005, 03:55   #1
standard
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distinguishing juvies from ahy females?

how can an amateur distinguish RT juvies from ahy RT females in the field? I've heard some folks say that it can only be determined with the bird in hand, and others say that experts can tell visually.
thanks
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Old Thursday 15th September 2005, 04:37   #2
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Ya' got me . . .

'
Quote:
Originally Posted by standard
how can an amateur distinguish RT juvies from ahy RT females in the field? I've heard some folks say that it can only be determined with the bird in hand, and others say that experts can tell visually.
thanks
What's an "ahy RT" anyway!?????
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Old Thursday 15th September 2005, 05:00   #3
Curtis Croulet
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"ahy" = "after hatch-year"
"RT" = "Ruby-throated"
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Old Thursday 15th September 2005, 05:33   #4
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Hey . . .

Quote:
Originally Posted by Curtis Croulet
ahy = after hatch-year
RT = Ruby-throated
. . . Even I knew the 'Ruby-throated' part!!!
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Old Thursday 15th September 2005, 10:37   #5
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Well, after a recent note I read on Humnet listserve, I am not sure it is as easy as people once thought. Generally, by this time of year, juvie males are starting to get some color in their gorget. This often occurs as scattered patches, which makes it easy, but if it occurs as a small cluster of 3 or 4 "red feathers" in the center of the throat, banders have recently reported banding multiple female RTHU on a single day with clusters of 3 to 4 colored feathers in the throat.
Long story short, when the color is in the center of the throat and I can count 1-4 feathers only, I'm not gonna guess.

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Old Thursday 15th September 2005, 13:43   #6
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That is very interesting! I've seen hummers with the patch of red in the middle of the throat and assumed it was a young male. So in otherwords, the females grow these red feathers and then they molt them out? How else are they sexed other than going by the gorget
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Old Thursday 15th September 2005, 14:38   #7
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Quote:
Originally Posted by Frankj
. . . Even I knew the 'Ruby-throated' part!!!
But some others may not.
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Old Thursday 15th September 2005, 15:24   #8
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Curtis would be better to explain this than I would, but gender determination at a banding station is based not only on character observations (color patterns, feather shapes, etc.) but also on measurements determining if they fall in the norm for that species. Gorget color is actually used very little at the banding stations from my observations.

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Old Thursday 15th September 2005, 20:19   #9
Curtis Croulet
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Quote:
Originally Posted by humminbird
but gender determination at a banding station is based not only on character observations (color patterns, feather shapes, etc.) but also on measurements determining if they fall in the norm for that species.
All of this.

Quote:
Gorget color is actually used very little at the banding stations from my observations.
In our project, the bander looks at it and may even count gorget feathers (there's a column for it on the data sheet), unless it's an AHY male. But, you're right, age & sex are often based on other characters. Age -- HY or AHY -- is usually established from the presence or absense of bill grooves.
---
Edited to fix a couple of glaring grammar errors.

Last edited by Curtis Croulet : Friday 16th September 2005 at 04:40.
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Old Thursday 15th September 2005, 22:59   #10
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Don't forget that Hatch Year birds of both sexes have buff edges to thier feathers, producing a 'scaled' look. If you can get close enough to them (window feeder for me), you can tell.
Here's a photo taken of a Hatch-Year female at the Georgia hummingbird festival this year. It shows the scaled look:
http://www.crickie.com/wp-gallery2.p...g2_itemId=6208
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Old Friday 16th September 2005, 14:33   #11
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pardon the confusion about the abbreviations.
I've read about the bill grooves, but I can't see them in the field.
that's interesting, mark, about the females with colored throat feathers. I hadn't heard about that.
I'll look for the scaled look on the juvies, heather. very interesting.
this ID must be as difficult as I thought.
anyone else?
thanks, folks.
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Old Friday 16th September 2005, 14:49   #12
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No, you can't see bill grooves in birds on the wing. In fact, even in the hand it requires magnification, which for the older ones among us means both an Optivisor and a loupe. But the grooves are characteristic of HY birds. It's very rare, but I've seen extended discussions between bander and subs over the ID of the species of a young bird -- never mind the sex. There's no shame in not being able to identify 100% of these on the wing. For those of you in solid RT territory, sometimes I've seen too much eagerness to grasp upon any trace of buff coloring as evidence of a Rufous, but the good side of this is that you're looking really closely at the birds. It's against the background of knowing the total range of variation of RT and knowing its behavior and vocalizations that you'll someday confidently recognize the true outsider.

Last edited by Curtis Croulet : Friday 16th September 2005 at 15:01.
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Old Saturday 17th September 2005, 17:12   #13
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thanks, curtis. I'm in solid RT territory here in nashville, and I don't think I've ever seen a rufous. many of the RTs here have a buffy wash on their sides, under their wings. the text in one book says that adult female RTs have a buffy wash on their flanks, and that juvies have a cinammon wash or vice versa. I can't distinguish shades and tones well, and wouldn't know buffy from cinammon. I think it's another way to say they look very similar.
very interesting that banders cannot always ID the species of a juvie. they must really look alike.
I'm not as concerned with determining gender of juvies as I am with positively identifying an adult female after the little ones have fledged.
the most recently fledged are my favorite to watch, and I think that I can ID them by their tentative curiosity and behavior, but they learn to fly and feed so well so quickly that stage doesn't last long.
thanks again, folks.
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Old Saturday 17th September 2005, 21:06   #14
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Quote:
Originally Posted by standard
very interesting that banders cannot always ID the species of a juvie.
They always come to a decision, and usually it's not too difficult with the bird in hand. But I remember one banding session where there was lots of discussion between bander and sub about the ID of a bird, and it continued for days after the banding session.

Bill Hilton's first post under "Hummingbird Secrets" has a link to a website with a photo of bill grooves -- and much else of interest, too.

Last edited by Curtis Croulet : Saturday 17th September 2005 at 21:14.
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Old Monday 19th September 2005, 11:00   #15
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Getting even more interesting with the number of hybrid incidence that are coming to our attention.

Mark
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