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Re: Brand-new & Double-brooded Hummers
GINGER & STEVE . . .
Please allow me to address both your messages about Ruby-throated
Hummingbirds (RTHU) in this one response. :-)
Both Ginger and Steve certainly certainly could be correct in
observing fledgling RTHU at your feeders this week, but it's also
possible you've just been observing the same recent frenzy of
activity that has occurred the past three days at Hilton Pond Center
for Piedmont Natural History near York, South Carolina.
One of the real privileges of being a hummingbird bander is that I
can hold the birds in my hand and discern with certainty their ages
and sex. From 3 April through 22 May this year I had banded 12 new
RTHU and recaptured four birds from previous years. These birds
became regular feeder visitors, but on 27 May there began an
onslaught of new birds. Since that date, I've caught 11 more new
birds and recaptured 16 birds banded from 1997-99. All these birds
have been adults, and I haven't seen any new fledglings thus far in
2000.
My records show that is not unusual for an increase in activity at
feeders about the first of June, following a relative dearth of
hummingbirds during most of May. (See
http://www.rubythroat.org/Chart01RTHUDates.html .) It is also worth
noting the the past several days of May this year have been marked by
low temperatures, which may have increased feeder visits by hummers
needing a quick fix of high-carb energy.
My earliest bandings of juvenile Ruby-throated Hummingbird here at
Hilton Pond Center for Piedmont Natural History were 9 June (a
female) and 11 June (a male). That doesn't mean that you folks aren't
seeing fledglings yet, but it's still a little early for the
Piedmont. If we take 1 April as the usual earliest arrival date for
males--my earliest ever was 28 March--and 10 April as the typical
date for early females AND allow several days for courtship and for
the female to build a nest, I would think the earliest she would be
on eggs would be about 15 April. Incubation takes about two weeks,
which would put hatch day at about 1 May, and the chicks are usually
in the next for about three weeks. This early-nest scenario does show
that fleglings could theoretically be out and about by 21 May or so,
but I believe they would be the exceptions.
There's a definite advantage to adults coming back early and getting
a head start on nesting because it provides opportunity for a second
brood no matter whether the first clutch or brood fails OR if it is
successful. There's also a distinct disadvantage to breeding early,
that being that cold and rainy spells in April may kill the eggs or
diminish the availability of tiny insects and flower blossoms. RTHU
that arrive or begin nesting later in the season don't have to deal
with the vagaries of weather, but they probably only get one chance
to pull off a brood in a given year.
I speculate that single-brooding among RTHU is the rule in the
Carolina Piedmont, that a second ATTEMPT after a failed first
clutch/brood is somewhat common, but that double-brooding is much
more unusual.
Anyway, this is just food for thought, as well as an encouragement to
keep on watching hummingbirds! :-)
Best wishes,
BILL
*********
>Hi, all. Last year there was a discussion here about our piedmont NC hummers
>possibly raising two broods a year. At the time I thought that that did not
>square with my experience at home, where the hummingbird action always went
>wild in early July at my feeders. I assumed there was one brood and that the
>babies came out then. But now I've reconsidered because I had the same
>experience described by Steve Schultz. Last Thursday evening I came home to
>find my small 8-oz. feeder emptied in 24 hours -- up till then it had taken
>days to empty. And for the first time I saw a lot of hummers at once -- 4
>female or immatures all in sight at the same time. On Friday I was leaving
>for the weekend, so I pulled out some additional feeders and filled
>everything up -- a total of 3 8-oz. feeders. When I got back last night, all
>were bone dry. Anyhow, I'm thinking this is the first brood of the year and
>will be interested to see if I can observe another flush of birds in July.
>Are two broods a year in piedmont NC a sure thing or a sometime thing or a
>rare thing, or what? Can anyone shed some light?
>Ginger_Travis@unc.edu
>near Chapel Hill, NC
**********
>I'm pleased to announce the debut of the 2000 crop of RT hummers. Our sugar
>bill spiked late last week with the arrival of several new faces.
>We went from
>feeding about 2 ounces a day early last week to about 10 ounces/day over the
>weekend. The newbies are fairly easy to recognize, for one thing they have no
>fear us whatsoever! The adults are pretty flighty when we stick our noses to
>the glass to watch. The little ones just poke their head around the
>feeder and
>watch us watching them! The little ones also tend to get along a
>little better
>than the oldsters, we had three little ones on the feeder at once yesterday.
>Hope yours are coming along well too!
>
>Best,
>Steve Shultz
>Cary, NC
*********
--
**********
BILL HILTON JR., "The Piedmont Naturalist"
Hilton Pond Center for Piedmont Natural History
1432 DeVinney Road
York, South Carolina 29745
USA
e-mail: <hilton@hiltonpond.org>
Voice: (803) 684-5852
eFax: (503) 218-0845
Hilton Pond Center for Piedmont Natural History is a 501(c)(3)
non-profit research and education organization, so all in-kind or
monetary gifts to Operation RubyThroat and the Center are
tax-deductible. Please visit our websites:
Hilton Pond: <http://www.hiltonpond.org>
Operation RubyThroat: <http://www.rubythroat.org>
"Never trust a person too lazy to get up for sunrise or too busy to
watch the sunset."
BHjr.
**********