Date: 7/20/20 10:43 am
From: Jane Stein <jeshawks...>
Subject: Re: [VTBIRD] Hummers, they are out
Fascinating info. Thank you!

Jane
(Shoreham)

On Mon, 20 Jul 2020 17:00:49 +0000, anneboby
<00000038cbe79a41-dmarc-request...> wrote:
> Hello Hummer Lovers - on Fri, 7/17, I banded the first newly fledged
imm.
> female Ruby-throat of the season at my Adirondack banding station at
Jenny
> Lake in Saratoga Co., NY.  Based on 29 years of banding records at this
> site, this date is 3 days earlier than the previous earliest date of
7/20. 
> The average earliest date is 8/3, ranging as late as 8/25 in 2013.
> Let me offer some further thoughts on the possibility of double brooding
> based on Cornell's information that the species can be single or double
> brooded.  That guidance needs to be put into proper geographical
> perspective.
> Northward bound male Ruby-throats hit the Gulf Coast last week of  Feb
> based on many years of records gathered on HumNet.  A few miles inland
from
> that coast the breeding territory of Ruby-throats begins, stretching
about
> 1100 mi. N into southern Canada at about 49 deg. N latitude.  It is
quite
> possible that Ruby-throats breeding in southern U.S. states can be
double
> brooded if they begin breeding in Mar, but that possibility diminishes
as
> one goes northward.
> My Jenny Lake station is at 41deg, 16 min. N latitude at an elevation of
> 1250-1300 ft.  Records there over 29 years show an average first banding
> date of adults 5/16, range 5/6-5/24; first banding date of a newly
fledged
> imm. 8/3, range 7/20 (prior to this year)-8/25.  The average last
banding
> date is 9/3, range 8/25-9/23.  In 16 of the 29 years, imm. have been
banded
> into Sep, average last date 9/8 with  dates of 12 of those 16 years
> occurring 9/1-9/10.
> If an average female were to double brood, she would require 3-5 days to
> rehab her nest, 2 days to lay 2 eggs, 14 days to incubate and 18-23 days
to
> fledge a second brood, a total of 37-44 days.  Based on the average date
of
> first banding of an imm. of 8/3, a female then attempting a second brood
> would take until 9/9-9/16 to bring off that brood. This puts her brood
out
> of the nest past the average 9/3 departure date.
> If we consider the case of the mother of the imm. I just banded on 7/17,
> and apply the same breeding time table to her, she could possibly pull
off
> a second brood by  8/23-8/30 which, again, provides precious little time
> for her newbies to develop the stamina for their upcoming over 1000-mi
> migration to Central America.
> At Jenny Lake, I have never seen male courting behavior after Jun.  Lots
> of territorial conflicts at the feeders, yes.  All in all, I feel double
> brooding at this latitude/elevation in the Adirondacks is not likely;
the
> same would apply to the Green Mountains of VT.  But, we live in changing
> times, including climate change and global warming which are affecting
> avian time tables.  We just need further proof that Ruby-throats double
> brood in the mountains of the Northeast.
> Bob Yunick
> Jenny Lake and Schenectady, NY
 
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