[va-richmond-general] Ruby-Throated Hummingbird populations
- From: Susan Ridd <susaneridd@xxxxxxxxx>
- To: va-bird <va-bird@xxxxxxxxxxxxx>, RAS Listserv <va-richmond-general@xxxxxxxxxxxxx>
- Date: Sun, 30 Jun 2013 10:29:20 -0400
*Posted for Joe Lively. The question is - are there fewer hummingbirds this
year?*
**
According to widespread reports, there does seem to be fewer hummers this
year. Normally (Past 20 years or so), we have had 300 +/_ each season. They
nearly worked me to death filling 25 - 30 large feeders during the two
population peaks. This season, they were both later than usual and
apparently fewer. Currently, we only have approximately 50 - 60 hummers.
The first bright, fresh hatchlings were seen at out feeders during the
first week of June - right on time. Numbers of adults and hatchlings were
definitely off, according to my 35 + years of records.
Noted ornithologist and hummingbird bander, Lanny Chambers plots the
migration progress on charts each year. He generously shares that
information with us as the data comes in. The explanation for what is
perceived as fewer numbers of hummingbirds might well be explained by
examining the dates of migration advance over the last several years. If
you really want to be scientifically valid, you might consider the 16 years
that Lanny has prepared his charts, as statistically significant.
R.T. Hummers have been shown to appear along the Gulf coast right on time,
about 20 -25th of Feb. This consistency has not varied for the 16 years,
since Lanny began keeping records. What has varied is the advance of
hummers into northern latitudes. The last 2 years show a remarkable
difference in northward migration. Temperature has to be part of the
equation.
We had an unusually warm winter in 2012 and waves of migrating birds were
being reported in NY and even Canada before many in Va saw the first one.
Then came a very cold snap. Many of those early migrants, in northern
latitudes, probably did not survive the frigid temperatures. Unlike many
western species, R.T. Hs do not have the ability to undergo torpor.
According to the 2012 charts, R.T.Hs were well distributed in Va. by the
first week in April. The first to arrive were in the last week of March.
This 2013 year, northward migration started on time in Feb. Then progress
began to bog down. If you recall, there was a strong mass of cold air
dominating the upper half of the country. Hummingbird sightings were being
reported up to an imaginary line stretching from Charlotte, N.C., across to
about mid-Tenn. This information can easily be extrapolated directly from
Lanny's chart data.Migration did not pick up again until the second or
third week in April.
Many reports of fewer numbers have come in from NC, Southern Va. all the
way over to Memphis, Tenn. It is obvious that R.T. Hummers do not tolerate
extreme cold for long.and most likely tend to avoid punishing themselves as
a survival measure. Did the birds that would have migrated to Va decide to
stay South of the cold air mass or did large numbers of birds perish in the
protracted cold. We may never know the answer to those questions. I would
hope that if we have a warm spring next year, hummingbird numbers will
rebound.
Joe Lively
Farmville, VA
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