Dear Sue and Scott,
Excellent points you both, and others. The most rational examination
of the facts I have seen!
Keep well, c.j.
-----Dr. C. John Ralph
--- USDA Forest Service, Pacific Southwest Research Station,
1700 Bayview Drive, Arcata, California 95521
Telephone (707) 499-9707 home: 822-2015
----------------------------------------------------------------------
cjralph@xxxxxxxxxxxxx c.ralph@xxxxxxxxxxxx
https://www.fs.fed.us/psw/programs/cb/staff/cjralph/index.shtml
On 3/4/2021 7:06 AM, Scott Weidensaul (Redacted sender scottweidensaul
for DMARC) wrote:
Sue,
I think it’s important to stress that extreme weather events of all sorts will
kill birds, regardless of species and situation. Hummingbirds have been moving
east because large-scale landscape and (certainly to some extent) climate
changes play into the ways evolution is always throwing spaghetti against the
wall to see what sticks. I suspect feeders are a relatively small part of the
story.
At the risk of stating the obvious: Some portion of hummingbird populations
have changed their migration routes and wintering areas because migration is an
innate, genetically encoded behavior — and thus, as with anything genetic,
prone to mutation. Some small percentage of any migratory hummingbird species
has, since time immemorial, been born with a hiccup in their software and
migrated the “wrong” direction. And likely since time immemorial, they were
culled from the gene pool year after year when they encountered hostile
conditions — until we changed the landscape and the climate.
All those backyards and gardens, farm fields and thickets, along with a
generally warming climate, have allowed hummers with the “wrong” genes to
survive, breed and pass on those genes to a new generation. (And of course,
it’s not only happening with hummingbirds. The situation with Eurasian
blackcaps developing a new wintering range and migration route in the UK is
almost perfectly analogous.)
When conditions deteriorate, especially as rapidly as happened in Texas, many
of those individuals that have been benefitting from the new habitat and
climate regime are going to suffer. It’s harsh, but it’s how nature works. All
the feeders do is make those losses more obvious to us. (I can’t help but
wonder if there is a similar level of concern about the doubtless significant
losses among insectivorous passerines?)
I would also point out that, harsh as the conditions in Texas were, they are
not the most extreme that some species can survive. A RUHU banded by Wayne
Laubscher in central Pennsylvania in 2012 holds what I believe is a minimum
temperature survival record, making it through two days of air temps as low as
-9F and wind chills of -35F.
Scott Weidensaul
Milton, NH
On Mar 4, 2021, at 8:08 AM, susan heath <susan.heath888@xxxxxxxxx> wrote:
Humbanders,
I need some perspective from this group. As you are all aware we had a
devastating freeze here in Texas a few weeks ago. Many winter hummers went
missing during the freeze and presumably died. I know of four different
Broad-billed Hummingbirds that disappeared mid-week of the freeze and numerous
Rufous. Several people reported finding dead hummers to me. So I know there was
significant mortality of hummingbirds as a result of the freeze.
I am doing a hummingbird presentation in a few weeks to an Audubon group and
I've already been told I will be asked given the effects of the freeze whether
we should put out hummingbird feeders during winter. I have thought this
question through at length and come up with some points to make. 1) we don't
know why hummingbirds are coming east for the winter instead of going south, 2)
we aren't causing it by putting out feeders because hummers have no way of
knowing there are feeders out here before they begin their migration, 3) the
human altered landscape with abundant flowering plants in winter is supporting
these hummers regardless of feeders being out. The only way I can see that we
may be adding to the problem by putting out feeders is that we are giving
additional support to these birds and perhaps allowing them to survive when
they wouldn't have otherwise (but see point 3 above). This allows them to pass
on their genes and IF migration route is inherited, then we are supporting more
hummingbirds coming east instead of going south.
What do you all think about this? What points have I missed? Is my thinking
sound on this subject? I really want to be prepared for this question so your
thoughts are most appreciated.
Sue
--
Susan A. Heath
Gulf Coast Bird Observatory
Lake Jackson, TX
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