Another factor to consider is predation, which confounds lots of questions
of behavioral energetics. My first thought is that perhaps your feeding
station now is a little more dangerous - more exposed, or there are more
known predators in the area, something like that, that leads to a higher
cost for the jays to sit and hack nuts. It may be more expeditious to dash
and cache than worry about calories.
On Tue, Mar 1, 2011 at 10:42 AM, Laura Erickson <
> I think your questions are fascinating and worth examining
> experimentally, but there are a few more points to consider. Blue Jays
> probably started "weighing" food morsels not simply to get the most
> calories per trip but also because in the case of their most preferred
> natural food, acorns, the heavier ones are the ones least likely to
> contain a larval insect eating away at the contents. So selecting the
> heaviest ones is even more advantageous than it seems.
> Peanuts start rotting pretty quickly when stashed, and the process is
> quicker when they're not in the shell, so it's possible that over
> time, some jays figure out that it's best when caching peanuts to keep
> them in the shell. But those in your area may also be, as you note,
> simply trying to speed up the time they spend at the feeder.
> I doubt if anyone has worked out a definitive answer to your question.
> To start teasing out answers, you might try offering a small number of
> peanuts already shelled to see if the jays eat those on site or also
> carry them away for storing elsewhere.
> Best, Laura Erickson
> On Tue, Mar 1, 2011 at 10:27 AM, Betsy Beneke <email@example.com>
> > I started feeding blue jays peanuts in the shell many years ago, when I
> lived in
> > Detroit Lakes. It was a Saturday morning ritual in the winter. Start a
> pot of
> > coffee, fill the feeders, and throw a couple of handfuls of whole peanuts
> out on
> > the platform feeder. I had two large picture windows in front of the
> > table from which to watch. It was a very relaxing way to start my
> weekend. I
> > LOVE watching behaviors in birds.
> > The blue jays would fly into the yard the moment they heard my storm door
> > There were 4-6 birds, I think. Their "mode" was to fly to the feeder,
> pick up a
> > peanut, drop it, pick up another one, drop it - until they found the
> > one - then fly to a nearby branch, where they would hold the peanut
> > their feet, poke a hole in one end of the shell, pull out the kernel, do
> > same to the other side, and then let the shell fall to the ground. This
> > was repeated until they got several kernels in their mouth/throat, and
> then they
> > would fly off to the woods to stash them. They would make repeated trips
> > all the peanuts were gone and there was a pile of shells left in my
> yard. All
> > the birds used this same process. I understand that the heaviest peanuts
> > chosen first because they have more nutrition per trip. The wimpiest
> > were always the last to be chosen.
> > I've been feeding the blue jays at Avon the same way this winter, but
> > noticed that the jays here fly in, grab a peanut and then immediately fly
> off to
> > the woods with the whole thing. They don't stop to pull out the kernels
> the way
> > the Detroit Lakes birds did. I know that there are at least 7 different
> > who come in for the treats - maybe more.
> > So my question for SOMEONE who knows more about this than me, is...why is
> > feeding pattern different? Is it a learned behavior within the local
> > population? Or could it be that there are more birds here - more
> > competition/grappling for the goodies, so they zip in to grab what they
> can, and
> > then fly off to stash it safely away?
> > I'd love to know the answer!
> > Betsy Beneke
> > Avon, Stearns County
> > ----
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> Laura Erickson
> For the love, understanding, and protection of birds
> There is symbolic as well as actual beauty in the migration of birds.
> There is something infinitely healing in the repeated refrains of
> nature--the assurance that dawn comes after night, and spring after
> the winter.
> --Rachel Carson
> Please consider the environment before printing this e-mail.
> Join or Leave mou-net: http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net
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Dept. of Zoology
University of Wisconsin - Madison
Madison, Dane Co, WI
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