[CT Birds] Nest predation

jtriana1 at sbcglobal.net jtriana1 at sbcglobal.net
Wed Jul 1 20:51:44 EDT 2009

There are the likely suspects, but then it could be a variety of animals
that you wouldn't expect.

Last week I attended a conference on urban wildlife at UMass.  A woman from
Florida (Christine Stracey) did a study to see if mockingbirds were more
successful nesting in urban areas vs. rural areas.  She set up cameras and
DVR's by a variety of nests to see if and what predated them.  Among the
culprits were Cooper's Hawks, Swallow-tailed Kites, snakes (eggs and
nestlings with mom sitting right on the nest), a house cat (eggs), and a
flying squirrel (eggs).  It turned out that urban mockingbirds were more
successful and less predated than their rural cousins although there were 3x
as many avian predators in urban areas than rural areas.  She hypothesized
that this might be due by urban avian predators being satiated with other
foods in cities that they don't get in rural areas.  In other words, if you
are a crow in a city, it is easier to go dumpster diving for a free meal
rather than fight off a pesky mockingbird parent.

Along these same lines....about 10 years ago in either the Journal of
Wildlife Mgt. or the Wilson Bulletin, there was a study looking at what
predated grassland bird nests in the midwest.  That researcher set up still
cameras to see "whodunit".  One shot caught a deer having an egg breakfast.
Another showed the dramatic attack of a thirteen-lined squirrel on a adult
sparrow as it sat on its nest.

Lastly, this Saturday in our backyard we had a chickadee nest in a nest box
on our garden post.  My eldest daughter saw a House Sparrow on it early in
the morning.  I told her to go out and chase him off.  We went out several
times that morning before we had to leave for a couple hours.  When I got
back, I saw the male House Sparrow on the box again and chased him away.  A
few minutes later I saw one of the adult chickadees go into the box with
some food and exit a couple seconds later....with the same food.  Bad sign.
I went out and opened the box to find it empty.  Note - there had been 5
nestlings on Thursday.  I closed the box, turned around, and found the
bodies of three of the nestlings on the lawn within 30' of the box.  Looking
around, I could find pieces of the nest lining all around as well.

Bottom line is that it is a tough world out there.  Many things could be a
threat that you wouldn't think of.  Some (like the SOB House Sparrows) don't
even do it to feed their young, but just kill for the fun of it.


John Triana

-----Original Message-----
From: ctbirds-bounces at lists.ctbirding.org
[mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of Shelley Harms
Sent: Wednesday, July 01, 2009 12:23 PM
To: ctbirds at lists.ctbirding.org
Subject: [CT Birds] Nest predation

Hi CT Birders -
I'm seeing a depressing amount of nest predation. Hooded mergansers were
nesting in our wood duck house - something opened it up and split the eggs &
strewed the nest everywhere.
My neighbors found a ruffed grouse sitting on her nest.  When they brought
me to see it, there were feathers & eggshells scattered about.
I just found an adorable little red-eyed vireo nest with three eggs.  The
next day, eggs and bird were gone.
Is it me?  When I find a nest, so do the raccoons & blue jays?

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