I am dismayed to say I have close to 50 cow-birds in my yard at once...it's
creepy! I've seen evidence of their egg-destruction about; robin's eggs on the
lawn, etc. With so many around, it will be a wonder if any of the other birds
will be able to raise their own, huh?
I read somewhere, an in-depth report about these parasitic birds...they reek
havoc on birds which build a new ‘floor’ right over-top of the cow-bird egg and
raise a family on the ‘second’ floor. Some nests are apparently several inches
tall…where the birds keep trying to foil the interlopers. Oddly, if foiled too
often, the cowbirds apparently get even…coming back to destroy all eggs and
even kill chicks. Ugg…I remain convinced; they are evil incarnate! LOL
Oh, I’ve also read some folks are all for removing cowbird eggs when they find
them…I’d be one. But…is that legal?
Thank you for your interesting report.
Beverly Jensen
La Veta, Huerfano County
www.RuralChatter.blogspot.com
P Please consider the environment before printing this e-mail
--- On Sat, 5/30/09, Jeff J Jones <jjo...@jonestc.com> wrote:
From: Jeff J Jones <jjo...@jonestc.com>
Subject: [cobirds] cowbird parasitism
To: cobirds@googlegroups.com
Date: Saturday, May 30, 2009, 10:11 AM
Last year I reported on some cowbird parasitism in nests I was monitoring on
the HP Campus at I-25 and Rockrimmon in Colorado Springs (El Paso County). This
campus is on the west side of I-25 and abuts the Ute Valley Park.
I want to report on current cowbird parasitism here and at my home in Teller
County, north of Woodland Park.
Blue-gray Gnatcatchers
These little guys have a tough go of avoiding cowbirds at HP. They started
their first nest along a bike path in a patch of scrub-oak about 3 weeks ago.
As I watched the pair build the nest from about 20 yrds away, it was also
obvious that a pair of cowbirds were also attracted by the activity. As a
female cowbird patiently, but not quietly, watched from the top of a nearby
ponderosa.
Before the nest was complete, and I can postulate due in part to the obvious
cowbird casing of the nest, they started a second nest in another patch of
scrub-oak about 80 yards away; but did so by dismantling the old nest
completely and using the material for the new nest. Duh! Obvious trail of
evidence for the cowbirds to follow from old to new. Well, they completed this
nest 12 days ago and laid their first egg 2 days after that. Upon which, a
cowbird promptly deposited its egg and removed the gnatcatcher egg.
Last year, this occurred much like this, and the gnatcatchers went on to lay
more eggs and incubated those and the single cowbird egg. The cowbird egg
hatched along with the first gnatcatcher eggs and succeeded in pushing out the
gnatcatcher nestlings and unhatched eggs. The adoptive parents fed and raised
the single cowbird to fledging.
This year however, the gnatcatchers appear to have recognized the devious
cowbird’s actions. I found the egg on the second day to have been pecked, a
small hole in one side. And they started dismantling this nest and started on
their third, where? – back at the original location of their first attempt, one
scrub-oak away! Two days later, the original nest (2nd one in this series) was
completely gone. No sign of it. And the third nest complete and ready to go
again. Let’s hope that the cowbirds don’t find this one. But I don’t see how
the little guys have any chance.
Dark-eyed Juncos
I have watched juncos in my yard in years past raise single cowbirds at the
expense of any of their own. This year, I reported a few weeks ago that juncos
had started a nest on my front porch where they successfully fledged young last
year – without cowbird intervention! Well, they abandoned that nest before
completion for no apparent reason. They then started one 4’ up in a small
spruce in our backyard garden. Again, they abandoned that before completion and
started one on the ground under a ground juniper just 3 feet away. They
completed this one and I found their first egg on Thursday. Yeah! I can see
this nest from my upper back deck with binos and monitor it easily without
disruption to the parents from about 40 ft away.
I awoke Friday morning and went out on the back deck in expectation of their
next egg (usually one egg per day, found in the morning – so assuming laid
sometime during the night or at first light in the morning). And, to my
chagrin, not one egg, but two more were present – now totally three. Well, I
knew what this meant. I doubt the little gal squeezed out 2 overnight. Upon
close examination, 2 were identical – mottling concentrated at one end – while
the third had heavier blotting and evenly distributed over the egg. Cowbirds!!!
And there she sat – the female cowbird – rattling from the nearby spruce. This
morning I awoke to a 3rd junco egg – now the nest has 4 eggs. And I know the
junco babies don’t have a chance
fyi
Jeff J Jones
(jjo...@jonestc.com)
Teller County - 8500' - Montane Woodlands
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