Advertisements
Posted by: atowhee | May 8, 2018

ORIOLES OR ELSE

The bright feathers and sharp beak may be a hint at the sharp personality inside…today my wife and the dogs and I were treated to loud and showy conflict between two male Bullock’s Orioles that brought them both into small trees along the sidewalk in front of us.   Quickly both contestants recovered their aplomb and retreated into the shade of big oaks nearby.  Here’s one of them, terribly back-lit:BOIN SHADEBOIN SHADE2BOIN SHADE3Just this morning a Black-headed Grosbeak was singing across the street from our garden.  Last evening there was one in tune above Wennerberg Park.  Finally this morning, at the north end of Pinot Noir Drive, one perched out in the open…less than two hundred yards away:BHG AFARThis grosbeak had found the tall dead Doug-fir spar favored by Peregrine and red-tail alike.  Good perch from which to broadcast your territorial claims far around the vicinity.
Recently I spotted this bird on a neighbor’s feeder:BHC MOMBHC MOM2This is a Brown-headed Cowbird, North America’s only nest parasite.  This one is unusually pale.  The female can lay up to sixty eggs in one summer, all in the nests of other species.  Thus the adult birds do not have to incubate,  brood or feed their own young.  They leave that to a pair of Song Sparrows or Hutton’s Vireos or some other innocent victim.  The cowbirds are an invasive species here on the Pacific Slope,  They followed the wagon trains and cattle herds west in the 19th Century and eventually populated much of the far west.

Cowbirds, related to blackbirds, grackles and orioles, evolved their lifestyle to fit the habits of the Great Plains bison herds.  Follow the big cattle, eat the insects and other stuff kicked up by the great beasts.  Occasionally fly back to the narrow line of trees along some river like the Platte or Arkansas,lay the latest egg, then return many miles to the bison for days of fine dining. Another egg forms, fly back to riparian woods…
As the name implies cowbirds do fine with large domestic beasts as well, and with man-made habitat of broken forests, suburbs, farms with hedgerows, etc.
They are very strong fliers after millenia of flying along with the bison, covering many miles daily.  If you go on pelagic trips off the Pacific Coast this is one of the few species of land birds that you can expect to see.  They’ll take a shortcut across the open sea, sometimes more than twenty miles out.  They must rank up with pigeons and doves as great distance fliers.

So now cowbirds parasitize species here in Oregon that have never before had to cope with cowbirds and are thus defenseless.  Robins, long co-habitating with their ilk, know a cowbird egg when they see one and flip it out of the nest.  I still think one of the most tragic “natural” things I have ever seen was a pair of gorgeous, small Common Yellowthroat struggling to find enough food for their gigantic (relatively) cowbird foster child.  The pair, or course, had lost their own eggs destroyed by the young cowbird.  Cowbirds hatch before most other eggs so the cowbird young can own the nest and destroy the tiny competitors.  Like climate change, we humans are responsible for the cowbird invasion and we have yet to find the will or method to cope with it.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Categories

%d bloggers like this: