Wednesday, June 6, 2012

Como Park Bluebird Trail Update: June 6th

 Post contributed by Sharon, volunteer Bluebird Trail monitor:

Remains of damaged bluebird eggs

Young cowbird that just fledged
One or two bluebird youngsters will fledge sometime in the next week.  Two nestboxes contain 9 bluebird eggs.  Two more nestboxes contain a total of 6 younger-than-two-week-old bluebirds.  When I checked on one of those boxes, I was surprised to hear a vigorous fluttering as I unscrewed the screw holding the door closed.  Before I knew it, out flew a little bird—not a bluebird—a young cowbird.  It landed on the grass in front of the box.  Cowbirds fledge in 8-13 days, earlier than bluebirds, at 16-22 days.  The little cowbird hopped and flew onto the low branches of a nearby pine.

A nest that last week contained 3 bluebird eggs had only the remains of destroyed eggs—yolk and a few tiny pieces of egg.  I removed the nest. 
A new grassy bluebird nest was built in the next nearest box, over the remains of the tree swallow nest that had not been incubated.

Tree swallow on nest

A tree swallow is incubating eggs in another nest.  When I opened the box I tried to part the numerous feathers to see any eggs, without any luck.  I finally realized the mother bird was inside incubating when I saw her straight dark tail feathers.  She did not make a move even with all my probing!
Chickadees will fledge soon from the last chickadee nest.

A male house sparrow sat upon the top of the last hanging nestbox.  He’d put just a bit of grassy material and sticks on the bottom of the box, which I cleared out.