Wednesday, May 21, 2014

Bluebird Nesting is Underway!

Post contributed by Sharon, volunteer Como Park bluebird trail monitor:

Seven chickadee eggs and two cowbird eggs
Three bluebird eggs
All but three boxes contain completed nests this week. House sparrows continue to attempt to nest in one box, and two other boxes have only small amounts of nesting materials inside.

There are six bluebird nests, one with three eggs and one with five. Incubation of the eggs has begun, as both mother birds flew out when I “knocked” before opening their boxes. Incubation lasts for about two weeks.

There is one chickadee nest with seven chickadee eggs and two cowbird eggs. Cowbirds lay their eggs in the nests of other birds. Both of these species’ eggs are speckled, but cowbird eggs are significantly larger than chickadee eggs. Unfortunately, I was unable to add a hole reducer to this box, which would have prevented the larger cowbird female from entering to lay her eggs. The original entrance hole had been enlarged just enough to make attaching the reducer impossible. Cowbirds develop faster than chickadees and bluebirds, and will likely hatch before their nestmates, putting the young chickadees at a disadvantage.

Tree swallows occupy one box, and have already laid three eggs. As I approached, a tree swallow poked its head out of the hole to see what was going on, as they often do.

Wary tree swallow