More Eggs

I would like to start off today with a few facts about Eastern Bluebirds then go on to the events from today. I get most of my facts from http://sialis.org/index.html .

For those of you that might not know, the male is very dark blue on the back and head with orange-red and white on throat and breast. The female is lighter in color. She has light bluish gray on her back and head with white, light orange, and gray on the throat and breast. The Eastern Bluebird can be found in the central or eastern United States. They like open areas with scattered trees and fence rows, farmlands, orchards, and suburbs.

This morning I noticed the male and female birds out back on the fence. I decided to watch them for a little bit. Momma bird flew into the nest and stayed for quite some time then flew out. About 5 to 10 min later she flew back in the nest. Daddy bird brought her some food (looked like a worm). She stayed most of the morning in there. I wasn't sure if she was just sitting on them or if she was laying another one. From what I read in the past she doesn't lay on the eggs much unless it is cool. Also, she doesn't incubate the eggs until she is finished laying them all so that they can all hatch at about the same time. So I waited until mid-afternoon to go check the nest. Sure enough there are now 4 eggs. I wonder if she will lay a 5th one?