Monday, November 26, 2012
I looked out the window early Sunday morning and saw a couple of bluebirds around the feeder. They are not seed eaters, so they weren't coming to the feeder, but were hanging around with the other birds that were on the feeder. A few minutes later, I went out on the front porch and my attention was attracted by several bluebirds that were flitting around a nest box I had built. One female especially was checking it out. No, they don't nest this time of year, but they will roost in a nest box on nights when it is bitter cold to keep each other warm.
Back in the mid to late 90's, my wife and I watched a flock of bluebirds do this with another nest box we had. We had a bitterly cold stretch for about a week and every evening just as the sun would be going down below the horizon, they would all enter the nest box one at a time. I counted seventeen going in one evening! The following spring when I cleaned out the nest box in preparation for the breeding season, I discovered the body of one of the bluebirds that had either suffocated or succumbed from the cold. The nest box was a little larger than the one pictured here, but not THAT much larger.
How do birds know what is coming weather wise? I'm sure there are plenty of theories about internal barometers and that sort of stuff, but somehow they can tell what kind of weather is coming. I fully expect that Sunday night is going to be well below freezing. Many times, we have had a larger than normal contingent of birds filling up at the feeder just before a snow storm. Somehow they know.
The female pictured here (they are not quite as colorful as the male) kept trying to go into the nest but wasn't able to enter completely. You can see there is something inside the nest on the left. Later, after they left, I went out and stuck my finger in there to see if I could tell what it was. I thought it may be a stick that a squirrel had shoved through the hole, but it wouldn't budge. So, I went and got a screwdriver and a step ladder and opened the nest to see what it was. I'll tell you about that tomorrow.
Here is a good comparison showing the difference in coloring of the male (top) and female. Notice how the hole has been chewed out by the squirrels. They are always a problem with nest boxes. I plan on building a couple of new boxes and I definitely am going to put a metal barrier around the hole so that they cannot ruin another one.
The male seemed to get perturbed by the female being unable to enter the box and they had a little spat about that.