From: St. Louis
I have put up many birdhouses this year. So far as I've seen only one of them is "occupied" and it by a house wren. I've never identified one of them before although they're quite common. They're strict insectivores (well not so strict, they eat spiders and centipedes too) and aren't interested in anything I put in my feeders. They would take mealworms I suppose if I could afford those. They're migratory and only come up here when there are bugs to eat. I have Carolina Wrens year round, they also eat bugs mainly but in the winter they feed on the peanuts and suet I put out. The House Wrens will have none of that. Anyway the male House Wren builds the nest and he often builds more than one in case the female spurns one, she might like one of the others. They don't mate for life and are rather promiscuous actually. This one, after building his nest has been singing his heart out. Here are the lyrics: "I need a woman, I need a woman baaaaad!" Now as you know, birds are unaware of our forum rule that boobs or boobies are the answer to everything. They know nothing of boobs but still desperately need female companionship, if only for a little while.
Anyway, yesterday morning I saw two of them, presumably the male who went in and out of the house and presumably a female who inspected the house. In the afternoon there were three. House Wrens are like this, one, presumably an interloping male was chasing the other, presumably the male nest builder, round and round the yard while the third, presumably the female, looked on. This went on for hours. This morning there was only one, it is a he and he is singing his heart out about how much he wants a woman. I have no way of knowing whether the female flew off with the interloper or the nest builder, but probably this is the nest builder and he's SOL for now.