A Nest Box is for the Birds

The day the bluebirds were checking out the nest box with the idea of roosting in it, I could tell there was something in there keeping them from entering. Upon opening the box, I discovered an extensive organ pipe mud dauber nest.  Mud daubers, which are not at all aggressive, build their nests in areas that are protected from rain, and the unused nest box provided a perfect place to build it.

Last summer one built it's nest on the side of a container I put recycled trash in on the side porch.  As often as I would throw stuff in there, I didn't notice the nest until it was about five pipes wide. I couldn't leave it there, so I scraped it off. To my surprise, not only did the pipes contain wasp larvae, but also spiders! The spiders were moving a little, but they were unable to run away. I googled mud daubers and found out that the adult will hunt down spiders and inject them with a paralyzing venom and pack them away in the pipes as food for the larvae when they first emerge. I have torn down mud dauber nests before, but I had never seen spiders in them.  They particularly like to use black widow spiders, so you might want to consider them an ally in your war against spiders.

You wouldn't believe the list of animals that have inhabited our nest boxes over the years. Toads that spent the entire summer perched on the hole looking out over the lawn. A huge black snake spent some time packed in one one year.  We had a flying squirrel spending the days (they are nocturnal) in one. My wife would feed it peanut butter and walnuts on the end of a stick every evening.  There are more of those around than you might think.  The reason you don't see them is because they are nocturnal.

While I'm thinking of it, where you orient a nest box may be more important than you realize.  This box, which has been the most successful one we have had, faces east and receives the morning sun, but it is also protected from the prevailing west winds (and driving rain) by the tree. You might keep that in mind.

Anyway, I removed the organ pipe nest so the bluebirds can use the nest for roosting if they want to.  Here is the back side of the organ pipe that was up against the side of the nest box.  This nest doesn't look like the one I removed with the spiders in it so I figure it must be a different variety. Can you imagine the amount of work that went into building this structure.  It stood out from the wall four pipes thick, which is why the birds could hardly get through the hole. It was built by a solitary wasp one mouthful at a time from mud brought in (one mouthful at a time) from somewhere it could find wet dirt. Each larvae is individually packed in it's own chamber. I hated to remove it, but the birds being able to use it as a roost took priority in my mind.