Since bluebirds aren’t especially common right around home, I was not aware that they can become easily trapped in the tubes people use to protect saplings. With the increase in ravenous deer, these tubes are becoming standard issue with new plantings. I imagine wrens would also be apt to explore and get trapped in the tubes as well.
This was posted as a reminder to the MDOSPREY list in Maryland; I’ve paraphrased a little. Thanks to my friend Cath for sending this along:
Bluebirds and tree tubes
It’s a good time to warn all bird lovers about tree tubes. These are used to protect saplings from deer. Usually consisting of a plastic tube about 4′ high held up by plastic ties and wooden stakes, these tubes are attractive nuisances for bluebirds: the male bluebird wants to explore all possible nesting cavities, so he will go into the tube and fall to the bottom and not be able to get out (this kind of thing doesn’t exist in the wild). I have freed quite a few trapped bluebirds from these infernal devices, and have removed even more dead ones.
The tree tube manufacturers sell (or include) woven plastic tops, or “socks” to go over the tops of the tubes. These will effectively prevent male bluebirds from going into the tubes.
If not, you can use some means to create a small exit slot or hole at the bottom of the tube, such as pulling the stake out of the ground 1.5 inches. I don’t want deer to eat saplings, but even more than that I don’t want any birds, much less native birds already suffering from competition from invasives, to die of starvation or dehydration due to thoughtless human activity.
Paul Kilduff, Baltimore
Tree Pro provides bird excluders with their tubes; instructions are at the bottom of the page.