I came by box 14A on my way back from surveying the 51 mountain bluebird boxes we have on a bluebird trail at Red Rock Lakes and had to stop and watch the action. A mountain bluebird pair has built their nest but haven't started laying eggs. They were defending the box against four tree swallows. It was so dramatic, I thought it needed to be presented in a slide show.
I put all my pictures from this fight on Flickr and someone who viewed them wrote me back to tell me that the Tree Swallows need the nest boxes more than do the bluebirds. AND the bluebirds are bigger and stronger and have been seen dragging tree swallows out of the nest. For an interesting article by tree swallow researchers, click here.
A few days after this happened, I was driving back with Dick, another volunteer. I had been helping him remove dead fish eggs from our little hatchery. If the dead eggs aren't removed, a fungus starts to grow on them and then, when there is enough of the fungus, it can kill living eggs.
We saw two ravens on nest box 13A. They flew off as we approached and then I saw the top was off the box. We stopped and I checked inside and only saw a few bits of grass. I put the top back on and then looked down to see the entire nest sitting empty on the ground. When I got home, I checked my data for this box. It had had 6 eggs and the female was sitting on them. The ravens had opened the box, eaten the eggs, and possibly the female, because, about 40% of the time she will stay on the nest when I open the lid. If this happens again, I'll have to add screws which will make it much harder to do the surveys.
|Replacing the roof - a wire is attached to the top and then the ends fit into holes |
in the side of the box
|The nest removed by the ravens - by Dick|
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Postscript, May 28
The tree swallows are ensconced in the nest box. But I think the bluebirds who lost this nest, are now in box 15. I had to put that box up after I got here so it was a new house to the birds.