Nestbox tidy-up

Last week we had a string of really warm days. I took advantage of one of these gorgeous, sunny afternoons to take the power drill and the puppy and walk back through our fields to clean out the nestboxes of last year’s nests. (Raven came along too, but declined to help.) I’d done the same thing last year, at nearly exactly the same date. It really does take the nice spring weather to motivate me to go out and take care of the task, even though there isn’t really any reason I couldn’t do it earlier in the winter, or even in the fall.

I visited nine nestboxes, though we have twelve officially on our 30 acres: one of them I just plain forgot about, but the other two are in serious need of repair (or better yet, replacement) and I declared them out of commission for this season. The boxes are all, with the exception of two, ones that were already here when we moved in. In fact, they look like they’ve been here for many years already, weathered and covered in lichen as most of them are. It doesn’t seem to put the birds off, though, and until such time as I can get my spare cash and spare time to coincide, we’ll probably just make do with these.

The first one I opened is the above. It’s one that Dan put up for me halfway through the summer on a stake at the corner of my veggie garden. Being in a (relatively) high-traffic area, plus absent at the start of the season, it came as little surprise that the box’s inaugural residents were House Wrens. I love these little brown birds, so full of spunk and cheer. Growing up we never had them around our house. It wasn’t till I was in university and won a nestbox somewhere, and gave it to my parents to erect near their house, that we had our first wren move in. I don’t think they’ve been without one in their garden since, and the only year that I missed having one was the spring we were at the lake house. (We probably could have got one there, too, but simply didn’t have any boxes up.)

Box number three: another wren. (I’m going to take these out of order, because it tells a better narrative.) Wrens build very distinctive nests. They like for their cup to be at or just below the level of the entrance hole, so in deep boxes this means filling the box up with something. Their material of choice is coarse twigs. And they stuff the box with them. Sometimes they’re so tightly wedged in that you have to wrestle with it to get it out again, and when the material does come out, it almost invariably retains its cube shape. (The odd one falls apart. Must be a young bird: still learning.) Only at the very top, and usually tucked against the back wall, is there anything other than twigs: their small concave nest is woven with fine grasses.

Box number eight: a third wren. Surprisingly, there were only three wren-rented boxes among the group. I seem to have neglected to include the tally in last year’s post, but I think there were five, and our available rental accommodations didn’t include the veggie garden box at the time which, if not included in this year’s tally, leaves only two. There were definitely more, anyway. Possibly a couple of those from last year were re-nestings, second broods from later in the year, and so there really were the same number of wren pairs this year as last. Also, at least one wren moved up to by the house, where there weren’t any boxes last year. I find it interesting how the resident of a box isn’t necessarily the same from one year to the next.

Box number seven. This is a good example of that. Last year when I cleaned out this box the previous summer’s resident had been a chickadee. I was really hoping that the chickadees would reuse it this year, since I had heard a male persistently hanging around that area and singing. If they tried, though, then they were evicted before they could get building. Last summer’s tenants were Tree Swallows. They build shallow nests of thin dried grass, and almost invariably include one or more white or mostly-white feathers. The white feathers here are a giveaway, though I also remember there being nearly-fledged young in this box when Dan and I checked it late last summer.

Box number five: this one also fledged Tree Swallows last summer. But they were some messy swallows. In the previous nest, the nest structure, including the fluffy feathers, is still mostly preserved. In this one, there’s so much packed poop that the stop was just a solid crusty layer. Eeew. I’ve seen this in the occasional swallow box, and I’m not sure why some get like this and some don’t. Perhaps in boxes like this, the nestlings reach fledging age (which also happens to be the age when the parents stop removing the fecal sacs) just as the weather turns cold and rainy for a stretch, so they spend a few days stuck in the box before leaving?

Box number four belonged to one of our Eastern Bluebird pairs. This one also raised a full brood of chicks to fledging, which we got to see when we checked the boxes last summer. I sometimes have trouble telling the bluebird nests apart from the tree swallows, but the bluebirds are generally frugal with their feather use in comparison, and often make deeper nests – two or three inches of grass instead of just one or so.

Box number six: our other bluebird box. I was surprised and delighted to discover we had two bluebird nests on the property, since the previous year we’d just seemed to have the one. We found this one later in the season with eggs, which led me to believe it might be a second nesting. As with the previous nest, this one has a couple of inches of dry grass forming the base.

But the clincher was the blue-green eggs; as a member of the thrush family (same as robins), their eggs are robin-egg blue. It was by these that we knew for sure who was using the box last summer. Unfortunately, the eggs never hatched. Being a later nesting, with eggs at mid-June, I wonder if it simply got too hot for them and they died. There were four when we checked last year, but only three when I opened the box up last week. At some point, one of the eggs had been broken open; by whom, I don’t know. It would be difficult for any land vertebrate to get up to the box because the post has a wide baffle on it, and there aren’t any trees or shrubs nearby. We don’t have cowbirds or House Sparrows in the area that I might consider as possible culprits, either. Also, the other three remain intact. It’s a mystery.

Box number two had two residents last year. The top material is pretty obviously the work of a wren, while the bottom stuff looks to be from a bluebird. Bluebirds seem to be fairly non-confrontational tenants and don’t put up much of a fight when someone with a sharp tongue and quick beak (like wrens or House Sparrows) decide they want the space for themselves. This seems to have been what happened last year. When we opened this box up last June, the wrens had already moved in and had half-grown babies.

And box number nine seemed to be the same. The poor bluebirds seemed to have gotten shunted around a bit before they were able to settle into one at last. I don’t know if there’s anything you can do to keep wrens from ousting the bluebirds once the bluebirds have picked a box. Perhaps all you can really do is put up more boxes, so there are more options for everyone.