I took a break from shoveling snow to do some annual cleaning of the bird houses. This is a post I write about annually, but it is always a good reminder.
Bird nest boxes need to be cleaned and inspected annually. It is a good time to look for water damage, and a good opportunity to inspect the boxes to see if they need any other repairs. At the minimum, remove the old nesting material, scrape off any mildew, and repack if you will be packing the house with saw dust (see here for more information).
I used to clean and re fill them right after the nestlings would fledge, but now I usually wait until early February to clean and refill the bird houses. I don't know if it is because of wisdom or laziness.
If left empty through the winter, birds may use the empty boxes as roosts. For example, this winter when we had several days below -10 F, flickers roosted in the flicker box and chickadees roosted in the chickadee boxes. However, in the past, squirrels have roosted (albeit temporarily) in the flicker box. But let’s just say that squirrel won’t be telling any of his friends about that warm spot to spend the night. Anyway, I digress, another reason to leave them empty after the nestlings fledge, is that our chickadees typically have two clutches and they will build their second nest right on top of their first nest.
Nevertheless, the sooner you get them repacked, the sooner you can watch for excavation activity. It is always amazing how quickly they start checking out the boxes, especially if we get a few warm days, and the little birds' thoughts turn to love.
Here are some important dates on nesting activities in the Missoula area from my backyard:
Red-breasted nuthatches are the first to begin excavating their selected box- they begin excavating in early to mid February (between February 5 and 21 at my house) and they are usually complete by the first week of April (April 1-9) when they begin to fill their boxes with nesting material.
Black-capped chickadees start excavating about a month after nuthatches, with peak excavating around first week of April (from March 25- April 4), until middle April when they bring in nesting material (April 11-15). But they investigate and start defending nest sites in February.
Northern flickers are on a similar schedule as chickadees and they begin excavating in late March – early April (March 24-April 8), but they search for nesting locations in February and may do some exploratory excavating as early as the beginning of February.