Last week I did my best to think spring by suggesting that it was time to put up a few nest boxes for cavity-nesting birds such as eastern bluebirds, tufted titmice, Carolina wrens, and chickadees.
This week it’s time for the next step despite a forecast for more severe winter weather. It will warm up – eventually.
One of my favorite March rituals is visiting my nest boxes to see that they are ready for the upcoming nesting season. I’ve already heard bluebirds, titmice, and Carolina wrens singing on a few balmy sunny days. Males are advertising for females looking for a secure nesting cavity. Nest building usually begins in mid March, so I feel obliged to be sure the boxes are ready.
Unfortunately, this is not always a pleasant task after a severe winter like the one we’ve been enduring. Bluebirds roost communally in natural cavities and nest boxes on long cold winter nights. And I suspect that January’s polar vortex may have taken a toll. Sometimes it just gets too cold to survive.
One March day back in 1983 while checking my nest boxes, I found four dead adult male bluebirds huddled on the floor of a nest box. I was crushed, but still had many nesting pairs later in the spring.
I tell this sad tale not to dismay, but to alert less experience nest box landlords to what may greet them when they check boxes this spring. If you don’t know it’s a possibility, finding a box full of dead birds can be terribly demoralizing. And if a child is tagging along, it can be devastating.
Most people blame themselves. They think their nest boxes are somehow the cause. They are not. If you find dead birds in nest boxes, you can be sure there are some in natural cavities as well. Multiple nights of 10 degrees below zero is one way nature weeds out the weak and the sick. On the bright side, you can assume that those that survive are strong and fit. They will make great parents for the next generation.
Finding a box with dead birds is a worst case scenario. Usually the task of preparing nest boxes for spring is more mundane. There may be a roof or two to replace or some squirrel damage to repair. At some boxes deer mice and white-footed mice will have to be evicted. And some may be filled with stashes of nuts store by flying squirrels.
Your job is to prepare the boxes for cavity-nesting birds, so evict the squatters and remove any debris from the box. Rodents plan for disaster and maintain several dens so my advice is not nearly so heartless as it sounds. Plus there’s always wiggle room. I love flying squirrels and even though they eat more than their fair share of eggs and chicks in the spring, when I find flyers in a nest box I just say “hello” and move on.
After your boxes are cleaned out and ready to go, sit back and observe. In just a few weeks birds will begin adding nesting material to the boxes. I usually have Carolina wren eggs by the third week in March. I find the season’s first bluebird eggs in early April, and the rest get busy by late April or early May. By the first week in May house wrens will return and join the nesting frenzy.
If you’ve never put up a nest box, it’s not too late. In fact as birds search for new nesting sites, now is the perfect to build or buy one. Bluebirds, Carolina wrens, and house wrens nest at least two and sometimes three times per year. I often have an active bluebird nest as late as August.
Nest boxes can be purchased at nature centers and wild bird specialty shops such as Wild Birds Unlimited. And if you are a do-it-yourselfer, you can find detailed nest box plans at http://www.nestwatch.org and click the “learn” button.