Many birders focus their attention on nest boxes in the spring and summer, hoping to see avian parents bringing food to nestlings – and if they’re lucky, getting to see the young fledge. Those blessed with yards or a voice in deciding what goes in public spaces may create more such places by putting up nest boxes on poles and trees. (Poles with baffles are a better choice as it makes it harder for snakes and raccoons to enter and eat the eggs and nestlings.)
What many people don’t always realize is that nest boxes can be enjoyable birding spots in the fall and winter, too. As more and more people choose not to leave snags in their neighborhoods and/or have trees removed from properties, birds are losing places to construct their natural nest cavities. Nest boxes help make up a little bit for that habitat destruction.
In the winter, birds check out nest boxes to get a head start on choosing possible nesting sites come spring and summer. In my own yard, especially the Eastern bluebirds (Sialia sialis) and brown-headed nuthatches (Sitta pusilla) will visit one nest box after another to decide which one they might choose as a brooding site in the spring. The nuthatches may be accompanied by a youngster from the past summer who will help raise their new siblings.
Various species of birds also use nest boxes as warm overnight abodes when the temperatures fall to near freezing and below. Besides the Eastern bluebirds and brown-headed nuthatches, I’ve seen white-breasted nuthatches, Carolina wrens (Thryothorus ludovicianus) and downy woodpeckers (Picoides pubescens) checking out a nest box inside and out.
Carolina wren Downy woodpecker
Some species even use a nest box as a communal overnight refuge, with 12 or more birds squeezing together to conserve their body heat. I haven’t seen so many birds enter a box but perhaps I’m not looking at the right time.
The competition for nest boxes as warm overnight roosting spots can also be intense. A male downy woodpecker in my yard has adopted one particular box as his overnight abode, but the bluebirds would rather have the refuge for themselves. He gets there in the late afternoon and sometimes must pass angry birds to squeeze through the hole.
The bluebirds will then scold from atop the box and while hovering in front of the entrance, but he hunkers down and refuses to leave.
It’s interesting to see that the nest boxes also serve other creatures. Various birds perch on nest boxes while checking out the yard to see what’s going on, like this beautiful Northern flicker (Colaptes auratus).
One day, when looking out my window, I was certain I had seen a lizard peeking out of a box hole. Shortly thereafter, when I was outside, I caught a glimpse of a head and went over to open the box. And it turned out that a Carolina anole (Anolis carolinensis) is sometimes using that box as a place to rest! The birds don’t enter when s/he is there as far as I can tell.
When it’s cold and damp, you can also see birds using other measures to stay warm and resist the cold. Most birds eat quite a lot to put on body fat that is used up at night through shivering (which helps keep them warm). This means you may have crowds at bird feeders with species sharing space as they increase their body mass.
You may also occasionally get an “invasion” of one species, like the pine siskins (Spinus pinus).
Puffing up their feathers is another strategy that our avian friends use – they trap pockets of warmer air around their bodies.
Ruby-crowned kinglet (Regulus calendula)
Brown thrasher (Toxostoma rufum)
Chipping sparrow (Spizella passerina) Dark-eyed junco (Junco hyemalis)
The birds keep their feathers in good condition by engaging in vigorous preening. Some water birds oil their feathers to waterproof them, while others grow special feathers that disintegrate, producing a special waterproofing powder. And birds like mallard ducks (Anas platyrhynchos) have a special blood circulatory system in their legs whereby they lose only about 5% of their body heat through their bare feet.
Creating wood piles and leaving dried leaves and stalks from summer and fall grasses and shrubs can provide birds with some shelter from winter winds and cold, so my yard is now home to five wood piles. Several species of birds also seek out protected roosting areas when the deciduous trees and shrubs lose their leaves and the branches no longer provide hiding spots from predators. My native holly bushes serve that purpose for the lovely white-throated sparrows (Zonotrichia albicollis), as well as Eastern towhees (Pipilo erythrophthalmus) and Northern cardinals (Cardinalis cardinalis). I’m glad it keeps them returning to the yard!
As 2021 gets underway, I wish you readers all the best – hope this new year is healthy, happy and as worry-free as possible for you! And thanks for reading my blog. 😊