After adding to their nest with strips of bark, they will take a piece and 'sweep' both the top and sides of the nesting box. This goes on for at least 5 minutes. I've also seen them do it with an empty beak and while holding a piece of fluff.
Another interesting behavior is when a squirrel approached, they would 'fan' their wings and sway back and forth. It works, because that poor squirrel found an alternate route. (Poor guys - between the nuthatches and bluebirds - they're avoiding the fence.) It was a great way to spend Easter Sunday, although I didn't get a lot of gardening work done because of them.
Any clues as to what they're doing? Sweeping for insects or?
Thanks and hope you're all getting a chance to enjoy the wonders of nature.
The fanning of the wings and swaying by the nuthatches is thought to act as deterrent to anyone moving too close to their nest. Nuthatches compete with squirrels to nest in tree cavities so I’m glad your squirrel moved on and took the hint that there was no vacancy.The bill-sweeping behavior you described is still a mystery to scientists. One theory is that rubbing objects around the entrance masks the bird’s own scent from the nest and prevents detection from predators. Another theory is that it is another distraction display. You may also see the nuthatches rubbing the house with bugs. Certain insects excrete strong smelling chemicals when crushed to warn predators away or again mask scent.
Anyway, whether we understand bill-sweeping or not, the nuthatches are still fun birds to observe. The White-breasted Nuthatch Sitta carolinensis is a common bird of deciduous forests and wooded urban areas. Known as the “upside down” bird, it is often observed creeping headfirst down tree trunks while searching cracks and crevices for insect food. The name Nuthatch probably results from the corruption of the word “nuthack” which refers to its habit of hacking away at a seed with its beak until it opens. At backyard feeders you may see them eating suet, nuts, or sunflower seeds. They feast on seeds and insects, and many times will hide food in tree bark for a snack later in the day or breakfast the next morning.
Nuthatches are monogamous and defend a territory throughout the year. The female White-breasted Nuthatch rarely strays far from her mate and stays in constant vocal contact when they are more than a few yards apart playing the dominate role as “watchdog”, leaving the male more time to concentrate on hunting for food. They are feisty birds, and pairs generally defend a territory of 10 to 30 acres.
You are lucky to have an up-close look at the nuthatches performing their nest site rituals. I love to hear people talk about what they observe in their own backyard.
Source: Cornell Lab of Ornithology
http://bna.birds.cornell.edu/bna/species/054/articles/breeding
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