Have you ever thought about the derivation of the Red- and White-breasted Nuthatch’s common name? It comes from their habit of wedging a nut, acorn, etc. into a tree’s bark, and by repeatedly striking the nut, “hatching” or exposing the seed within it.
Many of these seeds are then stored in bark furrows for later consumption. In one study it was found that nuthatches spend more time caching husked than unhusked seeds (71% of sunflower seeds cached were husked). This inevitably would lower the expenditure of energy and time spent when consuming the cache later in the season. Hiding time, and time and distance flying from feeders to cache sites were longer when nuthatches hoarded husked than unhusked seeds, perhaps indicating their increased value to the birds. (photo: White-breasted Nuthatch with husked sunflower seed)
White-breasted Nuthatches maintain their pair bond throughout the year. In the spring, after mating, the female builds her nest, lining the tree cavity (natural or old woodpecker hole) with fur, bark, and lumps of dirt and then making a cup nest of grasses and bark inside the cavity. She then lays her 5 – 9 eggs and incubates them for roughly two weeks, during which time the male brings her food.
After the eggs hatch, both parents provide their nestlings with food until they fledge. Initially the female remains with the young, and the male brings food for both her and the nestlings. His trips become more frequent during the first few days, starting at about 7 trips an hour and increasing to 13. After three or four days the female also participates in food gathering, as much or more than the male.
The average day length in June is approximately 15 ½ hours. At 26 deliveries/hour (13 per parent) that comes to a total of around 400 foraging trips a day for the majority of the 26 days before White-breasted Nuthatch nestlings fledge. Impressive, especially when you consider that many of these trips involve not only delivering food but also removing the nestlings’ fecal sacs.
The phenomenon of North American birds being killed by becoming entangled in Common Burdock (Arctium minus) has been documented since at least 1909, when one observer (in A.C. Bent’s compilation) described finding a multitude of Golden-crowned Kinglets in Common Burdock’s grasp:
They were visible in all directions, scores of them sticking to the tops of the clumps on the most exposed clusters of heads. The struggle had ended fatally for all that I saw, and its severity was evidenced by the attitudes of their bodies and the disheveled condition of their plumage. I examined a number of the burdock heads to determine that attraction had brought the kinglets within range of the hooks, and found insect larvae of two species present in considerable abundance.
Typically this phenomenon involves birds that are seeking either insects that are inhabiting the seed heads, or burdock seeds. The birds’ feathers get caught by the hooked bracts (modified leaves) that surround both the flower heads and seed heads of burdock. Small birds such as kinglets, gnatcatchers, goldfinches, nuthatches, hummingbirds, chickadees, warblers and siskins are the usual victims, but larger birds, including a Blue-headed Vireo and a Barn Swallow, have been caught as well. Most of these birds were found with their wings and tail spread, and caught by many parts of their bodies. The more they struggled, the more their feathers became entangled. Victims are not limited to birds — in 1925, a dead bat was discovered caught in a patch of burdock. (Photo by and thanks to Holly Brough)
There are two main ways that woodpeckers and occasionally other birds remove bark in search of insects beneath it. One is bark sloughing, where a bird pries off the entire dead layer of bark on a tree (see NC post on 12/5/14). Another method of locating insect larvae that both woodpeckers and nuthatches employ is the removal of individual scales of bark. This is referred to as bark scaling. The pictured hairy woodpecker has removed much of the bark of a dead eastern hemlock using this method.