This White-breasted Nuthatch is caching seeds in the crevices of tree bark for a future meal. Other birds in the London area that cache food include, Red-breasted Nuthatch, Black-capped Chickadee, Tufted Titmouse, and corvids. Photo by Paul Nicholson.
Through the fall, some of us will make jams and pickle pickles and jar tomatoes that we will enjoy through the winter and next year. Humans aren’t the only creatures that stash food for future use, however. Squirrels obviously squirrel away food for later use. There are also members of fifteen bird families that will cache food. Several of these overwinter right here in London.
Red-breasted and White-breasted Nuthatches plus Black-capped Chickadees are the species that we are most likely to see engaging in this behaviour. Tufted Titmice, jays, crows, and some woodpeckers are known to cache food as well.
If you are near a bird feeder, watch one of these birds carefully. Through the fall, you will see some birds simply dining, but you might also see a Chickadee take a seed and fly away with it. While it is possible that the bird has simply retreated to a safer perch on which to eat its food, it is just as likely that is taking the morsel away to cache it in the bark of a nearby tree or a some similar nook or cranny. This pattern will be repeated again and again through the day.
Caching behaviour increases as we progress through the fall. Some birds will hide thousands of seeds that they can retrieve at a future date when access to other foods is restricted by snow and other factors. It is like a kind of insurance and it is strategically sound.
Most often, it is seeds that are cached, but some birds might also store mealworms or even insects. Food-storing birds will also employ various strategies to ensure their stores aren’t raided by other birds. White-breasted Nuthatches are know to raid the stores of other White-breasted Nuthatches.
Some of the species that engage in food-storing are social species. Chickadees, for example, are birds that often flock together. This increases the likelihood that one birds will steal another’s hidden food. It was theorized that there might be “reciprocal pilfering” among birds that would be analogous to a broad-based insurance policy supporting survival and evolution of the species as a whole. A 2010 study involving Mountain Chickadees however revealed that this was a false hypothesis.
Ornithologists have studied other caching behaviours. For example, Dr. David Sherry of Western University’s Advanced Facility for Avian Research determined that food-storing birds ultimately retrieve their hidden stores of seeds by remembering the locations of their caches. To assist in these behaviours, these birds’ have a larger avian hippocampus. It is a part of the brain that plays an important role in spatial memory and enables navigation. Interestingly, Sherry determined that “the appearance of the cache sites themselves seems to be relatively unimportant in cache retrieval, perhaps because local features are subject to change during the lifetime of a cache.”
Most of the other bird species that overwinter in London and Middlesex County do not cache food. Birds such as Mourning Doves, Red-tailed Hawks, sparrows and finches simply try to eat what they need on a day-to-day basis, whether it’s seeds or small mammals.