Feathered hoarders steal seed
Sometimes when I fill my bird feeders in late afternoon, I notice the food is gone by morning. When food vanishes overnight, I suspect deer, raccoons, opossums and flying squirrels are the likely culprits. But when seed disappears during the day, feathered seed-hoarders may be responsible.
Years ago I learned about seed-hoarding birds by watching a white-breasted nuthatch as it repeatedly harvested acorns from a white oak tree. Often it took a single acorn, flew to a nearby perch, wedged the nut in a crevice in the bark, then hammered the acorn with its dagger-like bill and extracted the meat.
Just as often, however, the nuthatch didn't eat the acorn. Instead it flew to a nearby snag and stashed the nut behind a slab of peeling bark. The first time I observed this I peeled off of a piece of bark and a handful of acorns poured onto the ground. The nuthatch was storing about half the acorns it collected.
Chickadees, titmice and woodpeckers also sometimes store food in roosting cavities when weather gets cold and snowy. I've occasionally found such caches during midwinter nest box inspections.
Once I watched a red-bellied woodpecker make repeated trips to a knothole on an abandoned outhouse. Each time it dropped a mouthful of sunflower seeds through the knothole.
It inserted its bill into the hole, and then returned to the feeder. After jamming its mouth full of seeds, it returned to the outhouse and dropped the seeds through the knothole. After watching this for several minutes, I opened the outhouse door and found a pile of sunflower seeds on the floor. What the woodpecker failed to understand was that the seeds were not retrievable unless it could later get into the outhouse.
This reminded me of classic food caching behavior by acorn woodpeckers, which are native to the Southwest. They collect and store acorns, and in one published account, an industrious acorn woodpecker made its daily deposits in a knothole on the wall of an abandoned cabin. But those acorns didn't go to waste; the cabin's mice surely enjoyed the easy meals.
Like red-bellied woodpeckers, blue jays also cram their cheeks with large quantities of seed. I've often watched them carry off mouthfuls of sunflower seeds, shelled nuts, and even in-shell peanuts. Then they bury their stash just like squirrels. They fly to the edge of the yard and tug at tufts of dried grass. Then they deposit their treasure in the shallow hole. Who knows who finds more of these food caches, the jays or the squirrels? In the long run, however, it probably evens out when jays find nuts buried by squirrels.
Jays are probably responsible for more missing food than other birds because they visit feeders in flocks. A group of a dozen hungry jays can empty a feeder in a hurry. Nuthatches and woodpeckers visit feeders individually or in pairs.
Seed-eating birds are not the only species that caches food for future use. Shrikes, and a variety of hawks and owls kill surplus prey when it's available. Good times allow predators to make it through times when prey is less abundant.
Of course, storing food for future use would be futile if birds could not remember where they hid the food. If that were so, other species would be just as likely to find hidden food. To be adaptive, hoarding behavior must confer an advantage upon the hoarder. That advantage is that the hoarder knows where the food cache is and other birds and mammals do not. But to use that advantage, hoarders must be able to relocate their hidden food supplies.
Not surprisingly, experiments with both wild and captive birds demonstrate that hoarders do remember where they hide food, and they use a variety of cues to relocate it days, and sometimes months, later.
So if food seems to mysteriously disappear from bird feeders, don't assume squirrels or night visitors are responsible. It may simply be seed-hoarding nuthatches, woodpeckers and jays.
Send questions and comments to Dr. Scott Shalaway, 2222 Fish Ridge Road, Cameron, WV 26033 or via email to firstname.lastname@example.org.