Our Better Nature: The Quirky Habits of Animal Hoarders

If one routinely collects and stores gobs of stuff they can’t immediately use, it could point to a hoarding problem. But if they’re a species of wildlife, their fixation is apt and they should continue apace.

For humans, extreme hoarding exacts a heavy toll on those caught in its grip, and the behavior is best tackled with compassion and expert advice. It’s quite the contrary with animals. In the natural world, a host of bird and rodent species depends on stockpiling what might appear to be a ridiculous amount of food. Other hoarders range from ants to apex predators, and reptiles to marine animals.

Hoarding by animals, or caching as it’s often called, is a highly varied endeavor. Although some food-hoarding arrangements are cooperative and communal, most are solitary and competitive. Caches can be temporary, good for days or weeks. Others are designed to last a whole season, and certain cached-food items (if you check their expiration dates closely) apparently stay fresh for years.

Plenty of species take a minimalist approach to food storage. Look at our North American loggerhead shrike (Lanius ludovicianus), which is basically Vlad the Impaler cleverly disguised as a chickadee-like songbird. It skewers frogs, snakes, mice, large insects, and small birds on the thorns of trees like honeylocust and hawthorn. In a pinch, a spiky barbed-wire fence will do (the fact “spike” rhymes with “shrike” can’t be mere coincidence). As ephemeral as they are macabre, these cadaver-tree caches are great for keeping bad smells far from home as Ma and Pa shrike bring snake jerky and cricket crisps to the kids. This is a variation on what’s known as larder hoarding.

You’ll also find species that seem too fervent in their food-stashing protocol. Acorn woodpeckers (Melanerpes formicivorus), native to the U.S. Pacific coast as well as parts of Mexico and Central America, reportedly once glued 38,000 pennies to a 1949 Cadillac. Wait – sorry – that was an Indiana couple who got bored waiting for the cable guy. These birds do the same thing, but with acorns. They adorn utility poles, wood siding, fenceposts, and dead trees with acorns, which they ensconce in pre-drilled holes. A researcher once tallied acorns in a single tree and got to 50,000 (I assume that’s when the poor soul fainted from boredom).

No single bird can shove that many nuts into a tree in one season. Like beavers, acorn woodpeckers practice shared hoarding, with communal food collection and allocation. Their family groups, termed bushels (really), share everything, even spouses. Up to seven males and three females will mate and raise young together in one presumably blissful cavity nest. Their social framework includes the division of tasks, which helps their acorn-collecting hobby thrive. It appears not every bird checks the duty roster, though: an acorn woodpecker family in Arizona plunked nearly 500 pounds of acorns into an empty wooden water tank which they could not access. Hopefully a smarter bird was assigned to inventory control after that.

The exemplar of scatter hoarding may be the grey squirrel (Sciurus carolinensis), which includes its black melanistic variant. It was long assumed that when they weren’t practicing their Nik Wallenda routines on power lines or enhancing the feng shui of attic insulation, squirrels passed their days interring nuts, only to forget most within three seconds. No one thought to verify this until 1990 when a couple of Princeton University biologists observed grey squirrels in controlled trials. Their study found that after two weeks, squirrels retrieved 90 percent of the number they buried.

Each year, 10 percent of the acorns, hickory nuts, and walnuts squirrels bury will sprout in gardens, flower boxes, and lawns. Some in forests, too. Actually, grey and black squirrels are solely responsible for the survival of oak and hickory forests. Red squirrels don’t bury nuts, but hoard them in stumps and tree hollows where they soon become non-viable.

Though smaller than its cousin wolverine (the animal, I mean; not Hugh Jackman), fishers (Martes pennanti) have a gift for murder. Shy, svelte, and robed in luxurious fur, they hunt a home range as large as fifteen square miles. I once tracked one through deep snow and found where it had killed a grouse. A trail of blood and feathers led to a patch of trampled snow, beyond which no sign of grouse could be seen in the fisher’s tracks: it had cached its kill in the freezer. This is called cache spacing, where food is hidden over a large geographic area, making it unlikely a pilferer can find them all.

In arid and semiarid regions globally, a group of ants known broadly as honeypot ants treat shared hoarding the way ancient Romans ran their democracy: great for the in-group; unpleasant for the rest. North American honeypot ants, comprising 28 species in the genus Myrmecocystus, are found in western California and northwestern Mexico. As generalists, they scavenge all manner of things, including beads of condensed plant sugars excreted by aphids. Now it gets interesting.

Nearly half of each colony is composed of “repletes,” a class of unfortunates. Repletes are obliged to drink nectar, brought by interminable lines of workers, until they bloat to the size of marbles. Once a replete has swollen from its normal eighth-inch size to perhaps 1.8 inches, it is (somehow) hung upside-down from the ceiling, still alive, for as long as two years until the colony needs an urgent sugar fix. For a helping of regurgitated dessert, workers just stroke the antennae of a “honeypot.”