Western scrub jays are colorful camp robbers

By Jeff Mitton

I had laid out some food for lunch at my camp in Kodachrome Basin State Park, and some western scrub jays swooped in to share.

A bird at one end of the table distracted me, while a second bird at the other end of the table jumped on the edge of my plastic snack storage container, tipping it over.

I don't think it was an accident. Almonds, walnuts, sunflower seeds and raisins spilled onto the table, then onto the ground. The jays grabbed some nuts and immediately departed.

When they returned, they brought some friends, kicking off a hoarding frenzy.

I was annoyed that they had spilled my gorp (historically from "good old raisins & peanuts"), but entertained by the spectacle of a dozen scrub jays swooping in, filling their bills and hurrying off to cache their food. They grew bolder and bolder and soon they were working within a few feet of me, scrambling to collect the most appealing morsels.

The western scrub jay,  Aphelocoma californica, is distributed from southern Washington to central Texas and then south into Mexico. But opinions differ on whether this is one species with 14 subspecies or three species, each with four or five subspecies.

Proponents of the three-species model refer to our local scrub jay as Woodhouse's scrubjay, Aphelocoma woodhouseii.

Suffice it to say that these broadly distributed birds differ substantially among habitats and geographic regions, and if the original lineage has not yet evolved into three species, it is on its way.

I called it a hoarding frenzy because the jays were not eating my gorp, they were flying elsewhere to cache the food, then returning for more. Like Clark's nutcrackers, scrub jays are renowned for their ability to memorize the locations of numerous caches so that the food can be harvested weeks or months later.

Biologists who have studied caching behavior came to the conclusion that scrub jays can remember the locations of more than 200 caches as well as the contents of each cache.

Scrub jays not only rob the camps of humans, they also rob the caches of other scrub jays. Human observers have reported the impression that jays stealing from their neighbor's caches were furtive when they cached their stolen booty; they looked about to insure that no other scrub jays were watching. In addition, scrub jays have been reported to steal acorns from the cache trees of acorn woodpeckers and seeds and cones from Clark's nutcrackers.

Resourcefully opportunistic, scrub jays in California have established cleaning mutualisms with both mule deer and Columbian black-tailed deer. They land on a deer and comb its fur and probe its ears with their bills, searching for ticks. A tick swollen with blood is a nutritious meal for jays, and the deer are happy to cooperate by remaining motionless as they are groomed.

Although the phrase "camp robber" usually refers to gray jays, Clark's nutcrackers and Steller's jays, western scrub jays have the same boldness and trickery and should be included in this group of thieves.

They certainly taught me to be more careful with my gorp.

Jeff Mitton (mitton@colorado.edu) is a professor in the Department of Ecology and Evolutionary Biology at the University of Colorado. This column originally appeared in the Boulder Camera.