Gray squirrels are scatter hoarders, hiding hundreds of nuts individually or in groups of less than five. Most other squirrels are larder hoarders, placing large numbers of food items in one or a few storage areas. Left alone, squirrels make several holes before they bury a nut in one of them.
Deception
Most of the holes squirrels make are simply holes. When the squirrel decides to store a nut, it fills in the hole and places a leaf, stone, or twig on top of it. If these covered holes are dug up, acorns are usually found in each of them.
Michael Steele, a biology professor at Wilkes College in Pennsylvania, has studied gray squirrels caching for over twenty years, and identified this behavior as “deceptive caching." Steele suggests that squirrels exhibit this behavior because the squirrels themselves are inveterate thieves, stealing from each other more often than other animals do.
The Behavior Can be Modified
Professors Steele and Sylvia Halkin and her students at Central Connecticut State University, independently identified several interesting changes in this behavior.
- When hiding nuts, gray squirrels make many false holes and insert nuts into only a small percentage of these holes.
- If squirrels see that other squirrels are watching them, they increase the number of false holes they produce.
- When their nuts are stolen by other animals (squirrels, jays, or people), gray squirrels increase their deceptive actions by increasing the number of holes they produce, covering the false holes as well as those that contain nuts, burying their nuts underneath shrubbery, in mud, or in their nests where it is harder to observe where the nuts were placed.
Steele and Halkin surmise the increased number of false holes helps deter thieves because a thief that repeatedly dug into caches only to find them empty would soon lose interest in the activity. Prof Halkin's students found that when they began to dig up a squirrel's hoard, the squirrels produced more holes and the students became frustrated when they were not able to find as many nuts as at the beginning of the study.
- Gray squirrels dig up the nuts they bury after several days and relocate them someplace else. It appears that, unlike jays, squirrels do not have a very good memory for their caches. Steele says: “Digging up and relocating their caches may help [squirrels] ‘recharge’ their memories of where their food is located.”
This activity can easily be observed if a supply of raw or unsalted peanuts in the shell is provided. After eating their full, squirrels will take the nuts away and begin burying them nearby. If the observer were to remove the nuts from the squirrel's caches, there would soon be a change in the squirrel's burying behavior.
