Squirrel Behavior- Scatter Hoarding

Scatter-hoarding is a behavior exhibited by eastern gray squirrels, along with many other mammals and birds, in which individuals will make numerous small burrows throughout their spatial roaming regions and fill them with varying quantities of food for later consumption. The home ranges of eastern gray squirrels can vary anywhere from 0.5- 10 hectares (equivalent to 100,000 square meters), with older males tending to have the greatest territories. Due to these varying and often dizzying territorial claims, squirrels have excellent spatial memories to recall the many different caches of hoarded food that are scattered throughout. Caches can even vary by their temporality, as some are created and then consumed within hours or days, while other caches last for weeks or months without visitation from their creator.

Squirrels carry food in their mouths, often to be stored in caches for later consumption.
Photo credit http://cdn-small.cruncht.com/wp-content/uploads/2010/02/squirrel.jpg

The theory behind scatter-hoarding is to spread various caches throughout the region in order to create numerous low capacity holdings of food for later use by the organism, which reduces the energy of creation (small amounts of food in each, generally just one trip consisting of storing the food that is carried in the mouth of the squirrel), and also the risk of pilferage from other organisms (individual cache losses are less devastating because of their small creation costs and holdings). Pilfering is as common as hoarding in eastern gray squirrels, as well as other species, and consists of stealing another organism’s cache of food, which is found either by coincidence, or more frequently through conspecific observations in overlapping habitats. However, in order to minimize losses due to pilfering, it seems that eastern gray squirrels have adapted interesting behavioral traits for deception. While these have often been recorded in anecdotal evidence, little empirical evidence existed on the subject until only recently. A study published in 2006 by several American university biology researchers observed that free-living eastern gray squirrels exhibited behavior in which "squirrels frequently cover empty sites in the course of caching food, either before or after the food item is cached. The results of this study strongly suggest that this behaviour functions to deceive potential pilferers that may be watching and to decrease the probability of losing caches to them" (Steele et al).

That's quite the cache!

Photo credit: http://2.bp.blogspot.com

Michael A. Steele, Sylvia L. Halkin, Peter D. Smallwood, Thomas J. McKenna, Katerina Mitsopoulos, Matthew Beam, Cache protection strategies of a scatter-hoarding rodent: do tree squirrels engage in behavioural deception?, Animal Behaviour, Volume 75, Issue 2, February 2008, Pages 705-714, ISSN 0003-3472, 10.1016/j.anbehav.2007.07.026.

(http://www.sciencedirect.com/science/article/pii/S0003347207004988)

Written by Keenan