Squirrels place winning bet in unpredictable world In an evolutionary game of tug-of-war, red squirrels have gained the upper hand over the cunning spruce trees, says new University of Alberta research that suggests the clever animals are staying one step ahead of its food source.
A team of scientists, led by Dr. Stan Boutin from the U of As Faculty of Science, has discovered that red squirrels are able to counter the trees "swamp and starve" strategy of boom and bust seed production by producing an extra litter of babies in anticipation of a lush season of tree seeds.
In a paper published in "Science," Boutin and his international team of researchers, describe how they have studied the relationship between the American and Eurasian red squirrel and the trees they feast on. Over the 20 years Boutin has spent studying this chess match, he has noticed a surprising pattern. Red squirrels are somehow able to predict years when a bountiful crop is about to occur and remarkably produce a second litter of babies to take advantage of the onslaught of food about to arrive.
The international team of researchers found that the trees have been trying to outwit the squirrels by implementing a "swamp and starve" tactic. This is actually an evolutionary strategy by the trees to thwart the animals that eat its seed. In bust years the trees try to starve their seed predators so that in boom years there are few seed eaters around and they are swamped by all of the seed available. The seed predators cant respond in time to the increased production because they cant predict when it is going to occur. The net result is that more seed escapes to germinate in a mast year as compared to a strategy where the trees produce a constant amount of seed each year.
Normally this tactic works. By the time the seed matures in the fall, most seed eaters, like squirrels, have already made their "decisions" about having babies for that year. So when t
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Contact: Phoebe Dey
phoebe.dey@ualberta.ca
780-492-0437
University of Alberta
21-Dec-2006