Thursday, October 01, 2009

Forest Builders

Being birders, most of us here at the Audubon Center at Francis Beidler Forest have been irritated more than once by feeder-raiding squirrels. It might not be such an irritant, if the squirrels would not eat all of the seed set out for the birds or destroy the feeders in the process. However, squirrels also play an important role in the life of a forest.

You may have wondered how so many oak trees could sprout up in your yard. Left alone, many suburban yards would quickly become forested. Some of this simply a seed germinating in ideal conditions where it fell. However, many of the young oaks as well as hickories and walnuts can be attributed to the burying activity of the Gray Squirrel (Sciurus carolinensis). As winter approaches, squirrels are busy burying nuts as food to be located later. Although squirrels eat a variety of plant material, fungus and even bird eggs, nuts make up their main diet during the winter. Studies have shown that the squirrels find nuts buried by scientists at the same rate as nuts they buried themselves. They can smell the hidden nut and memory does not seem to play a role in nut recovery. In fact, they only find approximately 85% of the nuts they hide. However, they also find nuts hidden by other squirrels. The nuts are buried in shallow holes, which makes it easier to sniff out a meal once winter arrives, but also provides conditions conducive to seed germination and tree growth. Therefore, nuts undamaged prior to burial and undetected throughout the winter will likely begin to grow as trees.

The old-growth forest here provides ample cavities in which squirrels may nest. However, in summer months or in areas without sufficient cavities, squirrels will build leaf nests in the forks of branches. They often have two litters, spring and late summer, of 2-5 young per litter. The young from the first litter will be weaned in 12 weeks, while the young from the second litter will stay with the female through the winter. With leaves coming off of the trees, it's easier to see the leaf nests squirrels have constructed.

With October's low humidity, clear skies, and mild temperatures, it is a wonderful time to visit the swamp. Just be warned, squirrels are harvesting hickory nuts and are known to drop a few...could be bird feeder payback!

Images by Mark Musselman

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