Red Squirrel: The Grey Coats Are Coming!

"Once upon a time a squirrel could travel from the coast of Delaware to the mouth of the Mississippi without touching the ground". ~ Micah Myers

Britain is home to two distinct types of squirrel, but only the red squirrel is native to the country. A century ago, the red squirrel was cheerily portrayed as Squirrel Nutkin in the 1903 children's book written by Beatrix Potter. The North American Grey squirrel invaded their cheerful existence at the end of the 19th century. Today, Grey's outnumber the reds in the British Isles more than sixty-six to one.

The invader Grey squirrel (Sciuris carolinensis) spread rapidly, displacing the red squirrel (Sciuris vulgaris) throughout most of Wales, England, and the lowlands in Scotland. Near the identical time that the Grey squirrel shows up in an area, the red squirrel typically begins disappearing. The Grey's success has been pegged by ecologists as due in part to a superiority in competing for insects, nuts, and berries. Reds have an inability to digest acorns which poses no problem for the Grey squirrel.

The Grey squirrel also tends to raid the red squirrel stores. Grey squirrels put on an elaborate show of burying non-existent seeds and nuts to protect their winter food stores from potential thieves. Another reason for the reds decline is the successful reproduction rate of the Grey squirrel. The greys produce more young, which are called kittens.

Competition over food alone is not sufficient reason to account for the rate and pattern of Grey expansion and red squirrel decline. The missing component for the explanation may be a squirrel pox virus. The red squirrel population in the UK is under threat of the parapox virus. This virus seemingly does not affect Grey squirrels; but red squirrels develop skin ulcers with swelling of the eyes, mouth, and genitals. An infected red squirrel dies within weeks.

Evidence indicates that the Grey squirrels are a carrier of the virus, but do not appear susceptible to infection. The red squirrel appears to suffer near 100 percent mortality in the wild. Scientists are hopeful of developing a vaccine to save the red squirrel. For more information: http://www.snh.org.uk/ukredsquirrelgroup/

To show you how squirrelly our rodents in America are, California ground squirrels use special tactics when facing rattlesnakes. A squirrel will not back down from the snake. In trying to defend itself, it swishes its tail, kicks up dirt, and may attack the rattler. However, its most interesting natural defense is its tail heats up during the confrontation.

Rattlesnakes sense their prey through infrared signals emitted by heat. The temperature rises in the squirrel's tail giving off a signal that confuses the snake, and the rattler will slither away. The squirrel does not exhibit this behavior with any enemies other than rattlers.

Sources:

http://www.guardian.co.uk/environment/2008/oct/16/wildlife-endangeredspecies

http://www.npr.org/templates/story/story.php?storyId=12785578