I wrote to a biologist with MassWildlife about the red eft I found on Saturday and he wrote back:
Dear Mr. Mirick,
On November 14th, I was with a group of environmental educators looking for moose sign in the North Quabbin woods. We were happily examining moose scat and moose-browsed red maple stump sprouts when I spotted something in the leaf litter. It was a red eft - with two tails! Although many of us have seen these in our travels throughout the state, none of us had seen one with two tails. Amphibian deformities have been a hot button item when discussing the state of the environment and this one has piqued my interest. I'm curious to hear your take on this two-tailed red eft. I have attached two pictures of the red eft for your review.
Thanks for sending along the photos and telling me about this animal! This is the first such specimen I have seen from the Quabbin area, although I did see a 5-legged newt from the Berkshires a couple of years ago. We don’t get too concerned about a single case of amphibian physical abnormality because they can have so many causes. Unless several animals or several species from a relatively small area are found with such deformities, the cause is almost always natural. In my experience, most such “double deformities” are caused by the embryo being attacked in its egg by a nasty little nematode. This little “worm” has a habit of eating just a little of a developing amphibian embryo, but almost always in a location (a limb bud) that causes a limb (or tail in this case) to split early in its development, resulting in two appendages in the adult animal. I believe that is the most likely explanation in this case, but it is also possible some accidental or even deliberate (man-made) injury was inflicted on this animal when it was young, and either that divided the developing tail, or the regenerating tail simply developed abnormally following an amputation or near-amputation. Whatever caused this abnormality, it is VERY unlikely it was due to a pollution/chemical event, but it’s always best to remain suspicious and look for any further evidence of abnormalities in the area just in case. I am informing my contacts in that area, particularly those who work in the watershed, to be on the lookout for any other evidence of abnormal amphibians.