Wednesday, February 15, 2017

Delmarva Squirrel is Back

credit: M. Hendricks
The squirrel formally named Sciurus niger cinereus spent fifty years on the Endangered Species list.  2016 was the anniversary of its de-listing.  That event was not deplorable, but an affirmation that legal protection under the Endangered Species Act, which many conservatives want to emasculate in the interests of development, actually works to bring threatened species back from the brink of extinction.  The Delmarva fox squirrel has repopulated the peninsula for which it is commonly named.  Much of the population lives in Blackwater National Wildlife Refuge.  Data recently collected by scientists shows that the shy, sliver-grey squirrel continues to do well.  It is larger than common grey squirrels, reaching 2.5 feet in length with a tail of up to 15 inches long.  Despite its large size its behavior is furtive.  However, they have been known to noisily confront hunters lurking in tree stands.

marsh conversion, credit: W. Flanagan
This animal was one of the original species to be listed under the predecessor to the Endangered Species Act in 1967.  At the time of listing the fox squirrel inhabited only 10% of it historic range due to over-hunting and habitat loss.  It likes to live in mature, mixed forests of hardwoods and pine;  most of this has been lost to agriculture and development.  Surviving squirrels inhabited mostly private land where suitable habitat remained.  Any hope of restoring the beautiful squirrel depended on cooperation from private land owners and government conservation officials.  Fortunately, a successful partnership was formed.  Private landowners allowed the fox squirrel to continue living on their properties, and accepted translocated squirrels or returned their land to a more suitable, natural state.  Wildlife authorities think that without landowner cooperation, Delmarva's iconic squirrel would not have recovered from its endangered status.  After two status reviews in 2007 and 2012, the squirrel population on the peninsula is estimated to be 20,000, occupying about 28% of Delmarva.  Monitoring the population in Blackwater NWR, [photo] a twenty-nine thousand acre reserve of woods and water, will continue for five years as required under the Act to insure its gains are not reversed after de-listing.

So far, the data shows the population is stable, but the effects of global warming on sea levels are worrisome for some conservationists. Due to rising sea levels, Blackwater's marshes are converting to open water. [see photo above, computer simulation right] Every year Maryland looses 380 acres of its shoreline to the sea. There is little chance of restoring disappearing marshes in Blackwater. Sea level rise is inevitable, outruns sedimentary deposition, and the flat topography is uncooperative. The cost to fill open water with dredge material from Baltimore harbor runs into the billions.  So managers hope to facilitate the natural migration of marshes up slope.  When marshes do migrate, less salt-water tolerant tree species die off.  Hopefully, the beautiful fox squirrel will move too.