No. 61–Under the Radar Marsh Life, Part II

Continuing the discussion of rarely seen and seldom thought of estuarine creatures, I give you the Atlantic salt marsh mink (Mustela vsion lutensis). That’s right, mink – as in Mink Point on the shores of Battery Creek in Beaufort. Mink are ubiquitous throughout US wetlands to include our coastal marshes.

These solitary creatures, except during the late winter to spring breeding season, are upper echelon predators important in maintaining a balanced bio-system. Unfortunately their high metabolism leaves them quite vulnerable to man-made toxins. This had become quite evident by the early 60’s with the loss of coastal populations inhabiting marshes fed by river systems draining the Piedmont. The fresh water entering the marshes carried DDT residue and other chemical farm runoff pollutants.

Fortunately that watershed has since been cleaned up which has allowed for the reintroduction of mink to those previous habitats. In a SCDNR sponsored project, mink from our own Daufuskie and Hilton Head Island marshes were collected for the now completed and successful repopulation effort.

It should be noted that the reason our local populations of mink remained healthy while the others disappeared is because we lack the pollutant carrying fresh water rivers systems. This happy quirk of hydro topography is also partially responsible for, as stated many times in the past, our unique high salinity estuarine system.

I don’t know their sponsor affiliation but there’s a group calling themselves the River Rats that participates annually in the Water Festival raft race. They might be surprised to learn that the name they chose for the competition can be linked to the river they paddle.

I’ve yet to see one myself but the marsh rice rat (Orzyomys palustris) is widely distributed throughout the southeastern states ranging from fresh to brackish to salt water habitats on the Atlantic and Gulf Coasts.

In our marshes these nocturnal predators, I guess they like rice as a side dish, feed on crabs, snails, fish, insects, baby terrapins and birds and their eggs. At 9 inches to a foot in length, including tail, these secretive creatures are reputed by one source to be able to dive to 30 feet and cross open water up to 1,000 yards. Now that’s a river rat.

Note of interest: When marsh mink disappeared from afore mentioned habitats, rice rat populations exploded with the loss of one of their major predators. This led to increased pressure on clapper rail and marsh wren populations.

The following falls under the “Boy, was I wrong” category in the never ending training of a self teaching amateur naturalist. From the days of the North Street Aquarium individuals have occasionally stood at the door and asked with some trepidation, “any snakes in there?” Through the years, because my focus has been from the high marsh down, my standard answer had always assured the skittish that there were no snakes on display because snakes didn’t live in estuaries.

Imagine my surprise at stumbling across a web page listing entitled “Marsh snakes” while researching marsh habitat zones. It turns out there are three primary subspecies of the genus Nerodia found in estuarine environments in Florida and on the gulf coast. There are two populations of a related subspecies, the Florida green water snake (Nerodia floridana), known to South Carolina. It is not clear, however, as to whether they may be found in a salt marsh environment.

N. floridana is known to inhabit Savannah River Site wetlands and another population has been reported in the Cooper River basin of Charleston and Berkeley Counties. Except for a few sightings from old rice fields in Georgetown County, the Florida green water snake has not been seen elsewhere on our coast.

So I guess in a way I was half right in that snakes apparently don’t live in our estuary. But that doesn’t excuse my ignorance of salt marsh snakes found elsewhere. Perhaps it’s time to review the archives to see if accumulated knowledge warrants corrections to any of the columns of the last five years.