The Florida Salt Marsh Vole. Part I: What Is It?

USFWS Photo

Paddlers and hikers are extremely unlikely to see one of these elusive animals, but visitors should be aware that the salt marshes of the Lower Suwannee National Wildlife Refuge are home to the Florida salt marsh vole, one of the world’s rarest (or at least seldom seen) mammals.
 
What are voles? As children we had never heard of voles, but were familiar with these small rodents, knowing them as “field mice” or “meadow mice.” Having tiny ears, blunt snouts, and short tails, they look quite different from the familiar house mice. When one was spotted near the house, my mother would remark, “Oh, it’s only a field mouse,” giving reassurance that it would not be infesting kitchen pantries or lurking in hollow walls.
 
The refuge is one of two known locations of the Florida salt marsh vole, the other being nearby Waccasassa Bay. The vole is believed to frequent dense mats of salt grass (Distichlis spicata). Salt grass grows on the upper edges of salt marshes and somewhat resembles Bermuda grass. The exact habitat requirements of the vole are unknown because only a handful have been observed.
 
Our Florida salt marsh vole is regarded as a subspecies (variety) of the common and widespread meadow vole (Microtus pennsylvanicus), a species that ranges across the northern half of North America, from the Arctic Circle to coastal South Carolina, but no further south. Thus the closest relatives of the Florida voles (subspecies dukecampbelli) are nearly 300 miles away. Other outlier populations occur in New Mexico and Chihuahua, Mexico. These isolated southern populations are believed to be glacial relicts. The meaning and significance of this will be discussed in a future blog.
 
University of Florida scientists from the Florida Cooperative Fish and Wildlife Research Unit are undertaking studies of this endangered population, and I hope to be able to report on the progress of their research in future posts to this blog.