Marsh Harvest Mouse: Not All Rodents are Pests!

From Feb, 2009 Newsletter

By Kelsey Bechelli

This tiny little mouse is too cute to be afraid of; its soft brown fur and black beady eyes compel scientists, environmentalists and recreational salt marsh users alike to wonder about its story. Only those who are willing to get muddy will be lucky enough to spot this 2 1/2 inch-long mouse that occupies the salt marshes in and around the San Francisco Bay area. The mouse lives among pickleweed, a salty, abundant plant that has a cactus-like texture and appearance and grows in the brackish waters of the marsh.

The harvest mouse utilizes its small size, quick movements, and location among the dense pickleweed to hide from its natural predators: the hawk, owl, and clapper rail. The mouse does not need to look hard for its food because unlike other rodents, its body is adapted to tolerate high concentrations of salt in both food and water, allowing the mouse to eat the pickleweed it lives with and occupy an environment where not many other animals can survive.

Although the mouse has crucial survival advantages, it has been on the endangered species list for the last forty years. Salt marshes in the 1970's and 1980's were thought to be prime areas for landfill and ground water pumps. This construction greatly altered the harvest mouse's habitat and took an immediate toll on the mouse population. Fortunately, in recent years, the San Francisco Bay marshes and wetland areas have been protected by the national and local governments, allowing the harvest mouse populations to begin recovering and stabilizing. The salt marsh harvest mouse plays a key role in the salt marsh ecosystem and its presence is necessary to maintain the beauty and diversity that makes marshes so interesting. If you ever get lucky enough to see one, you'll understand why this animal is anything but a pest!


Info from:

Don Edwards San Francisco Bay National Wildlife Refuge

And Save the San Francisco Bay Organization

2.  SouthBayRestoration.Org