Natural History Journal

Mammals are among the most exciting types of wildlife to see, but also some of the most difficult.  Far less numerous than birds and often exhibiting secretive or nocturnal habits, many groups of mammals are rarely encountered in the wild.  Observant naturalists are far more likely to encounter signs of a mammal's presence than the mammal itself, the most obvious of which are tracks, scat and fur.  But more subtle clues may be discovered as well, such as dens, nests, burrows or bedding areas, as well as evidence of feeding, like chewed bark, twigs or pinecones.  All of these are forms of mammal "sign" and are good indicators that the mammal which left the sign is or has recently been present in the area.   I like to think of mammal signs as similar to bird songs and calls : proof of a species' presence in the area, and valuable for research purposes, even when I'm unable to get a look at the animal itself! Sure, seeing the animals is always more exciting, ...

Last week, I wrote about a few of my favorite local places to get outdoors and take a walk  in the remaining bits of wild (well, semi-wild) grassland and wetland of California's Great Central Valley.  This week, I had a chance to visit another beautifully preserved piece of our valley at Cosumnes River Preserve , just off I-5 west of Galt.  Access the informative trail map and nature guide  here.   The Preserve consists of over 50,000 acres of diverse habitat, much of which has largely disappeared from the Central Valley.  The seven Partners that own the land are The Nature Conservancy, Bureau of Land Management, California Department of Fish & Wildlife, Sacramento County Regional Parks, Department of Water Resources, Ducks Unlimited, and the California State Lands Commission. Together, they "seek to protect and enhance the habitat within the Cosumnes River Preserve project area, including riparian forest, wetland, vernal pool grassland, oak wood...

The North American Beaver ( Castor canadensis ) is unapologetically one of my favorite mammals.  Considered pests by some, this large rodent is a master ecosystem engineer and keystone species in its environment. During the 19th century, the humble beaver was nearly eradicated from the western United States, including California, through habitat loss, hunting and trapping for fur, and deliberate extermination.  The beaver is sometimes considered a nuisance species, since their enthusiastic lumberjack work may cause trees to fall across roadways, and their dams, ponds and levee burrows can cause flooding.  But it turns out that the beaver provides a suite of unexpected ecosystem services, including increasing wildlife habitat and water storage potential in the arid, drought-prone west.  Beaver lodge at San Luis National Wildlife Refuge, April 2017 Beavers are hydro-engineers and excel at altering the flow of water though the...