The other day, while exploring one of the remaining patches of wetlands around my county, I came across a furry little critter that was a complete surprise for me: an American Mink! Contentedly going about his (or her) business at the edge of the wetland, staying under the dense cover of an old clump of willows, the mink slipped out of sight before I was able to get a photograph.
But this mink sighting got me thinking about other mammals I've encountered here in California's Central Valley, and as it turns out... there have been quite a few!
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| California Ground Squirrel: A common sight in the Valley, and an important part of the ecosystem! |
Though the Central Valley is no longer the land of wild abundance it once was (at least not in terms of wildlife), more species of mammals than one might imagine still manage to make their living on the fringes of urban and agricultural land up and down the valley. National Wildlife Refuges provide much-needed havens for a number of species since, unfortunately, human-wildlife encounters in towns and farmland don't often end well for the wildlife. One chance encounter is often a delight, while repeated visits from marauding raccoons or squirrels or foxes can leave homeowners, farmers and ranchers frustrated and sadly, this frustration usually leads to the demise of the offending animal.
But surely, we can do better! We are, after all, tasked with being the stewards and caretakers of this earth, including its amazing wildlife.
So, you may ask, what exactly is out there? What kinds of mammals live and move and have their being just beyond our doorsteps?
I'm so glad you asked!
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| California Ground Squirrel |
Of course, there are the squirrels.
Common and familiar due to their diurnal habits, these endearing rodents come in two broad categories: the tree squirrels and the ground squirrels.
California Ground Squirrels (Otospermophilus beecheyi) are common across the state, and can be abundant in grasslands and other sandy edge habitats. Around picnic areas, they can be downright bold in their begging for handouts. Entirely uninvited, one particularly chubby individual once climbed up my leg and sat on my lap while I was sitting on the car bumper eating my lunch. (Obviously, these sorts of behaviors should be discouraged and wild animals should never be fed!)
While some consider ground squirrels to be pests due to their tendency to dig extensive burrows, they are an integral part of the ecosystems they inhabit. Eating a variety of seeds and insects, ground squirrels are in turn a key food source for just about everything above them on the food chain, from foxes and coyotes to hawks and snakes. In many cases, it's rodents like the ground squirrel that sustain the entire system.
Another important ecosystem service offered by California Ground Squirrels is the provision of burrows for other animals, most notably
Burrowing Owls, a species in steep decline across the West. As these small, ground-dwelling grassland owls don't actually dig burrows themselves, they rely on other animals, like ground squirrels, to do the digging for them, and so provide them with the spaces they need to hide from predators and raise their young.
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| A litter of young California Ground Squirrels at their burrow |
Western Gray Squirrels (
Sciurus griseus), one of California's native species of tree squirrel, may come down into the valley along riparian corridors, but they are more common in the foothills surrounding the valley. Though stereotypically associated with acorns, the main food source of gray squirrels in California seems to be truffles, a type of heavy, highly nutritious fungi. They can be easily separated from non-native squirrels species by their overall cool gray coloring and white undersides.
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| Western Gray Squirrel |
Two species of tree squirrels that have been introduced from eastern North America are encountered in the valley, usually in parks and park-like settings, but occasionally along rivers as well. These are the non-native Eastern Gray Squirrel (Sciurus vulgaris) and Eastern Fox Squirrel (Sciurus niger). Of the two, fox squirrels may be the more common species in California.
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Eastern Gray Squirrel
This introduced species is much warmer in color than our native Western Gray Squirrels. |
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Eastern Fox Squirrel.
The reddish coloration of the Fox Squirrel distinguishes it from our native Western Gray Squirrel. Also note the reddish undersides, in contrast to the creamy white undersides of the gray squirrels. |
Another rodent found in California, albeit a much larger one, is the American Beaver (
Castor canadensis). Like many mammals, beaver are largely nocturnal (active mainly at night) or crepuscular (actively mainly at dawn and dusk). As such, signs of beaver activity are more likely to be encountered than the animal itself; I've only seen beaver a few times, but signs of their presence are common along waterways. Look for felled trees, dams and lodges built of sticks and mud, and tracks in soft mud at the edge of quiet ponds and wetlands. (Read this older post for more about
beaver signs in the valley.)
While some argue that beaver are pests, I maintain that they are essential ecosystem engineers, even a keystone species, essential to the health of the surrounding ecosystem. Beaver ponds provide significant environmental benefits, particularly in arid climates like California. These ponds serve as quiet, freshwater habitat for a host of other species, as well as help with water retention and groundwater recharge. (Though I grant you, the one pictured below looks less than idyllic.)
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| A small beaver dam, with tell-tale tracks in the soft mud (bottom left of photo) |
Another conspicuous group of diurnal mammals are the lagomorphs. Or, more familiarly, the rabbits. In the Central Valley, three species are found: the Desert Cottontail (Sylvilagus audubonii), Brush Rabbit (Sylvilagus bachmani) and Black-tailed Jackrabbit (Lepus californicus).
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| Desert Cottontail |
Rabbits fill a similar ecosystem niche as that of the rodents: food for pretty much everyone who's bigger than they are. From coyotes to raptors, rabbits are on the menu.
While Desert Cottontails are common and abundant across their range, the subspecies of Brush Rabbit known as the Riparian Brush Rabbit is endangered and one of the rarest mammals in California. A population has been reintroduced at the San Joaquin River National Wildlife Refuge (my "home" refuge), and recovery efforts are currently on-going.
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| Riparian Brush Rabbit |
Denizens of arid shrublands and grasslands, Black-tailed Jackrabbits are another species of lagomorph (though technically a hare rather than a rabbit) that are an important prey item for a number of predators. Larger than either of our rabbits, jack-rabbits are readily identified by their enormously long ears, which they use for temperature regulation in warm climates, as well as detecting their numerous predators. When alerted to danger, Black-tailed Jackrabbits can run, often in a zig-zag pattern, at speeds up to 40 miles per hour!
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| Black-tailed Jackrabbit |
The ungulates, or hoofed mammals, are represented in the Central Valley by Black-tailed Deer (Odocolieus hemionus columbianus) and Tule Elk (Cervus canadensis nannodes).
The subspecies of Mule Deer known as Columbian Black-tailed Deer was extirpated from the valley floor in the last century, but in recent decades efforts to reintroduce these animals to the San Luis National Wildlife Refuge complex have been successful. Mule Deer may also be encountered along the foothill edges of the valley and are common throughout the Sierra.
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| Columbian Black-tailed Deer |
Tule Elk, the smaller and paler subspecies of elk that is found only in California, were nearly hunted to extinction in the 19th century, and the story of Tule Elk conservation and management has been long and fraught with controversy. As elk herds began to rebound and thrive after protection, they began causing damage to crops, fences and land. Today, around twenty herds continue to be closely monitored and intensively managed to ensure that this iconic species is able to coexist peacefully alongside humans.
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| Tule Elk |
Immediately recognizable by their bushy, ringed tails and black bandit masks, Common Raccoons (Procyon lotor) are largely nocturnal and not often seen during the day. They are omnivorous, shifting their diet as food availability changes throughout the seasons. I found this raccoon curled up in its den one day, barely visible but clearly keeping an eye on me!
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| Raccoon in its den in a hollow tree |
Canids in the Valley include foxes and coyotes. The Gray Fox (
Urocyon cinereoargenteus) is a small, agile, highly adaptable canine that is at home in towns as well as more wild areas. (This is the species that visits our backyard and occasionally cavorts on our roof during the wee sma's.)
Read more about the amazing (and I think endearing) Gray Fox here.
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| Gray Fox |
Coyotes (Canis latrans) are larger than foxes and restricted to the rural edges of the valley where they are fairly common across the foothill grasslands, wetland edges and on agricultural land (where, no surprise, they cause yet another wildlife controversy. You may have begun to notice a concerning pattern in human-wildlife relationships in California...) Coyotes are omnivorous, often opportunistic feeders, hunting small mammals, scavenging carrion, and munching fruits and berries. As one of the top mammalian predators in the ecosystem, coyotes play a key role in keeping populations of prey animals - like gophers and ground squirrels - in check.
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| Coyote |
Bobcats (
Lynx rufus) are not at all common on the valley floor, but I've encountered them several times along creeks at the edge of the foothills. These medium-sized wild cats are more common higher up in the Sierra and other more mountainous and forested parts of the state. (
Point Reyes National Seashore is a good place to spot them, along with a host of other wildlife.)
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| Bobcat |
Mink (Neogale vison) are medium-sized members of the mustelid family (Mustelidae), which is commonly known as the weasel family (but also includes otters, badgers and even wolverine!) They are semi-aquatic, often found in or near small bodies of water, like sloughs, rivers and wetlands, where they hunt their aquatic animal prey. Like many mammals, mink are more often seen at dawn and dusk.
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Unfortunately, I was unable to get a photo of the mink I encountered, so this is NOT my photo.
Photo By Needsmoreritalin - Own work, CC BY-SA 3.0
https://commons.wikimedia.org/w/index.php?curid=26244581 |
North American River Otters (
Lontra canadensis) are one of my favorite mammals to encounter in the valley. Large and frolicsome, otters are usually fairly conspicuous where they're present and a delight to watch. While wary of humans, they also tend to be curious and may approach an observer if one remains quiet and still. Other tell-tale signs that otters have been in the area include their "slides," well-worn pathways into the water, and latrine sites with scat that is often filled with bits of shells from the crustaceans they've been eating.
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| North American River Otter |
An iconic species of wide open grasslands in western and central North America, American Badgers (Taxidea taxus) are not at all common in the Central Valley but may be more abundant in the surrounding foothills (though sightings are still very rare). Badgers need plenty of open space for digging their burrows, where they sleep, raise their young and even cache extra food. Ground squirrels and other small burrowing mammals make up the majority of the badger's diet, but they will prey on reptiles and birds also, when available.
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| American Badger |
Of course, there are many more mammals that I haven't mentioned which can also be found in California's Central Valley and foothills: various small rodents, like native kangaroo rats, woodrats and deer mice; Muskrats and Virginia Opossums, which were both introduced to the Valley and are now naturalized (though not considered invasive); other small carnivores that are not often seen, like weasels and skunks; and Botta's Pocket Gopher, the species of critter known for ravaging lawns and gardens here in the Central Valley.
Neither did I mention the highly invasive Nutria, a rodent introduced from South America that is the cause of a great deal of trouble; check out this article from California Department of Fish and Wildlife to learn more.
But hopefully this overview of some of the mammals that share the Central Valley with us will serve to shed some light on the amazing biodiversity that can still be found here, clinging to life along the margins. And as always, my desire is to inspire the admiration, respect and protection of all God's creatures we're blessed to share this earth with!
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