North Yuba Naturalist: Mammals of the Lakes Basin

Lodgepole Chipmunk (?) - Tamias speciosus

There are over 40 mammals that inhabit the Lakes Basin including; Black Bear, Mule Deer, Mountain Lion, Bobcat, Coyote, Gray Fox, Pine Marten, River Otter, Weasel, Skunk, Raccoon, Marmot, Beaver, Mountain Beaver, Porcupine, Jackrabbit, Snowshoe Hare, Cottontail Rabbit, Pika, Flying Squirrel, Douglas Squirrel, Belding's Ground Squirrel, Golden-mantled Ground Squirrel, Chipmunk (5 kinds), Mole, Gopher, Rat (2 kinds), Mice (3 kinds), Vole (2 kinds), Shrew (2 kinds), and Bat (5 kinds)!

I haven't even seen half of these mammals, for several reasons. Firstly, a lot of them are active at night or live underground. Secondly, they are usually very good at being quiet and undetected. Whenever I see a wild animal it is already looking at me and withdrawing from view. Thirdly, they aren't that numerous! Below, is a short account of the mammals I have been lucky enough to photograph in the Lakes Basin!

The cute little Chipmunk above was eating some kind of seed right off the trail. It didn't seem disturbed by us at all, and stayed there until it was done eating! There are at least 5 different kinds of Chipmunks inhabiting the coniferous forests of the Lakes Basin. In the field they are very difficult to identify, as they are so close in coloration. I think the one pictured above might be a Lodgepole Chipmunk, and the one pictured below might be a Long-eared Chipmunk. They are both common in the Lakes Basin.

Long-eared Chipmunk (?) - Tamias quadrimaculatus

Chipmunks are primarily fruit, nut, and seed eaters, but will also eat fungi (primarily truffles), bird eggs, and insects (caterpillars, aphids, termites, ants etc.). They are known for climbing trees and shrubs to find food. They all have fur-lined internal cheek pouches for carrying nuts and seeds. They cache food for winter as they do not hibernate. They sleep most of the winter and awaken periodically to eat. Their nests maybe be in an underground burrow, or in cavities of trees, logs, stumps, or snags.

Golden-mantled Ground Squirrel - Spermophilus lateralis

Golden-mantled Ground Squirrels are not as commonly seen as Chipmunks, neither are they related. Visually they are easily distinguished from Chipmunks, by the lack of stripes on their head. They also don't climb trees and shrubs to get seeds, but prefer to eat them on the ground. In addition to seeds, nuts, fruits, and fungi, they also eat grasses and leaves. Although not as much of an insect eater as a Chipmunk, they will eat them if they are easily available. These squirrels hibernate in an underground burrow in the winter, and live off their stored body fat!

Douglas Squirrel/Chickaree - Tamiasciurus douglasii

Another noticeable squirrel is the Douglas Squirrel/Chickaree. They often scold me loudly from trailside trees! Conifer seeds are their main food, but they will also eat fruit, berries, seeds, fungi, bird eggs, flowers, and leaf buds. Douglas Squirrels/Chickarees do not hibernate in the winter! They store 100's of cones on the ground, in large caches for winter. They will dig down through the snow to eat the seeds in these stored cones. They do not live underground. Their nests are mainly found in hollow trees, or abandoned woodpecker cavities, 15'-20' above the ground. They will also sometimes build a ball or cup-shaped nest out of leaves and twigs, up in the branches of a tree!

Yellow-bellied Marmot - Marmota flaviventris

I'm always thrilled when I see a Marmot, as they aren't that common. Sometimes you can hear them emitting a loud repeated "chirp" call that indicates they are on alert. When frightened, Marmots increase the speed of these chirps into a series called a trill. The closer the danger, the shorter the call. They do this to warn other members of their colony that a possible predator is near.

Yellow-bellied Marmots are the most common large rodent in the Sierra, and generally live underneath rocky talus slopes from 5,400' to 14,000' near vegetated meadows. They primarily eat plant material, insects, and bird eggs! They store up fat for the winter, through which they hibernate underground. Most reside in underground colonies of about ten to twenty individuals, consisting of males, females, and their offspring. Their underground tunnels have many side passages, in which they raise their young, hibernate, and hide from predators. There is only one breeding season per year, which starts two weeks after they wake up from hibernation.

Columbian black-tailed Deer - Odocoileus hemionus columbianus

Surprisingly I rarely see deer in the Lakes Basin. They probably see me way before I see them, so it's always a delight when I spot some! The doe and fawn above were shedding their reddish summer coat and replacing it with a gray winter coat. That's why they look so blotchy!

California Mule Deer - Odocoileus hemionus californicus

This buck had been sleeping when I came hiking down the rocky slope above him. I startled him and he startled me! It was the first antlered buck I've ever seen in the Lakes Basin! From his ears and his tail, he was identifiable as a California Mule Deer! He stared at me for some time, and then slowly ambled off into some brush! What a great sighting!

There are two kinds of Mule Deer in the Lakes Basin, the Columbian Black-tailed Deer and the California Mule Deer. The California Mule Deer have larger ears (20”-22” compared to 8”) than the Columbian Black-tailed Deer. Another way to determine which species you are seeing is to look at their tail. Columbian Black-tailed Deer have a more-or-less solid black tail. The California Mule Deer's tail is only black on the tip, sometimes with a thin strip of black running down the tail.

Black Bear - Ursus americanus

This bear wasn't as close as it looks! Due to my great camera and its 2,000 mm zoom lens, I was able to get close from a distance! I don't know if it was male or female. There weren't any cubs accompanying this bear so maybe it was a male. I watched it forage on the green plants for several minutes before I left it to its afternoon meal! Another great sighting!

Bears are omnivores, but mainly eat insects, grubs, fruit, berries, roots, twigs, buds, honey, and tree cambium. Occasionally they will eat small to medium-sized mammals and carrion. They range in size from3'-3'5'' in height, 4'6"-6'2" in length, and 203lbs.-587lbs. in weight. Adults can run up to 30 mph, and are powerful swimmers and climbers! Here in the Lakes Basin, Black Bears don't truly hibernate. They build up fat to live off of in the winter, and spend most of their time sleeping, but may become active if the weather is unusually warm.

Fireweed - Giant Red Paintbrush - Western Eupatorium

Chamerion angustifolium - Castilleja miniata - Ageratina occidentalis

Late Bloomers!

The meadows and dry areas are still in bloom with thousands of flowers in the Lakes Basin! Gone are the Leopard Lilies and Buttercups, but many other beautiful flowers have taken their place! Get out there and enjoy them while you can!