UC Davis Natural Reserve System
Stebbins Cold Canyon Reserve

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Vertebrates of Cold Canyon  

The sign at the entrance to Cold Canyon warns one that they are about to enter mountain lion country. Despite claims of mountain lion encounters in the log book, most of the action is down near the ground where reptiles, mammals, and birds scurry into the manzanita brush at the sound of approaching footsteps. Frequently, the signs of animal activity are quite visible while the animals themselves remain elusive. Observing wildlife in Cold Canyon requires patience and persistence.

The reserve's canyons and hillsides are, in fact, home to scores of wildlife species. At least 10 species of snakes, including the western rattlesnake, live in the canyons along side salamanders, frogs, and lizards. In total, there are at least 25 species of reptiles and amphibians who make this their home, and with the possible exception of a few western fence lizards, most go unnoticed by the day hiker. So, too, do the 40-odd species of mammals who are mostly active only during the hours of darkness. While many of the canyon’s resident birds are active by day, many stay hidden in the brush. Other birds are active only at night, and many others are not even residents, using Cold Canyon as a rest stop during migration or other travel.

Signs of Wildlife.   While many vertebrates will elude the obervations of even patient observers, most of these animals will leave tell-tale signs of their presence. The most common signs of mammals are their tracks. In the rainy months, or in the mud near the creek, the ground is soft enough to preserve theanimals’ foot impressions. Because many mammals are elusive and nocturnal, their tracks are often the best way to determine whether they inhabit the area. Other common signs of activity by mammals are their scats. Look for them along the trail, sure sign that a mammal recently walked by. Like tracks, scats can also be used to identify the presence of particular species.

Other signs of animals include the houses they build. Most birds build nests, often hidden in the tangled branches of a chamise or manzanita bush, but sometimes more exposed and observable. Dusky-footed woodrats build a complex house out of sticks and other debris contain. These conical structures are impressive structures, up to 6 feet tall and 8 feet in diameter, with a thick roof and several passageways leading to multiple chambers.

Observing Wildlife. Here are some suggestions if you want to observe the vertebrates of Cold Canyon.

First, remember that many animals have much keener vision, hearing, and sense of smell than humans do. If you try to approach something moving in the brush, chances are that the animal will notice you and retreat, or freeze in fear and remain hidden in the bush. Often the best way to observe these animals is to sit motionless, be very quiet, and wait. If you escape detection by the animal for several minutes, the animal may come out from hiding. Better yet, start your observations without the animals knowing you are there. Pick a quiet comfortable place in which you are relatively hidden. Because many animals can detect you simply by your smell, your observation place should be downwind of the area you want to observe. Use binoculars to observe animals from a greater distance than they can detect you.

The animals you observe will greatly depend upon the time of day you visit Cold Canyon. To the midday visitor, first impressions can be misleading. Nothing seems to be out and about. Except for the chatter of a few birds, a fleeting glimpse of a squirrel, or the skitter of a lizard, there just doesn't seem to be any life to the area.

Come back at first light of morning, and you'll have a completely different sensation. Tread your way up the canyon, away from the highway, and you'll hear what birders call the dawn chorus. You'll be surrounded by dozens of songs, coming from just as many bird species. During this time, it is much more easy to spot particular birds, because they boldly sing from conspicuous perches and may even be attracted to you if you whistle.

Or, arrive in the late afternoon and wait for dusk to creep up the canyon slopes. At sundown, the coyotes begin their yipping up canyon, and owls start to call from their tree limb perches. Harvest mice and meadow mice will be roaming the grassy hills, searching for seeds and insects. And dusky-footed woodrats begin to stir from their complex houses of interwoven sticks and leaves, in search of food and more plant material to add to their houses.

The season you visit Cold Canyon is as important as the time of day for observing particular species of vertebrates. Many more bird species are active during the spring and summer than in other seasons, and your chances of seeing rare birds occur during the early spring and fall migrations. Reptiles depend on the warmth of sunshine, so most are active in late spring, summer, and early fall. However, most amphibians require moisture, and as a result can be easily observed only in late fall, winter, or early spring. Mammals are present year-round, but many are inactive through the winter.

Last Updated 03/09/06