Ladybugs Photo

Areas of open space in the Santa Clara Valley are home to hundreds of different animal species. There is more to know than a person could learn in a lifetime of studying them and visiting their habitats. We’ve provided a few bits of information about some of the animals you might see on a visit to OSA lands.


Mountain Lion

Mountain Lion
This is the fourth largest cat in the world. An adult male may be more than eight feet long from his nose to the end of his tail. Mountain lions can jump 20 feet straight up into a tree. They like high places and overlooks because that is how they catch their prey. They are stalkers. They creep up and leap. What do they eat? Mostly deer. As you walk along the trail, look for deer tracks. Mountain lion tracks may not be far behind. Mountain lions can scream and purr, but they cannot roar.


Yip, Yip, Yip, Arooooo! Have you heard a coyote call? These carnivores are wild dogs. When they’re young they run in packs of all males or all females. An adult female will be pregnant for two months and probably have six puppies, but some coyotes have been known to have as many as fifteen. What do you suppose they eat? Their diet is mostly small mammals like rabbits and squirrels but they also eat birds, snakes, lizards, roadkill and domestic pets. Occasionally they even work together to take down a deer.

Merriam’s Chipmunk

Merriam’s Chipmunk
These rodents are small, striped, and very quick. They eat many kinds of plants including the manzanita berries from bushes on the Mayfair Trail at Rancho Cañada del Oro Open Space Preserve. They live in the shrubs in small nests and dart in and out collecting and eating berries and small grass seeds. They make a high-pitched squeaky sound to warn each other of possible danger.



Say hello to one of the most elusive and interesting predators in our area. Badgers are short and squat, low to the ground, with a thick, muscular body and long hair. They do not chase their prey but dig them out of the ground with their powerful claws. They eat gophers and ground squirrels. When threatened, they hide by lying flat against the ground. Badgers can be ferocious and will often fight to the death. In winter they go into a partial hibernation until the weather changes and food is more prevalent.

black-tailed deer
Black-Tailed Deer
A good sized buck (male deer, not a dollar bill) can weigh as much as 250 pounds. They can be three feet tall at the shoulder and leap up to eight yards at a time. Did you know they can run up to 45 miles per hour? A buck’s antlers fall off every year in January. They start growing again in spring. The number of points on a deer’s antlers depends on the amount and quality of the food they are eating. It has nothing to do with age.



Mourning Dove
Doves are different from other birds because they sleep with their heads hunkered down, not facing their tail like other birds. Instead of tilting their heads back to drink, they also gulp water. They almost always lay two eggs, a male and a female. Affectionate birds, they frighten easily and you will hear their wings whistle as they take off from the fields.

turkey vulture
Turkey Vulture
These large birds are sort of gross but perfectly adapted for what they do: They eat dead things. They have bald heads and legs because they put both inside of carcasses. The ultraviolet light from the sun kills the bacteria on their black feathers. They urinate on their legs so the uric acid in their waste can kill any bacteria. When they’re alarmed, turkey vultures throw up, and their stomach acid smells so bad it will chase any mammal away. Once the threat is gone, the vulture recycles the food.

Red-Tailed Hawk
This is the most common and widespread hawk in America. The call of the red-tailed hawk is often used in movies to represent various raptor species. Did you know that female birds of prey rule the roost? Females are larger (by 25%), louder and more aggressive than the males. A male will challenge other males but if a female challenges him he fights to escape. Red-tailed hawks are sharp-eyed hunters: They can see a mouse from a height of one mile.

Western Screech Owl
With gray, black and white feathers, this little owl will blend into a tree’s bark so well you may not even realize you are looking at him. Western screech owls have a soft little trill of hoots that all run together. There are at least three of these birds in the meadow at Rancho Cañada del Oro. If you go at dusk and hoot softly, they may begin to call. Remember, they are small birds, just about six to seven inches tall, so don’t scare them with an overly loud hoot.

American Kestrel

American Kestrel
This is the smallest of the falcons in North America. It’s a little bird with confidence the size of the Grand Canyon. Kestrels hover when there isn’t a suitable perch available and then dive for their prey. They eat insects, rodents, snakes and smaller birds. They may be small, but they are feisty.



Reptiles and Amphibians

Gopher Snake
Gopher snakes will try to fool you into thinking they are rattlesnakes. Who better to pretend to be than a snake with venom and a fierce rattle? Gopher snakes have dark brown squares of color on their backs, making a ladder-like pattern. (Rattlesnakes have a diamond pattern.) Although they may press their chin into the ground to make their jaw bones stick out, they are actually streamlined in shape. They are most active in the daytime. Gopher snakes are constrictors. They squeeze their prey and suffocate it before eating.

Western Rattlesnake

Western Rattlesnake
In order to move quickly enough to hunt, rattlesnakes warm their blood in the sun. They kill by biting and injecting poison into their prey. Snakes have flexible, rubbery tendons in their jaws and a two-piece lower mandible, which allows them to open their mouth very wide. If you could open your mouth as wide as a rattlesnake, you could swallow a watermelon whole. If a rattlesnake loses a fang, it will grow another in its place.


Have you ever seen an amphibian that looks like it’s made of glass? This is an ensatina. It has no lungs and breathes through its skin. The moist, translucent skin helps ensatinas absorb oxygen and water. They only comes out at night when it’s very wet. Every winter they must absorb all the water they need for the entire dry season. If they’re exposed to sun or dry weather, their skin will dry out and they’ll suffocate.

Western Toad
Toads use their eyeballs to help them eat. When they swallow, their eyes go into their head and bulge into their throats, helping to push the food down. They have special feet for digging holes in the mud and dirt. Toads have interesting defenses. A female will blow herself up with air to make it really hard for a predator to swallow her. A male will squeak and chirp like a little dog. If toads get really frightened or hurt, they will ooze poison over their skin from glands behind their eyes.  

Western Rattlesnake
Western Fence Lizard (a.k.a. Blue Bellied Lizard)
Robert Lane of University of California, Berkeley has discovered that there is something in the blood of a western fence lizard that kills the bacteria that causes Lyme disease in juvenile ticks. This type of lizard likes to sit on raised surfaces where it can bask in the sun and watch for predators or potential prey. Western fence lizards like to eat small insects and arthropods and will keep a darker shade of skin in order to simulate a shadow in a rocky depression to ambush prey.


What does a bullfrog eat? Anything moving that fits in its mouth.. When a bullfrog sees prey, it shoots out a long, sticky tongue to grab it and pull it close. Then it uses its feet to stuff the victim into its mouth. What does all that croaking mean? It’s advertising. Male bullfrogs are telling the ladies they live in an area full of food. If a female sings back, she’s saying she’s interested. A female bullfrog can lay 25,000 eggs. Tadpoles can stay in the tadpole stage for up to two years. The longer they stay in this stage, the bigger and stronger they will be as frogs.

Insects and Arachnids


Have you ever found holes in the ground surrounded with a thick, blanket-like web? These are tarantula dens. Tarantulas have small, spear-like hairs on their abdomens. They flick the hairs at would-be attackers. Depending on the size of the predator, the hairs can irritate or even kill. Spiders have unusual, book-like lungs with thin membranes that hang down like pages. Air passes into their bodies through small openings in the underside of their abdomen. Because of their lungs’ open nature, it is very easy for a tarantula to drown.


Tarantula Hawk
This insect preys on tarantulas. There are many types of spider wasps, but the tarantula hawk is present on our preserves. It has a long black body and bright orange wings. This wasp has a very painful, venomous bite that paralyses or even kills the tarantula. The wasp then drags the body into a burrow. Many tarantula wasps only have one offspring, whose egg is laid inside the body of the tarantula where it can hatch and eat the remains. A common bee sting is said to be about a three on a pain scale of one to ten. A sting from a tarantula hawk is said to be closer to a seven or eight.

Oak Gall Wasp
Those spheres hanging in the oak trees that look like Christmas ornaments are oak galls. They are created by a tiny oak gall wasp. The wasp scratches a hole in the branch of a tree and lays an egg. The egg contains fake plant hormones that tells the tree to grow. The tree grows the gall, a tennis ball-sized home full of sugar and water that makes the perfect shelter and food source for the larva once it hatches. The larva grows until it becomes a wasp and eats its way out of the gall. If there are not enough male wasps to reproduce, the females can lay eggs on their own. The offspring will all be female, but it ensures the continuation of the species until more males are available.


Butterflies have three life stages. They start life as an egg, hatch as a larva (worm) and eat, eat, eat for a brief time, and then they go through a change called metamorphosis and turn into butterflies. There are dozens of different kinds of butterflies on our preserves. The most endangered and rare is the bay checkerspot butterfly. Did you know that butterflies smell with their knees and taste with their feet? When they land on a flower they stomp their feet. It kicks up “dust” particles of the scent which get stuck to chemoreceptors in their knees. These receptors tell them what they are smelling and tasting and whether or not this is the right plant to lay to lay eggs.