Critters you have a good chance of encountering in your backyard, while on a walk in the neighborhood park, in a strip mall parking lot, or in a golf course water trap. I've put ID & location tips in the Notes section for most species.
Sometimes found under stuff, particularly in the winter. Don't hassle these guys too much; they bite! Up to seven inches long, and grey/brown/pink with small bright yellow spots.
The most common lizard to see when out hiking. These like to sun on paths and rocks, and the males have bright azure bellies.
A popular pet that is often released into the wild or landscaped lakes. There are some in the Sunnyvale Arboretum pond, and probably lots of other parks in the area as well. Black overall, with some yellow detailing and red ear patches (and often quite muddy, obscuring the brighter colors).
Easier to hear than to see, though they will come and peck on telephone poles and yard trees and get quite close to the ground. Their call is a loud sort of "pid-it pid-it!" Example: http://www.allaboutbirds.org/guide/Nuttalls_Woodpecker/sounds
Males and juveniles have red caps.
Less common to see up close. The big black chest patch makes these easy to identify. Their wing feathers are tinted red, which is quite noticeable when they're flying above you (Northern Flickers in the eastern US have wings tinted yellow instead).
Escaped/released pets that have done well on their own. There are often some hanging out around the parking lot of the Orchard Supply Hardware in Sunnyvale, and I've heard that they come in to Las Palmas Park in the evenings.
Yep. Don't show up in suburban lawns, but can be found in all the downtowns and all along El Camino, often perched in rows on top of street or traffic lights. Come in quite a variety of colors and cross-breed with domestic pigeons.
Larger and much more skittish than regular pigeons. These are usually in small groups way up in tall trees, and will fly off when they see you coming. An unmarked grey-purple overall, with a bright white notch at the back of the head, yellow beak and feet, and a pale band and bright white patch under the tail.
Common. Tend to hang out in pairs or small groups and to stare at you like you've caught them doing something illegal. Dusky pink/brown with a long, pointed tail and black spots on the backs of the wings. Call is that sleepy coo-WOO, ooo, ooo, ooo: ...more ↓
Andrea's "demon ducks." All-black bodies, red eyes, white bill, and greeny-yellow feet. These like larger bodies of water and are more common towards the bay. There can be amazing numbers of them, particularly at the Shoreline golf course. Their chicks have bright orange fuzz and huge feet.
More often seen than heard, these are the things that make those loud eerie sounds at night. Check out "flight call" and the second "alarm calls" here:
http://www.allaboutbirds.org/guide/killdeer/sounds
They like athletic fields and schoolyards and making a ruckus.
Biggest, whitest bird around. Size of a Great Blue Heron. Long, all-dark legs, yellow bill (sometimes muddy greyish yellow), all-white feathers. Mostly in the baylands but can be seeing commuting overhead, or occasionally standing still in a field somewhere (they'll hunt squirrels and gophers). I sometimes see them standing on the grassy slopes next to 280, particularly around the ...more ↓
Big, mostly-grey bird; nothing else looks like it on this side of the country. Mostly in the baylands or along creeks but can be seeing flying overhead or occasionally standing still in a field somewhere (they'll hunt squirrels and gophers). I sometimes see them standing on the grassy slopes next to 280, particularly around the Stanford Dish, or in the Cuesta Park Annex. Fly with their ...more ↓
The most common hummingbird in the suburbs, these have a very distinctive, "squeaky gate" song. Examples here: http://www.allaboutbirds.org/guide/Annas_Hummingbird/sounds
Adult males have a bright, iridescent pink throat, face, and cap; while adult females have pink only in the center of ...more ↓
Easily found wherever there's water, these ducks readily acclimate to humans and often live and breed with loose domestic ducks. Mallards (and their domestic descendants) are the only North American ducks with such bright orange/yellow bills and feet, which, as they will hybridize with lots of other duck species, can be useful for telling if a particular "weird duck" has Mallard ancestry. ...more ↓
Often live in man-made ponds. They come in a variety of patterns and colors, but are always bigger and chubbier than wild ducks.
The most common hawk on the west side of the bay. These have a ton of color variations, some of which annoyingly don't have a red tail. But the "belly band" of brown streaks across their middles is another good way to distinguish this species.
Large, all-dark birds sometimes soaring up in the sky. Immature birds have dark heads and are a little browner. The lighter black part of their wings can sometimes weather to almost white and them look a bit like condors, but the white in California Condors' wings is in the middle and doesn't extend to the bottom edge: ...more ↓
Swallows hunt bugs on the wing and do wonderful high-speed maneuvers quite close to the ground or people. They like just-mowed lawns or people walking across fields, both of which help stir up bugs. They have long, forked tails (fork not always visible), reddish throats, and bellies that are solid light reddish.
Common around outdoor food courts. Males are black and iridescent green/blue/purple with pale eyes, and females and juveniles are dark brown with only a hint of more exciting colors. Make a "chuk, chuk" sound: http://www.allaboutbirds.org/guide/Brewers_Blackbird/sounds
Noisy little guys ("tsicka dee dee"): http://www.allaboutbirds.org/guide/oak_titmouse/sounds
Hop around up in trees calling; I haven't ever seen them come near the ground.
Small, active birds with distinctive black and white faces. Calls: http://www.allaboutbirds.org/guide/Chestnut-backed_Chickadee/sounds
Haven't seen these around more suburban parks and houses, but there are usually some in downtowns and outdoor seating areas around strip malls/El Camino Real (Rose Market and Sufi Coffee in Mountain View, for example).
Call an infinitely-repeated "Cheeyup. Cheeyup. Cheeyup.": ...more ↓
Downcurved beak, pronounced white eyebrow, tail striped and held upwards (tail posture characteristic of wrens). They like places with cover-- behind hedges, around plant pots and patio chairs, under eaves and hanging vegetation, etc. Raspy scolding call: ...more ↓
Robins like lawns and move like hop-hop-hop STAND. They have a variety of distinct calls and seem to particularly like being vocal in the evenings: http://www.allaboutbirds.org/guide/american_robin/sounds
Immature birds have less bright red breasts and brown streaks, and look kind of ...more ↓
Like the leopard, they pounce from above!
Like Black Phoebes (and leopards), bluebirds like to hunt by sitting on a high perch overlooking an open area and flinging themselves at prey that goes by. These are less common but I do see them in suburban yards, parks, and campuses (and tons in Arastradero Preserve and Fremont Older Open Space Preserve). They're often not very brightly ...more ↓
Mostly black with white bellies. Sit on high perches looking around and dart off to catch bugs mid-air in a flurry of wings. They like open areas with scattered/bordering trees, so are often in parks and yards. Slight head crest. Sweet tiny cheeps ("simple call"): ...more ↓
Small and usually rather drab. They appear on paths in front of you when you're out for a walk to the park. This species has a few subspecies/color forms; our western kind with the black head is called "Oregon Junco."
A bit less common to see. They like to stand at the very tips of trees and sing: http://www.allaboutbirds.org/guide/spotted_towhee/sounds
Common in backyards and parks. Often in pairs. Orangey under the tail and a bit on the chin, and otherwise the plainest, most bird-shaped bird I ever did see. Call a single "chip!" or string of chip-chip-chipchips: http://www.allaboutbirds.org/guide/california_towhee/id
These are the things that will just not shut up in the spring at 2am. They sing from the tops of telephone poles and trees, sometimes making short upwards flights in the middle of a phrase. Mimic any sounds, ranging from other birds to frogs to car alarms. Big white patches on both sides of the wings very noticeable in flight.
Noisy and curious, they'll bury acorns in all your plants. And shriek a lot: http://www.allaboutbirds.org/guide/Western_Scrub-Jay/sounds
Regular ol' crows. Omnipresent. Sometimes really a lot of them gather together and harass a hawk or owl, or make a house look like a murder scene.
Distinctive bright blue and black with a crest. Likes wooded areas and often goes around in pairs. More common up in the foothills, but there are some around Stevens Creek Trail and probably other places.
These act and look very much like House Finches, and the two species seem to hang out together on power lines quite often. Lesser Goldfinches have less streaking overall, no streaks on their fronts, and are tinted with yellow on their entire heads and undersides (the yellow can be bright or dull). Adult males are brighter yellow and have black caps. Often heard, with little "tchweeee. chup ...more ↓
Sparrow-sized birds that go around in small groups. The females look pretty similar to female House Sparrows, but the males have red all over their heads and fronts (some birds have yellow or orange instead of red, but red is much more common). Both sexes also have chests and bellies with lots of brown streaks, whereas House Sparrow's undersides are unstreaked grey.
Might see some while driving home after dark or out for a jog. They seem to use the drains/sewers as a subway.
Might come across one when out for a late-night jog, but most likely to smell where one used to be while driving on a freeway.
Introduced from the eastern US, apocryphally for a failed fur farm enterprise. White face (very pale in a flashlight beam) with a pink nose and a naked pink/grey tail. Nocturnal, disliked by dogs, and dumber than a sack of hammers.
Usually only visible as a little furry head peeking out of a burrow. They have very short ears, and are the only species of gopher in most of California. They live in a variety of habitats but are easiest to see in vacant lots, short-grass meadows, and lawns.
These come in either regular grey & brown or in all-black. The black ones are often more prevalent around certain locations, like the Stanford campus or Cuesta Park in Mountain View. These are the familiar squirrels that climb trees, rob gardens and birdfeeders, beg for scraps in parks, and chew on your property.
This species was introduced from the eastern half of the US and ...more ↓
These squirrels were introduced from the eastern US for some reason, and are now well-established in various spots in the west. Locally they seem to be particularly abundant around San Jose. These climb trees and eat your Halloween pumpkins and do all the regular squirrel stuff.
They look similar to Eastern Grey Squirrels, which were also introduced from the eastern US, but with ...more ↓
Not in suburban lawns, but in pretty much any bit of spare land towards the bay or hills-- baylands parks, salt pond berms, railway and airport land, next to walking or biking trails, etc. These graze and live in burrows but will climb fences or short trees to escape or sun themselves (the fences around the Stanford Dish are often covered in ground squirrels, for example). Tell them apart ...more ↓
Common introduced species. Small and pale greyish. You can find lots of these under rocks, in compost piles, and wandering around on sidewalks on nights after rain.
Big (up to 4") slugs that come out at night or appear under the lid of the compost bin. Mottled yellow and grey.
Supposedly introduced for escargot farming. Now a big garden and agricultural pest. Sometimes there are just amazing numbers of these on lawns at night.
Introduced from Europe, these spiders make large, impressive webs around houses and vehicles. Base color ranges from brown to quite red, but they always have a white cross on the top side of their abdomens.
Preys upon pillbugs, so can be found wherever those are found. I usually see them in the compost heap, or scuttling away when I move things around outside.
Big, fat, vivid green caterpillars with white stripes and a bright red spike at one end. Eat a prodigious quantity of tomato leaves and have interestingly-shaped poop. They pupate underground and turn into brown moths.
A small, moth-colored butterfly. Their tiny fuzzy green/pink caterpillars are adorable and feed on legume seed pods.
Common white butterfly introduced from Europe. Almost always on the move. Will thoroughly infest all cabbage/broccoli/cauliflower with its green caterpillars.
Little flutterbys that seem to be particularly abundant in the fall. The out-side of their wings is mostly orange with small brown spots.
Large, dark, shiny bees with wonderful iridescent colors. They drill round holes into wood to raise their young in. Alarmingly big and loud but actually mild-mannered. One of the sexes can have some yellow fuzz, but I forget which.
Those tiny little ants that sometimes come into the house in the wet season. After rain (particularly the first fall rains) you can sometimes see aggregations of winged ones embarking on their nuptial flight. An invasive species accidentally introduced to the US in the soil of oleander plants. They form supercolonies with hundreds of queens each (look this up, it's amazing. each ...more ↓
Invasive species that makes those little papery honeycomb nests up under the eaves of houses.
Junebugs that fly in great numbers in May/June and always manage to get into the house somehow.
Introduced from Europe. Not harmful to humans, but can be a real annoyance in gardens.
A fly and not a giant creepy wasp! Their larvae like compost heaps and rotting things.
While there are native pillbugs, these introduced ones are the most common and most abundant. Ones that are blueish/purplish are not a different species, but rather the same species infected by a blue/purple iridovirus.