Species of the Refuge
Want to learn more about the Don Edwards San Francisco Bay National Wildlife Refuge? Check out this quick and easy learning module to get to know the animal and plant species that call the Refuge home. Whether you learn more about Salty the Salt Marsh Harvest Mouse or watch a video of Snowy the Snowy Plover - there is something here for all ages to get excited about!
This special module was created for the Refuge's annual Marsh-In Summer campers, and we are so thrilled to finally bring it to you!
If you are interested in learning more or want to know how you can apply your newfound knowledge to visiting the Refuge, please email firstname.lastname@example.org.
Here are some of the animal and plant species that call the Refuge home:
What is a producer? Producers are green plants or organisms like phytoplankton that produce (make) their own food! Here are some that you’ll see around the marsh and slough:
- Western Snowy Plover*
- California Ridgway’s Rail*
- American Avocet
- Black-necked Stilt
- Great Egret
- Peregrine Falcon
- Red-Tailed Hawk
- Great Horned Owl
What is algae? Algae is not an actual species, but an informal term for a large and diverse group of photosynthetic organisms in water.
Phytoplankton is a type of microscopic algae at the base of every water food chain. These “plants” get eaten by zooplankton and other small organisms, which in turn get eaten by fish, and so on.
Video to Watch: Biologist Karli Woodward investigates San Francisco bay plankton. https://youtu.be/A9AKf6OnuPg
Pickleweed (scientific name: Salicornia) is a common plant that grows on salt marshes and beaches. It is a very important part of the wetlands food chains because it gets eaten by many animals, including Salty, the Endangered Salt Marsh Harvest Mouse!
Video to Watch: Learn more about this colorful, edible marsh plant. https://youtu.be/1rFeRjSqp50
Tule (scientific name: Schoenoplectus acutus) is a plant native to freshwater marshes all over North America.
Ohlone people use tule roots, pollen, and flowers as food. The spongy stems are used to make baskets and boats for fishing.
Video to Watch: Building a Tule Boat at the 2018 Ohlone Youth Summit https://youtu.be/EbrT2uFYa5w
Western Snowy Plover *
This species is a threatened small shorebird, approximately the size of a sparrow.
Predators: Falcons, raccoons, coyotes, owls, crows, dogs.
Freshly hatched chicks This small bird is at risk of becoming endangered because of habitat loss and human disturbances. Kites and drones look like predators to plovers, so when they fly away in fright, their babies become exposed to real predators.
Video to Watch: Learn more about the Western Snowy Plover https://youtu.be/mWH4b2jZLCM
California Ridgway’s Rail (Cali) *
Cali is an endangered species that currently only appears in the San Francisco Bay Estuary. She is secretive and hard to observe, but if you’re lucky, you might see her hiding in the marsh!
Eggs: Usually 7-11, sometimes 5-12+. Incubation by both parents
Nest sites: In clump of grass or marsh vegetation, often with a ramp of plant material leading up from
Predators: Squirrels, rats, weasels, gray foxes, skunks
Diet: Crustaceans (crabs, crayfish), insects, fish.
Video to Watch: Bird call https://youtu.be/JvbdWFtWGuk
Cheep, cheep! If you see a Black-necked Stilt (Recurvirostra americana), you might see American Avocets mixed in with them.
These birds breed in the Great Plains and are found along the coasts of California and Texas.
Eggs: 4, sometimes 3-5. Female incubates at night, both sexes take turns during day. Both parents tend to young, who self-feed and start flight around 4-5 wks old.
Nesting: Often form colonies. Aggressively and loudly protect nests, sometimes flying straight at intruders.
Life span: 9-15 years
Diet: Small crustaceans and insects, also seeds
Video to Watch: Bird call https://youtu.be/MVpneSwOuAA
Kek kek kek! Do you hear that? That’s our Black-necked stilt (Himantopus mexicanus). You can often find a stilt parent with their babies in the shallow waters of the marsh!
Diet: Insects (brine flies, beetles) and crustaceans (shrimp, crayfish), sometimes tadpoles or tiny fish
Eggs: 4, sometimes 3-5. Both parents incubate eggs. Young feed themselves & start flying at 4-5 wks old.
Nesting: Often form colonies in groups of 6-10 nests. If predators approach by foot, several adults may fly to a spot and perform a distraction display there.
Life span: 20 years
Video to Watch: Bird call https://youtu.be/_6zncP-AkAs
Great egrets are one of our biggest birds on the marsh. Formerly endangered by hat plume hunters, these beautiful birds love to forage in the marsh, slough, and mudflats.
Often mixed up with the Snowy Egret, which is smaller and has a black beak.
Diet: Mostly fish, also crustaceans, snakes
Eggs: 3-4, sometimes 1-6. Pale blue-green. Both parents feed by regurgitation.
Nesting: Sometimes isolated, usually in colonies with other types of birds in trees, shrubs, or low in thicket or marsh.
Life span: 15 years
Video to Watch: Watch this clip of the Great Egret self-grooming, socializing and flying! https://youtu.be/Jb8G6aga728
A fierce predator, the Peregrine Falcon can sometimes be spotted flying over the refuge, looking for its next meal. They can dive 200-240 miles per hour, making them one of the fastest animals on the planet.
Eggs: 2-4. Both parents tend to eggs, and chicks fledge (leave the nest) at around 6-7 weeks old
Nesting: Typically nest on cliffs or other high rocks jutting out. They use sticks, grasses and other plant matter.
Life span: 8-10 years
Diet: Carnivorous; mostly other birds such as pigeons, doves, waterfowl
Video to Watch: The Fastest Bird on Earth https://youtu.be/LHQSdJti4JA
Did you see that flash of orange-red in the sky? That was the red-tailed hawk! A top predator, this bird is known for its impressive soaring and diving while searching for prey or defending territory.
Eggs: 1-3, mostly 2. Both parents incubate eggs, with female spending more time.
Nesting: Known for reusing the nests of birds such as crows and ravens, or build their own in trees or on cliffs.
Life span: 10-15 years
Diet: Rodents, rabbits, snakes, other birds
Video to Watch: Bird call https://youtu.be/lP0BPc023qg
Great Horned Owl
Whoo’s hooting? That might be the great horned owl– and there’s a nest at the Fremont refuge right across from the Visitor’s Center parking lot!
Eggs: 2-3, sometimes 1-4. Chicks fledge (leave the nest) at 6-7 wks old.
Nesting: Known for reusing the nests of other birds such as hawks and crows. They build simple nests in trees, cliffs, and even on the ground.
Life span: 5-15 years
Diet: As apex predators, they eat small mammals (i.e. rodents), birds, reptiles, and even other owls and skunks.
Video to Watch: Bird call https://youtu.be/ugjnrjz23lI
Not to be confused with the larger native species the Black-tailed jackrabbit, the California Brush Rabbit is a type of cottontail rabbit you might see bounding past the trails at the refuge or hear rustling in the brush.
Diet: Herbivores – grasses, leaves, and other plants Predators: Hawks, owls, foxes, and coyotes
Reproduction: Females have multiple litters throughout the year, birthing 2-5 each time. Young rabbits become independent around 4-5 wks old.
Life span: 1-2 years
Video to Watch: Learn more about Brush Rabbits https://youtu.be/geiePEElPNo
Salt Marsh Harvest Mouse *
Salty is one of the most endangered mammals in the United States. Efforts are underway to protect and restore its habitat!
Diet: Omnivores – seeds, insects, snails
Habitat: ONLY the salt marshes of the San Francisco Bay Area!
Predators: Owls, hawks, snakes, and other small mammals
Reproduction: Females have multiple litters throughout the year, birthing 2-5 each time. Young mice become independent around 4-5 wks old.
Life span: 6-12 months
Fun Fact: Salty is only the size of your thumb!
Video to Watch: Biologists conduct annual surveys of the salt marsh harvest mouse. https://youtu.be/_P8uG45zioc
It’s not uncommon to find raccoon tracks in the mud of the salt marsh. These foragers love the food they can find at the refuge!
Diet: Fruits, nuts, insects, small mammals, even fish Predators: Coyotes, bobcats, other large mammals.
Reproduction: Breed in late winter or early spring, litters of 3-5 young born blind and helpless, cared
for several months before becoming independent
Life span: 2-3 years, but some have lived 5+!
Video to Watch: Learn more about this masked Bay Area resident from a wildlife ecologist https://youtu.be/qaF3LXO56aw
Gopher snakes are non venomous and usually harmless. If you see one, quietly step away and make
sure not to disturb it!
Diet: Birds and their eggs, small mammals such as rodents. Gopher snakes are constrictors, wrapping their body around prey until they suffocate, then swallowing their prey whole.
Predators: Coyotes, foxes, bobcats, birds of prey, cars, humans who mistake them for dangerous snakes
Length: Up to 7 feet long
Fun Fact: They use dry leaves or the ground to imitate the rattling sound of rattlesnakes and ward off predators.
Video to Watch: Learn more https://youtu.be/0IV_5fXRJZY
Western Fence Lizard
This is the most common lizard species of California! It is characterized by its blue belly and ability to escape predators by breaking off their tails.
Diet: Mostly insects
Predators: Snakes, foxes, coyotes, birds of prey
Life span: 5-8 years
Fun fact: When ticks carrying Lyme disease feed on western fence lizards’ blood, a protein in the blood kills off the bacteria, stopping the spread of Lyme disease!
Video to Watch: Learn more https://youtu.be/fy9yXjnbXV8