How does this work?
Martinez, California, United States

Briones Regional Park Exploration

Just a 10-minute drive from Berkeley, Briones Regional Park is a 6,117 acre park in Contra Costa County.

provided by
Viewed 39247 times
    This guide contains photos
 (14 votes, 5 reviews)
Difficulty: Moderate
Length: 2.2 miles / 3.5 km
Duration: 1-3 hours
Overview: Just a 10-minute drive from Berkeley, Briones Regional Park is a 6,117 acre park in Contra Costa County. Its home to plentiful East Bay wildlife, including birds, snakes and newts. In some areas, it's still used as grazing land by local herds, part of a cattle ranching history that's more than 100 years old. The park's ridge tops offer stunning views of Mount Diablo and the San Francisco Bay.


California Newts

One of the most unique species found in Briones Regional Park is the California Newt (Taricha torosa). With a brown dorsal and bright orange belly, they look almost exactly the same as another amphibian found in the park, the rough-skinned newt (Taricha granulosa). Their coloring isn’t just for decoration. California newts are actually poisonous. They contain tetrodotoxin, or TTX, the same neurotoxin found in pufferfish. The toxin acts as a deterrent against predators, but recently, scientists discovered that one predator, the garter snake, had found an advantage. Charles T. Hanifin, an evolutionary biologist at Stanford, and colleagues studied 20,000 garter snakes and 500 newts in habitats along the Pacific Coast. They discovered in four areas, garter snakes had developed a resistance to the newts’ poison. One of the areas is Briones Reservoir, directly next to Briones Regional Park. This toxic arms race between species is known as “co-evolution.”


With rolling hills and narrow valleys, the park can be accessed from Lafayette, Orinda, and Pleasant Hill.

Alhambra Staging Area 2537 Reliez Valley Road Martinez, CA (Map)

Phone: 925-370-3020

The park is open from 8 a.m. to 10 p.m.

There is a $3 parking fee at most staging areas

Points of Interest


Velcro Plant

You'll find this weed, also known as "bedstraw", growing along the trails of Briones. The leaves of the Velcro Plant (Galium aparine) have tiny hooks, much like Velcro, that help it cling to other surfaces.

Briones is still used as pasture land for cattle herds, much as it was used in its early history as a working ranch. The grazing is carefully managed by the park to help keep fire danger low.


California is home to 18 native oaks and you can see six of those in Briones. In this spot, you can see Valley Oaks, a species most often found along the coast and Black Oaks, a species found in the foothills and mountainous areas of California.

These "oak apples" are actually created by gall wasps. Female wasps lay their eggs into the branches of oak trees. The oak forms the gall around the larvae as a defensive response.

The gall protects the wasp eggs and larvae until they tunnel out of it, as these tiny holes show.

High in the branches of oaks and other trees, you'll see mistletoe growing in Briones. It actually acts as a parasite, pulling water and nutrients from its host.

Wolf Spider

Spring is mating season for wolf spiders and these solitary hunters can be spotted around Briones. Male spiders can be identified during that time by their enlarged pedipalps - the pseudo fangs near their mouth - where they keep their reproductive material.

The hills of Briones are normally a dry, golden color. But winter rains turns the hills bright green and small wildflowers can be seen among the grass. This flower is known as red maid (Calandrinia ciliata).


A bee investigates a catkin - the reproductive structure of a willow tree.

This corral on the side of th trail is still used by the cattle herds. Old Briones Road Trail was once a road used by the ranchers in the area.


The rock and soils of Briones are actually very sandy. Millions of years ago, this was a shallow inland sea, where many nearby rivers were depositing material. This loamy soil combined with the three active faults in Briones means much of the landscape is constantly shifting.

Twelve million years ago, the East Bay was home to a shallow inland sea. You'll see shells and other fossils that were laid down then in the rocks of Briones.

Another shell fossil found in the rocks along the Old Briones Road Trail.

Oak Tree

You'll find a wide array of oak species in Briones because it is a transitional area. Both California coastal species and California interior species can live in Briones' climate.

These leaves are from two oak species found in Briones. The leaf on the right is from an Interior Live Oak (Quercus wislizeni), and the left is from a Coast Live Oak (Quercus agrifolia). You can tell you're looking at a Coast Live Oak leaf, because they have small, fuzzy hairs on the underside of their leaves.

Western Fence Lizard

Western fence lizards are common in California. Amazingly, scientists have found that they may play an important role in limiting the spread of Lyme disease. When ticks feast on the lizards, something in the lizards' blood helps destroy the Lyme disease microbes found in ticks.

Photo by Squamatologist

Stock Ponds

You'll see several small ponds like this one throughout Briones. Some are stock ponds, created for the cattle herds that use the park. Others are vernal pools, which fill in the rainy season and dry up during the summer. Both types of pools provide important habitat for amphibians and other species.

If you're near a body of water, these small frogs will let you know. Despite their size, Pacific Chorus Frogs (Pseudacris regilla) have a loud, high pitched call. You probably won't see them, though. These frogs hide in burrows and holes around bodies of water.

Many species of frogs lay eggs in loose clusters, such as this one. They're often attached to sticks or foliage in ponds or pools.

During mating season, you'll see California Newts (Taricha torosa) in many of Briones' ponds. They arrive beginning in December each year for mating season, having migrated to the ponds from their homes on land. If you do encounter newts in the ponds, make sure to give this sensitive species plenty of space.

Female California Newts lay their eggs in dense balls in the shallow areas of ponds or pools. After mating, both the female and male newts leave the ponds and head back to their life on land.

View from the Ridge

From this spot, hikers can see Mt. Diablo and the San Francisco Bay. On clear days, you can often see the snow-capped Sierra Mountains directly east.

California Newt

The bright orange color of California Newts (Taricha torosa) is a warning sign. These newts contain a neurotoxin called tetrodotoxin that helps protect them against predators like garter snakes. It's the same toxin that is found in pufferfish.

Each year beginning in December, California Newts (Taricha torosa) leave their land dwellings and make a slow migration to ponds for mating season. If you see them on the trails, make sure to give them plenty of space.

Yellow Star Thistle

This invasive was introduced to California in 1849 with alfalfa brought from Chile. It has now spread to 15 million acres in California. The spiny plants causes problems for livestock and wildlife, and also has high water usage, competing with native plants for resources.
Pictures in this guide taken by: craigrosa, Squamatologist
uffff.... it was a narrow escape

by inqueba on Jul 17, 2014
i remember that day... i was feelin sick.. but mt freinds gave me a great time

by hairtransplant on Jul 17, 2014
The trails are easy to walk on, and you have great views of the local mountains including Mt. Diablo. I have taken many photos of birds, insects, deer, etc... Make sure you take a insect spray for ticks. They do have ticks with lyme disease there, so be careful. I have never ahd any issues though! Bring water to drink, it can get hot in areas with no cover!!
Visited on Aug 16, 2010

by aynrutter on Mar 04, 2011
OK, we got to meet some newts on this one. Anyone seen newts on their hikes?

by craigrosa on Nov 15, 2010
I went backpacking in Point Reyes in December last year and they were everywhere on the way back (once it started raining). We had to watch our steps. That was also the first time I ever saw someone hiking with an umbrella...

by chris on May 04, 2010

Briones Regional Park Exploration Trail Map

POIs: numbers | icons View large Trail Map

Have an iPhone or Android?

  • Map your route while you move
  • Add trip photos to your map instantly
  • Share trips right from your phone
  • Find and follow trips from other travelers

Available For:
iPhone | Android

About the Author

20 guides
view craigrosa's profile
Hi. I'm a Senior Interactive Producer for KQED in San Francisco, CA for KQED Science , which covers science,...

Briones Regional Park Exploration 3 Day Forecast

Extended Forecast
How To Get There
Get directions from: