Presidio’s Greatest Lists: Signs of Winter

Thursday, Dec 01, 2016 Category Nature and Science

It's Winter Solstice, and all around the Presidio we're seeing our natural landscape respond to the season. After months of drought, fall rains are coaxing seeds to sprout to life. Creatures, like birds and banana slugs, are currently more active and visible. To help you embrace the season, here are some of the greatest signs of the season, and some great places – and ways – to experience the beauty of winter in the Presidio.

Find the Fungi in the Forest

Mushrooms might be called "the wildflowers of winter." When the rains begin, these sometimes colorful, moisture-loving organisms "bloom" like flowers. They're actually the "fruit" of organisms called fungi and are critical to the overall health of the forest. As you walk along Presidio trails, try to spy some of the season's fantastic 'shrooms and share your findings via the free iNaturalist app, a great public resource developed by scientists at the California Academy of Sciences. Above is a recent find in the park: the red-capped (and toxic!) Fly agaric spotted by Presidio wildlife ecologist Jonathan Young seen in the woodlands near Infantry Terrace.  

Learn more about iNaturalist and share your mushrooms and other forest finds >>

Count Christmas Berries at Crissy Field

Christmas berries – also known as toyon (Heteromeles arbutifolia) – are native to California. They're the fruit of coastal sage scrub, evolved to be highly drought-resistant. Due to their appearance, they're also called California holly, and their abundance in the Los Angeles hills gave rise to the name "Hollywood." Here in the Bay Area, their fruits herald the arrival of cooler, wetter weather. These bright-red berries mature in the fall and maintain a significant presence well into winter, providing food for birds and adding vivid splashes of color to many Presidio places. They've been spotted at Golden Gate Promenade and beneath the eucalyptus trees at San Francisco National Cemetery.

Take to the Presidio trails to find Christmas berries >>

Slug it Out Along Lobos Creek

Banana slugs, a bright yellow shell-less gastropod mullusk – and dearly beloved mascot for UC Santa Cruz – are found throughout the Presidio this time of year. In Latin, "gastropod" translates to "stomach-foot," which doesn't necessarily sound pretty – though these guys are pretty spectacular looking! At least two types of banana slugs are found in the San Francisco area, the larger of which can grow to almost 10 inches in length. Logic dictates these gentle giants should be easy to spot as they barrel along at a zippy six-and-a-half inches per minute. But many boast brown spots – much like an overripe banana – which helps them blend into their surroundings. Banana slugs love moisture, which is why the chances of spotting them is the greatest during the winter season. The Presidio might actually be the best place in the city to see the official California state mollusk. Most recently, they've been sighted along Lobos Creek, but you can find them throughout the park, particularly after rains.

Visit the Lobos Creek Valley trail >>

Frolic Among Bright Green Ferns

You may have noticed the Presidio is looking very green right now – in large part due to the abundance of ferns in the park. There are seven species of native ferns found in the park, including sword ferns (Polystichum munitum), lady ferns (Athyrium filix-femina), and the above bracken fern (Pteridium) – all flourishing at this time of year in the Presidio. These lovely varieties have been spotted recently (via iNaturalist) along the Coastal Bluffs. Learn more about these and other native plants by dropping into the Presidio Nursery. Or volunteer to help support the restoration of MacArthur Meadow on Planting Day, December 10, 2016.

Put your green thumb to use at Presidio Planting Day >>

Wonder at Winter Waters

Tennessee Hollow Watershed is the Presidio's largest watershed, encompassing 20 percent of the park. The water from El Polin Spring, Tennessee Hollow's central tributary, flows all year, but during the winter months, water can often be seen flowing through the east and west tributaries as well. All three streams connect in the newly restored MacArthur Meadow before eventually draining into Crissy Marsh. During the Army era, many stream zones were substantially altered and pushed underground, but over the last few years, there's been a dedicated effort to daylight creeks in the Tennessee Hollow​ area, restoring natural habitats in the watershed. You can discover the waterways of the Tennessee Hollow Watershed on your own – take a two-hour loop through the area to visit some of the restored habitats and see for yourself the life-enabling magic of our waterways at work.

Download a Tennessee Hollow Watershed Self-guided Walking Tour (pdf) >>

Meander the Migratory Superhighway at Mountain Lake

The Presidio lies along the Pacific Flyway, an international migratory route that connects from South America to Alaska. During the winter months, 65 bird species visit Mountain Lake, stopping to rest, eat, and perhaps even nest. The lake's habitat – improved greatly after recent restoration efforts – provides food and shelter for a wide array of species, including the yellow-rump warbler (Setophaga coronate), pictured here. Take a walk around the lake, do your own bird watching, and enjoy eight new trailside story signs celebrating the lake's ecology and history.

Head to Mountain Lake for winter bird watching >>