Urban Wildlife Adapt to San Francisco’s Changing Landscapes

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Egrets at Heron’s Head Park. Photo: Jacob Bourne
Egrets at Heron’s Head Park. Photo: Jacob Bourne

Last fall, the World Wildlife Fund, a 50-year old global wildlife conservation organization, published the Living Planet Report 2016: Risk and Resilience in a New Era. The document utilized a Living Planet Index to measure the population status of vertebrates around the globe. The numbers are bleak. Between 1970 and 2012, vertebrate populations have diminished by 58 percent. Freshwater animals, such as amphibians, have taken the greatest hit, declining by 81 percent. Terrestrial and marine wildlife have dropped in abundance by 38 and 36 percent, respectively.

Johan Rockström, executive director, Stockholm Resilience Centre, one of the report’s contributors, cited the Anthropocene as a central theme in the publication. Though not officially a part of the Geological Time Scale, the Anthropocene is increasingly being referenced to describe the period in Earth’s history, beginning with the Industrial Revolution around 1800 current era, in which human activities have and continue to leave an indelible mark on the planet. Some of the signs of this era, like the decline and extinction of non-human species brought about by poaching, deforestation, human development, and global climate change, are apparent in people’s daily lives. The irony of the Anthropocene is that the more entrenched individuals become in the artifacts of constructed environments – the metal and concrete of cities; the machinery of modern agriculture – the more invisible nature becomes, reducing the impetus to protect ecosystems.

In San Francisco, the Anthropocene became relevant in the mid-1800s, when the Peninsula’s population grew from 200 to 36,000 human inhabitants in six years, mostly those seeking gold-based wealth.  Today, San Francisco is home to 864,816 people, with formerly industrial neighborhoods such as Dogpatch expected to double in population over the next few years. This growth will greatly increase housing density, presenting challenges to creating adequate open space and recreational areas.

Ed Carpenter, a microbial biologist at San Francisco State University, predicted blooms of toxic diatoms, a type of algae, along the coast as a result of increased development, potentially contaminating seafood, and threatening marine wildlife. “Generally, if you have an increase in residential in an area, the amount of nutrients going into the water increases, which feeds the phytoplankton,” said Carpenter. “This could be a bad thing or a good thing. Blooms of phytoplankton can fall down into deep water and be broken down by bacteria. The bacteria then use up oxygen in the water, required by other organisms, during the decomposition process. It could be a good thing, as it provides food sources for fish and shellfish.”

The San Francisco Bay Area is one of the world’s fastest growing economies, attracting migrants seeking opportunity. The City, neither among the largest nor oldest of human-centric global hubs, is geographically positioned as a key point in global trade routes, creating a constant state of flux, not just for people, but other organisms.

Andrew Chang, an ecologist at the Smithsonian Environmental Research Center, Marine Invasions Research Lab in Tiburon, has spent years studying Bay waters and creatures that live near the tideline. One of the few Bay natives is the Oyster; the Atlantic Oyster Drill, an invasive species, is also found in the Bay, and preys on the Oyster.

“I try to avoid saying that native species are good and invasive species are bad,” Chang commented. “It’s just part of the character of the place. Around 90 to 95 percent of the biomass in the Bay is made up of non-native species. The Bay is one of the most invaded places in the world. Historically, commerce has been a big driver of this; species come in on the hulls of ships and ballasts. The role that it plays now is something that we’re studying.”

According to Nathanael Johnson, one needn’t travel as far as the Bayfront to delve into urban ecology. In Unseen City: The Majesty of Pigeons, the Discreet Charms of Snails & Other Wonders of the Urban Wilderness, Johnson takes readers on a journey through the urban wild lands of San Francisco and Berkeley, exploring an ecosystem hidden behind the veil of human distraction. The main actors in this bustling world are synanthropes, animals and plants that prosper in environments dominated by humans, such as squirrels, crows and weeds. Johnson was inspired to write the book during walks with his toddler-aged daughter, whose young mind noticed what adults often regard as banal. “…I had just wanted to demonstrate to her, and to myself, that my nonhuman neighbors are important by paying attention to them,” Johnson wrote.

In his chapter on crows, Johnson shares a remarkable discovery: the birds, along with dogs, pigeons, sheep and other species, can distinguish between the faces of individual humans. Although people can usually differentiate between individual domesticated animals, like dogs, most would fail a facial recognition test of crows or bees. According to Johnson, there are other beings in the urban environment that’re keenly aware of us — as individuals — while we walk by oblivious.

“Nature never misses an opportunity to exploit a catastrophe,” Johnson wrote.  He spoke with biologist Chris Thomas, who studies synanthropes, and discovered that the emergence of new plant species over the past 150 years is on par with the amount of mammals lost to extinction. Research has found that though cities aren’t conducive to many non-human species, urban areas with large parks have a greater amount of bird biodiversity than rural woodlands.

Technology Helps Illuminate Ecosystems in Urban Areas

A citizen-science movement has been growing over the last few decades, in which amateur and professional researchers collaborate informally and mostly without pay to compile information on various scientific topics. Technologies like the Internet, smartphones, handheld GPS devices and mass-market drones have been a boon to the spread of citizen-science programs.

One global citizen-science social network, iNaturalist.org, started in the Bay Area, has compiled three million observations covering almost 97,000 species of plants and animals recorded from six continents. According to Alison Young, California Academy of Sciences citizen-science engagement coordinator, when iNaturalist co-founder Ken-ichi Ueda first moved from Connecticut to attend the University of California, Berkeley, he felt lost not knowing much about local ecology, and wanted to connect with other nature enthusiasts. With a background in biology and software development, Ueda started iNaturalist as part of a graduate project while pursuing a master’s degree at University of California Berkeley’s School of Information in 2008. In 2009, he partnered with environmental scientist Scott Loarie to further develop the platform.  In 2014, the California Academy of Sciences acquired iNaturalist and hired Ueda, Loarie and others full-time.

“The Academy has a history of aggregating people’s observations of nature,” said Young. “Professionals and amateurs alike have contributed knowledge. We provide a place and a way to share observations. iNaturalist community members make identifications; other users corroborate them. It’s a social network. Users build their reputations by helping others with their observations. It’s one of the friendliest social networks.”

Young and Rebecca Johnson, Academy citizen-science lead, use iNaturalist to foster stewardship and build community through projects and events held throughout the Bay Area. One of these is a “bioblitz,” a congregation of iNaturalist members who observe and record as many organisms as possible in a particular geographic area over a short period. According to Johnson, a bioblitz was held in Heron’s Head Park last December. At Pier 94, just north of Heron’s Head, a spring bioblitz is anticipated in collaboration with the Golden Gate Audubon Society.

For the 94107 zip code, encompassing Potrero Hill, Dogpatch and part of South-of-Market, iNaturalist has recorded 436 observations covering 193 species. The Brewer’s Blackbird topped the charts, with 11 observations made mostly in the vicinity of Yerba Buena Center for the Arts, with one in Mission Bay and another at the Potrero Hill Recreation Center. The species, found year-round in western states, is protected under the Migratory Bird Treaty Act of 1918. The birds prefer open areas, and can nest in a variety of places, feeding on seeds, insects and berries. 

A cluster of three Coast Redwood trees was observed in northwest Potrero Hill, with another two sightings in SoMa. The Coast Live Oak is another native tree species seen Southside, with flowers appearing in spring and acorns produced about eight months after pollination.  Although the diversity of observations is dazzling, birds steal the show, with a wealth of records for a wide array of avian species.

A prime wildlife viewing spot in Dogpatch is Warm Water Cove. In addition to the Northern Mockingbird, plant species like the California Sagebrush, Coyote Bush, and Mission Prickly-Pear can be found there. The Mission Prickly-Pear is a plant native to Mexico that’s become an important food source in dry regions of the world. Many parts of the plant can be eaten; the cactus fruit can be made into jams or alcoholic beverages once the spines are removed.

Mariposa Park is home to a variety of plants and insects, including the Monarch, Honey Bee, Orange Sulphur, Veldt Grass and Manzanitas.  Starr King Open Space hosts Shepherd’s Purse, Green Bottle Flies and Foothill Desert-Parsley, which belongs to the carrot family, with a native habitat that spans the West Coast. Himalayan Blackberry, Blueblossom and Cotoneaster adorn Pennsylvania Garden. The Yellow-Faced Bumblebee and California Buckeye have been found near Carolina and 23rd streets.

The Potrero Hill Recreation Center contains sufficient vegetation to host a variety of bird species, such as the Eurasian Collard-Dove, California Towhee, Chestnut-Backed Chickadee, Black Phoebe, Dark-Eyed Junco, Western Scrub-Jay, Anna’s Hummingbird and Hooded Oriole. The California Towhee, native to several western coastal areas, has adapted well to urban park living.

iNaturalist data for Bayview-Hunters Point indicate even more biodiversity, with 2,541 observations of 517 species, mostly along the shoreline. Another hotspot is Bayview Hill, home to a variety of organisms, including the Ringneck Snake, Sea Fog Lichens, Syrphinae, and California Manroot.

Liam O’Brien, a local lepidopterist, conducted complete surveys of butterflies in the City in 2007 and 2009, documenting 34 species. He found that more than half the species, 18, which usually only lay eggs on certain plants, have adapted and now use a variety of plants as hosts.  “Some species of butterfly still need native plants, but some females are becoming generalists and are using weeds in the sidewalks,” explained O’Brien. “This is a more evolutionarily promising choice.”

According to O’Brien, the Western Tiger Swallowtail uses street trees to lay their eggs. There were five observations made of this species in SoMa and Mission Bay. The Common Checkered Skipper and Painted Lady butterflies have also converted to being generalists, and have been observed on Potrero Avenue and Third Street. Generally, butterflies that’re active and fly year-round are the species found in City streets, O’Brien said.

Other species spotted Southside include the Northern Anchovy and California Sea Lion in Mission Bay, a Seaside Daisy in Dogpatch, California Slender Salamander near Highway 280, 23 observations of Sweet Fennel — an edible plant — in Bayview-Hunters Point, and the Red-Tailed Hawk in Potrero Hill. The highest concentration of observations were made along Mission Bay, in and around the Potrero Hill Recreation Center, Piers 94 and 96, and Candlestick Point State Recreation Area, though numerous sightings have occurred throughout Southside, from species living in parks and in pavement cracks.

“There’s a lot more going on ecologically where there are more gardens and hilltops,” said O’Brien. “Insects are opportunists, but they don’t get a lot from cement. Things can get better if redevelopment opens things up and they put plants in. I’m not against development if they add green space; it’s better than concrete.”

John Hafernik, a biology professor at San Francisco State University who specializes in the ecology and evolution of insects, cited iNaturalist as the best source for recorded wildlife observations, especially in the City’s Southeastern neighborhoods, which have been historically lacking in these types of records. He said that San Francisco has gaps in its natural history record largely due to the Great Fire of 1906, when the California Academy of Sciences, located Downtown at the time, was destroyed along with its records. Hafernik said that significant efforts are underway to create an inventory of biodiversity in the City. The records are likely much higher quality than those from more than a century ago, at least in part due to modern technology.

“In general, the Southeastern end was one of the most ecologically diverse parts of the City before development, due to better weather and more soil types,” said Hafernik. “It was probably home to a more diverse set of species. This would have been in the pre-European era prior to the 1850s or so. After the Gold Rush significant development in San Francisco began.”

Hafernik views the shifts in these neighborhoods from industrial to residential mixed-uses as an opportunity to plan open space that’s recreational and can serve as habitat for plants, insects and birds. He’s concerned that as the world becomes more urbanized, children are increasingly growing up disconnected from nature, with few places to explore. He encourages urban planners to prioritize open space amenities.

“It’s about getting out and finding things that might be hiding in plain sight, such as butterflies nesting in weeds on sidewalks,” added O’Brien. “The Southeastern neighborhoods hold a lot of mystery.”

Restoration in Progress Alongside Development for Southern Bayfront and Parks

San Francisco’s Southern Bayfront, from Mission Bay south to Candlestick Point, is poised for dramatic change, as large-scale development projects flow through the urban planning process. According to the Southern Bayfront Strategy Working Group, an initiative of the City’s Office of Economic and Workforce Development, 20,000 new housing units and 35,000 additional jobs will dot the shoreline in the coming years. Accompanying the buildings, 520 acres of existing and newly created open space will provide recreational opportunities for people, and habitats for other organisms, which already live in some of these areas.

Amber Hasselbring, executive director of Nature in the City, an organization that advocates for the protection of San Francisco’s natural areas and offers eco-literacy programs, acknowledged collective efforts to restore wetlands areas along the shoreline, but stated that they don’t adequately meet the needs of wildlife. “The more of a wetlands buffer we have, the more species we can support,” offered Hasselbring. “The Bayfront efforts need to allow for more wetlands edges, as there are issues with brick back covering the soil in the marshlands. It would be amazing if there was a more ecologically-minded design for the Bayfront development.”

Nature in the City partners with other groups to hold nature walks and sponsor habitat restoration projects. Its efforts are currently focused in the Inner Sunset and the Haight, but there may be a future watershed planning project in the Southeastern neighborhoods if the organization receives state funding this year.

A significant advocacy effort is underway to preserve the Palou Phelps Open Space in Bayview. Zahra Kelly, Nature in the City’s director of public advocacy, is organizing residents to support preserving the neighborhood open space area from proposed development, by having the City purchase two privately-owned parcels encompassed within the grassland area. Developing the parcels would require an easement through the publicly-owned portion to connect it with streets. According to Park advocates, that would disrupt park use and have a deleterious effect on the prairie ecosystem.

Kelly collaborates with the Recreation and Parks Department’s Natural Areas Program to protect native plant species by holding a monthly volunteer clean-up and restoration community workday. Nature in the City staff conduct outreach; the Natural Areas Program funds restoration resources and equipment.

“There is pressure on these lands for development,” explained Kelly. “We have a lot of land like this in the City, so this would set a negative precedent if the parcels were developed. It’s been a hard balance, because people have to be aware of what’s going on in order to tell the City that they want the land preserved. There are some rare native grass species. The area is incredibly steep and provides a really cool view. There are a lot of mature trees. It’s a beautiful site, especially in the spring.”

Local writer and natural history educator, Joel Pomerantz, created a project, Seep City, to map San Francisco’s underground freshwater sources. He emphasized that there aren’t any flowing underground creeks apart from the artificial flows through the City’s sewer system, but that there’s a significant amount of fresh water beneath the soil that emerges in places as springs. Prior to human alteration of the landscape, water from the higher elevation springs flowed down to the lower elevation shoreline, washing the wetlands with freshwater, contributing to habitat for many species. Today, besides providing irrigation for some plant life, the runoff’s only function is to flush sewers during the dry season.

“The marshes were very diverse in terms of bio systems,” Pomerantz said. “People are trying to recreate these wetlands by creating a larger intertidal zone in the restoration areas. Species can use these areas as habitat, but it won’t be like the original because it’s not being refreshed with fresh water in the same way.”

Two major structural barriers prohibit water flow to the restoration areas. First, when the water seeps up through the soil and attempts to run down grade it’s diverted by sewers. According to Pomerantz, the Southeast Treatment Plant lies in the midst of a significant former marshland, which effectively captures seeping freshwater. Second, even if the water isn’t diverted, the vast majority of the Bayfront from Downtown to the southern boundary is filled in with concrete, other materials or diked, which block water like a dam.

“There are only a few 100 foot long spots of original shoreline,” he claimed. “The western tips of the Islais Creek Channel and the Yosemite Marsh restoration areas touch the original shoreline. Also, the easternmost tip of Hunters Point and right around Heron’s Head there are a couple tiny spots that were part of the cooling pond for the former power plant that’s original shoreline.”

One possible approach is to irrigate the natural shoreline areas with fresh ground water.  According to Pomerantz, groundwater is being brought from Tennessee Valley Creek to Crissy Field Marsh in the Presidio.  Many species are returning to the area as a result.

The Port of San Francisco is leading restoration efforts at places like Pier 94 and Heron’s Head Park, working with the Recreation and Parks Department.  The Eco Center at Heron’s Head Park provides environmental education and community engagement. Efforts so far have involved improving the wetlands and adjacent grass and scrubland habitats, creating a buffer zone between restricted wildlife areas and development, and implementing public access for recreational and educational uses.

According to Noreen Weeden, Golden Gate Audubon Society conservation project manager and volunteer coordinator, GGAS advocated for the creation of Heron’s Head Park and habitat at Pier 94 subsequent to an oil spill in 1996 that impacted local bird species.

“With the 1996 oil spill many birds died,” said Weeden. “We spoke with the Port about using Pier 94, which wasn’t being used for maritime activities and had become an informal dump. We applied for mitigation funding from the state and got funded to hire experts to design the shoreline and remove debris. Our first volunteer event was on Earth Day in 2002. It’s a five acre site that’s more for birds and wildlife than people. Heron’s Head is more for people. We have monthly restoration events at Pier 94.”  GGAS, a local chapter of the National Audubon Society, will be 100 years old next year. The organization has ongoing volunteer and educational activities geared towards the public, including 160 free field trips a year.

One of the species monitored by GGAS is the Burrowing Owl, which has been declining in California. Weeden said that the bird has been seen in Southeastern neighborhoods during winter months, but that they choose other locations for breeding. Other species watched closely Southside are the Black Oystercatcher and the Osprey, a bird of prey that consumes fish which is found on six continents. Osprey in warmer states, such as Florida and California, remain year-round, while other birds migrate to South America for the winter.

“One positive sign about the health of the Bay is that we see Osprey increasing in the area,” offered Weeden. “They have been nesting out at Candlestick. We’re studying what’s contributing to their success and people are monitoring them. We’re seeing more birds around the Bay and more nesting. It’s a positive.”