Stories in the Sand
Guest Speaker: Lorri Ungaretti
7:30pm, Thursday, June 20th, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA
Author Lorri Ungaretti will guide us through the quick development of the Sunset District from “inaccessible” sand dunes to a city suburb. Her talk is based on her book: Stories in the Sand: San Francisco’s Sunset District, 1847-1964.
You can find more about the book, and some more about what we might be learning in this article on SFGate.com.
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20 years ago, Nancy DeStefanis, was at Stow Lake and was lucky enough (although one imagines a keen eye probably helped) to find Great Blue Herons nesting at Stow Lake — the first Great Blue Herons recorded as being seen in the city in fact. Every since, then she has been following these big beautiful birds as they come to breed, nest, and rear their young. The pictures she presented at our lecture on April 18th, 2013, presented a shorthand version of their lives in and around the nest. (Forgive me if I get some of the details wrong — I was running the slideshow and not able to take notes.)
The males arrive first as a Christmas nest, looking to stake a claim on the nests left behind from previous years, waiting for the arrival of their mates. When the females arrive nest building starts, the males presenting sticks to be added to the ever growing nests. This leads into the courtship, and eventually mating. The eggs are small, only slightly bigger than chickens eggs, but the nestlings that hatch quickly begin to grow. The mother and father bring food to the nest, but don’t necessarily feed the chicks through regurgitation.
Great Blue Herons not only snack upon fish, they also hunt gophers and other rodents that populate our parks. Not much preys upon Great Blue Herons in turn although Great Horned Owls have been known to hunt them at times. There are 4 nests currently being used on the tree, but there is about 6 total. The most prized on is near the top of the tree, of enormous size as it has just been added to over the years. One nest fell off the tree at one point — which has since ended up at Audubon Canyon Ranch.
The young herons sitting in the nest are wonderfully silly to behold sporting black mohawks that get tossed about in the end. The birds quickly grow though and it is only some weeks before they are nearly as tall as their parents and are stretching their wings, and beginning to hop from branch to branch.
After the birds fledge, the birds go they own way. The juvenile young herons at this point are on their own. Parents don’t teach the young. Their survival rate is very low. 67% don’t make it past their first year.
You have a couple more weeks to be able to see the birds with the aide of Nancy and her crack crew of volunteers and great spotting scopes. At 1030am she walks her guest around (young kids are free, adults are $10) the lake and over to the Strawberry hill, looking at not only the herons, but with an eye for the other nests and species that inhabit the park. It’s well worth a trip — head over to the Stow Lake boathouse, and look for Great Blue Heron signs.
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Rethinking Invasive Species in San Francisco Bay
Guest Speaker: Michael McGowan
7:30pm, Thursday, May 16th, 2013
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA
Could a new non-native mud shrimp be good for the sub-tidal ecosystem? Michael McGowan, fisheries oceanographer and aquatic ecologist, will discuss how an invasive species may actually be beneficial.
Michael was a guest speaker last year speaking on Sturgeon. He is a restoration ecologist with 20 years experience in research, teaching, and community-based ecological restoration. He has monitored the impacts of dredge spoil disposal, assessed potential impacts to fishes of runway expansion into the bay, analyzed data on spread of invasive wetlands plants, and evaluated the habitat benefits of native oyster restoration.
Posted in Upcoming Events | Tagged bay, invasive species, invasives, shrimp | Leave a Comment »
As you walk about the hills of San Francisco, you can consider many things: the blue sky, the fog rolling in, the birds tweeting about you, a beautiful building, a tree, a garden, the fabulous inhabitants. Even living in earthquake country, it is easy to think of the ground under our feet as something immutable. Dr. Jean DeMouthe, Senior Collection Manager at the California Academy of Sciences, on March 21st, 2013, brought us around to thinking about what and how the rocks of San Francisco came to be under our feet.
Fifteen thousand years ago, one could walk to the Farallones Islands, the golden gate a river . 125,000 years ago, San Francisco was an island, Lake Merced a remnant of the Colma Straight. The rocks of those days were “forged” much much earlier as the pacific plate crashed into the north america plate, subducting under it, and giving rise the the volcanoes in the (now) east bay and to the north. Out of that, and the movement of plates came our main rocks: serpentenite, chert, and sandstone. Our serpentenite (not as nice looking as in other areas of the world) is a metamorphic rock formed under heat and pressurel; chert is remnants of biological activity — shells of radalarians that accumulated on the sea floor, and buried, and under pressure solidifies the silica in the shells recrystallizing, separated by layers of clay and siltstone; our sandstone is graywacke, the weathered remains of volcanoes washed out to sea. The latter two, laying as they did on ocean floors, owe their place in our hills due to the movement of earth.
Today the subduction is done, the plates now moving in opposite directions (there’s still subduction going on in the Pacific Northwest part of the “ring of fire” around the Pacific). But those rocks are now with us (at least for our short stay on this world) and help give rise to the unique landscape of our city. Serpentenite, for instance, is detrimental to most plants, it is poor in calcium and magnesium, the opposite of what most plants need to thrive, but of course evolution comes in to play and there are plenty of endemic species that survived the harsh climate and adapted to the conditions.
Not much of our rock was particularly good for buildings, (like our wood presumably) a lot of that rock came other places where there was volcanic rock to be had like from Marin. In other places, serpentinite might have been used as a decorative piece, but ours is not as pretty as some.
Our city is dotted with little rocky outcroppings, along the shore, at the tops of many of our hills. You can see the layers thrust up and out by the movement of the earth. If you look closely and in the right places, you might see the remains of other processes, rare materials, and fossils (be warned that it is not longer legal to take, so just look!).
Posted in Lecture Notes | Tagged faults, geology, ground, rocks | Leave a Comment »
Celebrate the 20th Anniversary of the Great Blue Heron Colony in GG Park
Guest Speaker: Nancy DeStefanis
7:30pm, Thursday, April 18th, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA
Nancy DeStefanis, Director of SF Nature Education, will speak on the 20th Anniversary of the first nesting pair of the Great Blue Herons at Stow Lake in GG Park. DeStefanis discovered the first nest in 1993, and has monitored and studied the behaviors of the herons since then.
Posted in Upcoming Events | Tagged foragers, foraging, wild foods | Leave a Comment »
San Francisco Under your Feet
Guest Speaker: Jean DeMouthe
7:30pm, Thursday, March 21st, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA
Geologist Jean DeMouthe, will take us through our local geologic history. We start with the big picture beginning in the Mesozoic Era (Dinosaurs) and end with what lies under our city today. Local rock types and fossils will be illustrated and discussed.
Dr. DeMouthe is a geologist in the department of Invertebrate Zoology and Geology of the California Academy of Sciences.
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From the Federal Government on down there is a not so virtual alphabet soup (swamp?) of public and private organizations collaborating to protect and restore San Francisco’s wetlands. In fact as of Feb 2nd, it’s become an international concern with San Francisco Bay being named an Wetland of International Importance. Arthur Feinstein, our speaker on February 21st, 2013, has been part of this mix for along time as an Audubon and Sierra Club activist, and as a board member of the San Francisco Bay Joint Venture (SFBJV).
This Joint Venture is one of 18 that were established by the Migratory Bird Act of 1971 to protect birdlife. The joint ventures originally got off the ground protecting ducks, building on the work of Ducks Unlimited, and their efforts to preserve habitat and species for hunting. These Joint Ventures were so successful that the Fish&Wildlife Service decided to expand the program to in essence save all the birds in the country — and now really goes beyond that to all species in general.
SFBJV — the Joint Venture that is smallest in area of all 18 — has three main areas in restoration: wetlands, riparian habitat, and associated uplands. It works with organizations like Audubon, Save the Bay, Sierra Club and government agencies like the Fish and Wildlife, that have funds. The joint venture’s board and staff work on things like acquiring land, doing evaluation and monitoring, project development and implementation, outreach, and most importantly funding support, looking to get the biggest bang for the buck in these restoration programs.
Arthur spent the rest of his talk walking through the projects up and down the bay looking at the challenges and successes of these projects. One thing that you might not expect is that wetlands restoration is a lot about earth moving. Dyked off areas of the bay begin to sink (think New Orleans). The most famous place locally for this is Alviso in the south bay 16′ below the water line. This means you can’t just breach a dyke, you have to bring in dirt and a lot of it to bring the bottom up.
Happily this leads to a fine talking point — restoration means construction jobs, which is a selling point which reaches past people who are primarily concerned about the environment into a broader community.
These projects can also take a lot of time. This might be negotiating with a land owner, like the Navy at Scagg’s Island (worried about the implications of past contracts with adjacent landowners), others require lots of study — and Army Corps of Engineers studies can take a long time. The South Bay’s wetland restoration program (the largest project in the country outside of the Everglades) will take 50 years, with time built in for study and evaluation. The work is as much art as science, it’s not always certain how things will work. Inshore communities also need to be protected against potential flooding.
There are unintended environmental consequences as well — birds like Canvasbacks like shallow water salt ponds, but with some of these being removed this bird is not coming back in the same numbers. Snowy Plovers have been using dry salt ponds for nesting ground. Some of the restoration projects are now trying to take this into account — leaving a variety ot habitat.
There are all sorts of political & legal battles in this too — elections deciding between development and restoration, at places like Redwood City (46 votes decided one referendum on Bair Island) and Cullinan Ranch (which 20 years ago nearly became a Marina).
All of these things take a lot of effort from a lot of different people and organizations. What we get out of it — the past 30-40 years to make the Bay a better place — includes some intangibles: more resilience against climate change events like rising seas, healthier bay ecosystems, better spawning grounds, and better fisheries, but we also get to see beautiful things like the Clapper Rail returning to San Francisco at Heron’s Head park, and maybe all this effort has also gone to help with the return of harbor porpoises, the otter at Sutro Baths, and the huge herring runs the last two years has brought. I’m looking forward to what the next 30-40 years of restoration might bring.
If you want to play a part — you can look for opportunities in many places, but I will leave it with http://sfbayjv.org today.
Posted in Lecture Notes | Tagged bay, wetland, wetland restoration, wetlands | Leave a Comment »
