SF Natural History Series

SFSU Professor and California Academy of Science Board of Trustees President John Hafernik introduced us to the green roof of the Academy’s new building, and research into what has been finding its way up there.

His graduate students, lead by Jessica Van Den Berg, have been methodically catching and cataloging the insects that find there way into traps both on top of and near the museum for over a year. The roof was designed by Renzo Piano to lift up the park, but it is a good deal different from the surrounding flora.

Nine species of native California plants were originally planted on the roof. Native plants that were thought best adapted to surviving the somewhat harsh conditions of the roof, and the shallow soil. Those plants have been joined since by another 70 species or so (mostly planted near the observation deck).

The results of the study so far show that the roof’s insect population is much more diverse than that on the ground (dominated by two imports: the devil’s coach horse and pill bugs) . They have been pleased and surprised to see how quickly a rich web of species has been established: from herbivores (beetles and grasshoppers), pollinators like honey bees (and their mimics: drone flies) and bumble bees, predators like lacewings and wolf and jumping spiders, plenty of recyclers, i.e. flies, and perhaps most surprisingly a host of parasites and parasitoids.

Over 55 morphospecies (morphologically different species but still unidentified) of tiny and tinier wasps have been found (they make for beautiful pictures, but these are wasps species that are parasitoids: laying their eggs inside another insect species which then hatch and the eat their way out and eventually kill the host).

Other surprises have been native californian species like pigmy locusts, tricolor beetles not previously found in SF, but thought to be stowaways — carried here along with the plants from their original nursery. The surprising thing is that these species are still surviving the conditions (both generally live long creeks).

Also found was Agonum Muelleri, a European-Siberian beetle that has been slowly spreading around the world (and had as recent as 2008 been found in the Presidio).

What hasn’t been found so much is butterflies — unsurprising since not many host plants have been planted —  and ants. Native ant queens have been spotted  landing, but so far no colonies have been found. The argentinian ant has not yet found its way up, though it seems only a matter of time.

What next? Once cataloged and photographed, large and small, the insect samples will be turned in for genetic studies, fine tuning the knowledge of what is what on the roof.

As for the roof there is plenty more to study and to decide: how much to further encourage natives insects: nesting sites for bees, wood and other items for shelters, more host plants for butterflies and moths, and perhaps even importing some species that otherwise might not find their way up (ground dwelling species for instance).

Other studies might be done on other native gardens and how they compare. The academy, using citizen science will carry on the study of what is up there, to see how things will change over time. The studies will also be good information for future green roof projects.

More information on the roof and future projects can be found on the California Academy of Sciences green roof website.

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I now know at least a little bit about newts. Karen Goetz, with beautiful photographs,  introduced us to the natural history of the California Newt (Taricha torosa). Karen, as part of her graduate studies in Conservation biology, had studied how female newts selected their egg laying sites in the hills of the East Bay.

She lead with the life cycle of these amphibian’s (a type of salamander in fact): from their start as eggs the size of o large cherry, through their larval stage on into their adult life, their mating habits, and how they lay eggs, growing 6-8 inches, with toxins in their skin, and living for a surprisingly long time (20 years at least in the wild, with a record of 35 in captivity). Despite their toxic skin, they still have their predators, crayfish and garter snakes, and other newts as well.

What Karen had studied in particular was where the female salamanders lay their eggs. It turns out they tend to lay their eggs in deeper pools (greater than 37cm in depth), on woody objects of 9mm diameter or greater,  near muddy banks. Her hypothesis being that their choice relates a lot to biomechanics — how eggs fare in the seasonal flooding of California creeks: eggs fare best when laid on woody branches resilient to turbulent waters, and deep enough that they would avoid being hung out to dry before the eggs hatched.

Her pictures from under the water were ethereal glimpses of the lives of these animals. Probably the part we know best, as when they crawl out from the creek, there’s not a lot of data of how far, or doing what. We do know that newts, like many other amphibians, are vulnerable because they are so dependent on water for such a crucial part of their life. Humankind has had a huge impact in what it has been putting into the water, as well as how the water flows.

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