Butterflies

Frequently on Backroads we explore big open spaces and urban settings alike.  But we’ve never before gone to those places specifically to search for butterflies.

Art Shapiro is about to change that.  Art is a professor of evolution and ecology at UC Davis and one of the world’s leading butterfly experts.

“It’s absolutely incredible to me that anybody would pay me to do what I do,” he exclaims.

Art has been recording data on local butterflies for nearly four decades and he’s written a guide to identifying butterflies in the Bay Area and the Sacramento Valley.

“There is no other place in North America that has this much topographic, climatic, vegetational diversity in such a small area as the ten Bay Area counties,” he says.

Art is taking us on sort of a butterfly tour to three vastly different parts of the East Bay.

According to Art, “You can find some butterfly species in almost any open space in our area.”

We start our search at Sibley Volcanic Regional Preserve, in the Oakland hills.  It’s part of the East Bay Regional Park District, and it features the remains of a ten million year-old volcano, a labyrinth and some good butterfly habitat.

At first, it’s pretty quiet.  But soon, Art begins spotting the flying insects.  And he deftly catches one, a male Ox-eyed Satyr.

Art describes this species as “locally common in grassland in the Bay Area, usually near water.  This is actually a drier site than I’m used to seeing them.”  He adds, “Usually you’ll see them bobbing up and down, with a very strange flight motion.  Up and down, up and down, up and down!  It’s almost annoying to watch.” 

Nearly 120 species of butterfly are found in the Bay Area.  They’re attracted to different kinds of host plants and they have some ingenious strategies for survival.

Art shows me a beautifully colored butterfly called the Chalcedon Checkerspot. 

He explains, “Now this is warning coloration.  This is an advertisement to predators: I taste bad.  Do not eat me.”  Art says the warning comes from “the combination of black, red and pale yellow or white.”

The Chalcedon Checkerspot tastes bad because of what it eats, which I find out when Art has me taste a plant similar to the Chalcedon’s host plant.

Most of the butterflies we’re seeing live their entire life cycles in the same general area.  But there are some species, such as the California Tortoiseshell, that embark on tremendous migrations. 

On a separate trip, our camera caught a spectacular emergence of tortoiseshells on Inverness Ridge, in west Marin County.  These butterflies will fly to a faraway mountain range to breed.  Their offspring will somehow navigate back to the coast, where they’ll breed, and the next generation will start the process all over again.

“They’re notorious for not breeding in the same spot two years in a row,” says Art.  “One interpretation is that they are driving their natural enemies nuts.  That is, there is no way that their enemies can track them if they’re in a different place every season.”

Meanwhile, at Sibley, every time we start to leave an area, we see more butterflies.

“Well this is like the law of so-called Cybernetic Entomology,” quips Art.  “This means there is always another bug.”

In fact, as we’re heading out, we stumble upon the greatest concentration of butterflies so far.  They’re taking nectar from a plant called teasel.

Art explains, “This, of course, is a plant that’s introduced.  It’s only been in North America since the 1700’s.”  Before that, he says, “they would have nectared on some native plant or other which may not be here anymore.”

Eventually, we make it to our second stop, Eastshore State Park, near the Berkeley Marina.  It used to be a landfill site, and even then it attracted butterflies.

That’s because, says Art, “It’s full of exactly the weeds that our native butterflies have adopted as host plants and now rely on.”  Indeed, we soon walk past several different butterfly host plants.

Art spies a butterfly laying eggs.  It’s a non-native Cabbage White.

Art recounts, “This female was flying along the fence, laying eggs on almost every plant of wild radish that she encountered.  And wild radish is a host plant of this butterfly back in Europe.  It’s not native here either.”

The larval form of the Cabbage White is the caterpillar that leaves cabbage patches full of holes.

According to Art, “It’s one of the few butterflies that can be a significant economic pest.”

We soon catch a glimpse of an Anise Swallowtail laying eggs on sweet fennel plants.

“They always will fly between each individual egg laying event,” says Art.  “The plant would not be able to support too many caterpillars.  Also, dense concentration of the caterpillars would attract natural enemies.  So having them widely scattered over the landscape increases the probability of survival.”

You don’t need to be in a protected open space to see butterflies.  Art takes me to a north Berkeley neighborhood where we’re practically greeted by them.

“We have a bunch of host plants, some of which were deliberately planted as ornamentals,” explains Art.  “But they serve as either nectar sources or, in the case of this passion vine, larval host plants for some of our urban fauna.  So these old neighborhoods in Berkeley, particularly in north Berkeley, function as butterfly gardens even though they probably weren’t designed to be butterfly gardens.”

Though we’ve been seeing lots of butterflies, Art says their numbers have been steadily declining in recent years.  He’s working to pinpoint the reasons.  Global warming could be a factor, as well as what Art calls “habitat fragmentation.”

Art says, “Populations turn over all the time.  They go locally extinct.  But if their resources remain, the place gets recolonized by a pregnant female coming in from somewhere else.  But if there’s now a freeway and three subdivisions between this patch and the next occupied patch, the odds of that female finding this patch go way down.”

Even with the decline, and the fact that we came out in the summer, a little past the peak season, I’m impressed with the diversity of butterflies we saw – about twenty species in all.

Art grouses, “It’s pretty good by British standards, but by California standards, it’s a really mediocre day.”

For me, though, it’s been a wonderful day, learning a lot about fascinating creatures I used to simply pass by, and discovering one more thing to look for when I’m out on the backroads.

The peak time to see butterflies in Bay Area wildlands is March through June.  In gardens, the best months are September and October. 

Art Shapiro’s book is called “Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions.”  It’s published by the University of California Press.  He also has a terrific butterfly website:
http://butterfly.ucdavis.edu/

For more information about the places we visited:

Robert Sibley Volcanic Regional Preserve
6800 Skyline Blvd
Oakland, CA
http://www.ebparks.org/parks/sibley

Eastshore State Park
The park includes property along 8.5 miles of shoreline from Oakland to Richmond.  The part we visited is accessible from University Avenue in Berkeley, just west of I-80/580.
http://www.ebparks.org/parks/eastshore

East Bay Regional Park District Headquarters:
1-888-EBPARKS or 1-888-327-2757

BKR7259