Newly published research examining more than four decades of data collected in central California by Art Shapiro, UC Davis distinguished professor of evolution and ecology, clearly reveals the effect: a marked difference between how butterfly populations fared at low and high elevations.
It's basically good news for the valley or low-elevation butterflies and bad news for the mountain or high-elevation butterflies.
The research, "Impacts of Millennium Drought on Butterfly Faunal Dynamics," is published in the journal Climatic Change Responses.
Lead author Matthew Forister, a biology professor at the University of Nevada, Reno, is a former Ph.D. student of Art Shapiro's, as are two co-authors James Fordyce of the University of Tennessee, Knoxville, and Chris Nice of Texas State University, San Marcos. UC Davis co-authors, besides Shapiro, are James Thorne and David Waetjen of the UC Davis Department of Environmental Science and Policy.
The six-member team analyzed the data in Shapiro's 10-study site dataset, which dates back to 1972 and encompasses 163 butterfly species. The sites, representing what Shapiro calls the "great biological, geological and climatological diversity of central California," range from the Sacramento River delta, through the Sacramento Valley and Sierra Nevada mountains, to the high desert of the western Great Basin. See his research website. Shapiro walked the study sites every two weeks between 45 and 29 years, noting the presence or absence of all butterfly species. (He still does. Of course, he walks during what he calls "good butterfly weather," when conditions are suitable for insect flight. This is nearly year-around at low elevations but understandable, there's a more narrow period at higher elevations.)
Of the research paper, Professor Shapiro said: "This is the most important contribution from our research group in a while. It documents the responses of entire butterfly faunas to the recent California drought. It demonstrates that, counter to intuition, butterfly faunas near sea level apparently benefited from the drought, temporarily reversing long-term declines, while montane Sierran faunas were severely harmed...the study has broader implications for the biological impacts of climate change."
Bottom line: Climate change, aka global warming, is real. Wikipedia describes it as "the observed century-scale rise in the average temperature of the Earth's climate system and its related effects. Multiple lines of scientific evidence show that the climate system is warming." Indeed, we should all be concerned with the increasing severity and frequency of extreme weather events, such as drought, and the challenges that plant and animal life face.
"Despite ongoing political controversy swirling around climate change, the vast majority of scientists dealing with the subject have no doubt that it is occurring and that its ecological implications are profound," Shapiro told us today. "One way to address potential long-term impacts of climate change on living things is to examine in detail how they are reacting to shorter-term climatic events, especially climatic extremes. The recent 'millennia'-scale California drought affords just such an opportunity. We have been monitoring entire butterfly faunas along the I-80 corridor in California for many years (in some cases way back to the early 1970s), so we have a huge baseline for comparison to data from the drought years. There are very few comparably continuous and extensive data sets on any group of organisms world-wide. As we explain, butterflies reacted to the drought in mostly unexpected and 'counterintuitive' ways. By trying to understand those reactions, we can approach longer-term trends in a much more sophisticated way. Or so we think."
Read the research paper here and learn how the scientists compiled the statistics and obtained the results.
The Anise Swallowtail, Papilio zelicaon, fluttered into our pollinator garden and headed straight for the Verbena.
Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis, identified the gender: "it's a girl."
The Anise Swallowtail, our first sighting of the season, bypassed the butterfly bush, Buddleia davidii.
But she'll be back--hopefully to gather some more nectar and lay her eggs on our fennel.
The Verbena patch was a little too populated for her liking--honey bees and yellow-faced bumble bees, Bombus vosnesenskii, wanted their share of the nectar, too.
"The Anise Swallowtail is a complex set of ecological races, or 'ecotypes,' whose seasonality has been adjusted by natural selection to match that of their host plants," says Shapiro on his research website. He's studied butterfly populations in central California since 1972.
"In multivoltine populations the spring brood is typically small, pale, heavily marked with blue and with narrow dark borders on all wings. Summer individuals are larger, with richer yellow color, broader black borders and little or no blue in males. Univoltine populations tend to be intermediate between these extremes. The small larvae resemble bird droppings. Large larvae are pale green with black bands containing orange spots; in hot, dry sites there is more green and less black, while under cool, humid conditions the green may even disappear! The pupae may be brown or green."
Read more about the swallowtail, including its food sources, on Shapiro's web page.
Meanwhile, whether you see your first Anise Swallowtail of the season or the last of the season, you'll want to see more of this yellow-mellow butterfly!
So here's this Gulf Fritillary (Agraulis vanillae) clinging to a lavender stem in our pollinator garden.
It is all alone--for a little white.
Then here come honey bees seeking to forage on the lavender, too.
One bee buzzes next to the butterfly's wing. Then it soars up and over.
Too much traffic for this butterfly. It moves to the nearby catmint patch.
The showy butterfly, a brilliant orange-reddish masterpiece with silver-spangled underwings, first appeared in California in the vicinity of San Diego in the 1870s, according to noted butterfly researcher Art Shapiro, professor of evolution and ecology at the University of California, Davis. He's been monitoring the butterfly populations of central California since 1972 and maintains this website.
From San Diego, “it spread through Southern California in urban settings and was first recorded in the Bay Area about 1908," says Shapiro. "It became a persistent breeding resident in the East and South Bay in the 1950s and has been there since.”
Shapiro says it “apparently bred in the Sacramento area and possibly in Davis in the 1960s, becoming extinct in the early 1970s, then recolonizing again throughout the area since 2000.”
The Gulf Frit's host plant is the passionflower vine (Passiflora). Plant it and they will come. Plant some lavender and catmint, too, for food sources. You'll be rewarded by the joy of seeing these beautiful masterpieces fluttering into your yard./span>
This quote, often falsely attributed to Mark Twain, is a favorite of Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis.
Speaking at the second annual Butterfly Summit last Saturday, May 26 at Annie's Annuals and Perennials, Richmond, Shapiro discussed his research and offered his observations and views on the state of butterflies. He maintains a website at http://butterfly.ucdavis.edu/
Shapiro has monitored butterfly population trends on a transect across central California for 46 years. The 10 sites stretch from the Sacramento River Delta through the Sacramento Valley and Sierra Nevada mountains to the high desert of the Western Great Basin. Shapiro visits his sites every two weeks "to record what's out." The largest and oldest database in North America, it was recently cited by British conservation biologist Chris Thomas in a worldwide study of insect biomass.
"The vast majority of the butterflies we monitor are emerging earlier in the year now than they were in the 1970s," Shapiro said. He mentioned the Red Admiral butterfly, Vanessa atalanta, which spends the winter as an adult, is "our biggest responder to global warming, coming out 21 days earlier on average that it use to, exactly the same in England, same species. It's not weird at all. It is winter active."
His research shows that not only are butterflies coming out earlier, but "we also find trends in population and species richness."
Shapiro, a member of the UC Davis faculty since 1971 and author of the book, Field Guide to Butterflies of the San Francisco Bay Area and Sacramento Valley Regions, said that "in a nutshell, at low elevations, butterfly faunas have been declining slowly until 1999. In 1999, 17 species had an abrupt fall in abundance, spontaneously. On its face, this was a non-random event. The decline was then rapid from 1999 to the onset of the recent drought and then things went up again."
Shapiro noted that by and large, immature butterflies spend the winter underground or right at the surface. "This is the worst possible environment for overwintering butterflies in the early stages, what with the combination of warm and wet." The high humidity and temperature are very favorable for fungal and bacterial pathogens, he said, adding that "Overwintering survival in warm wet conditions is poor."
"When we have a dry winter, it's colder at night but not cold enough to be lethal, he said. "It's a healthier environment to be an overwintering caterpillar. That's what we think is going on."
In the mountains or higher elevations, changes are strongly correlated with climate. "As it gets too warm and dry down below, butterflies are moving uphill, but plant resources are moving up the slope more slowly. When resources are not available yet higher up, butterflies have a real problem. There's no where to go at all for truly alpine species; they're already at the top of the mountain. The next stop is heaven." Shapiro described the decline of butterfly populations in the mountains as "worrisome."
Neonicotinoids, which Shapiro defined as "a class of synthetic pesticides chemically derived from the chemistry of nicotine," are often targeted as a cause of butterfly decline. "Neonics are not in Scotland and there's been no butterfly decline in Scotland," he pointed out. "But, anyone who has taken a statistics course knows that Correlation Is Not Causation."
Turning to monarchs, Shapiro said "More than half of the questions I get from the public deal with monarchs."
Describing the monarch as "the poster child for conservation," Shapiro said: "There's a lot of stuff out there in the media, and it's not all to be believed." Butterfly population counts differ from summer breeding data and the overwintering data.
"If you want the scoop on monarchs--unconnected with fundraising or politics," he said, "read Anurag Agrawal's book, Monarchs and Milkweed." The book is subtitled "A Migrating Butterfly, a Poisonous Plant and their Remarkable Story of Coevolution." Agrawal, the James A. Perkins Professor of Environmental Science at Cornell University, Ithaca, N.Y., received his doctorate in population biology from UC Davis in 1999.
"Monarchs in California have had a long decline, perhaps more dramatic than the decline in the Midwest and the East," Shapiro said, adding they have never been as common in California than they are in the East. "If they're relatively scare, that doesn't mean a decrease. We need to do comparisons over time. During the drought, they came back. We don't know why."
Shapiro also said that monarchs are winter-breeding in California, something they didn't do 10 years ago. "It started in southern California, maybe a decade ago and is now spreading to the inland empire. They're well established in the East and South Bay." He said he heard one report of monarchs winter-breeding in Woodland, Yolo County.
"Monarchs can't breed in the winter here under natural conditions," Shapiro said. "A non-native, non-dormant milkweed, tropical milkweed (Asclepias curassavica) allows winter breeding. These plants are often contaminated with the parasite, Ophryocystis elektroscirrha or OE, a problem in Southern California, but not yet in northern California. "People who are really committed to native plants would like you to get rid of your exotic tropical milkweed and replace it with native species that go dormant." He recommends "cutting them back three times a year" to allow fresh new growth.
Some of his take-home messages:
- Butterfly faunas are declining in most parts of the North Temperate Zone where monitoring is done. The most severe declines have been in European grassland faunas. By those standards, we're not that bad off (yet?).
- At low elevations in California, declines were moderate until 1999, when they accelerated abruptly. Our multivariate statistical analyses suggest (but cannot prove!) that climate change has been only a minor factor, while habitat conversion and loss, and loss of habitat connectivity share the blame equally with pesticides, specifically neonicotinoids.
- At higher elevations in the Sierra Nevada, species at tree-line have declined in response to climate change but there have been no losses attributable to habitat conversion or pesticides. Many species are moving upslope (or trying to, because they are more mobile than their essential plant resources).
- The recent “1000-year drought” had dramatic impacts. At low elevations, butterfly faunas rebounded from recent lows, probably due to a better environment for overwinter survival. In the mountains the opposite happened: lack of snow cover led to poor overwinter survival and faunas plummeted to unprecedented lows at places like Donner Summit. The heavy snow pack of winter 2016-17 did little to improve things, because the number of animals going into overwintering was already so low.
- We are already seeing low-elevation faunas slipping back into decline. Because most montane butterflies have only one generation a year, it will take several favorable years to rebound from the losses there.
- Our research revealed that California monarch populations had been in decline for decades, perhaps more so than in the East and Midwest.
- This was true even though the usual “suspect” causes – GMOs and milkweed shortages – do NOT appear to apply here.
- There was also a change in the seasonal breeding pattern of monarchs during the worst of the decline.
- During the drought, monarch populations rebounded significantly here, and their historic seasonal breeding pattern returned. But this year we seem to be going back to pre-drought patterns.
- Winter breeding by monarchs began in Southern California several years ago and has now spread to the Bay Area. Overwintering monarchs are supposed to be in reproductive diapause cued mainly by daylength. Why a growing percentage of them are not is a mystery which has not been solved as of this afternoon.
You can find out at the second annual Butterfly Summit, a free event hosted by Annie's Annuals and Perennials in Richmond. The event takes place from 10 a.m. to 4 p.m. on Saturday, May 26 at Annie's nursery, located at 740 Market St.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis, will speak at 11 a.m., covering the status of butterflies in the area. The author of Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions (UC Press, 2007), he has collected data over 46 years, tallying 150 species, and maintains a research website at http://butterfly.ucdavis.edu/.
The distinguished professor will cover such questions as:
- Are insect faunas in free fall (as reported in Germany)?
- What have we learned from 46 years of butterfly monitoring?
- What are the relative impacts on butterflies of climate change, land use change, introduced species and pesticides?
- Are there differences in how butterfly faunas are behaving near sea level vs. in the mountains?
- Are the scary headlines about the monarch butterflies being "endangered" true? If so, why? If not, why the fuss?
Shapiro began monitoring north-central California butterflies in 1972. His is the largest and oldest such dataset in North America.
The family friendly event will include displays of the life cycle of butterflies and information on creating and preserving habitats. Tables will be staffed from 10 a.m. to 4 p.m. to offer information to visitors. The presenters are:
- Tim Wong, aquatic biologist at the California Academy of Sciences and known as "the pipevine swallowtail whisperer."
- Tora Rocha and fellow members of the Pollinator Posse at the Gardens at Lake Merritt, a volunteer group that supports pollinators and rears monarch caterpillars
- Andrea Hurd of Mariposa Garden Design, specializing in permaculture methods and songbird, butterfly and pollinator habitat gardens, using California native and pollinator friendly plants. Hurd will share methods for designing meadows for butterflies.
- Kelli Schley-Brownfield of Wild Flower Garden Design, Devil Mountain Nursery, and Pollinator Posse member, who will demonstrate butterfly puddling spots using Annie's plants.
- Evelyn Orantes, independent curator, arts educator and teaching artist and a new member of the Pollinator Posse, will share visual representations of butterflies in arts and culture.
- Andy Liu, landscape architect and garden design specializing in butterfly habitat, will explain why his neighborhood is alive with swallowtails, gulf fritillaries and "many other winged wonders."
- Sal Levinson, author and entomologist specializing in butterfly habitats. She is the author of Butterfly Papercrafts, which contains 21 indoor projects for outdoor learning.
Another attraction, from 11 a.m. to 3 p.m. is "Giant Puppets Save the World," featuring the silk and bamboo menagerie of monarchs, hummingbirds "and more" with Toni Tone, an artist, puppeteer and stilt walker. It's billed as "super fun for the kids."