In between the rains today, we saw them.
So beautiful! Painted ladies, Vanessa cardui, nectaring in patches of colorful wildflowers in the Biological Orchard and Gardens (BOG), located behind the Mann Laboratory on University of California, Davis campus.
The migratory butterflies, passing through California on their way to the Pacific Northwest, stopped there for some flight fuel: sipping nectar from tidy tips, Layia platyglossa; five-spot, Nemophila maculate, and blue lupine, Lupinus.
They've been in the national news a lot, these butterflies, as has butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology. Known for his expertise on all things butterfly, he's monitored the butterfly population of Central California since 1972 and maintains a research website.
Yes, it's been a big year for painted ladies, thanks to the heavy rainfall and super blooms in the deserts near the Mexican border. And, as Shapiro says, tremendous wildflower blooms are typically great years for the painted ladies.
New York Times reporter Julia Jacobs interviewed Shapiro for her March 17th piece, in which she marveled that millions of the painted ladies are migrating. Shapiro told her: "The striking thing is they're moving very rapidly and directionallly. So it's almost like being in a hail of bullets.”
Rita LeRoy or "Farmer Rita," the self-described "Farm Keeper" on the Loma Vista Farm, Vallejo, part of the Vallejo City Unified School District, saw the butterflies passing through the farm on Monday, March 17. Her description is fabulous:
"They came through Vallejo on Monday," she said. "Art's description was right on. It was like being in a hail of bullets. This was because they were flying so low and it was a constant stream, like standing in the middle of a 500 lane expressway. I kept telling the students, 'Look! Another, another, another...' The path was at least as wide as the farm which is about 200 yards. When I stood in one spot, I would agree they were passing within my vision (about 100') at about 1 every second. They rarely stopped to nectar but were flying in a very direct NE direction when they came through the farm. They flew through nonstop from before 1 p.m. and the flow started to dwindle around 4 p.m. Still enough at that point to show the after school kids. They didn't fly in huddled groups or clouds and they moved fast. I tried taking a video but it was like a bad remake of The Blair Witch Project, with unfocused, whiplash camera moves of uncertain objects since they are so small in the overall background. I'm so glad Art saw them."
Today (Wednesday) we didn't see the hail of bullets, but we did see about a dozen of them grabbing some flight fuel on the UC Davis campus over a 10-minute period.
If you get a chance, check out the Biological Orchard and Gardens. A 24,000-square-foot garden, located behind the Mann lab, off Kleiber Hall Drive, it's planted with several dozen species of heritage fruit trees, and landscaped with flower gardens. The painted ladies are elsewhere on campus, too, including the UC Davis Arboretum and Public Garden.
A flash of orange.
Usually we see assorted orange butterflies--Gulf Fritillaries (Agraulis vanillae) or Painted Ladies (Vanessa cardui) or Monarchs (Danaus plexippus)--on our butterfly bush (Buddleia davidii).
This time the flash of orange proved to be a California Tortoiseshell (Nymphalis californica).
Its wings are pumpkin orange with huge black spots while the underwings are dullish brown and gray, resembling a dead leaf. What a perfect camouflage!
This particular Cal Tortie is probably a female, according to Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis. He has monitored the Central Valley butterfly population since 1972 and maintains a research website.
"Along with the Painted Lady, this is a mass migrant that makes news at irregular intervals by tying up traffic!" Shapiro says on his website. "The 'Tortie' overwinters as an adult and can sometimes be seen sunning itself in midwinter on mild days. It is generally common in foothill canyons in late winter, ovipositing on the young, tender growth of various species of Wild Lilac (Ceanothus)."
And just as the Gulf Frits can defoliate its host plant, the passionflower vine, so, too, can the Tortie defoliate its host plant.
"The spiny, black-marked-with-yellow larvae feed gregariously, without a web, and in big years can defoliate whole stands of the plants," Shapiro notes on his website. "They often pupate on the bare, leafless stems en masse, the grayish-violet pupae looking like some strange kind of leaf and twitching in unison when disturbed. Adults emerge in late May to early June and almost immediately emigrate, going north or east and upslope."
They're often misidentified as monarchs, Shapiro told the recent Butterfly Summit at Annie's Annuals and Perennials, Richmond. He also mentions this on his website.
"Breeding localities in summer vary widely from year to year - sometimes in the high southern Sierra, sometimes in the Cascades... sometimes only in far northeastern California or even farther north," according to Shapiro's website. "The migrant females lay on the tender growth of high-altitude Ceanothus such as Tobaccobrush and Snowbrush, which again may be defoliated. Adults emerge in late July and migrate to estivating grounds, generally above tree-line. These are often in the high country of Yosemite, Sequoia and Kings Canyon National Parks, but can even be in the Trinity Alps, South Cascades, or (as in 2005) on Mount Rose! Estivating Torties do little but 'hang out,' and many high-altitude hikers have described their encounters with millions of them in mystical terms (they often identify them as Monarchs!). In late September these butterflies scatter downslope to hibernate in the foothills--they are the late-winter butterflies of the new year. Estivators-hibernators thus may live 9 or 10 months as adults." (See more about this amazing butterfly on his website.)
Naturalist and insect photographer Greg Kareofelas, an associate of the Bohart Museum of Entomology, UC Davis, says there are a lot of Cal Torties around now. And when they disperse, "they can end up anywhere, including the valley. So not often seen in the valley, but not all that unusual."
This butterfly ended up on its namesake, the butterfly bush in our Vacaville pollinator garden.
Migrating monarchs are fluttering daily into our yard in Vacaville, Calif., one by one, two by two, three by three, and four by four, for a little flight fuel. They're sipping nectar from the Mexican sunflower, Tithonia rotundifolia, and tropical milkweed, Asclepias curassavica.
They're on their way to overwintering sites, such as the Natural Bridges State Park's Monarch Grove Butterfly Natural Preserve, Santa Cruz.
The park's monarch sanctuary "provides a temporary home for thousands of monarchs," according to the website. "In 2016, 8,000 monarch butterflies overwintered at Natural Bridges. From late fall into winter, the monarchs form a 'city in the trees.' The area's mild seaside climate and eucalyptus grove provide a safe place for monarchs to roost until spring."
The numbers typically peak between late October to mid-November. It's an awe-inspiring place, especially if you rear monarchs. And admission is free. The preserve is open to the public from 8 a.m. to sunset daily, or visitors can participate in a free one-hour tour on Saturdays and Sundays at 11 a.m. to 2 p.m.
Meanwhile, scores of monarchs are on their way. Some won't make it. Predators, especially birds, will nail many of them. The weather will deter many others.
We know of at least one that probably won't make it. On Friday, Oct. 27, while we were gathering mllkweed seeds from the Asclepias curassavica, we noticed two lady beetles feasting on aphids.
Wait, what's that beneath that leaf?
Could it be? It was. A monarch caterpillar! Talk about late!
The 'cat is now tucked inside our indoor butterfly habitat, munching on milkweed leaves. With any luck, it will become a mid-life chrysalis and then an adult monarch.
It will take a lot of luck, however, for it to join its buddies in Santa Cruz. Its late start will be exacerbated by the cold, the wind, the rain, the predators....
On a wing and a prayer...
A Sept. 7 article in Reuters, headlined "Monarchs in Western United States Risk Extinction, Scientists Say," indicated that "Monarch butterflies west of the Rocky Mountains are teetering on the edge of extinction, with the number wintering in California down more than 90 percent from the 1980s, researchers said in a study published on Thursday."
Reuters' reporter Laura Zuckerman wrote that "The migratory monarchs of the western United States have a 63 percent chance of extinction in 20 years and an 84 percent chance in 50 years if current trends continue, according to the study."
The scientists, led by Washington State University conservation biologist Cheryl Schultz, published their work in the journal Biological Conservation. It was funded by the U.S. Fish and Wildlife Service, which is weighing the prospect of offering federal protection for monarch butterflies through the Endangered Species Act. The Xerces Society for Invertebrate Conservation is among those spearheading the effort.
Noted lepidopterist Arthur Shapiro, UC Davis distinguished professor of evolution and ecology who has studied butterflies, including the monarchs, for more than four decades, doubts that the western monarchs are teetering on the edge of extinction.
Shapiro, who maintains a website, Art's Butterfly World. says that yes, the western monarchs have been declining faster than the eastern monarchs, as per the Biological Conservation paper. However, during the drought, California populations appeared to rebound significantly, and it is not known whether the trend will persist, he says.
Their comprehensive and well-researched work, titled "Understanding a Migratory Species in a Changing World: Climatic Effects and Demographic Declines in the Western Monarch Revealed by Four Decades of Intensive Monitoring," was funded in part by the National Science Foundation. Their Oecologia abstract: "Migratory animals pose unique challenges for conservation biologists, and we have much to learn about how migratory species respond to drivers of global change. Research has cast doubt on the stability of the eastern monarch butterfly (Danaus plexippus) population in North America, but the western monarchs have not been as intensively examined. Using a Bayesia hierarchial model, sightings of western monarchs over approximately 40 years were investigated using summer flight records from ten sites along an elevational transect in Northern California."
"Multiple weather variable were examined, including local and regional temperature and precipitation. Population trends from the ten focal sites and a subset of western overwintering sites were compared to summer and overwintering data from the eastern migration. Records showed western overwintering grounds and western breeding grounds had negative trends over time, with declines concentrated early in the breeding season, which were potentially more severe than in the eastern population."
"Temporal variation in the western monarch also appears to be largely independent of (uncorrelated with) the dynamics in the east. For our focal sits, warmer temperatures had positive effect during spring. These climatic associations add to our understanding of biotic-abiotic interactions in a migratory butterfly, but shifting climatic conditions do not explain the overall, long-term, negative population trajectory observed in our data."
In acknowledgments, Shapiro and his colleagues thanked the Xerces Society for Invertebrate Conservation and the North American Butterfly Association for the monarch counts and making the data publicly available.
Meanwhile, since late August, the western monarchs (Arizona, California, Nevada, Oregon, Washington, Idaho and Utah) have been winging their way to their overwintering spots to forested groves along coastal California.
And then, around February, they will head inland to start the process again.
It's an amazing phenomenon.
As I write this, four monarchs are gathering some flight fuel, nectaring from two M's: milkweed and Mexican sunflower in our little pollinator garden in Vacaville, Calif., part of their migratory path to the coast. They flutter from flower to flower, seemingly unaware of the California scrub jay circling them and a photographer zeroing in on them. Or the rain about to fall.
For years we've marveled at the migrating whales passing Point Reyes as we stood glued to our binoculars.
And we've expressed awe that a bird--a plover--makes nonstop flights over the central Pacific Ocean from Alaska to Australia and New Zealand.
Amazing. Nothing short of incredible, especially when you consider that many homo sapiens can't find their way out of a parking lot.
They're all on the move. But how many of us have seen the lesser known migrants, such as winged aphids, ballooning spiders, mites, locusts, pelicans, grasshoppers, and armyworm moths, on the move?
Enter Hugh Dingle, an emeritus professor of entomology at the University of California, Davis, and a worldwide authority on animal migration.
Dingle, who was featured in National Geographic's cover story on "Great Migrations in November 2010 and interviewed by LiveScience for its November 2010 piece on “Why Do Animals Migrate?", has just published the second edition of his book, Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996.
The full understanding of migration, or “life on the move,” involves genetics, physiology, and morphology, as well as behavior and ecology, Dingle says.
"The program or syndrome includes specific modifications of metabolic physiology like enhanced fat storage to fuel migration and of sensory systems to detect inputs from the sun, stars, and magnetic field lines to determine compass direction. Intimately involved in the latter are daily and yearly biological clocks. The pathway followed is an outcome of the syndrome of migratory behavior and is part of the ecology that provides the natural selection acting to determine the evolution of migration.”
Not all migration is a round trip; sometimes it's one-way, Dingle says. “Important defining behavioral characteristics are specific departure and arrival tactics and the refusal to stop even in favorable habitats until the migration program is complete,” Dingle says. “In the words of National Geographic reporter David Quammen migrants ‘are flat-out just gonna get there.'"
Why is it important to understand the biological basis of migration and its evolution? “Because migration is so widespread and because migrants have such impact on both natural and man-altered ecosystems,” says Dingle, who achieved emeritus status in 2003 after serving on the faculty of the UC Davis Department of Entomology (now the UC Davis Department of Entomology and Nematology) from 1982 to 2002.
In his book, Dingle covers the interaction between behavior and outcome. Another important focus: he covers the relation between migration and life histories, including the evolutionary genetics of the relationship. Long-distance round-trips, for example, require long lifespans, hence most insects, although not all, migrate only one-way.
“Natural selection acts differently on long versus short lives," Dingle says. "With long lives there are usually many opportunities to produce offspring; with short lives there may be only one. Thus reproductive opportunities may determine when and where to migrate. Migrating aphids postpone reproduction until they colonize new host plants; birds reproduce following migration in the spring, but not in the fall. Some birds and insects use migration to exploit ‘rich patches' and breed in different places in different years or even in the same year."
Dingle, former secretary of the International Society for Behavioral Ecology and past president of the Animal Behavior Society, says he wrote the book for "students of migration and for those biologists who are generally interested in the functioning and adaptations of whole organisms."
Dingle is a fellow of the American Association for the Advancement of Science and the Animal Behavior Society. His research has taken him throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia.
In some respects, he, too, migrated.