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.
It's National Pollinator Week!
Do you know where your pollinators are?
Or better yet, do you know how to attract them and protect them?
Pollinator Partnership has announced that June 19-25 has been designated National Pollinator Week by the U.S. Department of Agriculture and the U.S. Department of the Interior.
Talk about alliteration: pollinators can be bees, birds, butterflies, bats and beetles. (And many other species, including flies.)
We stepped into our pollinator garden this morning (before the heat shot up to 107 degrees) to check for butterfly diversity.
- A Gulf Fritillary, Agraulis vanillae, flutter over to the pink mallow.
- A mournful duskywing, Erynnis tristis,warm itself on the butterfly bush.
- And a cabbage white butterfly, Pieris rapae, linger on the lavender.
They're all pollinators.
Of course, the larvae of the cabbage white is considered a pest (see UC Statewide Integrated Pest Management website), but the adult looks like a lady in white.
The adult cabbage white butterfly can yield you a prize--a pitcher of beer or its equivalent--if you collect the first one of the year in the annual Beer-for-a-Butterfly Contest, hosted by Art Shapiro, UC Davis distinguished professor of evolution and ecology. The bug must be collected in the three-county area of Solano, Yolo or Sacramento.
Shapiro, who has studied butterflies of Central California for more than four decades and posts research information on his website, usually wins. Read why he sponsors the contest and where he found the first one of 2017 on Bug Squad.
Have you seen me? Can you identify me?
No, you're a skipper, but which one are you?
The colorful brown skipper butterfly that touched down on our Jupiter's Beard in Vacaville, Calif., on May 17 puzzled us. First skipper we've seen this year in our pollinator garden, but what was it?
Butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology, who has studied butterflies for more than four decades--and who posts his research and observations on his Art's Butterfly World website--identified it as Poanes (Paratrytone) melane, the Umber Skipper.
"It's having a HUGE year," Shapiro told us today. "It was extinct in Davis for over 30 years! But it came back a few years ago."
The Umber Skipper is also recorded on his website. "Although common in parts of the Bay Area where it is an urban 'lawn skipper,'" on our transect this is entirely a species of riparian forest and is generally uncommon or even rare. It perches in dappled light and shade along streamsides, generally well off the ground...In Berkeley it breeds happily on Bermuda Grass, which seems to have not discovered farther inland."
The Poanes melane adults visit Yerba Santa, dogbane, milkweed, thistles, yellowstar thistle, California buckeye, and coyote bush, among others.
The larvae of this skipper feed on the leaves of various grasses. Wikipedia describes the wings as "umber brown, the forewing with a darker disc and pale spots and the hindwing with a light yellow-brown band."
Quick research indicates that J. B. Heppener of the UC Berkeley Department of Entomology wrote about its 1941 spread in San Diego County in a piece published in 1972 in the Journal of Research on the Lepitoptera. He mentioned that when it spread into San Diego County in 1941 it "was sudden and well noted by resident collectors due to its previous absence from the county."
San Diego residents reportedly first encountered it in August 1941. "F. T. Thorne was one of the first collectors to encounter melane and he vividly recounts his excitement upon realizing what was being caught," Heppener wrote.
We know that feeling...that excitement!
So there we were, on Mother's Day, looking at the yet-to-bloom English lavender in our yard.
And there it was, something golden staring back at us.
It was showing a face that "only a mother could love"--or an entomologist or an insect enthusiast.
Scathophaga stercoraria, the golden dung fly. A red-eyed blond fly.
It's a beneficial insect. The larvae are often found in the feces of large animals, including horses, cattle, sheep, deer and wild boar, where the insect breeds. (Note: We have no horses, cattle, sheep, deer or wild boar near us!) The larvae eat the dung, making this insect important to natural decomposition.
The adult is a predator, it hunts for flies and other small insects. The adults also sip nectar, just like honey bees and other pollinators. Nearby was another golden dung fly, dead. Art Shapiro, UC Davis distinguished professor of evolution and ecology, looked at its swollen belly and said it died "from entomophagous fungus--perhaps the same one that 'glues' houseflies to window panes."
For more information on these fascinating insects, check out the BugGuide.Net entry on the golden dung fly. The insect was first described in 1758 by Carolus Linnaeus as Musca stercoraria, according to BugGuide.Net.
Like a ballerina on the dance floor of life, a newly eclosed Western tiger swallowtail, Papilio rutulus, flutters from its host plant, a sycamore tree, to a crape myrtle.
The yellow-and-black butterfly spreads its wings, warming its flight muscles.
It lingers longer than it should (predators abound), but it is in no hurry and neither are we. It folds its wings, looks at the near-cloudless blue sky, and just pauses.
This tiger has no paws, but it knows how to pause.
"The Western tiger swallowtail is basically a species of riparian forest, where it glides majestically back and forth along the watercourse," says butterfly expert Art Shapiro, distinguished professor of evolution and ecology. "It has expanded into older urban neighborhoods where several of its host genera are grown as shade trees, and behaves as if the street were a watercourse," he writes on his website. "Spring individuals are smaller and usually paler than summer. Low-elevation hosts include sycamore (Platanus), ash (Fraxinus), cherry and other stone fruits (Prunus), willow (Salix), privet (Ligustrum), lilac (Syringa) and (in Sacramento County) sweet gum (Liquidambar)."
Soon the Western tiger swallowtail will head for a nectar floral source and find a mate--not necessarily in that order.
Have a safe flight!