Posts Tagged: Danaus plexippus
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.
A mighty male Monarch on the move. On its way to one of coastal California's overwintering sites, it stops to sip from flight fuel (nectar) from a Mexican sunflower, Tithonia. (Photo by Kathy Keatley Garvey)
The western migration of the Monarch butterflies (Danaus plexippus) to their overwintering sites along the California coast is underway.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis, recorded four Monarchs at his Suisun monitoring site yesterday. He's been monitoring butterflies in Central California for some four decades.
This morning, a male Monarch fluttered into our yard to sip some nectar from a Mexican sunflower (Tithonia). (A distinguishing feature of the male Monarch: a small black spot on each of its two hindwings. See photo below.)
Monarchs head for sites along the coast, including Santa Cruz, Monterey, Natural Bridges and Pacific Grove, to overwinter, Shapiro noted.
"There used to be a small site in Fairfield, near the old Juvenile Hall on West Texas Street, in a row of Eucalyptus. It's been gone for decades. Some years they try to overwinter in Marin and Sonoma counties, but usually give up and shift south in December. In the past few years there has been a little winter breeding on the south coast. This was never recorded before."
The migration of the Monarchs to overwintering sites in central Mexico is well-publicized, but some monarchs head for the California coast. According to the monarchwatch.org website, monarchs east of the continental divide generally migrate to central Mexico from as far away as Ontario, Canada. "Monarchs west of the divide fly to the coast of California to spend the winter. They cluster together on tree limbs during the winter months in California by the thousands, and in central Mexico by the millions." (Download the PDF on the monarchwatch.org site.)
We're glad to see the huge national campaign to plant milkweed, the host plant of the Monarchs. The Xerces Society for Invertebrate Conservation has posted a wealth of information on its website for us to take action. The Monarch population has declined by more than 90 percent in under 20 years.
“Monarch butterflies are declining due to loss of habitat,” said Monarch Watch director Chip Taylor. “To assure a future for monarchs, conservation and restoration of milkweeds needs to become a national priority.”
It also helps to provide nectar resources for the Monarchs to help them along in their migration. In our yard, they like the Mexican sunflower (Tithonia), the butterfly bush (Buddleia davidii), and blue beard (Caryopteris × clandonensis). See list of Monarchs' favorite plants on the monarchwatch.org site.
Meanwhile, an occasional Monarch flutters into our family bee/butterfly garden to sip some nectar. Sometimes territorial native bees chase them away but the Monarchs return, determined to grab some flight fuel.
A male Monarch nectaring on Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)
Side view of the Monarch. (Photo by Kathy Keatley Garvey)
Monarch gets ready for flight. (Photo by Kathy Keatley Garvey)
When a monarch butterfly comes fluttering through your yard, grab your camera. Marvel at it beauty, celebrate its presence, and keep it in your memory. It may be become an endangered species the way things are going.
The Xerces Society for Invertebrate Conservation recently reported that the monarch population has declined by more than 90 percent in under 20 years. And, “during the same period it is estimated that these once-common iconic orange and black butterflies may have lost more than 165 million acres of habitat — an area about the size of Texas — including nearly a third of their summer breeding grounds.”
So a trio—Center for Biological Diversity, Center for Food Safety, and the Xerces Society—filed a legal petition asking the U.S. Fish and Wildlife Service for Endangered Species status to protect the monarch (Danaus plexippus).
The widespread loss of milkweed, the butterfly's host plant, especially throughout the Midwest, is troubling.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis, says there's plenty of milkweek in Northern California. “The problem is that nobody's there to breed on it.” For example, he sees large spreads of milkweed (Asclepias speciosa) around his many monitoring sites, including one by the Vacaville (Calif.) Transit Center. “Probably 75 stems, but I have never ever seen a monarch there, let alone any evidence of breeding." (See his entry on monarchs on his website.)
So, a monarch's solo visit to our little bee garden seems like a major event. When we see one, as we did Sept. 17, it heads straight for the Mexican sunflower (Tithonia).
Backlit, the monarch resembles a stained glass window. What a gorgeous butterfly, worthy of the royal name, “monarch!”
The only question is: will we consider it worthy enough to save it?
- Plant milkweed, its host plant.
- Avoid insecticides or herbicides.
- Become a citizen scientist and help record sightings.
- Support conservation efforts.
- Promote public awareness.
Backlit, the monarch resembles a stained glass window as it touches down on a Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)
Side view of a monarch on a Tithonia. (Photo by Kathy Keatley Garvey)
Monarch spreads its wings, a glorious sight, even as the afternoon light fades. (Photo by Kathy Keatley Garvey)
The Xerces Society for Invertebrate Conservation issued news today that is both disturbing and hopeful.
Disturbing in that the monarch butterfly population (Danaus plexippus) has declined by more than 90 percent in under 20 years.
Hopeful in that the monarch may receive federal protection through the Endangered Species Act.
The Xerces Society, the Center for Biological Diversity, the Center for Food Safety, and monarch scientist Lincoln Brower, have filed a legal petition with the U.S. Fish and Wildlife Service to protect the monarch through the Endangered Species Act. The agency must respond within 30 days as to whether the petition warrants further review.
“Monarchs are in a deadly free fall and the threats they face are now so large in scale that Endangered Species Act protection is needed sooner rather than later, while there is still time to reverse the severe decline in the heart of their range,” related Lincoln Brower, preeminent monarch researcher and conservationist, who has been studying the species since 1954.
Tragicallly, the monarchs have lost more than 165 million acres of habitat, including nearly a third of their summer breeding grounds that contain their host plant, milkweed. The female monarchs lay their eggs on milkweed and this is the only food their larvae eat.
As Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis, told us today: "Might be too little too late but they have to preserve/conserve milkweeds (Asclepias spp.) That's more important than the butterfly itself."
Xerces earlier sounded the alarm on the critical role that milkweeds play in the monarch's life cycle.
Senior scientist Tierra Curry of the Center for Biological Diversity, hammered home this point in the news release: “The 90 percent drop in the monarch's population is a loss so staggering that in human-population terms it would be like losing every living person in the United States except those in Florida and Ohio.”
And the loss of habitat is equal in size to the state of Texas.
The news release said that the butterfly's dramatic decline is "being driven by the widespread planting of genetically engineered crops in the Midwest, where most monarchs are born. The vast majority of genetically engineered crops are made to be resistant to Monsanto's Roundup herbicide, a uniquely potent killer of milkweed, the monarch caterpillar's only food. The dramatic surge in Roundup use with Roundup Ready crops has virtually wiped out milkweed plants in midwestern corn and soybean fields."
Science policy analyst Bill Freese of the Center for Food Safety was quoted as saying: "The widespread decline of monarchs is driven by the massive spraying of herbicides on genetically engineered crops, which has virtually eliminated monarch habitat in cropland that dominates the Midwest landscape. Doing what is needed to protect monarchs will also benefit pollinators and other valuable insects, and thus safeguard our food supply.”
Monarch butterflies are known for their spectacular multigenerational migration each year from Mexico to Canada and back, the news release said.
"The population has declined from a recorded high of approximately 1 billion butterflies in the mid-1990s to only 35 million butterflies last winter, the lowest number ever recorded," according to the release. "The overall population shows a steep and statistically significant decline of 90 percent over 20 years. In addition to herbicide use with genetically engineered crops, monarchs are also threatened by global climate change, drought and heat waves, other pesticides, urban sprawl, and logging on their Mexican wintering grounds. Scientists have predicted that the monarch's entire winter range in Mexico and large parts of its summer range in the states could become unsuitable due to changing temperatures and increased risk of drought, heat waves and severe storms."
Endangered species director Sarina Jepson of the Xerces Society worries--and rightfully so--that the monarch may become extinct, just like the passenger pigeon.
We are, too. We've seen only two--two--of these majestic butterflies fluttering in our family bee garden this year.
Monarch butterfly nectaring on Mexican sunflower, Tithonia, as a territorial male longhorned bee, Melissodes agilis, takes aim. (Photo by Kathy Keatley Garvey)
Monarch butterfly heading toward a butterfly bush. (Photo by Kathy Keatley Garvey)
This is milkweed, the monarch's host plant. (Photo by Kathy Keatley Garvey)
Just call it "The Battle Over the Tithonia."
A female monarch butterfly--gender identified by butterfly expert Art Shapiro, professor of evolution and ecology at the University of California, Davis and Lynn Kimsey, director of the Bohart Museum of Entomology--fluttered into our bee garden early this morning and dropped down on a Mexican sunflower (Tithonia).
Her landing was perfect. The monarch (Danaus plexippus), a species that Sharpio rightfully says "requires no description"--claimed her flower as several male long-horned sunflower bees, Melissodes agilis, began targeting her.
Talk about a friendly "welcoming party." Not!
Those Melissodes agilis aren't called "agile" Melissodes agilis for nothing.
The monarch zipped over to another Tithonia, only to be trailed by the Melissodes dive bombers.
After foraging on her third flower and failing to evade the tactical squad, the monarch apparently figured it just wasn't worth her efforts.
Off she went, escorted out of the bee garden by the bomb squad.
A male sunflower bee, Melissodes agilis, targets a monarch. (Photo by Kathy Keatley Garvey)
Watch your backside! (Photo by Kathy Keatley Garvey)
Head to head: a monarch and a Melissodes square off. (Photo by Kathy Keatley Garvey)