Monarch Habitat

“Houston! No! Sacramento, we have a problem!”

by Jim Anderson of Sisters, OR
this piece first appeared in Volume 23 issue 35 of the Source Weekly, Bend, OR.

The title of this piece was a common statement back in the 70’s and 80’s when NASA was doing all they could to place men and machinery in space as we reached for the stars. It also became a common statement for all kinds of problems in our society for many different reasons, and now I use it to bring your attention to a problem: the lack of migrating monarch butterflies in spring.

My wife, Sue, and I just returned from an event we have been a part of for over five years — helping with the annual butterfly survey at Lava Beds National Monument in Northern California, just south of Klamath Falls. In fact, it was Sue who started the interest in keeping track of the butterflies of Lava Beds. We were regular visitors there when she obtained Monarch butterfly tags from the University of Toronto back in the early 90’s. Our kids were just the right age to start working with butterflies, and that long-legged eldest son of ours, Reuben, could outrun and net the fastest butterfly on the monument.

In those days, Lava Beds was THE place to visit to see Monarchs. The native Narrow Leaf Milkweed on the monument and adjacent USFWL refuge was/is the perfect food source for Monarch caterpillars, and native wildflowers for nectaring were very abundant. Most winters delivered plenty of water in the form of snow, and in summer, thunderstorms added their moisture.

We came to know all this quite by accident. As we were slowly rounding a curve on the refuge touring road, our son Caleb, who was then about 6-years old, suddenly announced, “I gotta go pee!” I came to a quick stop and when I took him to a place where he could get the job done we noticed monarchs flitting about the blossoms of a plant we had never seen before. When we went on to Lava Beds we found hundreds of the same, which we discovered were Narrow Leaf Milkweeds, many of which had monarch caterpillars munching away on the leaves.

Well, years later a lightning storm hit the monument resulting in a wildfire that destroyed much of the Monarch breeding habitat. It took several years for the milkweed to regenerate. But in spite of the recovery, many of the plants with larvae on them along the monument roads were being mowed down for “weed removal.” That led the butterfly people to plead with the road maintenance crew to stop mowing alongside the pavement. The summer rain runoff from the pavement was supplying the needed moisture for the milkweed which Monarchs were utilizing to raise new butterflies.

However, even with the cooperation of the road maintenance crew to raise the sickle bar and leave the milkweed alone, the Monarchs did not recover their numbers like they were in the old days. Then, just this year, after finding no Monarchs on the monument during the annual survey, I hit the panic button; “Houston, we have a problem!”

Thank goodness a friend who is an exceptional entomologist, and once a member of the Xerces Society staff (an invertebrate conservation organization), was on the survey. She opened the door that provided what I believe is the answer to why there were no Monarchs at Lava Beds this year, and why the population never regained its numbers after the wildfire in summer 2008: the Monarch breeding habitat in Coastal California was/is going downhill and the native milkweed is dying off, halting the Monarchs from producing butterflies to continue their northern migration in spring.

Monarchs’ annual migration is a widely-known phenomenon — particularly the eastern populations that fly to Mexico. In the western U.S., over one million monarchs from Arizona to Washington and north into British Columbia, fly to more than two hundred groves along the California coast each fall. These butterflies mate, then leave their overwintering sites in spring, and fly eastward to California’s Central Valley, the Sierra Nevada foothills and north to Oregon, Washington, and British Columbia in search of milkweed on which to lay their eggs.

However, past and recent annual counts of overwintering monarchs on the California coast have revealed significant population declines. For example, in 1997, Natural Bridges State Beach near Santa Cruz had an estimated 120,000 monarchs. In 2009, only 1,300 butterflies overwintered. This past season showed an alarming loss of 95% of overwintering California monarchs. This loss is reportedly due to urban and agricultural development and the application of herbicides in croplands, pastures, and roadsides.

The protection and restoration of native plant communities in these areas is critical to reversing this trend. We must place stronger controls on the use of herbicides, especially those neonicotinoids that are so deadly to every living invertebrate. Also we need to set aside all the native milkweed locations as monarch conservation areas and make sure there’s enough water allocated to their survival.

MILKWEED

Fifteen species of milkweed are native to California. These drought-tolerant plants play a critical role in supporting a tremendous range of pollinators, and occur in nearly all of the state’s eco-regions.

The showy flowers of milkweeds offer abundant, high quality nectar to pollinators, making them notable honey bee plants in many parts of the country. However, an enormous range of other pollinators from hummingbirds to butterflies are frequent flower visitors.

Milkweeds are named for their milky, latex sap, which contains alkaloids and cardenolides, complex chemicals that make the plants unpalatable to most animals.

The plants have fleshy, pod-like fruits (“follicles”) that split when mature, releasing the seeds. Fluffy hairs, known as pappus, silk, or floss, are attached to the seeds. These hairs aid in wind dispersal. Milkweeds have a variety of ethnobotanical uses.

Native Americans used stem fibers to make string, rope, and cloth. Also, the sap was used by some tribes to heal sores and cuts and for wart removal. During World War II milkweed floss was used to fill life vests and is currently used as hypo-allergenic filling for pillows and comforters.

In addition to native species, California has three introduced milkweeds, A. curassavica, A. fruticosa, and A. tuberosa. While these species are widely available, there is debate among ecologists about their effects on wildlife and native plant communities. Given this uncertainty, they should not be introduced to natural areas.

Though a few milkweed species are common in disturbed areas such as roadsides, railways, and fields, most require specific habitat conditions and are not common as cropland weeds.

Milkweed Pollination – Milkweed flowers have a unique shape and are pollinated in a more specific way than most other insect-visited flowers. Rather than occurring as free grains that are accessible to any visitor, milkweed pollen is contained in pollinia, waxy sacs located inside vertical grooves of the flower. When an insect visits the flower to obtain nectar, one of its legs may slip into a groove (“stigmatic slit”), attaching pollinia to the insect’s leg. Fertilization occurs when pollinia are then inadvertently transferred by the insect to another milkweed flower.

Monarch Butterflies – Milkweeds are the required host plants for caterpillars of the monarch butterfly (Danaus plexippus). Caterpillars sequester the plants’ chemical compounds, giving them protection by making them distasteful to predators.

California’s Native Milkweeds (commercially available species) – Due to their ability to grow in a wide range of conditions, two species of milkweeds — narrow-leaved and showy — are the most suitable for the majority of restoration efforts.

© Aaron Schusteff Narrow-leaved milkweed (Asclepias fascicularis)
Elevation: 50 – 2,200 m (150 – 7,200 feet)
Flowering time: May – October
Flower color: corolla pink, corona white
Maximum Height: 3 feet
Description: Narrow-leaved milkweed is the most widespread species in California, growing in every region of the state except the Sonoran Desert and the upper montane, subalpine, and alpine zones of the Sierra Nevada. Suitable locations include dry to moist soil in open, sunny areas. It is typically found in plant communities such as valley grasslands, wetlandriparian areas, foothill woodlands, and chaparral, and clearings within yellow pine, red fir, and lodgepole pine forests.

© Rod Gilbert Showy milkweed (Asclepias speciosa)
Elevation: 0 – 1,900 m (0 – 6,250 feet)
Flowering time: May – September
Flower color: corolla pink, corona pink or white
Maximum Height: 5 feet
Description: Showy milkweed grows in dry to moist soil in open, sunny areas and occurs in many plant communities including wetlands, meadows, savannah, and forest clearings, as well as disturbed sites along roadsides, railways, and waterways. The species occurs in the forested montane regions of the Sierra Nevada, the North Coast Ranges, and the southern Cascade Ranges, and in the arid northern Central Valley and Owens Valley.