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by David F. Marriott, Ph.D.
Executive Director, The Monarch Program
Mystery Monarch
Monarch Program associate Donna Grubussic reared a monarch butterfly from an egg and released it as an adult on the 30th of September, 2007 from Carpinteria, California. It was a female with tag #64231 placed over the right forewing. On the 4th of January 2008 the entire forewing of the butterfly was found in Phoenix, Arizona. A forewing alone without damage usually indicates a bird attack, often by kingbirds (Tyrannus spp.) The distance it traveled was about 430 miles (straight line distance).
The mystery about this butterfly is that the tagged wing was found inside a butterfly enclosure at The Desert Botanical Garden by a volunteer pruning bushes. The enclosure was open to the public from September 29th through November 11th. An average time frame for this butterfly to arrive in Phoenix from Carpinteria would have been late October (based on the history of migration movements). How did the butterfly end up inside the enclosure? The best scenario is that a visitor found the tagged monarch in the garden and placed it inside the enclosure because it was tagged. The facility hosts a tagging program in the autumn and someone may have thought the tagged monarch was part of the program. This is why it is called a mystery monarch.
Monarch Program Tag #64231 from Carpinteria, CA to Phoenix, AZ
There is only one other known monarch flight to Arizona in the autumn. It was one of 300 monarchs released in late September at El Rosario de Arriba, near San Quintin, in northern Baja California about 12 years ago. This monarch traveled nearly 200 miles and was found in early October near Phoenix. However, the recovery is not recognized by scientists because it was a monarch captured in Northern California and released in Baja California, commonly called a monarch transfer.
The Monarch Program has three spring tagged retrievals in Arizona from California and Baja California overwintering sites:
1. Santa Barbara, CA (7 Nov. 1987) to Portal, AZ (9 April), 565 miles
2. El Sauzal, B.C. (13 Dec. 1997) to Gila Bend, AZ (13 March), 250 miles
3. Santa Barbara, CA (Dec. or Jan. 2000) to Page, AZ (14 April), 480 miles
These records show that some overwintering monarchs fly inland during the spring to Arizona. It may not be unusual for California autumn monarchs to fly southeast into Arizona according to butterfly expert/author Robert Pyle. During his journeys nearly a decade ago, he followed autumn monarchs throughout the west and discovered that many traveled southeast into Arizona (Chasing Monarchs, Houghton Mifflin Company, 1999).
Are Monarch Butterflies Losing Their Migration Instinct?
Beginning in June, 2006, butterfly gardens with milkweed plants (Asclepias) in the Southwest have had more monarchs flying in their gardens than any previous year since the Monarch Program was founded in 1990. There have been numerous requests for milkweed plants from people with defoliated plants due to monarch larvae consuming the leaves. This demand has often resulted in sold-out situations with nurseries throughout the Southwest during the summer and autumn months since 2006.
Several tagging experiments have recently been conducted in order to monitor autumn migrants that emerged as adults from wild monarch livestock. In 2006, 112 locally reared monarchs were tagged and released from October 4th through November 16th, within 12-20 miles east of the San Diego coast/bay. Some were reported within days of their release and one was retrieved dead (5 miles east of its release point) at an elementary school butterfly garden several weeks after its release. No tagged monarchs were sighted during a visit to 17 monarch overwintering sites from San Diego to Santa Barbara Counties by Monarch Program volunteers in November and December of 2006.
In the autumn of 2007 in San Diego County, 55 reared monarchs from La Mesa were tagged and released from November 2nd through the 17th. In Escondido, 45 reared and tagged monarchs were released from October 28th through November 10th. None of the monarchs were sighted at overwintering sites visited by Monarch Program volunteers between November 16th and December 9th at 33 sites from San Diego to Santa Barbara Counties.
Monarchs in the Southwest seem to be “happy” during the winter days living in people's backyards as opposed to diapausing a few months near the coast on eucalyptus trees. The number of monarchs reported locally in backyard gardens during the winter months is unusual. They are behaving as a butterfly that has no reason to migrate to the coast. They have host plants, shrub/tree protection in most areas, nectar sources, and warm weather.
Monarch butterflies along the coast of Santa Barbara have occupied people’s backyards every month of the year since records were kept since the 1960’s. Some resident monarchs fly a few miles to live with other monarchs at nearby overwintering sites. They migrate a mile or two to overwintering sites and hang-out for a few months. Santa Barbara has more monarch overwintering sites, including year-round resident monarchs, than any other county in California.
Are new Sub-Tropical Butterflies Residing in Southern California?
1. In 1992, we had an invasion of the sub-tropical giant swallowtail (Heraclides cresphontes). The butterfly ignited news broadcasts and front page stories in local newspapers. It came from the south and southeast and has remained a resident.
2. The sub-tropical orane-barred sulfur (Phoebis philea) has been a resident in Southern California since 2004. However, their flight period in 2007 has been sparse. Only one larva was collected on Cassia didymobotrya in mid-August at our facility in Encinitas, CA and it emerged as an albinic (white) female. Adults have not been reported recently.
3. A new sub-tropical butterfly to this area was spotted in the early afternoon in Del Mar, California on 31 July, 2007 (32° 56.734' N - 117° 15.305' W at 380’ elev.). Three people viewed a red-spotted purple butterfly (Limenitis arthemis arizonensis) sipping nectar from a decaying nectarine fruit. It was also seen chasing a mourning cloak (Nymphalis antiopa). Adult Limenitis feed on sap, fruit, flower nectar, decaying wood, dung, and carrion. Male adults patrol all day near the host plants (usually willow, Salicaceae). There are previous recordings of the red-spotted purple butterfly from Southeast California near the Arizona border. This information is available on www.butterfliesandmoths.org. Otherwise, no records are known from west of this area.
One of the three people that viewed the butterfly identified it from the specimen shown in the photograph. She is a butterfly gardener and has reared many native species. She claimed it was not a pipevine swallowtail (Battus philenor) because she has reared the species. The red-spotted purple is a Batesian mimic of the poisonous pipevine swallowtail. “This one did not have tails. It was smaller, had darker forewings along the edge, with iridescent blue on the hindwings, like a morpho butterfly. It reminded me of being in the tropics,” she said.
A Red-Spotted Purple butterfly (Limenitis arthemis arizonensis) specimen
collected by Mark Walker in Garden Canyon, Cochise County, AZ on July 23rd, 2001
Nine Possible Reasons the Monarch Population is Changing and Why We Have New Butterfly Species in the Southwest
1. The National Arbor Day Foundation has assigned a range of zones to different tree and perennial species that reflect where they can thrive. Much of coastal Southern California from Santa Barbara to San Diego has gained a zone, changing from 9 to 10. From 1990 to 2006, the zones have moved north, with some areas shifting by as much as two zones. Butterflies and other insects shift with the climate zones.
2. These shifts of zones affect plant life and the animals that use the plants as a food source. An example is forests expanding into higher Rocky Mountain elevations due to global warming threaten to wipe out the meadow habitats of a high-mountain butterfly, including the apollo butterfly (Parnassius). Research by biologist Jens Roland (University of Alberta) shows that as colonies of Parnassius become isolated from each other by the new forests, the gene pool is depleted. One particularly cold winter or summer may be enough to wipe out an entire colony of Parnassius, Roland writes in the “Proceedings of the National Academy of Sciences.”
3. The California Department of Forestry and Fire Protection conducts a survey of plant moisture content every year. The survey showed that vegetation during the summer of 2007 in the Southwest was the driest in 90 years. This type of prolonged dryness has a great effect on insects.
4. A new ten year climate prediction model indicates that global warming will not increase significantly during the next two years, but will set in with a vengeance after 2009. This prediction is from the U.K.’s Hadley Center for Climate Research and Prediction. This prediction was based on a ten year climate outlook made possible by plugging current weather and ocean data into well established long term climate algorithms.
5. The Fahrenheit temperature in Southern California is 2.2 degrees higher since 1950. San Diego County was the fourth driest year, and Riverside and San Bernardino Counties were the driest ever in 2007. The study WeatherBill found that 57 percent of cities in the United States showed significant warming trends in the winter.
6. “After eight very dry years on the Colorado River watershed and a record breaking dry winter in Southern California in 2006-2007, the situation in the American Southwest is dangerously dry,” said oceanographer and forecaster Bill Patzert at the Jet Propulsion Laboratory in Pasadena, CA (JPL).
7. La Niña, the oceanic phenomenon that almost always brings a dry winter in Southern California, now appears inevitable. Long-range forecasters at JPL say the La Niña brewing in the central Pacific Ocean is intensifying -- more evidence that the Southwest could face another dry year. However, San Diego had an average rainfall by January 1st 2008.
8. Southern California wildfires in late October of 2003 and late October of 2007 have had major effects on plants and wildlife, including monarchs. Thousands of migrant monarchs that entered the Southwest during this time were probably killed by flames and smoke. The fires may have influenced the low overwintering populations by early November during these seasons because the butterflies usually enter the area by late October, based on a study of 20 years by Monarch Program volunteers.
9. Climate experts claim that global warming is intensifying nature’s cycles by lengthening fire seasons and prolonging droughts in parts of the the west. However, “The connection between global warming, Santa Ana winds, and extremely low Southern California precipitation last winter are not known with sufficient certainty to conclusively link global warming with this disaster,” said researchers at the University of California, Merced, and the University of Arizona. Another study from 2006 in Geophysical Research Letters, the publication of the American Geophysical Union, suggests that Santa Ana winds may occur more frequently in November and December as Southern California’s climate becomes warmer. In turn, that would heighten the risk of deadly blazes.