Marin County California Overwintering Site Report

[Paul Cherubini]

Marin County is a coast county immediately north of San Francisco.
Prior to 1992, the Marin county coastal towns of Muir Beach, Stinson Beach and Bolinas were consistently home to 10,000 - 80,000 monarchs every year, including the severe drought years of 1971, 1976-1977 and 1988-1991. Then a sharp butterfly population downturn started in, ironically, the wet year of 1992 followed by a brief recoveries in 1995 and 1997-1998, followed by an even an more severe and prolonged downturn from 1999-2006 when only 100's or 1000's of butterflies were present. By 2007 only 10's to high 100's of butterflies were present. Now this fall, in 2008, it appears only 10's to low 100's of butterflies will be present - about a 95-99% decline from pre-1992 levels.

On Wednesday, Oct. 1, 2008, I visited the Muir Beach, Stinson Beach and Bolinas, Calif. cluster sites and here is what I saw:

Muir Beach: Visited the Terwilliger Grove and Seascape Ave pine groves and drove casually around town. Not a single monarch was seen despite good weather.

Stinson Beach: Visited the Chapman Ravine cluster site. http://i85.photobucket.com/albums/k75/4af/sba.jpg Only about a half dozen or so solitary butterflies were seen and no clusters. Drove around the hills of the town and saw
only a few monarchs nectaring on the blooming english ivy plants. http://i85.photobucket.com/albums/k75/4af/sbb.jpg

Bolinas: Visited the Terrace Ave eucalyptus grove: no monarchs seen.

Visited Elm St x Kale Rd street eucalytpus grove. About 75 monarchs total including a few small clusters of 5-10 monarchs. http://i85.photobucket.com/albums/k75/4af/kale.jpg

Visited west end of Larch Rd eucalytpus grove: About 100 monarchs total including three small clusters of 5-20 monarchs. http://i85.photobucket.com/albums/k75/4af/yucca.jpg

Visited Purple Gate site: One solitary monarch seen

Visited various west end of Mesa Rd eucalyptus groves. No monarchs seen.

CONSERVATION IMPLICATIONS OF THIS EXTREMELY SEVERE AND LASTING POPULATION DECLINE

Over the past 30 years, many hundreds of thousands dollars worth of donations and taxpayer dollars has been used to protect and manage many of the above listed overwintering sites in Marin County. The monarch scientific community has claimed protection and management of these overwintering sites "is critical for the long-term welfare of western monarch butterflies." http://www.creeksidescience.com/monarch.html

However, because of the 95-99% decline in the numbers of fall migrant monarchs arriving in Marin county since 1998, the cluster sites are no longer occupied by significant numbers of butterflies, hence the money spent on site protection and management has largely gone to waste. And since these now nearly unoccupied sites will not likely be sold, the funds that were used to purchase and manage them
will probably not ever be returned to the taxpayers.

Will we learn anything from this experience? Like learn that it was wrong for conservationists to arbitrarily assume that droughts or the number and quality of overwintering site habitats are the critical factors limiting the overall size of the western monarch population? Or learn that it would
likely have been wiser to have invested available conservation funds into identifying and protecting the high quality summer milkweed breeding habitats which are far more likely to be critically important? Or learn to start studying and monitoring the types and abundance of parasites, predators and disease pathogens of the summer breeding monarchs - factors which DO change over time (because new ones are constantly arriving at our shores from other countries; e.g. the european paper wasp)?