2012-01-15 "Colorful Monarch butterfly has been scarce, experts puzzled as to reasons" by Irma Widjojo from "Vallejo Times-Herald"
Many lepidoterists, or butterfly enthusiasts, should anticipate an exciting winter: Monarch butterflies are expected to make a come back after a disconcerting decline in population.
About 15 years ago, one could drive in the winter by the small park by St. Peter's Chapel on Mare Island and find a few of the the trees had suddenly turned color.
The hue was caused by clusters of Monarch butterflies perching on the cedar and eucalyptus trees.
"They used to hang on the leaves, groups of them," said Wally Neville, a Vallejoan wildlife enthusiast. Neville worked on Mare Island for more than 30 years until his retirement in the early 2000s.
However, in the past decade, the number of the orange-and-black butterflies has dwindled to the point of extinction on Mare Island. The cause of the decline is a mystery, even to experts.
The Mare Island Heritage Preserve offers guided bird watching tours, but volunteer manager Myrna Hayes said she no longer even bothers mentioning the possibility of seeing the Monarch butterflies.
The Xerces Society tries to track the number of Monarchs seen along the California coast during the winter. Its findings are not optimistic.
The butterfly population has fallen by 90 percent since 1997, said Sarina Jepsen, endangered species program director. The Xerces Society is a nonprofit, Oregon-based organization dedicated to protect wildlife through the conservation of invertebrates and their habitat.
The Monarchs aggregate on the coast of California and Baja California, Mexico, during the winter before dispersing to breed in spring, Jepsen said.
The organization's data has no data recorded for Mare Island since 1994.
"It's difficult to get volunteers to go out to the site where they don't even see the butterflies anymore," Jepsen said. In 1994, only 50 Monarchs were recorded on Mare Island.
Neville still goes to the island regularly to look at birds, as well as to seek out the disappearing Monarchs.
"We've seen individuals recently," Neville said. "Not the large number that we had seen in the past. We haven't seen those in more than 10 years."
There have been many theories about the butterfly's disappearance.
Jepsen said the most dominant theories are the lost of the breeding and overwintering habitat for the butterflies. The milkweed that the caterpillars feed on and the trees where the butterflies gather during the winter have been increasingly destroyed by construction and development, she said.
Art Shapiro, a professor of evolution and ecology at University of California, Davis, has studied the butterfly for many years.
"There have been definite trends," Shapiro said. "They are baffling, and we do not understand it."
He said there is a change in the breeding trends of this particular species. He agreed that there was a pronounced downward trend in the number beginning in the mid- to late-1990s, bottoming out last winter.
"To try to give an explanation, I would just be waving my arms," Shapiro said. "We don't have any hard evidence for the explanation."
He said the trend could be blamed on many factors, including climate change and diseases.
However, he said, things might be looking up this winter.
"We are expecting to see the number to be better this year," Shapiro said.
The Xerces Society has also recorded an increase in the Monarch population this winter, even though Jepsen was quick to point out that the number was no where near where it was in the early 1990s.
During a recent interview on Mare Island, Vallejo's Neville pointed out about five Monarchs fluttering in between the eucalyptus and cedar trees by the St. Peter's Chapel.
"That's promising," he said while looking through his binoculars. "At least we get to see a few of them today."
Monarchs at a glance -
* Danaus plexippus
* Wingspan: About 4 inches
* Weigh: Less than half an ounce
* Life span of an adult butterfly: Mostly four to five weeks
* The Monarchs migrate over generations from Canada and the United States to the center of Mexico and back.
-Source: World Wildlife Fund
Wally Neville looks through his binoculars searching for Monarch butterflies up in the trees at the park by St. Peter's Chapel on Mare Island. Neville is a member of the Audobon Society, and used to work on the island for more than 30 years. (Irma Widjojo/Times-Herald)