FREMONT -- Livermore couple and longtime Bay Area residents Jay and Chris Tavris have traveled around California to observe and take photos of wildlife. But last week they traveled to the Ardenwood Historic Farm for the first time for a special reason: hundreds of monarch butterflies.
"I just love them," Chris Tavris said. "I don't know, they're just my favorite insect."
More than 40 people, including many young children, attended an hourlong monarch butterfly walk. Clusters of the orange and black insect (Danaus plexippus) could be seen clustered on the branches on a grove of eucalyptus trees. While they could be easily seen with the naked eye, a telescope offered a closeup view.
The butterflies have migrated from the Canadian Rockies and as far north as Alaska to the California coast where the weather, food and shelter are ideal for reproduction, Ardenwood naturalist Trent Pearce said.
They come every year to Ardenwood farm, where they will roost until February before traveling back north.
"Monarch butterflies don't do well in cold temperatures," Pearce said. "They're very small insects and they're not able to regulate their body temperature the way we can."
The population of monarch butterflies at the grove can vary widely from year to year, though the numbers generally are declining. This season there's less than 1,000, Pearce said.
"There used to be a lot," said Melissa Fowlks, an interpretative student aide at Ardenwood, who visited the farm as a child. "You would come in and they'd be everywhere."
Fowlks and Pearce said the reduction in numbers is likely due at least in part to climate change -- though through colder, harsher temperatures, not warmer.
"They can't cope with us," Fowlks said. "They can't keep up. Nature's cruel."
During the winter, the monarchs are attracted to the warmer climates near the California coast. While the larvae feed on milkweed, eucalyptus trees provide the adults with camouflage, shelter from the elements, a high place to be away from predators, and nectar and water.
While eucalyptus trees are not native to California, the monarchs have adapted to them because of the decline of preferred trees, such as redwoods and Monterey pines.
"This is a comfortable place for them to stay," Pearce said.
There was plenty of oohing and aahing and picture snapping when the group approached the grove and saw the butterfly clusters high in the branches.
"Oh, I see them," said one woman as she picked up her daughter. "You see them, sweetie? You see them out? They're out flying above us."
"I see it, I see it," said another little girl.
"They're incredible when seeing them up close," said Berkeley resident Sara Hougan, who attended the walk with her husband, two young children and friends. "They're gorgeous, they're so fragile. It's amazing they survive at all."
Tara Baker, of Berkeley, came with her husband and two young sons. She said the insects were beautiful and she was fascinated by the migration patterns.
While the butterflies can live through the southward migration, it can take four to five generations to travel back to their summer grounds. That's due in part to harsh weather and other reasons that are up for debate.
"It travels so far and there's a genetic code that keeps that happening," Baker said. "It's an amazing natural phenomenon. I think it's a special thing to find in the natural world."
With the exception of the weekend of Dec. 4, Ardenwood will be holding monarch butterfly walks, and related children's programs and slide shows beginning at
11 a.m. every Saturday and Sunday through Feb. 6. Ardenwood is at 36400 Ardenwood Blvd. in Fremont. For more information, call 510-544-2797 or go to