Nectaring Experiment at P.G.’s Monarch Grove Sanctuary Creates Quite a Flap

As monarchs alight on the eucalyptus and pine trees of the Pacific Grove Monarch Grove Sanctuary, Bob Pacelli digs into the black soil. He removes a shrub in a plastic pot from one of many planter boxes.

Feeding Frenzy: When P.G.’s monarch population plummeted to fewer than 1,000 in 2009, many blamed the city for over-pruning the wind barrier.

“Where are the Cal Poly students? Where’s Public Works?” he asks, removing the pot and replanting the shrub in the box. “If they want to help out, great. But it’s all about the monarchs.”

His irritation can be traced to a long-standing communication gap between the sanctuary’s citizen volunteers, City Hall officials and outsider scientists – a tension that seems to be as native to P.G. as the butterfly habitat.

Researchers with California Polytechnic State University’s Monarch Alert program have planted a buffet of bushes, echiums and other nectaring plants in the sanctuary in an effort to learn more about which blossoms monarchs like to munch.

But their bouquet acquired uninvited blossoms. Sanctuary volunteers, including Pacelli, planted additional flowering plants last month, introducing x-factors to the Cal Poly experiment.

Pacelli, a freelance filmmaker who grew and donated many of the plants for the experiment, brought in the extra flowers with best of intentions, hoping to revitalize monarch food sources nibbled by deer earlier this year. But Cal Poly biological sciences professor Francis Villablanca says the new plants fudge up his experiment.

The experiment incorporates planter boxes with various species of nectaring plants, arranged so access to certain buds is easier in one box than in another. If a butterfly chooses one type of flower consistently, regardless of the box, it’s likely monarchs prefer that flower as a food source.

The introduction of plants outside the experimental parameters confounds these results, Villablanca says. It has also delayed data collection, which was supposed to start earlier this month.

Yet this is a project that began with cooperation.

After Pacelli cultivated the plants, public works staff transplanted them to planters in October, as part of a plan designed by Monarch Alert scientists. But Pacelli says they didn’t use all the plants he’d provided – so he took it upon himself to transplant the extras in time for the monarchs’ fall migration.

In a heated exchange of emails, Public Works Superintendent Mike Zimmer criticized Pacelli for not getting city clearance to landscape the grounds. Pacelli and his supporters responded by blaming Public Works for not using every available donated plant.

“What we’re asking from Bob Pacelli is that he communicate through proper channels with the city,” Zimmer says. “They’re not communicating with Public Works, so they don’t know what other docents and volunteers are doing.”

It’s unclear if Villablanca will be able to rectify his design to incorporate the unexpected plants. Conservationists could use information from this experiment to create habitats that are more attractive to monarchs and boost a declining population.

The massive dip in monarch numbers once estimated in the hundreds of thousands concerns many. It also makes management of the P.G. sanctuary a particularly hot political topic.

In fall 2009, city management took withering criticism for dramatically overpruning the sanctuary’s trees. Monarch numbers plummeted to below 1,000 that winter.

“The monarchs were all over the grass, hanging on for dear life,” Pacelli stated in a 2009 email.

After Pacelli and others intervened, leading an effort to fill the wind gaps with potted oak and eucalyptus, numbers rebounded to nearly 5,000 the following winter. The counts reached more than 7,400 in early November.

Further counts may show whether an increase in food correlates to more butterflies, but without proper controls, researchers can’t determine which plants are attracting the monarchs.

“Why do they leave? Why do they stay? It’s the million dollar question,” Villablanca says.

But the relationship between the city and its citizen monarch guardians may be permanently damaged. Sanctuary volunteer Frances Grate, however, has faith her citizen brigade can work with the scientists to find answers. “This is an ongoing experiment,” she says. “We will continue to find out what is the best flowering plant.”

The question now is how to coordinate everyone’s good intentions for the good of the monarchs. Villablanca suggests a resident scientist who could help skillfully coordinate things around the site with both the city and volunteers.

“It takes constant management,” he says, “or the butterflies go somewhere else.”

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