Stuart Weiss works to re-introduce the Bay Checkerspot Butterfly to Edgewood Park

by Linda Hubbard on February 27, 2013

Conservation biologist Stuart Weiss (pictured above) first roamed the hills of what is now Edgewood Park when he was an undergrad at Stanford, producing his honor thesis on the area. Later he became involved in saving the land from becoming a golf course. Now, in activities that help celebrate the Park’s 20th anniversary, he’s working to re-introduce a species he once observed, the Bay Checkerspot Butterfly.

“I’d monitor the Checkerspot more out of interest than study,” says Weiss, who received his PhD from Stanford in 1996 and now heads a small consulting firm in Menlo Park, Creekside Center for Earth Observation, that does restoration and conservation planning. “Edgewood had the last Checkerspot population on the Peninsula. From 1997 to 2002, I watched the population collapse and go into extinction.”

Kid with caterpillar_EdgewoodThe main cause, Stu was to discover, was automobile emissions from the cars along highway 280, adjacent to the Park, which, he explains “fertilizes the grasslands with excessive amounts of nitrogen.”  That results in grasses growing over shorter wildflowers like the Dwarf Plantain, which is caterpillar food.

“We’ve since figured out how to manage the habitat by mowing,” he says. “A well-timed mow in the spring basically knocks the annual grasses back. By taking off the seed heads, there would be a further reduction the following year.”

Seeing the positive effects over the past five years, Stu and others tried to reintroduce the Checkerspot in 2007 by releasing 1,000 caterpillars. That proved to be one of the driest years in a century, and their efforts failed.

In 2011, they tried using what Stu describes as the “big hammer approach,” releasing 4,000 caterpillars. That netted 2,000 new caterpillars in 2012 and another 5,000 were brought in.

“This year we estimate there are 3,000 out there,” he says. “And we brought in another 5,000 this month [Feb. 21 and 24]. It’s very exciting, and lots of groups worked together to make it happen. In an era when species are continuing to disappear, we must get much more active.

“Nitrogen overdose is a world wide problem that’s gotten very little attention compared to climate change, but it’s documented to be  a much more immediate threat to biological diversity. We have a nice little microcosm at Edgewood to show what causes it and what we can do about it.”


Two more Checkerspot-related events are scheduled to take place at Edgewood Park:

  • Citizen Science: Monitoring Bay Checkerspot Butterflies. Join trained citizen scientists as they carefully look for and count Bay checkerspot butterflies as part of the reintroduction effort at Edgewood County Park and Natural Preserve. You will enjoy brilliant displays of wildflowers as you walk through butterfly habitat that is normally off-limits to the public. March 24 through April 6, 1 – 4 pm.
  • The Bay Checkerspot Butterfly Story. Follow Dr. Stuart Weiss into this protected butterfly habitat at the height of the wildflower season, where he will explain the mystery of this butterfly’s disappearance. Apr. 13, 1:00 – 4:00 pm

Both events require reservation through the Friends of Edgewood Park website.

Photos by Frances Freyberg

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