• Pacific Grove Monarch Numbers Still Healthy

    Supporters of the Pacific Grove Monarch Grove Sanctuary addressed a curious occurrence this week. More than 300 dead monarchs have been observed in the Pacific Grove Monarch Grove Sanctuary over the past several weeks, many with their abdomens missing. “This is consistent with wasp predation, but it is difficult to determine if wasps are solely responsible.” asserted Francis Villablanca, Ph.D., the science advisor for Cal Poly State University’s Monarch Alert Program. “This predation on the monarchs should not be too alarming.”

    Stuart Weiss, Ph.D., the scientist working with the City of Pacific Grove on the Sanctuary Maintenance Plan states that “Such predation is a normal feature of overwintering monarchs. Some birds learn to avoid the distasteful parts, as do some rodents.”

    Currently, an estimated 2.5% of the overall Pacific Grove monarch population has been affected by the predation. The Monarch Alert Program, tracking weekly changes in the estimated monarch population size, has observed a normal decrease in the Pacific Grove Sanctuary monarch population that is consistent for this time of year and consistent with other overwintering sites throughout San Luis Obispo and Monterey Counties.

    Monte Sanford, Ph.D., an Environmental Science Advisor observed, “There is nothing unusual about the predation by wasps at the sanctuary, but the City should continue to monitor the situation.” The City agrees. Mike Zimmer, Public Works Superintendent for the City of Pacific Grove stated, “The City of Pacific Grove works diligently to maintain a healthy monarch sanctuary. Before the start of this overwintering season, we put together a Sanctuary Maintenance Plan with members of the City’s Natural Resource Commission, the City’s Museum Board, and public works staff. We are closely monitoring this situation with the help of scientists, the Monterey County Agricultural Commissioner’s office, and the Pacific Grove Museum of Natural History.” The Pacific Grove Museum of Natural History’s monarch docents are tracking the numbers and genders of observed dead monarchs, and the docents are collecting the dead monarchs for scientific study.

    With over 8,800 monarchs still hanging in clusters in the sanctuary, visitors continue to enjoy the monarchs’ beauty. The sanctuary is open from sunrise to sunset and the admission and parking is free. The sanctuary is located on Ridge Road off Lighthouse Avenue near downtown Pacific Grove. Plan to visit on warmer days between 12 and 3, when Museum monarch docents are available with spotting scopes, and the butterflies are active.

    -Lori Mannel, Director, Pacific Grove Museum of Natural History
    – Mike Zimmer, Director, City of Pacific Grove Public Works

    posted to Cedar Street Times on December 22, 2011

    Topics: Current Edition, Front PG News, Green, Breaking News, Butterflies


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