Thursday, April 16, 2009

A Visit to San Bruno Mountain

A Visit to San Bruno Mountain

Today, the endangered mission blue butterfly (Icaricia icariodes missionensis) was on the wing and relatively common during a hike on the southeast ridge of San Bruno Mountain. The beautiful metallic blue males and greyish-blue females were flying about or perching on the lupine foodplants. Other animals were enjoying the warm spring day, including ring-necked snakes, California ringlet butterflies (Coenonympha tullia california), painted lady butterflies (Vanessa cardui), anise swallowtail butterflies (Papilio zelicaon), and pipevine swallowtails (Battus philenor). Johnny jump-up (Viola pedunculata) and other beautiful wildflowers were in bloom.

This is a special place located a few miles north of the San Francisco International Airport on the west side of the San Francisco Bay. It's a 3000 acre semi-wilderness located within one of the largest cities on Earth. It is home to the endangered callippe silverspt butterfly (Speyeria callippe callippe) San Bruno elfin butterfly (Incisalia mossii bayensis), San Francisco lessingia (Lessingia germanorum), and the San Francisco garter snake (Thamnophis sirtalis tetrataenia). Last year, a young mountain lion was spotted on the Mountain! Of course, being surrounded by city, there have been numerous proposals to utilize San Bruno Mountain ranging from removing the top 300 feet and using to enlarge San Francisco International Airport to development of homes.

In 1983, a special permit known as a habitat conservation plan was issued by the Department of Interior that in return for allowing urban development of portions of San Bruno Mountain, the majority was set aside forever as habitat for the endangered butterflies and the snake. Yet, a problem that was unforeseen 26 years ago imperils the site and unless it is brought under control will extirpate many of the endangered and native species of plants and animals.

The threat is a constellation of exotic and highly invasive plants including eucalyptus, gorse, French broom, fennel, Oxalis, and many other species. In addition, the grasslands which are inhabited by the mission blue butterfly and the callippe silverspot butterfly are being replaced by coastal scrub. It is not unreasonable to say that unless dramatic measures are undertaken in the near future, the value of San Bruno Mountain to the four listed butterflies and snake, and many other native species will be minimal or non-existent.