Home  |  Photos  |  Calendar  |  Directions  |  Contact  |   Donate/Join/Renew

Species that Specialize

 
species_that_spec Showcasing Edgewood’s endangered, threatened, or “species of special concern” animal and plant species, this exhibit illustrates how specialization can lead to extinction when habitat is lost. Species include the blind harvestman, San Mateo thornmint, western bluebird, fountain thistle, Bay checkerspot.

In this Exhibit

Microcina Edgewoodensis (Micro-blind harvestman)
Edgewood Micro-blind Harvestman

The Edgewood Micro-blind harvestman (Microcina Edgewoodensis) is a minute spider-like creature (about 1mm long as an adult) that lives in Edgewood Park. Spider-like because the harvestman has eight legs; however, this invertebrate animal is of a different order from spiders. It has a pale orange body, yellowish-white legs, and lacks eyes. The Micro-blind harvestman is found beneath serpentine rocks in grassland adjacent to scrub oaks. This species is threatened by habitat loss due to the invasion of exotic grasses in serpentine grassland.

San Mateo thornmint is an annual herb from the mint family (Lamiaceae). This plant is found only in serpentine soils that have a heavy clay inclusion–an uncommon soil type known as serpentine vertisol. The San Mateo thornmint is listed as federally endangered, state endangered, and a CNPS List 1B.1. Edgewood has the last naturally occurring population of San Mateo thornmint in the world.

Western Bluebirds (Sialia mexicana) are small thrushes that live and breed in Edgewood County Park. Males are easily identified by the brilliant blue plumage of their heads, wings, and tails, and by their rust-colored breasts. Females are duller and have more brown and gray in their feathers. This species requires a stable environment that has low-growing grasslands sprinkled with oak trees. It is important that the grass be low-growing because bluebirds like to perch on fence posts and other vantage points that rise above native grasslands. The higher non-native grasses make it more difficult for the birds to spot insects and can interfere with the bluebird’s ability to forage.

Fountain thistle is a rare, native thistle currently found only in serpentine seeps or perennially moist areas in San Mateo County. This herbaceous perennial is federally and state-listed endangered, and a CNPS 1B.1.

Fountain thistle (Cirsium fontinale var. fontinale) is no longer found at Edgewood, but there is a chance it could be reintroduced. It was last seen in the late 1990s at a seep along the Clarkia trail. There are plans to reintroduce it to the San Francisco Water District property on the west side of Highway 280, adjacent to Edgewood.

Bay checkerspot butterfly (Euphydryas editha bayensis) is a threatened species that relies for its food on the plants that grow in serpentine soil. Timing is important too. Host plants for the larvae need to be available at just the right time, when the larvae first emerge from their eggs, and they also need to keep growing for as long as the larvae need to feed on them. It is also important that host plants do not get crowded out by invasive fast-growing species such as Italian ryegrass. By 2003, no Bay checkerspot butterflies were seen at Edgewood. Since then, much work has been done to restore the butterfly’s habitat and to reintroduce the Bay checkerspot butterfly to Edgewood.