Distribution
This species was once considered to be "relatively common" on its home island. Since then the habitat has been severely degraded, mainly by feral goats which were introduced there. The island was also used for grazing sheep and cattle, and some feral pigs were present. The animals may have eaten the plant at times, but they mainly damaged the land by trampling the soil, which led to soil compaction, loss of topsoil, and erosion. The introduction of exotic plant species such as ripgut brome (Bromus diandrus), wild oat (Avena barbata), and red brome (Bromus madritensis rubus) also degraded the habitat.
Due to sttep terrain of San Clemente Island the exact abundance of Castilleja grisea is not currently known. Recent surveys have discovered new populations of this species. Surveys in 2007 estimate more than 10,000 plants existing. This plant has been a federally listed endangered species since 1977, when it was one of the first species to be designated so. The plant's population had been drastically reduced by the activity of the feral goats. Its populations has increased at least ten-fold since the removal of these non-native herbivores. The species has recovered so well through management programs by the Navy, it was recommended for downlisting during the last review conducted by the United States Fish and Wildlife Service. Remaining threats include erosion, invasive grasses, and wildfire from military exercises.
The species has a relatively high genetic variability for an uncommon island endemic. This and its steady recovery from low numbers give an optimistic outlook for the species' recovery.
Read more about this topic: Castilleja Grisea
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