Note: according to Schoenherr it wasn't goats and sheeps per se, as places like the Central Valley had grazers for a long time; it was over-grazing by farmers.

Note: according to Schoenherr it wasn't goats and sheeps per se, as places like the Central Valley had grazers for a long time; it was over-grazing by farmers. The Californian islands are another matter. The introduction of large herbivores usually cause all kinds of havoc on small islands, as the plants are usually not adapted to them. That said, the ecology of small islands tends to be very unstable generally.