In nature, not all organisms are created equal. Some species may be lost from an ecosystem without particularly severe consequences for other members of the biotic community. Others, however, play critical roles in the systems' ecology; the loss of these focal, "keystone" species can have disastrous results, unbalancing the system and leading to the loss of several other species. Ultimately, such cascading disturbances have the potential to permanently alter the character of the entire ecosystem. In addition to the discrepancies in biological importance, certain species and groups are often singled out for conservation for legal, economic, or aesthetic reasons. Threatened or endangered species, for instance, attract detailed study because the legal mandate to avoid harming these creatures necessitates learning all we can about their biology. Regardless of the underlying reasons, some organisms warrant particular attention beyond normal biodiversity studies; the reports in this section will describe the biology of the San Miguel valley's key species, and will detail their importance to local conservation.