Not all protected areas are created equal. Transition zones like Sonora, Mexico's Nacapule Canyon, where tropical deciduous scrub forest meets the Sonoran Desert community, often boast especially rich biodiversity and endemism, thus demanding top priority for protection from development, extraction and other habitat degradation. At least five endemic plants and two vertebrates are found in this small drainage in the volcanic Sierra El Aguaje mountain range. It is protected as part of the Cajón del Diablo Biosphere Reserve.