Reptiles and amphibians around the lake, including the rough-skinned newt (Taricha granulosa), the Cascades frog (Rana cascadae) and the garter snake (Thamnophis sirtalis), feed as well on insects and young fish (among other prey). Many mammals can be found around the lake and in the adjacent wilderness area, national forest, and parklands. These include black bear (Ursus americanus), blacktail deer (Odocoileus hemionus), river otter (Lutra canadensis), black-tailed jackrabbit (Lepus californicus), and mountain lion (also known as cougars or puma) (Puma concolor). Castle lake cougars have on occasion been known to crouch in the bushes and watch humans, their eyes shining in the moonlight. No attacks have been noted.