This document summarizes information about several endangered animal species found in Ecuador, including the black-headed spider monkey, bare-tailed armored tree rat, giant otter, and Ecuadorian sac-winged bat. It provides details on each species such as their habitat, behaviors, population status, and conservation threats. The black-headed spider monkey population has declined 80% due to hunting and habitat loss. The bare-tailed armored tree rat is known from less than 10 individuals and lives in a small altitude range. The giant otter lives in family groups along rivers and wetlands. The Ecuadorian sac-winged bat lives in caves and abandoned mines in colonies and has seen population decreases.