The document discusses endangered species and the various threats they face such as habitat loss, disease, pollution, hunting and poaching. It provides examples of species that are now extinct like the passenger pigeon or endangered such as tigers, manatees, spotted owls and whooping cranes. All of these species have faced declining populations primarily due to human activities that destroy habitats or kill the animals. The document emphasizes that endangered species are an indicator of larger problems in the environment and stresses the importance of individual actions to help protect vulnerable species through learning, volunteering, responsible consumption and caring about conservation issues.