Texas Wildlife Science

Wildlife enthusiasts often remember the individual animal experiences—the trophy buck, the life-list falcon, the rattler that made the heart jump, the baby bird we rescued, or the playful otter glimpsed on a fishing trip. We tend to value that one animal that left an impression on us.

On the other hand, agencies and organizations often focus on the overall status of a wildlife species. The U.S. Fish and Wildlife Service and Texas Parks and Wildlife Department maintain lists of threatened and endangered species that reflect a picture of how the species is doing rangewide or in the state. NatureServe is a non-profit organization that networks with other organizations and professionals to assess the status of North American species. They classify species and subspecies across different geographic areas as Secure, Apparently Secure, Vulnerable, Imperiled, or Critically Imperiled. The International Union for the Conservation of Nature (IUCN), a world-wide partnership of government agencies and non-government organizations, maintains a “Red List” for species across the globe. They classify species as Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, Extinct, Data Deficient, or Not Evaluated. These various rankings help biologists understand how species are doing overall.

Wildlife scientists tend to focus somewhere between the individual animal and the whole species. They think in terms of wildlife populations. As defined in Chapter 3, a population is a group of organisms belonging to the same species occupying a particular area simultaneously. This is the scale at which a biologist can often apply management actions to benefit a species. In order to manage a wildlife population, a biologist must identify the goals, measure the population, understand population dynamics (how populations tend to change over time), and apply the right tools.