A rhinoceros (pronounced ry-NOSS-ə-rəss) is a large animal that belongs to any of the five species that still live today (or many species that no longer exist). It is part of a group called odd-toed ungulates, which are hoofed mammals in the family Rhinocerotidae. This family is the only one in the group called Rhinocerotoidea, and all members of this group are sometimes called rhinoceroses.
Manatees are large sea animals that live in slow-moving rivers, canals, saltwater bays, areas where rivers meet the sea, and along coastlines. They move to different places throughout the year, spending winters in Florida waters and traveling as far north as Virginia and the Chesapeake Bay. During warmer months, they may be found as far north as Baltimore, Maryland, and as far west as Texas.
The Bald and Golden Eagle Protection Act is a United States government law that protects two types of eagle. The bald eagle was chosen as a national symbol of the United States by the Continental Congress in 1782. It received legal protection under the Bald Eagle Protection Act of 1940.
The California condor (Gymnogyps californianus) is a type of vulture found in the Americas and the largest bird in North America. It disappeared from the wild in 1987 when all the remaining wild birds were captured, but it has been reintroduced to northern Arizona, southern Utah (including the Grand Canyon and Zion National Park), the coastal mountains of California, and northern Baja California in Mexico. It is the only living species in the genus Gymnogyps, though four other species in the same genus are now extinct.
The conservation of bison in North America is a continuing effort to help American bison (Bison bison) recover from near extinction. Plains bison, a type of bison (Bison bison bison), are important for the health of the North American Great Plains. Bison are a species that needs special care because their numbers dropped very low at the end of the 19th century.
The history of wolves in Yellowstone includes the removal, disappearance, and return of gray wolves (Canis lupus) to Yellowstone National Park and the Greater Yellowstone Ecosystem. When Yellowstone National Park was created in 1872, wolf numbers were already decreasing in Montana, Wyoming, and Idaho. The park’s creation did not protect wolves or other predators, and government programs to control predators in the early 1900s helped remove gray wolves from Yellowstone.
The Lotka–Volterra equations, also called the Lotka–Volterra predator–prey model, are two mathematical equations used to describe how populations of two species change over time. One species is a predator, and the other is prey. The equations show how the sizes of these populations change: $$ frac{dx}{dt} = alpha x – beta xy, quad frac{dy}{dt} = -gamma y + delta xy $$ Here, $ x $ represents the prey population, and $ y $ represents the predator population.
A keystone species is a type of organism that has a much bigger impact on its environment than its numbers suggest. The idea was introduced in 1969 by zoologist Robert T. Paine.
Trophic cascades are strong, indirect effects that can influence entire ecosystems. They happen when one level in a food chain is reduced. For example, a top-down cascade occurs when predators are effective at hunting, which reduces the number of their prey or changes their behavior.
Rewilding Europe is a non-profit group located in Nijmegen, the Netherlands. Its goal is to restore natural areas across Europe. The organization has helped increase the number of animals that were once in danger of disappearing, such as the European bison and the Iberian lynx.