Impala in the context of "Diurnality"

In geology, a depression is a landform sunken or depressed below the surrounding area. Depressions form by various mechanisms.

Ethology is a branch of zoology that studies the behaviour of non-human animals. It has its scientific roots in the work of Charles Darwin and of American and German ornithologists of the late 19th and early 20th century, including Charles O. Whitman, Oskar Heinroth, and Wallace Craig. The modern discipline of ethology is generally considered to have begun during the 1930s with the work of the Dutch biologist Nikolaas Tinbergen and the Austrian biologists Konrad Lorenz and Karl von Frisch, the three winners of the 1973 Nobel Prize in Physiology or Medicine. Ethology combines laboratory and field science, with a strong relation to neuroanatomy, ecology, and evolutionary biology.

A horn is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. Horns are distinct from antlers, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone.

One pair of horns is usual; however, two or more pairs occur in a few wild species and in some domesticated breeds of sheep. Polycerate (multi-horned) sheep breeds include the Hebridean, Icelandic, Jacob, Manx Loaghtan, and the Navajo-Churro.

The rut (from the Latin rugire, meaning "to roar") is the mating season of certain mammals, which includes ruminants such as deer, sheep, camels, goats, pronghorns, bison, giraffes and antelopes, and extends to others such as skunks and elephants. The rut is characterized in males by an increase in testosterone, exaggerated sexual dimorphisms, increased aggression, and increased interest in females. The males of the species may mark themselves with mud, undergo physiological changes or perform characteristic displays in order to make themselves more visually appealing to the females. Males also use olfaction to entice females to mate using secretions from glands and soaking in their own urine.

During the rut (known as the rutting period and in domestic sheep management as tupping), males often rub their antlers or horns on trees or shrubs, fight with each other, wallow in mud or dust, self-anoint, and herd estrus females together. These displays make the male conspicuous and aid in mate selection.

Strangling or strangulation is the compression of the neck leading to restriction of the flow of oxygen through the trachea. Strangling causes an increasingly hypoxic state in the brain, which can lead to unconsciousness or even death. Fatal strangulation typically occurs in cases of violence, accidents, and is one of two main ways that hanging causes death (alongside breaking the victim's neck).

Strangling does not have to be fatal; limited or interrupted strangling is practised in erotic asphyxia, in the choking game, and is an important technique in many combat sports and self-defense systems. Strangling can be divided into three general types according to the mechanism used:

Aepyceros is a genus of African antelope that contains a single living species, the impala (Aepyceros melampus). It is the only known member of the tribe Aepycerotini.

Two extinct species are known, Aepyceros datoadeni and Aepyceros shungurae. A third species, Aepyceros premelampus has been transferred to a new genus, Afrotragus.

The oxpeckers are two species of bird which make up the genus Buphagus, from Ancient Greek βοῦς (boûs), meaning "ox", and φάγος (phágos), meaning "eater", and family Buphagidae. The oxpeckers were formerly usually treated as a subfamily, Buphaginae, within the starling family, Sturnidae, but molecular phylogenetic studies have consistently shown that they form a separate lineage that is basal to the sister clades containing the Sturnidae and the Mimidae (mockingbirds, thrashers, and allies). Oxpeckers are endemic to the savanna of Sub-Saharan Africa.

Both the English and scientific names arise from their habit of perching on large mammals (both wild and domesticated) such as cattle, zebras, impalas, hippopotamuses, rhinoceroses, and giraffes, eating ticks, small insects, botfly larvae, and other parasites, as well as the animals' blood. The behaviour of oxpeckers towards large mammals was thought to be exclusively mutual, though recent research suggests the relationship can be parasitic in nature as well.