Territory (animal)
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In ethology, sociobiology and behavioral ecology, the term territory refers to any geographical area that an animal of a particular species consistently defends against conspecifics (and, occasionally, animals of other species). Animals that defend territories in this way are referred to as territorial.
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[edit] History
The idea of animal territories was first introduced by the British ornithologist Eliot Howard in a book published in 1920. In the 1930s it was developed further by the American ornithologist Margaret Morse Nice through research on the song sparrow. It was widely popularised by Robert Ardrey in his book The Territorial Imperative, and the popularity of this book led to an exaggerated perception of the importance of territory in social ethology. In fact only a minority of species maintain territories with well defined boundaries, within which they live and find all the resources they need.
[edit] Classic territories
The most obvious examples of the "classic" territory are birds and fish, often brightly coloured ones like the European Robin or the Siamese Fighting Fish. Animals like these defend territories that contain their nest site and sufficient food resources for themselves and their young. Defense rarely takes the form of overt fights: more usually there is a highly noticeable display, which may be visual (as in the red breast of the robin), auditory (as in much bird song, or the calls of gibbons) or olfactory, through the deposit of scent marks. Many territorial mammals use scent-marking to signal the boundaries of their territories; the marks may be deposited by urination, by defecation, or by rubbing parts of the bodies that bear specialised scent glands against the substrate. For example, dogs and other canids scent-mark by urination and defecation, while cats scent-mark by rubbing their faces and flanks against objects. Many prosimians use territorial marking; for example, the Red-bellied Lemur creates territories for groups of two to ten individuals in the rainforests of eastern Madagascar by scent marking: the male Diademed Sifaka also scent marks defended territories in some of these same rainforests.
[edit] Defense
Territories may be held by an individual, a mated pair, or a group. Territoriality is not a fixed property of a species: for example, robins defend territories as pairs during the breeding season and as individuals during the winter, while some nectarivores defend territories only during the mornings (when plants are richest in nectar). In species that do not form pair bonds, male and female territories are often independent, in the sense that males defend territories only against other males, and females only against other females; in this case, if the species is polygynous, one male territory will probably contain several female territories, while in some polyandrous species such as the Northern Jacana, this situation is reversed.
Quite often territories that only yield a single resource are defended. For example, European Blackbirds may defend feeding territories that are distant from their nest sites, and in some species that form leks, for example the Uganda kob (a grazing antelope), males defend the lek site (which is used only for mating).
Territoriality is only shown by a minority of species. More commonly, an individual or a group of animals will have an area that it habitually uses but does not necessarily defend; this is called its home range. The home ranges of different groups often overlap, and in the overlap areas the groups will tend to avoid each other rather than seeking to expel each other. Within the home range there may be a core area that no other individual group uses, but again this is as a result of avoidance rather than defense.
Behavioural ecologists have argued that food distribution determines whether a species will be territorial or not. Territoriality is only expected to emerge where there is a focused resource that provides enough for the individual or group, within a boundary that is small enough to be defended without the expenditure of too much effort.
Territoriality is least likely with insectivorous birds, where the food supply is plentiful but unpredictably distributed. Swifts rarely defend an area larger than the nest.
Conversely, large solitary (or paired) carnivores, such as bears and the bigger raptors require an extensive protected area to guarantee their food supply. this territoriality will only break down when there is a glut of food, for example when Grizzly Bears are attracted to migrating salmon.
