Flight Behaviour and Avoidance of Predators in Thomson's Gazelle (Gazella Thomsoni Guenther 1884)

[As a suhsidiary result of a study on social behaviour of Thomson's gazelle in Serengeti National Park (Tanzania) there are given informations on flight behaviour and avoidance of predators. Alert posture, flight in galloping and stotting, and especially the relatively soft alarm call are more or less contagious and can release alertness or flight in conspecifics. Shaking of the flank (BROOKS, 1961) does not initiate flight only but galloping in general. It is the last link in a chain of actions which appears completed only in intraspecific situations. In perception of enemies the tommy reacts to optical stimuli from silhouettes and movements. The senses of smell and hearing are not so important in this context. If the tommies have recognized an enemy in time they try to keep it under control (behaviour of fascination). The territorial ♂♂ are especially important in this context. Bachelor herds are found predominantly at the periphery of an area inhabited by a gazelle population. Thus predators often encounter them first. Gaits and behaviour patterns in flight are described with special regard to stotting display. The young fawns stay put (Abliegen, WALTHER, 1059/60) and so are difficult to be seen. The way in which the mother manages her fawn especially during the first days of its life lead to the view that the fawn and the place where it rests are kept from contamination with odors attractive to predators. In rare cases even adult gazelles try to evade predators by lying down. Tommies do not fight against predators when hunted. The mother defends her fawn against jackals and tries to divert hyenas which hunt for her fawn. Factors which influence the flight distance are discussed. The flight distance varies with the different predators according to their danger for gazelles. Experiments showed that adult ♂♂ in herds (bachelors) have a lesser flight distance than ♀♀ in herds, adult ♂♂ have a lower one than subadult ♂ ♂ , territorial ♂♂ have a lower one than adult bachelors, but solitary wandering ♂♂ show the greatest flight distance of all gazelles. Thus age, sex and social status are all significant factors influencing flight distance. By observations of the behaviour in response to predators, human beings, cars and especially by the study of the mistakes in flights from animals which are not predators of gazelles, it was possible to find a few flight releasing factors, most of them similar to or identical with sign stimuli : sudden appearance, direct course (toward the gazelles), size, good perceptibility (contrast), large number of enemies, high speed, proximity, strangeness, and experience. In concrete cases usually several of these factors operate concomitantly. A remarkable number of them are also known as factors which release the following reaction in young ungulates (WALTHER, 1964a, 1966). This may explain certain cases of ambivalent behaviour, especially of gazelle fawns in regard to predators. A few observations on kills of predators lead me to the view that the age, sex and social groups are preyed upon by various predators at different rates. There are relationships between the differences in flight distances, and the spatial distribution according to the social grouping of gazelles on the one hand, and the different hunting methods of the predators on the other hand. The ecological importance of each predatory species depends on its specialization and preference for gazelles as prey animals, its number, and its preferred biotype. Implications for the management of national parks and game cropping outside the protected areas are discussed. Thomson's gazelles show very few behaviour patterns of alertness, alarm, flight and hiding that are restricted to predators only; most patterns are also seen in intraspecific situations. Certain observations lead to the view that these behaviour patterns are adapted primarily to special conditions of the intraspecific realm and work better in it., As a suhsidiary result of a study on social behaviour of Thomson's gazelle in Serengeti National Park (Tanzania) there are given informations on flight behaviour and avoidance of predators. Alert posture, flight in galloping and stotting, and especially the relatively soft alarm call are more or less contagious and can release alertness or flight in conspecifics. Shaking of the flank (BROOKS, 1961) does not initiate flight only but galloping in general. It is the last link in a chain of actions which appears completed only in intraspecific situations. In perception of enemies the tommy reacts to optical stimuli from silhouettes and movements. The senses of smell and hearing are not so important in this context. If the tommies have recognized an enemy in time they try to keep it under control (behaviour of fascination). The territorial ♂♂ are especially important in this context. Bachelor herds are found predominantly at the periphery of an area inhabited by a gazelle population. Thus predators often encounter them first. Gaits and behaviour patterns in flight are described with special regard to stotting display. The young fawns stay put (Abliegen, WALTHER, 1059/60) and so are difficult to be seen. The way in which the mother manages her fawn especially during the first days of its life lead to the view that the fawn and the place where it rests are kept from contamination with odors attractive to predators. In rare cases even adult gazelles try to evade predators by lying down. Tommies do not fight against predators when hunted. The mother defends her fawn against jackals and tries to divert hyenas which hunt for her fawn. Factors which influence the flight distance are discussed. The flight distance varies with the different predators according to their danger for gazelles. Experiments showed that adult ♂♂ in herds (bachelors) have a lesser flight distance than ♀♀ in herds, adult ♂♂ have a lower one than subadult ♂ ♂ , territorial ♂♂ have a lower one than adult bachelors, but solitary wandering ♂♂ show the greatest flight distance of all gazelles. Thus age, sex and social status are all significant factors influencing flight distance. By observations of the behaviour in response to predators, human beings, cars and especially by the study of the mistakes in flights from animals which are not predators of gazelles, it was possible to find a few flight releasing factors, most of them similar to or identical with sign stimuli : sudden appearance, direct course (toward the gazelles), size, good perceptibility (contrast), large number of enemies, high speed, proximity, strangeness, and experience. In concrete cases usually several of these factors operate concomitantly. A remarkable number of them are also known as factors which release the following reaction in young ungulates (WALTHER, 1964a, 1966). This may explain certain cases of ambivalent behaviour, especially of gazelle fawns in regard to predators. A few observations on kills of predators lead me to the view that the age, sex and social groups are preyed upon by various predators at different rates. There are relationships between the differences in flight distances, and the spatial distribution according to the social grouping of gazelles on the one hand, and the different hunting methods of the predators on the other hand. The ecological importance of each predatory species depends on its specialization and preference for gazelles as prey animals, its number, and its preferred biotype. Implications for the management of national parks and game cropping outside the protected areas are discussed. Thomson's gazelles show very few behaviour patterns of alertness, alarm, flight and hiding that are restricted to predators only; most patterns are also seen in intraspecific situations. Certain observations lead to the view that these behaviour patterns are adapted primarily to special conditions of the intraspecific realm and work better in it.]