Recent advances in animal behaviour

Abstract

Ethology, a fast developing field of animal sciences has considerable relevance in animal husbandry, agriculture, control of animal populations, pest control, medicine, wildlife biology, etc. It has made vast strides of progress during the past few decades and some of these trends are reviewed. Communication signals play a salient role in sociobiology of animal groups. Animals deploy visual, acoustic, tactile and olfactory signals during their social interactions. Among these, olfactory cues have certain specific advantages over the other modes concerned. Recently considerable attention has been focussed on chemical signals in animals, especially those of economically important forms such as insects, fishes and mammals. Regarding insects, sex pheromones, aphrodisiacs, trail markers, aggregating and alerting pheromones have been isolated in various insectan orders. The factors controlling sex pheromone behaviour and impact of pheromones on control of insect population have been elaborated. Investigations on chemical cues of lower vertebrates indicate that fishes, amphibians and reptiles deploy them in their social interactions. Pheromones modulate the schooling, reproductive and alarm response behaviour in fishes. Among mammals, urine, fecal pellets, saliva and secretions of specialised skin glands function as sources of olfactory cues. Data on histophysiology, and ultrastructure of specialised skin glands, biochemistry of their secretions have been collected. Osmetrichia, scent marking patterns and fiehmen responses and their hormonal control have been elucidated. The neuroendocrinological basis of scent marking has been made explicit. Relatively only very few of the mammalian pheromones have been isolated. The role of Primer pheromones in modulation of reproductive processes in some of the rodents and signalling pheromones in social interactions of some mammals have been elaborated. Data on olfactory cues in human social interactions indicate the presence of social pheromones. Visual signals of some insects and their role in reproductive activities have been investigated. Social postures in some rodent pests and their behavioural relevance have been studied. Acoustic signals in insects facilitate congregation, sexual attraction, aggregation and alarm responses. Further various aspects of vocalisations in birds and mammals have been investigated. Reproductive investment patterns and sex ratios in insects and parental investment in birds have been elucidated. Play behaviour and their role in behavioural development has been investigated. Etiological analysis of drug action in aggressive behaviour in certain mammals has been made.