The effects of post-hatching nutrition on the behaviour of red grouse in captivity

• Main Author: Marquiss, Mick
• Published: University of Aberdeen 1977
• Subjects: 591.5
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.464947

Part of the current model of the population of red grouse is that the food of the grouse chick affects their aggressive behaviour when adult. The aim of the present study was to test this experimentally using captive grouse. In 1971 and 1972 I reared a group of chicks on high (control group) and low (treated group) planes of nutrition. The treated chicks grew more slowly than the control but for longer period so that they become slightly smaller adults. It was shown that the protein limited the growth of 1972 treated chicks whereas it was uncertain which nutrient (or energy) was limiting in 1971. I measured several aspects of the aggressive behaviour of adult cocks. Individuals that were most aggressive behaviour in one situation tends to be so in others. They also had the largest combs and sang most frequently. Cocks of high dominance tended to be aggressive but this association was week. Cocks implanted with androgen became first more aggressive and only subsequently more dominant. Dominance abd aggressive are probably separate traits and the later may be determined by the circulating testosterone level. The low plane of nutrition does not change aggressiveness but lower dominance. The relationship between growth rate and dominance also applied to the individuals within the treated group. Some similar results have been found in studies of other captive vertebrates, mainly domestic and laboratory animals. Relative to the control captives, wild grouse chicks had a low level of protein in their diet and grew slowly so their dominance relationships may also have been affected by their planes of nutrition. Assuming that dominance reflects the ability of a cock to get a territory and aggressiveness, the size of the territory it would take, a hypothesis is presented: that a high plane of nutrition for grouse chicks enhances their ability to compete for territories and reduces the average size of territory that successful cocks attempt to take. This hypothesis applies only where grouse chicks have a plane of nutrition as high as that of the control captives (as, perhaps, on a fertilized moor or a moor overlying base-rich rock).