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Title: The feeding ecology of red grouse in N.E. Scotland
Author: Savory, C. John
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1975
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The feeding activity of wild and captive red grouse is similar. In the evenings, both have marked peaks of feeding which are greater in winter than in summer, and monthly variations in their food intake are also alike. Heather forms at least 90% of the diet of wild red grouse for most of the year. At one moor it was calculated that each bird would eat between 18 kg and 25 kg (by dry weight) of heather in a year, which means that grouse eat only 1.3 - 2.4% of the total annual production of heather shoots and flowers there. The food intake of captive grouse was positively related to body weight and day-length, and negatively to air temperatures. It increased during the summer moult, and hens ate most while producing eggs. The preferences of grouse for particular ages of heather were studied on three moors and also in captivity. Preferences in the wild were associated with the interrelated factors of density, age, height an chemical composition of heather. The last three factors affected preferences separately in captivity, where preferences also varied with the physiological state of the birds. Heather preferences of free ranging mountain hares, sheep and red deer were also studied. Wild grouse selected heather with a relatively high concentration of nitrogen and phosphorus compared with the available heather; this, confirmed, earlier work. The: amount of selection was related to feeding rates and sometimes to the mean weight of heather particles eaten. In autumn and winter, grouse selected less in the evening, but did not change their selection with time of day in spring. In spring, both sexes were equally selective for nitrogen and phosphorus, but the hens' food was richer in calcium than that of cocks. However, hens ate much more food in spring than cocks. Wild grouse chicks ate a more varied diet than adults, but still mostly heather shoot tips. They often ate invertebrates during their first few weeks, but these formed only a small proportion of the diet by dry weight; chick survival was not related to the abundance of invertebrates available. Chicks selected heather containing more nitrogen, phosphorus and calcium than adults did.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available