Territories and the Food Plant of Individual Red Grouse: I. Territory Size, Number of Mates and Brood Size Compared with the Abundance, Production and Diversity of Heather

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Abstract
Within areas, the size of individual territories of red grouse [Lagopus lagopus scoticus] varied inversely with the proportion of ground occupied by vegetation containing the birds'' main food plant, heather [Calluna vulgaris]. This apparent adjustment was most obvious where the heather was sparse and heavily grazed by sheep and cattle. The smallest territories and the densest breeding stocks tended to occur where the heather sward was broken up into numerous small patches (whether as a result of burning or otherwise), with a large length of heather-patch edge per hectare. Territory size was not related to the yield of green shoots per hectare of heather on the territories in spring. Territories of cocks paired with hens were larger than those of cocks with no hens. As territories did not differ in the productiveness of their heather in spring, those belonging to mated cocks contained most green shoots. The number of young reared by individual pairs was not related to the total weight of green heather shoots on their territories in spring or to the mean yield of shoots per hectare.