The role of diet on the growth, survival and movement of red grouse chicks was examined. We compared two areas of moorland in Scotland; a dry heath with a low density of red grouse and poor chick survival and a wetter heath/bog with relatively higher red grouse numbers and higher rates of chick survival. There were no differences in clutch size, or the proportion of eggs hatching between the two moors but brood survival was significantly lower on the dry heath. Radiotagged hens with broods were monitored during the first 12 days following hatching, the chicks captured, weighed and faecal samples collected. Invertebrate samples were collected within brood feeding ranges. Analysis of chick faeces was used to identify dietary components. Heather comprised the major dietary component on both moors. Invertebrates formed a higher component of diet on the wet moor, and this was positively correlated with growth rates, which in turn were positively correlated with chick survival. We present data from an experiment carried out in 1982, in which chicks showed higher growth rates with increasing insect availability. We also show that broods in which all the chicks survived (4-10 days) had smaller home range areas than broods in which some of the chicks died during this period. We suggest that the differences in chick survival between the two populations was due to variations in the abundance of invertebrates, particularly Tipulids. The protein provided by a high invertebrate component in the diet is, therefore, an important determinant of young red grouse chick growth and survival in some areas.

We assessed the influence of habitat characteristics on nest site selection and nest success of red grouse Lagopus lagopus scoticus in three populations on managed moorland in Scotland during 1998-1999. We measured habitat char acteristics at the nests of 148 radio-tagged female grouse and compared them with similar measurements taken at fixed and random points within their home range. Red grouse nested in vegetation that was significantly taller and denser, and with greater canopy cover, than points adjacent to nests or to ran dom points. They nested more in mature heather and less in grass-dominated vegetation than would be expected by chance. Red grouse nest success was high with 77% initial success rising to a minimum of 80% success once re-nesting had occurred. Nest success was weakly related to vegetation height in 1998, but no similar relationship was found in 1999. We suggest that the high nest success of red grouse and the relatively small influence of habitat character istics on the outcome of nesting attempts is due to predator control on man aged grouse moors in Scotland.