Strongylosis in England
Following the grouse population crash in 2005, red grouse populations are increasing. With increasing numbers of grouse, and the very mild autumn in 2007, there has been a considerable increase in the worm numbers, in particular in the young birds (see Figure 1).
Parasite burdens in these young birds have increased more than 10 times from 2006 to 2007. However, worm burdens in adult birds have remained fairly static. Correct application of medicated grit should help to keep parasite burdens down in 2008.
Figure 1: Mean worm burdens in adult and young red grouse on eight moors in the North of England
Strongylosis in Scotland
In contrast to England, the worm burdens were very variable across Scotland in 2006. Data from five sites sampled since 1990 suggest that although burdens are moderate, they are still above the very low levels seen in the early and mid-1990s (see Figure 2).
Figure 2: Mean strongyle worm burdens from shot grouse (young and adults) sampled at five moors in Scotland 1990-2006