Steve,
There's plenty of heather and they're not endangered. Dunno how many times you need telling. Of course, you can always look it up instead of making it up.

RSPB say different.

"Red grouse depend on heather for food and cover. A major cause of their decline has been the destruction, fragmentation and deterioration of heather moorland. This has reduced the plant food for adults, while drainage has reduced the boggy plants and insects on which grouse chicks depend. In Scotland, 4,165 km2 (23%) of heather was lost between the 1940s and 1980s, while an even greater proportion (27%) was lost in England.8 The loss was substantially greater in some areas, such as 48% of heather from Langholm Moor between 1948 and 1988.11 A further 510 km2 (3.6%) of heather was lost from the UK between 1990 md 1998.9 There is broad agreement that grazing by sheep and deer is responsible for much of this loss. Sheep numbers more than doubled to 40 million animals between 1950 and 1990 and there are 500,000–750,000 deer in Scotland alone, the most at any time since the last Ice Age.
https://www.rspb.org.uk/Images/birdofprey_redgrouse_tcm9-188710.pdf