Ecology Food
Adults
The diet of adult black grouse varies between seasons, so they need a
range of food plants within their habitat. Vital plants include bilberry
and heather, which are eaten throughout the year, the latter particularly
important in winter. The wide range of foods taken by adults is detailed
in the table below.
Annual diet of black grouse
There are also some regional differences in food preference across the
UK. This may be due to recent adaptation as the birds are forced to survive
on what is locally available. The table below outlines some of the differences.
| Northern England |
Habitat |
Food |
| Spring |
blanket bog and in-bye land |
cotton grass flower buds, clover, buttercups, sorrel, marsh marigold
and other herbs |
| Summer |
rough grassland, wet flushes |
Juncus seeds, seeds and flowers from grasses and herbs
(adults). Invertebrates, especially sawfly larvae (young) |
| Autumn/Winter |
heather moor, rough grassland, in-bye land |
Ling heather, berries from shrubs |
| Scotland |
Habitat |
Food |
| Spring |
pine/birch woodland and heather moorland |
birch, larch shoots, bilberry |
| Summer |
wet flushes and heather |
often in woodland birch, bilberry (adults), invertebrates (young)
|
| Autumn/Winter |
heather and birch woodland |
bilberry, crowberry, berries from shrubs such as rowan and hawthorn,
birch, heather |
| Wales |
Habitat |
Food |
| Spring |
conifer woodland, bogs, heather moor |
bilberry, conifer buds, heather and cotton grass shoots |
| Summer |
wet sedge or rush flushes, usually on open moor |
bilberry, heather shoots, sedge (adults), invertebrates (young) |
| Autumn/Winter |
Woodland and moorland |
winter berries from shrubs such as rowan and hawthorn, bilberry,
heather |
Regional differences in typical diet of black grouse
in the UK
Chicks
Chicks are largely dependent on invertebrates during their first two to
three weeks. Moth caterpillars and sawfly larvae are particularly important,
often forming the bulk of the diet. The hatching date of eggs may be timed
to coincide with their peak abundance. Chicks also eat grasshoppers, beetles,
spiders, ants and flies. As with the adults, there are regional differences
influenced by what is available. Certain plants host a particularly high
abundance of these invertebrates, and broods are often found in wet or
damp habitats with relatively tall ground vegetation, such as grasses,
rushes or bog myrtle, which provides cover from predators and a rich source
of invertebrates. Moorland or field vegetation with plenty of bilberry
is also important brood rearing habitat as this can include a great abundance
of the insects that black grouse chicks prefer.
As the chicks mature, vegetation becomes more important in their diet,
and by the age of three weeks they start to eat mostly high-protein plant
material on which they will feed for the rest of their lives.
Recent research by Ludwig et al
2006 has shown that chicks are suffering higher mortality because
of climate change. Using long-term data from Finland, the study showed
that black grouse have responded to spring warming by advancing both their
egg-laying and their hatching times. However, early summer (when the chicks
hatch) had not advanced and the chicks faced colder post-hatching conditions,
which the study showed is a critical factor in survival rates.
More on black grouse ecology...
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