Good afternoon folks,
I can't believe that's a week gone by again! I hope you are all well and staying safe.
An informative blog for you today, from Ewan, all about our four species of grouse on Abernethy, but before that, just to say there's still no news form our osprey nest I'm afraid - birds are in the area but no nesting action unfortunately. Now, over to Ewan...
There are four types of grouse in the UK, and all of them can be found on the Abernethy reserve. But why do we need so many? Why shouldn't there be one best possible grouse, that could replace all the others?
If you are lucky, when out walking deep in the Abernethy Forest (very, very lucky), you might catch a glimpse of the largest, most impressive, and rarest. Capercaillie, from the Gaelic capall-coille, meaning ‘horse of the woods’, are perfectly adapted for life in the Caledonian forest. During the lean times of winter, when many leave or go into hiding, capercaillie are one of the few animals able to survive on a diet of pine needles. A large and muscular gizzard, a sort of pre-stomach, helps break down the tough needles, with the aid of small stones swallowed for this purpose. Early on a winter's morning, the birds may be seen emerging onto a forest track, an easy source of grit for grinding down those needles. Even then, there is not much nutrition in a pine needle, and their large size helps them eat enough to live on, until more favourable times arrive.
Male capercaillie (Ben Andrew rspb images)
During the spring and summer, capercaillie gorge themselves on much more nutritious blaeberry. This deciduous shrub thrives on the floor of the mature forest, underneath the Scots pines, and its buds, shoots, leaves and, in late summer, berries make up a key part of the adult birds' diet. Blaeberry, with its delicate and tasty deciduous leaves, also hosts large amounts of insects, which become an excellent protein-rich food for hungry capercaillie chicks when they hatch in June.
Capercaillie habitat – mature Caledonian pine forest with blaeberry understorey (Andy Hay rspb images)
The highly specialised capercaillie are excellent at making a living in the forest, and thrive in areas of mature, productive forest with large trees to perch on to roost and feed and a healthy variety of other plants to supplement their diet. There is nevertheless room for another species of forest grouse, though. Smaller then capercaillie, the black grouse tends to associate with younger and more open areas of forest, around clearings, boggy areas, and forest edges. In the transition between mature forest and open ground, pockets of different microhabitats merge together in a habitat mosaic, providing a multitude of different feeding opportunities. The trees here are too small and may be either too densely packed or widely dispersed for the capercaillie, and the shrub vegetation doesn't provide enough cover. For the black grouse, however, this habitat provides a wide variety of shoots, buds, leaves and seeds on which to feed. Wet flushes and mires are particularly valuable foraging habitats for newly hatched chicks, which like capercaillie young, feed mainly on insects and other invertebrates in their first few weeks.
Male black grouse (Andy Hay rspb images)
The loss, fragmentation, and degradation of our native forest over the past few centuries have been disastrous for these two birds here in Scotland. Capercaillie have already gone extinct here once in the 18th century, and despite a reintroduction and population recovery in the 19th century, have since declined rapidly again and are in real danger of going extinct for a second time. Black grouse too, though more widespread and numerous, are in the UK Red List due to their severe decline. Once common across Britain, the magnificent sight and sound of the breeding males is now something only a privileged few have experienced. At certain sites like RSPB Corrimony near the Great Glen, however, forest expansion and management for black grouse have stabilised and even increased local populations. Although the exact ways that habitat fragmentation and degradation affect them is not yet fully understood, through the work of the RSPB and many others it can be hoped that both these magnificent birds will survive as a part of the Caledonian forest for the future.
Black grouse habitat – woodland edge and wet flushes (Andy Hay rspb images)
In contrast to these two, the red grouse is one of the most numerous birds in Scottish upland areas, thanks to its popularity with the sport shooting community. It leaves the rich forest resources to its larger cousins, and makes its living by being tough enough to survive higher up the hillsides, above the treeline. Large areas of the Highlands are managed specifically for red grouse, the hillsides burned in rotation to prevent trees from growing and promote the growth of succulent young heather shoots to feed the adult birds' and support the insects that the chicks will depend on. The 'traditional' moorland landscape created by this management, that flushes spectacularly purple in late summer, is not a natural landscape, however.
Red grouse (Louise Greenhorn rspb images)
The name for the continental variety of this species, willow grouse (or willow ptarmigan), is a clue. If the Abernethy forest were to reach a natural tree line on the edge of the Cairngorm mountains, the forest would gradually thin out as conditions become too hostile for trees to grow. From about 650 metres above sea level, pines would grow smaller, more twisited, and further apart, slowly giving way at increasing elevation to a scrub of montane willows, juniper and dwarf birch, as well as other shrubs like heather, blaeberry and bearberry. This habitat is almost totally gone from Scotland, but in Norway, with a similar climate and topography, it is here that the red or willow grouse is found. There is more nutrition for a grouse in willow buds and leaves than the scaly leaves of heather, and a much wider variety of plant material to exploit here than on a Scottish grouse moor. This scrub habitat is also host to many other bird species, rare or absent in Abernethy and across Scotland, like the ring ouzel, yellow wagtail and bluethroat. Last year cuttings were taken from some of the last remaining specimens of montane willow species hanging on the Cairngorms (some of the last remaining in all of Scotland), clinging to a few remote crags out of reach of hungry deer or sheep. As part of the Cairngorms Connect landscape partnership, these cuttings are being grown on in the tree nursery here at Abernethy, to be cross-fertilised to produce a new generation for planting out, beginning the restoration of this lost habitat.
Red grouse habitat - heather moorland, though this one isn’t heavily burned (Andy Hay rspb images)
The last of the grouse species found on the reserve, the ptarmigan (or rock ptarmigan), is even hardier and ekes out its living in an even more extreme and seemingly inhospitable habitat. Being, along with the capercaillie, one of perhaps the only birds whose common English name comes from Gaelic, the tarmachan is a true Highland specialist, living above even the red grouse and the Montane scrub, only on the highest of mountains. How it can survive year-round in this Arctic-alpine world can seem extraordinary to those of us who are only ever visitors to these heights.
Ptarmigan in winter plumage (Tom Marshall rspb images)
Famously turning white in winter, for camouflage in the snow, its feathers cover its feet, face and even eyelids to help it stay warm in the coldest conditions anywhere in Britain. Mottled grey in its summer plumage, to blend in amongst the bare rock and scree, it somehow finds enough food from the few plants that are also tough enough to survive up here.
Ptarmigan in summer plumage (Graham Goodall rspb images)
The highest parts of the Abernethy reserve, on the Cairngorm plateau, are an excellent place to encounter ptarmigan. Perhaps not forever, though, for in a warning climate, all of its amazing adaptations may become useless - a white ptarmigan, if there is no snow, becomes rather poorly camouflaged. The RSPB is a member of the Stop Climate Chaos coalition, campaigning for action on the climate to protect wildlife like the ptarmigan from rapid change. Forest expansion and peatland restoration, as is happening on Abernethy, have a part to play too in reducing overall net carbon emissions.
Ptarmigan habitat (Tom Marshall rspb images)
These four grouse species, though closely related and having similar diets, have adapted and evolved to make use of the different habitats available at Abernethy, from the mature pinewood up to the highest mountaintops. A generalist grouse, trying to make equal use of all four habitats, would not be as successful in any one habitat as as the grouse specifically adapted and specialised to that habitat. In evolution, there are no prizes for second place. This is an example of what ecologists call 'niche partitioning': every type of living thing must make different use of the resources in the landscape to every other, creating it's own unique 'niche' in the ecosystem, in order to survive. In a complex and stable system, there can be many such niches, enabling the amazing diversity of life on Earth. So, Long Live Complexity!, and long may there be room at Abernethy for all four of these grouse.
Please note: Capercaillie are a legally protected species. Between April 1 and August 15, it is against the law to intentionally search for and disturb breeding capercaillie – either males at the lek or females at the nest or with young. When walking in capercaillie forests during these dates, please keep to tracks and paths and if you have a dog, ensure it is on a lead. Thank you.
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