Why are black grouse numbers rising?
The black grouse population is booming in parts of Scotland and Wales, figures show, but why has the mating or "lekking" season been so successful there and not in other parts of the UK?
"As the sun rises, you get this fantastic view, you get the lovely black sheen on their backs and the really white tails.
"They are impressive birds," says Dr Kathy Fletcher, a scientist with the Game and Wildlife Conservation Trust (GWCT), describing what it is like at the crack of dawn on the hunt for a black grouse lekking.
Lekking is the distinctive territorial display of the male grouse during the mating season in which the cocks compete with one another to attract hens.
Black grouse are one of only three species of British birds to show this behaviour.
The display means that between mid-April and mid-May, conservationists, landowners and local study groups have the opportunity to count them by listening to calls and spotting them at lek sites.
"They're very loud. They make a lot of noise. They've got white tails and they fan those out and run at each other and do this kind of jumping display," Dr Fletcher says.
- In spring, male black grouse or "blackcocks" gather at "lek" sites at dawn where they display competitively to attract females.
- During the displays, males strut or dance, inflate their necks, raise their tails and make a bubbling sound.
- Leks are visited all year round, but the peak of activity is in spring when females are present.
- The dominant males occupying the central ground of the lek tend to attract and mate with the most females.
- After mating, males take no part in caring for the eggs or young.
"They don't actually attack each other but it's quite aggressive while they display to show who's the best male."
By contrast the females, also known as "greyhens", are brown and stay camouflaged in their habitat.
This means the preferred method for estimating the population as a whole, particularly where the birds are scarce, is to count the males on display at the leks, rather than trying to find the broods.
A complete UK-wide count takes place every 10 to 12 years, with the next one scheduled for 2017.
Black grouse are one of the UK's most threatened bird species.
The ground nesting game birds used to be prevalent across the UK but their population suffered a sharp decline in recent decades as their habitat was changed by agricultural activities, weather patterns and loss of vital food sources, such as bilberry, heather and birch scrub.
Populations fell from an estimated 25,000 displaying males in 1970 to just over 5000 at the time of the last national survey in 2005. It is a decline that sparked a number of projects designed to bolster numbers.
The latest reports of successful conservation efforts suggest that the trend has been reversed in a bumper year for black grouse.
In north Wales 328 displaying males were spotted by conservation agencies in 2011 compared to 238 in 2010 according to the Royal Society for the Protection of Birds (RSPB) Cymru. These sightings exceeded their 2015 target by 58 birds four years ahead of schedule.
In Dumfries and Galloway, RSPB Scotland reported 194 lekking males at 71 lekking sites in 2011, a 31% rise on the previous year. Monitoring projects revealed 390 lekking males in the Scottish borders.
Some of this success is down to habitat management.
Duncan Orr-Ewing, head of species and land management with RSPB Scotland says: "If you have the right habitat management… you should be able to maintain a consistent population.
"Black grouse can breed at quite a young age, so within one or two years they can produce large numbers of young, so when the conditions are right, they can thrive."
Black grouse need a varied habitat. A combination of blanket bog, unimproved farmland, moorland and open forest enables them to make a home rich with lekking sites and provide cover in which to seek refuge and nest.
Trees are an important source of food during the winter when snow cover can restrict access to their food supply.
But weather also plays a big part in the outlook for black grouse populations.
Young chicks are particularly vulnerable to cold or wet weather after they hatch, during June and July.
End Quote Steve Westerberg Site manager, RSPB Geltsdale
With black grouse especially you can never be complacent”
Dr Sean Christian, RSPB Cymru's head of conservation says: "The excellent results of last year's survey show that appropriate land management combined with warm dry June weather in consecutive years has had a lasting effect on the birds and their long-term recovery in Wales."
But in spite of the success in some areas, Mr Orr-Ewing says it is "a vulnerable species".
"We know that it can decline in population quite rapidly… it does require human management to help it thrive and we have to keep a wary eye on how its populations are performing.
"In some parts of Scotland unfortunately the increase in numbers is not uniform, and places like Argyll in the south of Scotland, the populations are still not doing very well, so more effort is required."
That could also be the case in the northern Pennines.
The count of lekking males at RSPB Geltsdale came to 45 in 2011, a significant growth since 2004 when Geltsdale numbers were at a low of around five males.
The success of the black grouse population at Geltsdale in Cumbria has been put down to reducing the intensity of sheep farming on the land, from around 4000 to 500 and the planting of trees. It meant vegetation became less uniform and better suited to the birds.
Steve Westerberg, site manager at RSPB Geltsdale says the difficulty will be "maintaining that population".
"They've responded to that change in vegetation and that's why we've got such high numbers but in the long term the number of birds that we can carry may be lower," he says.
Early reports for this year's spring counts confirm this, suggesting about 35 lekking males are now living there, about a 25% decrease from last year.
"With black grouse especially you can never be complacent, they go down as quickly as they go up," Mr Westerberg says.
Dr Fletcher says in order to stabilise the populations in Scotland and northern England, conservationists want birds from the two areas to mingle.
"That gives us our best chance of recovery if all these birds are mixing together, but we have this gap kind of between Edinburgh and Newcastle… where the birds are in really low numbers and therefore they're really struggling."