Going into the hills on the west side of South Uist to about 2000ft, in an area that looks devoid of wildlife, you get out of your vehicle and stand stock-still, not making a sound - and you hear a roar in the distance.

You still can't see the animals, but you can hear them. Then, your eyes adjusting, you start to pick them out.

"You see a red stag silhouetted on the skyline, with his harem of hinds behind him, roaring at other stags to stay away. You're still not seeing much and you stay as quiet as you can. The roar continues as other stags come into the area, ready for battle. It's deafening and surreal, like entering a gladiator ring. Fifteen stags roaring all about you, some with massive heads and antlers with up to 18 points. There's a lot of posturing. The main man is saying, 'Look at how big I am. I will fight you if you come too close.' It's amazing, like the wilderness equivalent of a city-centre pub on a Friday night, but perhaps a bit more spiritual."

So say James McLetchie and Rory MacGillivray, lifelong friends who last year launched Unwind In Nature, tailored eco-tours in the Outer and Inner Hebrides, and have already had 250 customers from as far afield as Dubai, North America and India. This year they launched their Roar Of The Stags photographic tour to the Uists, using all-terrain vehicles, and it's clear they are still in awe of their subject matter. They invite clients to shoot their subjects – not with a gun, but with a camera. The fundamentals of sustainable tourism are at the core of their business.

"What strikes me time and again is that this rutting happens every year, but so many people haven't seen it," says McLetchie, 49, who has been named one of the top 10 eco ambassadors in the UK. "We wanted to make our indigenous wildlife accessible. We think we're looking at these magnificent beasts, but I get the feeling they're looking at us. They have been here for thousands of years – we are mere human beings, and in many ways we're encroaching on their territory. We have to be still and silent because they have good eyesight and a keen sense of smell, which means you have to stay downwind."

On the company's first photographic deer expedition in mid July, Mcletchie and his five clients saw a couple of newly born deer calves.

"I have worked in sustainable tourism all over the world, including the Falklands, Iceland, Malta, Sicily, Australia, South America, Chile and Greenland, but this was the first deer calf I had seen and it was huge for me," he says. "We watched an eagle trying to get at the calf and the mother hind was desperately trying to protect it. It was like something you'd see on the Discovery Channel.

"Scotland is the most unique environment I've been in – but it doesn't market itself. All the images of Scotland tend to be Highland mountains and castles. If we marketed this to our own people more would know about it."

South Uist, Benbecula and Eriskay are community-owned and run by the Storas community, while North Uist is privately owned. Although there is no trespass law in Scotland, McLetchie and MacGillivray emphasise the importance of maintaining good relationships with the landowners.

Red deer have lived in Scotland for 10,000 years, and although numbers dramatically declined over recent centuries they have increased again and now stand at 350,000, with about 1,300 of those in Uist with herds split between North and South.

MacGillivray, 48, is from Benbecula, and is a stalker for South Uist Estates. "We have the purest red deer you can get," he says. "Ours have the biggest, most majestic heads. Most people will be familiar with the smaller Sika, or Japanese, deer on the mainland, which have reached as far as Skye. We don't want them here in the Outer Hebrides."

Red deer herds are managed by culling. "On Uist they only shoot the weakest beasts. They don't want to take out the big trophy beasts with up to 15 points; only the nine-pointers will be shot. They wouldn't survive the winter, and they don't want them breeding with the hinds."

"I'm addicted to this," admits McLetchie. "Being right in the middle of a red deer rut is almost primeval. I'd go so far as to say it's a spiritual experience." n

Visit unwindinnature.com.