Away from the busy mountain bike trails there's a wealth of wildlife
Coed y Brenin is becoming world-famous for its mountain bike tracks, but in quieter corners of the forest deer, badgers, red kites and otters all make their home.
The wildlife can be hard to spot, but forest ranger Iori Jones knows how to get a glimpse of a shy deer or a wily fox by mimicking their cries.
Another of Iori's favourites is the hairy wood ant. "Their nests are all over the forest," he says. "Yet there are none in other forests nearby. There must be something about Coed y Brenin they really like."
Iori has watched one nest grow four feet tall and six feet in diameter over his 30 years in the forest. His goal is to stake out a new nest and measure how fast it takes the millions of ants to drag over the pine needles and build a new home.
"They're very hard-working," he said. "The forest floor is covered with their paths going up and down as they build the nest and protect the queen."
Although the hairy wood ants aren't as likely to bite as their red ant cousins, you might just get a squirt of foul-smelling acid if you're unlucky.
"One cameraman got a bit too close and got acid on his lip, which is a very sensitive area," said Iori. "But I've put my hand in and never been hurt."
One threat to the ants' nest is the fallow deer which roam the forest. "They can destroy a nest by using the needles to clean the velvet off their antlers," said Iori, who spends a lot of time patiently waiting at dawn and dusk to track the shy creatures.
Iori is also on a mission to pin down the number of red squirrels in the forest. "I would see them a lot in the 1980s, but I hadn't seen one for years until recently when one crossed the road in front of me.
"We've had further sightings, so I'm looking forward to doing some squirrel control of the greys to give the reds a chance."
Iori has seen some big changes in the forest over the years. "Now we've got cycling routes, a trail run, walking paths and a slip line where you can zip through the trees," he said.
There are more changes to come. The Forestry Commission is opening up the streams more and replacing the softwoods with more traditional hardwood trees like oak and silver birch.
And any timberwork in progress near an active birds' nest or badger sett is stopped in an effort to allow both animals and humans to enjoy life in the forest.
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