Trees saved Rob McBride. Sick and stressed out, the IT worker from Shropshire, England, found his way to a conference about ancient trees, a moment that he says changed his life. A decade later, McBride has turned the tables. Now, he saves trees. He's known as the "Tree Hunter," and he travels through the United Kingdom and Europe searching for the oldest trees and serving as an ambassador for their protection.

It was a difficult time in McBride's life when a friend suggested he go to a local conference on trees. Living in the verdant countryside of Ellesmere in Shropshire, McBride had always dabbled in his garden and grew up with a plant-loving mother who filled their small backyard with plants. So it wasn't a stretch that something just clicked when Ted "Mr. Ancient Tree" Green started speaking.

"My life changed that day," McBride says. "I volunteered for the council and wildlife trust, worked hard physically and in the woods and countryside, installing stiles and gates and bridges and footpaths and bridleways."

rob mcbride inside an ancient tree

Soon the trees became McBride's passion. "Every time I went in the greenery and woodlands, I felt so much better."

After he learned that up to 80 percent of the ancient trees of northern Europe were in the United Kingdom, McBride began volunteering for a project called the Ancient Tree Hunt. The project's goal is to discover and measure ancient trees and put them on an interactive map. Green, McBride says, calls the U.K. "the European rain forest" and McBride felt inspired to make it his mission to start promoting the ancient trees of Europe.

Defining 'ancient'

What defines a tree as "ancient" depends on many factors, including the type of tree and where it's growing. According the the Ancient Tree Forum, for example, a birch tree could be considered as ancient at 150 years old, but an oak tree would not be thought of as ancient until it’s at least 400 years old. Yew trees aren't deemed ancient until they are 800 years old.

Ancient trees have different characteristics, but they typically have three key features:

  • a fat, squat shape
  • a wide trunk, compared to others of the same species
  • a hollow trunk
It's often difficult to measure the age of an ancient tree, says McBride, but the usual method is to measure the girth of the trunk.

Counting them up

So far, McBride says he's recorded somewhere between 3,500 and 4,000 trees. Probably 3,000, he says, were in the U.K. and the rest were in Europe. He'd love to put on his hunting cap and head to the U.S.

"There are many well-known U.S. trees including the oldest in the world, the bristlecone pine. There is talk of a Swedish tree being the oldest, but I know from a friend, a German tree professor, that it is not. He visited it and proved it wrong, but they still say it is the oldest. We tree folks know it is the bristlecone pines."

Pen-y-maes oak

In all his travels, McBride says his favorite tree was is the Pen-y-Maes Oak (pictured at right).

"That's Welsh for 'top of the field.' It's a beautiful 9-meter (30 feet) girth oak pollard hidden in the Welsh landscape. My friend texted me that he saw a big tree, so I went. It was brilliant."

On the tree horizon

Right now, McBride says he is excited about European trees and Welsh trees, but is looking forward to a big tree day in June.

"On the 15th of June, it will be 800 years since the signing of the Magna Carta at Runnymede near London on the banks of the Thames. There is a world famous tree there. The Ankerwycke Yew tree, which the Magna Carta was signed under or near, is possibly 2,000 years old. So it would have been substantial even back then. I know already this year there have been thousands of folks to see it."

McBride is also still in the process of trying to visit all 14 trees in the European Tree of the Year 2015 contest.

"I've had many adventures, but many are very close to home. The good thing with trees is they are (hopefully) all around, and if folks just take the time to get out there, they will find and see great things."

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Watch McBride go hunting for an ancient yew on this BBC special:

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.