Modern natural resource work including arboriculture may be embracing state-of-the-art technology, but one time-honoured tool is making a comeback – in the shape of the canine nose. In the second part of our feature, here we tell the story of the UK’s only professional tree-care hound. 

ASK anyone who the star of 2023’s ARB Show was and you’d likely be met with almost universal agreement. Forget chainsaws, ropes, and woodchippers, it was Sika, a decay-detecting dog, who led the way at May’s showpiece event – and with good reason. 

Believed to be the only working dog in European arboriculture, the border collie has been trained by her owner – Ivan Button – to identify pathogens such as Kretzschmaria deusta, Meripilus giganteus and Fistulina hepatica, many of which can be invisible to the human eye.

And in the months since the ARB Show, she has been in high demand, with the Forestry Commission and the Arboricultural Association among those keen to explore the idea of sniffer dogs. 

Forestry Journal: Could sniffer dogs be more widely used in tree care? Could sniffer dogs be more widely used in tree care? (Image: Supplied)

“I decided I wanted to get another dog,” Ivan, a tree inspector by trade, said. “I couldn’t take one to work or leave it at home, so if only there was some use for a dog at my job. Then I had this idea. Was it possible to have a sniffer dog? 

“There had been some research done in Sweden in the 1960s, but that hadn’t come to much, and they are used to detect dry rot on some National Trust buildings. But that’s pretty easy. 

“I wasn’t sure if this was going to work or not, but I decided to try it. I Googled it, watched some tutorials, and went on some courses to learn how to train a sniffer dog. I did it myself.

“You can see the results. She’s fantastic.”

Sika, who was raised on the steep slopes of the South Pennines, joined Ivan’s Crown Tree Consultancy team in 2013 and has proven a hit, with her talented nose even able to detect where decay is present beneath the buttress roots and deep within the lower stem. 


“I wanted a dog like Lassie that would appear and bark at me,” Ivan continued. “I didn’t want to have to keep an eye on her all the time. I wanted to be able to do my job and let her sniff about and tell me when she finds something. 

“She’s brilliant. You have to watch out for false positives and false negatives. She can miss things. That is entirely possible, but she doesn’t tend to.

“She almost never indicates when she hasn’t found something. But, of course, any collie that thinks she is going to get a tennis ball when she barks will try it on. They aren’t stupid. So when she barks, I walk away. If she’s trying it on, she’ll follow me. If not, then she will be insistent. And that’s such an important part of training dogs.” 

It is believed the only other detector dog working in tree care is in Taiwan, but, unlike Sika, it only sniffs out one specific fungus, whereas Crown Tree’s mutt has a nose for just about anything that can latch onto a tree. 

“I use her in specific circumstances,” Ivan said. “If I have an old beech, for example, and it looks healthy enough, I just want her opinion. If she sniffs around the bottom of it and doesn’t bark, I can be reasonably confident there is no Meripilus giganteus attacking that tree. If she goes mad and concentrates on a particular place, I then take her and let her sniff some more trees before coming back an hour later. 

“If she’s still doing it, then I am all the more confident and know there is something going on.

“I need to do the investigation. It might be a small pocket, it might not be life-threatening. 

“She’s the only dog in this country that does it. There is one in Taiwan that sniffs out a specific decay, so she’s not the only one in the world. She’s more of a specialist, however, than that dog. 

“People are blown away by Sika. She was the star of the ARB Show. 

Forestry Journal: Sika and Ivan at the ARB Show 2023. Sika and Ivan at the ARB Show 2023. (Image: eA)

“There is a lot of potential. I am not suggesting it is straightforward and easy, more research is needed.” 

That research, Ivan believes, could lead to sniffer dogs being more widely used to detect pests and diseases on imports into the UK. 

“We really, really should be using detector dogs there,” he said. “We are importing all these pests and diseases; we just have a man or a woman with a clipboard in a warehouse surrounded by pallets that may have beetles in them or another pest, and people are just signing them off.

“We are not properly testing them. I am not a professional trainer, but imagine a professionally-trained dog being sent in to hunt for Asian longhorn beetles.” 

As for the here and now, Sika has really made a name for herself in British tree care, to the point where arborists at last year’s ARB Show were cursing themselves for not thinking of introducing a sniffer dog to their own work. 

Ivan said: “Everybody that came up to our stall was like: Why didn’t I think of that?

Forestry Journal: Sika has been trained to sniff out the possible presence of fungus. Sika has been trained to sniff out the possible presence of fungus. (Image: Supplied)

“Why aren’t we doing this? Why aren’t we using dogs to help us detect tree decay or biosecurity issues at the borders? 

“Conservation dogs are becoming very popular now. They can identify a particular species of pine marten by its poo. Not just any old pine marten, but one species. 

“Detector dogs can detect anything you train them to detect, and there is no reason they shouldn’t be detecting decay in trees.”