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A tractor experiment sets spider senses tingling

University researchers test new spider survey technique

A field crawling with spiders might be the average person’s nightmare, but for some University of Southern Queensland researchers, it was a dream come true.

The concept was simple – could a diesel tractor, idling in a dry field, attract hordes of creepy-crawlies from their hiding places?

The research was part of University of Southern Queensland student Rachael Harris’ Honours project.

“During my undergraduate degree, I did a study on spider silk and it wasn’t until then I realised how understudied and undervalued spiders were,” Ms Harris said.

“The goal of my research was to see if the vibrations from the tractor could attract spiders.

“We compared this technique to the traditional methods (of capture) to see which one was the most effective.”

Ms Harris did her research on land owned by the Sporting Shooters Association of Australia Queensland.

She was supervised by two arachnid enthusiasts, international spider specialist Dr Robert Raven and University of Southern Queensland wildlife researcher Associate Professor Peter Murray, who helped design the study.

Together they mapped out study sites for the spider collections. Once the tractor was moved into position and switched on, they collected as many spiders as they could in an hour period.

They also conducted two traditional surveying techniques; night collections and pitfall traps at the same study sites.

“It takes a minute or two once you turn on the tractor – but then they start to churn through the leaf litter towards the tractor,” Dr Raven said.

“It can be quite exhausting, and you run out of breath, but it was wonderful to see the spiders come in like that.

“I have done a lot of surveys in my time. In a high-quality rainforest you would usually see 180 species of spider; here we are seeing well over 200 – we’ve even found new species.”

Associate Professor Murray said while the tractor method wasn’t fully understood, it was believed to draw spiders in through vibration.

“It’s a big tractor, and the vibration from it goes a long way through the ground,” Associate Professor Murray said.

“We see a different range of spiders to those caught in the pitfall traps and in the night collections – we catch a lot more ground-dwelling spiders with the tractor.

“However, you can’t take a tractor out into the field every time you want to collect spiders.

“So in the future, it would be great to create a portable device that is able to create the same vibrations – something that can fit in a suitcase. This will make spider surveying a lot easier.”

Although the tallying is not yet complete, it is believed the final number of spiders caught in the study will be in the thousands.

A fan of all things that creep and crawl? The University of Southern Queensland’s Bachelor of Science majoring in Wildlife Management could be the course for you. Learn how to preserve and protect our wildlife with expert guidance from a team of industry experts. Learn more.

three people standing outside
Conducting the spider study are (from left) University of Southern Queensland Associate Professor Peter Murray, honours student Rachael Harris, and International Spider Expert Robert Raven.