We decided to call him Gammy.
He was a feisty old fox, with worn teeth and a stiff ankle where a once-broken bone had healed. It was the second-last day of my field trip and I’d been debating whether to pull the traps in as I drove up the road. We had already checked them at dawn and caught nothing, but here was Gammy at 11 o’clock in the morning – my fourth fox of the week.
Although Gammy was old, he looked healthy enough and was the second-heaviest fox I’d caught. So we fitted him with a GPS collar, administered the anti-sedative and tucked him under a bush with a hot water bottle to recover. A couple of hours later, he was gone and the tracking beeps from his collar indicated he was moving through the shrubs nearby.
Over the next five weeks I collected some of the oddest movement data I’d seen. Unlike the other foxes, Gammy didn’t move around a regular territory. Instead, he had three hotspots where he’d stay for days, travelling no more than a few hundred metres, before trekking a couple of kilometres to the next one. Also, most of the other foxes were active from just after sunset until dawn, and then lay up during the day. Gammy’s activity peaked from 10am to 3pm. Strange fox.
It wasn’t until I went to collect his collar at the end of the study that it all made sense. After sneaking through a couple of electric fences and dodging rain-soaked cows, I found Gammy’s collar on the edge of the forest, near the area he had used most intensively. Just next to it was a huge pile of old cow hides, teeth and bone. Mystery solved: it was a farmer’s carcass dump. Gammy may have been old but he had his territory thoroughly sussed.
GPS-tracking collars are amazing. I could never have collected such high-resolution data on fox ranging behaviour and movement if I’d had to track them all on foot. Yet, sometimes hiking in the rain and falling in cow slush (thanks John! Field rule #1 – always let someone else go first when wading through sedge-bog) can explain so much.
This experience with Gammy reminded me of a comment back at the start of my PhD. I had been sitting in the lounge room of our field house, replacing batteries in motion-sensing cameras, when one of the older naturalists on our team walked in. Tens of thousands of dollars’ worth of cameras were piled up around me, each one needing its screen cleaned and batteries replaced before I could put them out in the forest again. Sixty cameras x 12 batteries = a lot of fiddling around getting the positive terminals at the correct end.
‘Jeez,’ he said, squatting down to help. ‘In my day, we used to just go out to the bush and look for stuff’.
He had a point. Remote-sense technology inevitably creates a barrier between you and the ecosystem you are trying to understand. When I use cameras to survey mammals, I tie each one to a tree in the middle of the forest and come back three weeks later to collect it and assess the vegetation structure. By the time I’ve done this 120 times, downloaded the photos and spent weeks identifying mammals, I’ve forgotten which site was which.
Because the sites are numbered, this isn’t really a problem – I can still test for statistical associations between, say, long-nosed potoroo occurrence and understorey vegetation cover. But I have no innate understanding of this relationship – it is so different to the feel for species’ habitat preferences you develop when you’re up at dawn every morning checking your traps.
On the other hand, potoroos are apparently pretty tricky to trap. If I had been trying to catch (rather than just photograph) them, I would probably have spent most of my time looking at empty traps and cursing. Instead, the cameras have given me mountains of data on the distribution and activity patterns of potoroos, as well as bandicoots, bush rats, possums, feral cats, foxes and umpteen other species.
They also allow you to glimpse animal behaviours you would never see in person:
So, I dunno. Probably both approaches have their place.
What do you think?