One of my favourite films, for a variety of reasons, is the Newfoundland production called “Rare Birds”, where Phonse, played by comedian Andy Jones, often quips “Always have a Plan B, Dave. Always have a Plan B”. In field work, you also often need a Plan C, or D, or E, especially when working in remote places.
As I’ve written before, our main goal on Tristan this year was to photograph the Atlantic Yellow-nosed Albatross from a helicopter, and ground-truth to get a reliable population estimate – the first assessment of any kind since 1974.
That didn’t really work out.
Poor weather, rain, low cloud, and fog kept the helicopters on the SA Agulhas II grounded during our 5-day window for flights. All is not lost, however, as we can try again next year. So when faced with two and a half months on a remote island with the main study objective scuttled, what does one do? Boil rats. Well, more of a slow poaching, really.
As I wrote in the last Tristan Adventure post, the bird populations on Tristan aren’t what they used to be. There are, however, both rats and mice on Tristan, and though we don’t have any plans for an eradication, understanding the ecology and demography of the rats and mice is needed for any future attempts. So with that in mind, we set about trapping.
A typical round of trapping goes something like this: in mid-afternoon, we head out to set traps. We have about 50 snap traps, and the two of us take half, attach them to numbered plastic poles, record the GPS position, habitat type, and bait the trap with a smidge of peanut butter. Since much of rodents’ activity is just after sunset, we go back after dark (usually between 9 and 10 pm) to check each of the traps, retrieve any caught rats or mice, and re-bait as needed. The next morning (early, or else the rats start to balloon up as the temperature rises, which I don’t have to tell you is generally unpleasant), we go again, retrieve any rodents, and pack the traps in our backpacks, ready for the next night.
Then it’s off to the lab! We take general body measurements (head and body length, tail length, length of the right hind foot, and length of the right ear), identify the sex, and then dissect the stomach so we can look at the contents. We also remove the skull, skin it, and put it in the well of a muffin tray (though strictly speaking, muffins have not/will never be made in this tray, so perhaps we could call it a rat tray?). A little hand washing powder, some water, and two days at 80 ºC, and voila! A rat skull that’s ready for measuring and aging.
Why, you might be asking, would we go to all this trouble? Understanding the age structure of the population is important should there be any future eradication attempt. The same goes for figuring out when the breeding season is, how fecund the females are, and if there are any differences among Tristan’s habitats or altitudinal gradients.
So while we didn’t plan to study rat ecology this austral spring, having a Plan B allowed us to easily switch when things didn’t work out quite as we expected.
As I write, the MV Baltic Trader is sitting off Edinburgh of the Seven Seas, about halfway through offloading its cargo. When it’s done (hopefully in a few days), I’ll hop aboard, and if the weather’s good, be in Cape Town in 9 days. My 2014 Tristan Adventure is coming to a close, but plans for next year are already in the works.