Ants active at dim light face a very interesting problem: they have to do everything that ants active in bright light do, but at very low light levels. It is hence that nocturnal ants have piqued my interest over the last few years. A recent addition to the growing list of nocturnal ants that I have had a chance to watch and study is the Dinosaur ant, Nothomyrmecia macrops. These ants similar to nocturnal Myrmecia, have a strong association with the local Eucalypt trees. They climb up trees, stay up the tree for a significant part of the night and return before sunrise. We always use headlamps with red filters to watch ants at night. It works fairly well and gives one a good opportunity to watch natural behaviour with relatively little intrusion. In Poochera, we knew roughly the type of trees that N. macrops prefer and we started checking such trees for foragers in the evening twilight.
Day 1, we started checking for the presence of these ants from just before sunset and continued till about 2am and had absolutely no luck. We appeased ourselves with odd looking Camponotus, some nice Podomyrma, and even a couple of Myrmecia, but not a single Nothomyrmecia. It was incidentally a new moon day and quite overcast giving us enough reason to console ourselves that perhaps the extremely low ambient light levels which did not support the activity of Nothomyrmecia. The next night, just 20 minutes after sunset, we found one forager on a tree and subsequently we found several on other trees. Each tree that we found ants on got a unique ID and was tagged with retro-reflectors. These reflectors are great as they shine only when light hits them directly. This is very handy to have when working at night and in fact all our fine equipment, especially forceps, magnifying lens are always tagged with these reflectors. And once we had these reflectors on the trees, we developed a routine of checking trees giving us the best chance of finding the ants. Every night, from then onwards we continued to see several foragers of Nothomyrmecia and identified 10 trees within a 15 sqm area on which we found foragers. We even found a dealate queen foraging on the tree – that doesn’t happen to often in the ant world!
We tracked a few workers returning with prey (mostly Dipterans and Hompoterans) to help us find the nests. But finding nests was quite a task as ants often played dead (the record was 25 minutes for one ant!) at the slightest of disturbances and hid well underneath the leaf litter. Add to it the highly inconspicuous nests that were hidden amazingly well within the leaf-litter. After a couple of nights, we eventually found 4 nests all located within 1m from the tree they foraged on. Most surprising was the structure of the nest entrance itself, which collapsed quite easily by the slightest of movements of a small twig or a gum nut. Nest density was quite high and on one particular occasion we found 3 nests within 30 cm of each other, foraging on the same tree. Even more surprising was that ants from multiple nests got along well, exhibiting no signs of aggression when we kept them together in small containers.