Following my gallery opening last week in Minnesota, I was privileged to spend a couple hours poking around at Macalaster College’s beautiful Ordway Field Station on the banks of the Mississippi. Fall had advanced suddenly and the temperature was too cold for much insect activity. Of course, the ubiquitous cool-tolerant winter ants, Prenolepis imparis, were foraging.
Along the trail we happened across an unusual sight. About 100 ants in a cluster on the forest floor, moving cautiously around each other, sometimes lunging with open mandibles, sometimes cautiously tasting other ants, moving from ant to ant.
I am not 100% certain what they were doing, but the scene looked a great deal like the ritual battles known from other ant species. When two ant colonies meet, they sometimes estimate each other’s strength by engaging in a bit of pushing and shoving, apparently tallying the size and number of the opposition. This behavior is thought to allow them to retreat in the face of a stronger opponent before matters escalate into loss of life (see this 1981 work by Bert Hoelldobler for an example from honeypot ants.)
Photo details- Panorama: iPhone
Macro photos: Canon MP-E 65mm macro lens on a Canon EOS 5D Mk IV, f/13, ISO 200, 1/200sec, diffuse twin flash.