We had a windy, sunny day here in Southwestern Colorado. I decided to go out and take some Western Thatching Ant (Formica obscuripes) photographs.
To get low angle photographs of the ants, I need to crouch (or lay down) near the them. Getting the ants in focus is kind of fiddly, so I usually need to stay in these positions for a while. Since nests usually contain a lot of ants, and they can be quite aggressive, one is wise to carefully pick one’s photo opportunities.
I was hoping that the sunny weather would bring the workers to their nest surface, but the cold ground and wind would slow them down, and perhaps keep them localized to their nest entrance.
The nests of these ants are large, and usually covered by a thick thatch mound made of twigs, pine needles and grass.
The nest I was going to photograph was the nest I’d visited last year and watched a Short-horned Lizard hunting the ants. When I got to the nest, I found that the Winter winds had eroded much of the thatch mound away. What portions of the mound remained had pits dug into it, presumably where Flickers or Skunks had been digging at the nest.
There were numerous ants gathered around the nest entrance, soaking in the sunshine. It looked like somebody had swirled red-and-black paint on the surface of the nest as the ants seethed around.
Only a few of the ants were traveling away from the nest, perhaps to hunt. I think the wind was discouraging them from going too far, though – every now and then a gust would lift them up and carry them a few inches. It must have been quite disconcerting for them.
There were a lot of ants working on the thatch of their nest. They’d grab twigs that were larger than their bodies and try to move them.
In order to grasp the twigs, they’d spread their mandibles far apart. Then, since the twigs were large, the ants would remain more or less in position as they struggled to lift the massive twigs.
It was a form of ant isometric exercises, I guess.
I suspect that there were so many large twigs on the nest thatch because the finer twigs and pine needles had blown away over the course of the winter, so that only the twigs too heavy for the wind to blow remained.
