Nests: Building, Structure, and Maintenance

Home, home building, and home improvement. Pogonomyrmex ants and their nests , at various locations in North America.
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Pogonomyrmex salinus

● Horse Ridge, SE of Bend [Deschutes Co], OR USA [el. 1310 m / 4297 ft] view location in Google Maps » ● 7/20/09 6:50AM sunny, air temp: 10°C / 50°F

This massive P. salinus nest is built around large rocks, and covered with a staggering amount of gravel. The nest entrance (there was only one, last time we visited) is located under the edge of the large central boulder. The distance between the two yellow markers is approximately 1.9 m / 76 inches. [scroll down for additional notes/references]

ADDITIONAL NOTES/REFERENCES: On our first visit to this nest (7/15/08) the air temperature was 28°C / 82°F, and the ants were foraging along a trail in the shade of a large rock. Soon after I approached the entrance, many dozens of workers (defenders) poured out, and ran toward me. Most turned back after I backed away, but approximately 10 workers continued pursuing me more than 3.6 m / 12 ft from the entrance, often stopping to stand on small pebbles and twigs while waving their antennae wildly, and opening their mandibles. At many other P. salinus nests nearby, workers were not aggressive, and ignored us - even when inches away from the entrances. We think the physical size of the large nest (mentioned above), may have something to do with the very aggressive worker response to our presence. The gravel-covering of this nest was approx. 1.9 m / 76 in. wide, measured on its longest axis. This means that I had to walk over a large portion of the nest 'dome' in order to reach the entrance - undoubtedly collapsing many tunnels and galleries that lay just below the gravel covered surface. This would result in alarm pheromones being released in great quantities by the ants underfoot, alerting nestmates to the defense of their colony.