[IMAGE 3 of 3] The ability of Pogonomymrex
ants to carry excavated sand in their psammophores
is well known and documented. But, despite a few vague references on the Web , we have not yet found any descriptions of these ants using this structure to gather and/or transport seeds in the wild, under natural conditions (nor have we observed this behavior ourselves, prior to 6/22/10).
These Pogonomyrmex californicus
workers were picking up (and transporting) multiple seeds of Descurainia sophia
(a.k.a. flixweed). The nest of these ants was located in a sandy area, under a living Salsola
(tumbleweed) plant - surrounded by many other plants including (and most abundantly) Descurainia sophia
The multiple-seed-gathering behavior was taking place approx. 60 cm / 2 feet away from the nest entrance - in an area strewn with the tiny orange D. sophia
seeds. It was probably the high density of seeds (estimated to be 0.3 - 0.5 per cm²), along with their small size and proximity to the nest, that made this unusual type of foraging possible . Workers returning from other areas, and from greater distances, carried only single items (as is usual for these ants). Individual workers were observed to successfully carry three of these seeds at a time, usually with one in the psammophore, and two 'stacked' in the mandibles
(one worker was seen to have two seeds, side by side, in the psammophore). As can be seen in these images, the Pogos sometimes used the tips of their antennae to maneuver the seeds into position, before attempting to pick them up. Once fully loaded, they headed straight for the nest. There were many empty seedpods in the area where the seeds were being gathered, and it is possible that the ants had broken open the pods earlier and liberated the seeds - but it is just as likely that the seeds fell naturally. One worker was seen manipulating a seedpod, but it was already empty.