Observations during the flood revealed that foraging workers often ran or swam
on the water surface in order to reach the nest entrance before it was submerged.
Ants can be influenced by inundation in a number of different ways. This behaviour
is reflected in the way they avoid drowning. For example, the annual inundation
of the Amazon region (Adis, 1984; Majer and Delabie, 1994) leaves the forest
floor flooded for 5–6 months. The only way ants can survive these conditions is to
move their nests up in the trees. Adis (1982) reports that leaf-cutting ants of the
genus Acromyrmex can swim or “walk” on the water surface during foraging in the
flooded periods. This resembles the swimming behaviour observed for Polyrhachis
sokolova when they returned to the nest at incoming tide in the present study.