Unusual Behaviour in Large Colony of Leaf Cutters,Trinidad

[Acromyrmexbob]

This got my attention when I was in Trinidad around a year ago. When these colonies get to a certain size they become almost entirely nocturnal. I expect this is because in the heat of the sun the leaf fragments they are carrying will lose a large portion of their water content on the journey back to the nest. But I was on the north coast of Trinidad, right by the sea, and I spotted this very big colony giving it the full works right in the middle of the day, in full sun. I was very puzzled. There was a 30cm wide line of ants hitting a cashew nut tree on the beach and carrying a huge volume of leaves back. I started to look at why this might be and it occurred to me that the reason may be their location. During the night their colony would be directly in line with the wind blowing inshore from the sea. This wind would be relatively cold. Foraging in these conditions, away from the shelter of the trees more inland, they would be slower and less active. So I believe they switched to diurnal activity due to this and started gathering food at the only time of the day when conditions permitted them to do so. A really interesting behaviour I thought, which showed their ability to adapt what you would think would be a behaviour that was pre-programmed and hard wired.