How is the relationship between loading ratio and speed affected by trail gradient?
For ants measured in the field, walking speed declined with loading ratio (F1,368 = 86.97, P < 0.001), trail gradient had a significant effect on walking speed (F10,368 = 3.21, P = 0.001), and there was no significant gradient x loading ratio interaction (F10,368 = 1.44, P = 0.162). Similarly, for the captive colony, walking speed decreased with loading ratio (F1,145 = 28.49, P < 0.001), trail gradient had a significant effect on speed (F4,145 = 4.69, P < 0.001), and there was no evidence that the slopes of the relationship between loading ratio and walking speed varied among gradient treatments (F4,145 = 1.77, P = 0.138). Do individual workers adjust load size in response to trail gradient? In the captive colony, gradient had a highly significant effect on loading ratio (F4,150 = 5.99, P < 0.001; Figure 2c). Atta cephalotes workers operate under the highest loading ratio when the foraging site is vertically above the nest. The next highest loading ratio is for horizontal foraging trai
