Fig 1.
Diagram of the entrance chamber.
A schematic vertical cross section of a typical P. barbatus ant nest. The solid line indicates the ground surface, and the dashed line indicates where a horizontal section was made to observe activity inside the nest. Interactions occur in the entrance chamber, connected to the outside by the entrance tunnel, with tunnels leading to the deeper nest.
Fig 2.
A photograph of the entrance chamber of colony N_4 covered with the window used during filming. The tunnels to the deeper nest are labeled, as is the trail of returning and outgoing foragers.
Fig 3.
Comparison of activity distribution by colony.
Each bar shows the mean proportion of ascending ants that foraged (black), did nest maintenance (white), or ascended into the nest entrance but then descended back into the deeper nest without leaving the nest to forage (grey), over the course of three days. Error bars show standard errors of the mean.
Fig 4.
Comparison of interaction rate and time in entrance chamber in outgoing foragers and descending ants.
A) Each bar shows the mean rate of brief antennal contacts, in interactions per second, of ants in the entrance chamber. B) Each bar shows the mean time in seconds that ants spent in the entrance chamber. Black: ants that subsequently left the nest to forage (outgoing foragers); White: ants that descended from the entrance chamber to the deeper nest (descending ants). Error bars show standard errors of the mean.
Table 1.
Lag times found after removals were performed.
The lag values in seconds between returning foragers and ascending ants, returning foragers and descending ants, and ascending ants and descending ants. Mean and standard deviation across all colonies and days also shown. For cross-correlations in which more than one lag time was detected, all significant lags are reported. A “—” indicates that no significant lags were found.
Fig 5.
Comparison of significant cross-correlations in lag times for a single colony.
All lag times are from colony 367 on August 20, 2013, the only trial that showed significant lag times for all three cross-correlations. Each bar shows the lag of a significant cross-correlation between 1) rate of forager return and rate at which ants ascended to the entrance chamber from the deeper nest, 2) rate of forager return and rate at which ants descended to the deeper nest, and 3) rate at which ants ascended to the entrance chamber and rate at which ants descended to the deeper nest.
Fig 6.
Comparison of time lags between ant activities.
Each bar shows the duration in seconds of the lag between two rates, with data pooled across six colonies and eight days: 1) rate of forager return and rate at which ants ascended to the entrance chamber from the deeper nest, 2) rate of forager return and rate at which ants descended to the deeper nest from the entrance chamber, and 3) rate at which ants ascended to the entrance chamber from the deeper nest and rate at which ants descended to the deeper nest from the entrance chamber. The figure shows lag values only for the cross-correlations that were statistically significant. Error bars show standard errors of the mean. Numbers above bars signify sample sizes.
Fig 7.
Comparison of number of interactions in the entrance chamber before and after removals.
Black: the number of interactions observed from one film frame at the start of forager removals; White: the number of interactions observed from one film frame 3–5 minutes after removal of returning foragers was completed.
Fig 8.
Spatial distribution of interactions.
Each interaction utilization distribution map shows the location of interactions, brief antennal contacts between ants, that were observed from instantaneous images. The left figure of each pair shows interactions at the very beginning of an experiment that decreased the rate of incoming foragers, and the right figure shows interactions 3–5 minutes after the experiment was complete. White shows the areas of highest interaction density for each pair of heat maps, yellow shows areas with some interactions, and red shows areas with no interactions. The tunnel entrance/exit is indicated with a T and the nest entrance/exit is indicated with an N. The scales for size and color are relative to each pair of maps.