An informational analysis of the alarm communication by drumming behavior in nests of carpenter ants (Camponotus, Formicidae, Hymenoptera)
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- Fuchs, S. Behav Ecol Sociobiol (1976) 1: 315. doi:10.1007/BF00300070
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The influence of an artificial drumming signal on the activities of worker ants and on the frequency distribution of activities inside an undisturbed laboratory colony of C. herculeanus L. was investigated by applying the mathematical theory of communication.
The measure of uncertainty as to the activities of worker ants at any given time (initial act) is 1.4 bit. After a drumming signal has been applied, the reactions of the ants (second act) cause a decrease to 0.84 bit. The transinformation between first and second acts is 1.07 bit without and 0.48 bit with a drumming signal between the acts. In reference to the proportion of activity groups, the information transferred to the worker ants as a group is 0.043 bit.
The information transferred by the signal to the worker ants as individuals was calculated by referring to the proportion of the two-act sequences (uncertainty 1.9 bit) with and without drumming. The result is 0.12 bit, which is 12% of the signal's information content (1 bit). It differs widely between sub-groups as defined by initial activity (0.005–0.61 bit); the signal reduces the uncertainty as to the behavior of the animals by 0.5%–35%. The information transferred by signals of lower acceleration amplitudes is less than that transferred by higher acceleration amplitudes. Sexual animals react similarly to worker ants, but are less sensitive.
Besides an increased tendency to changes of activity two typical reactions to the signal occurred: a “freezing” reaction and a reaction characterized by fast, aggressive runs (57% and 6% respectively of the transferred information). The first was interpreted as an unspecific reaction to vibration stimuli, which is adaptive only outside the nests; the second as a specific “alarm” response.
The kind of alarm responses to the drumming signal is highly dependent on the situational context. The drumming communication was thus classified as a combined alarm and alarm modulator system.