Mixed Signals? Blue Jays (Usually) Know What To Do

Blue Jay (Cyanocitta cristata)

Animals acquire information from their environment in many different ways, one important method being communication with other animals.  This communication is heavily reliant on signaling.  Many of these signals are complex, having multiple components to them.  These signals have often been thought to be beneficial to their receivers, as it is believed that these complex signals more effectively influence the receiver’s behavior.  This view, however, conflicts with economic models predicting that a single component is enough to affect the behavior of receivers. This study developed a model to predict the response of receivers to simple 2-component signals.  It was predicted that the most reliable component would be the one followed by the receivers, and that the second component would be ignored.  An experiment was then carried out to test the model on blue jays, an artificial signal with color and pattern components of varying reliability.

The subjects were found to follow the more reliable component when there was a large difference in reliability (Figure 5). However, when there was a no difference in the reliability of the signals, or even when the color signal was slightly less reliable than the pattern signal, the blue jays would often choose to follow the color signal.  Less reliable components had low rates of influence on response, or were simply ignored.

The data for the most part support the predictions of economic models of receiver behavior.  However, there is an indication that the other component may have slight influence as well, since the less reliable signals were often shown to have some effect on behavior, even if said effect was small.  This was not predicted, and may merit further study to investigate if these components are used in a separate way from how the primary components are used.  The bias toward the coloring component was also unexpected, but may be due to previously suggested innate color biases present in birds.

These results are a step toward better understanding the manner in which signals are utilized by animals.  It had been widely believed that complex signals were more beneficial to an animal, but this experiment tested economic models’ predictions that following multiple signal components may not be so useful under basic conditions.


  1. Rubi, T.L., Stephens, D.W. (2016) Should receivers follow multiple signal components? An economic perspective. Behavioral Ecology 27 (2016) 36-44




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