Ation pattern whose orientation was changed by 908 half way down the tunnel. Despite maintaining a constant flight direction on their way to the food source, our bees interpreted their journey as a flight through an L-shaped tunnel, as revealed by the `shortcut’ direction that they indicated in their dances. Thus, it appears that changes in flight direction are sensed primarily in terms of changes in the orientation of the overhead polarized light, when such cues are available. While the bees signal the direction of the vector that specifies the ALS-008176 cancer apparent location of the food source in Experiment 4, they do not signal the length of this vector in their dances. Rather, they signal the total distance travelled along the two (seemingly perpendicular) legs. This finding is in good agreement with earlier studies of distance estimates conveyed by the waggle dance in other ALS-008176 structure conditions where bees flew around a hill [1], along an outdoor route and then throughrstb.royalsocietypublishing.org Phil. Trans. R. Soc. B 369:a tunnel oriented at right angles [32] or along tunnels that comprised a horizontal leg followed by a vertical leg [33]. In a foraging experience that is riddled with ambiguity, as in Experiment 4, do different bees signal different locations (with each individual displaying a preference for a particular location), or does a given bee signal more than one location in a single dance? The data in figure 7 and electronic supplementary material, figure S3 suggest that both outcomes are likely. While certain bees appear to display individual preferences, others behave as though they carry up to four different representations of the location of the food source, and can signal all of these locations simultaneously in a single dance. It is not inconceivable that ambiguous, `multiple’ solutions arise even when bees forage in natural outdoor conditions. For example, ambiguities of 1808 in flight direction could arise when the sun is low on the horizon and obscured by a hill or a cloud, so that the unoccluded part of the sky provides only e-vector information, but no cues on spectral or intensity gradients. It would then be beneficial for a bee, returning from an attractive food source, to signal all of the (equally) likely positions of the targets in its dance, so that at least some of the recruits arrive at the correct location. Signalling just one of the possible locations (by arbitrary choice) would waste colony resources, if this happened to be the wrong location. Multimodal dance directions have previously been observed in the presence of contradicting information, for example, when the landscape is set in conflict with a learned ephemeris function for the sun [31]. Results analogous to ours have recently been obtained by Lebhardt et al. [34], who studied polarized-light-based navigation of the desert ant Cataglyphis by training them to walk to a food source in a tunnel that provided polarized overhead illumination, and observed their trajectories when they were allowed to return to their home in an open environment under the natural sky. When the entire length of the tunnel provided a single direction of polarized light, the ants’ homing directions displayed the same 1808 ambiguity that we have observed in the dances of our bees, although the ants showed a considerable preference for one direction over the other (e.g. when homing they preferred to walk towards the sun, rather than away from it, when the tunnel presented transversely orien.Ation pattern whose orientation was changed by 908 half way down the tunnel. Despite maintaining a constant flight direction on their way to the food source, our bees interpreted their journey as a flight through an L-shaped tunnel, as revealed by the `shortcut’ direction that they indicated in their dances. Thus, it appears that changes in flight direction are sensed primarily in terms of changes in the orientation of the overhead polarized light, when such cues are available. While the bees signal the direction of the vector that specifies the apparent location of the food source in Experiment 4, they do not signal the length of this vector in their dances. Rather, they signal the total distance travelled along the two (seemingly perpendicular) legs. This finding is in good agreement with earlier studies of distance estimates conveyed by the waggle dance in other conditions where bees flew around a hill [1], along an outdoor route and then throughrstb.royalsocietypublishing.org Phil. Trans. R. Soc. B 369:a tunnel oriented at right angles [32] or along tunnels that comprised a horizontal leg followed by a vertical leg [33]. In a foraging experience that is riddled with ambiguity, as in Experiment 4, do different bees signal different locations (with each individual displaying a preference for a particular location), or does a given bee signal more than one location in a single dance? The data in figure 7 and electronic supplementary material, figure S3 suggest that both outcomes are likely. While certain bees appear to display individual preferences, others behave as though they carry up to four different representations of the location of the food source, and can signal all of these locations simultaneously in a single dance. It is not inconceivable that ambiguous, `multiple’ solutions arise even when bees forage in natural outdoor conditions. For example, ambiguities of 1808 in flight direction could arise when the sun is low on the horizon and obscured by a hill or a cloud, so that the unoccluded part of the sky provides only e-vector information, but no cues on spectral or intensity gradients. It would then be beneficial for a bee, returning from an attractive food source, to signal all of the (equally) likely positions of the targets in its dance, so that at least some of the recruits arrive at the correct location. Signalling just one of the possible locations (by arbitrary choice) would waste colony resources, if this happened to be the wrong location. Multimodal dance directions have previously been observed in the presence of contradicting information, for example, when the landscape is set in conflict with a learned ephemeris function for the sun [31]. Results analogous to ours have recently been obtained by Lebhardt et al. [34], who studied polarized-light-based navigation of the desert ant Cataglyphis by training them to walk to a food source in a tunnel that provided polarized overhead illumination, and observed their trajectories when they were allowed to return to their home in an open environment under the natural sky. When the entire length of the tunnel provided a single direction of polarized light, the ants’ homing directions displayed the same 1808 ambiguity that we have observed in the dances of our bees, although the ants showed a considerable preference for one direction over the other (e.g. when homing they preferred to walk towards the sun, rather than away from it, when the tunnel presented transversely orien.