Meeting Abstract
Some birds have a bill-tip organ, a sensory structure that comprises multiple touch papillae, or groups of mechanoreceptors organized in layers around trigeminal afferent fibers. The bill-tip organ mediates specialized feeding behaviors such as probing for food by providing the high tactile sensitivity needed to, for example, locate prey items by remote touch. Thus, its presence may indicate specialized feeding capabilities in birds, but it is not known whether tactile feeding behaviors and morphological evidence of bill-tip organs are correlated in their distribution among birds. Another potential correlation is between the touch papillae of the bill-tip organ and the foramina that house them in the rostral end of the bill. If the bony foramina in the bill are consistently associated with the soft-tissue touch papillae, then the foramina can serve as proxies for the papillae in skeletal specimens or fossils. Foramina are present on the bills of all birds to some extent, and neurovascular structures other than touch papillae may also be housed in them, so the reliability of this potential osteological correlate is unknown. To explore the validity of these potential anatomical correlates of behavior, the patterns of distribution of foramina on bones of the bill were studied in 60+ species of birds spanning 24 orders. Behavioral data and data on the bill-tip organ were compiled from the literature for qualitative comparison to the studied specimens. Our results indicate that using foramina to predict bill-tip organs or using bill-tip organs to predict specialized feeding behaviors in birds should be done with caution. However, preliminary results from other studies indicate that the size of other components of the trigeminal system may serve as correlates for tactile sensitivity in the bill tip.
