A major challenge in biology is to link cellular and molecular variations with behavioral phenotypes. Here, we approached this by studying somatosensory neurons from a panel of bird species from the family Anatidae, known for their tactile-based foraging behavior. We found that tactile specialists exhibit a proportional expansion of neuronal mechanoreceptors in trigeminal ganglia. The expansion of mechanoreceptors occurs via neurons with intermediately and slowly inactivating mechano-current. Such neurons contain the Piezo2 ion channel, whose expression positively correlates with the expression of factors responsible for the development and function of touch receptors. Conversely, Piezo2 expression negatively correlates with expression of molecules mediating the detection of temperature and pain, suggesting that the expansion of Piezo2-containing mechanoreceptors with prolonged mechano-current occurs at the expense of other types of sensory neurons. Our study reveals a general mechanism of tactile specialization in vertebrates at the level of somatosensory system. Overall design: High-throughput deep sequencing of the mRNA isolated from trigeminal ganglia of 7 bird species 3 biological replicates per species Total of 21 samples.