Bottlenose dolphin mothers modify signature whistles in the presence of their own calves

"Motherese" is a speech pattern that is nearly universal across cultures and languages in human caregivers interacting with children, but evidence among nonhuman species is sparse. Here, we report evidence for motherese in the bottlenose dolphin, a species that shows parallels to humans in their long-term mother-offspring bonds and lifelong vocal learning. Female bottlenose dolphins increase the maximum frequency and frequency range of the same vocalizations (signature whistles) when in the presence or absence of offspring, paralleling similar changes in human motherese. Our data provide an example of convergent evolution of motherese in a nonhuman mammal and support the hypothesis that motherese can facilitate vocal learning and bonding in nonhumans as well as humans.