Scientists Document Cultural Change In The Dialects Of Wild Parrots Over 22 Years

Like humans, parrots have distinct vocal dialects and, like humans, they learn those dialects from their family and friends, so those dialects change when they relocate to a new area.

Humans speak in their own languages and dialects, but in general, people are unaware that other animals may also speak in their own languages and dialects. Likewise, whales, chimpanzees, and bats are known to speak in their own dialects. Perhaps unsurprisingly, another such example of speaking with regional dialects is parrots: a recent study published by a collaborative team of researchers, Christine Dahlin of the University of Pittsburgh at Johnstown and Timothy Wright, Grace Smith-Vidaurre, and Molly K. Genes from New Mexico State University documented the dialects of wild yellow-naped Amazon parrots throughout their natural range in Costa Rica over a 22-year span.

Yellow-naped amazons, Amazona auropalliata, are large, mostly yellowish-green parrots that form long-term pair bonds, living along the Pacific coast. They roost in large flocks at night, and disperse into smaller groups to forage throughout the rainforest during the day. They share a variety of calls with their roostmates, of which contact calls are the most common. Contact calls are used to maintain contact and to communicate with each other over distances. It is these calls that show distinct regional differences that are characteristic of dialects.

In their initial surveys in 1994, the researchers recorded three acoustically distinct contact call types, which they named North, South and Nicaraguan, based on the geographic region where each specific call type could be heard. In 2005, the researchers returned to check on the parrots and their dialects. They found both the parrots' acoustic call structures and dialect boundaries were essentially unchanged.

Original Call of the Southern Yellow-naped Amazon Parrots

But tragically, during this same time period, the parrots' populations suddenly collapsed. In the last three generations alone, yellow-naped Amazon parrot lost more than 92% of its population in Central and South America, mostly due to habitat loss and poaching for the illegal wildlife trade. In response, the IUCN quickly uplisted the yellow-naped Amazon parrots' conservation status twice, first to vulnerable and then to critically endangered.

As the persecuted parrots' populations crashed, their regional contact calls also changed. The researchers found that many parrots were becoming bilingual as they formed pair bonds across the formerly distinct North-South acoustic boundary. Amongst parrots speaking the North dialect, the researchers observed many bilingual parrots using both the North and the South dialects. Not only is this acoustic drift creating bilingual parrots but it is giving rise to new contact call types and to calls with greater overall acoustic variation.

New Call of the Southern Yellow-Naped Amazon Parrots

"The observed cultural changes may represent adaptive responses to changing group sizes and patterns of social association," Dr Dahlin and collaborators noted in their published study.

This study's findings suggest that cultural traditions in wild parrots, such as dialects, are flexible and appear to change in response to population and environmental changes. This flexibility has worrying implications for threatened species — how will bilingual parrots be able to communicate with each other? (Read more about that here .)

"Some of this change could be disruptive, with the potential to further exacerbate population declines," Dr Dahlin and collaborators observed in their paper. "However, an increase in bilingual sites could also be a sign of adaptability."

In fact, the acoustic flexibility of bilingual parrots may indeed provide a survival advantage. Birds that can communicate with more groups may be able to share more information, locate suitable mates, access foraging areas, or gain roosting privileges.

Of course, more research is necessary to directly tie the cultural changes that Dr Dahlin and collaborators documented in these parrots' learned vocalizations to the demographic upheaval experienced by this species. Thus, this data emphasizes the importance of long-term studies for understanding how culture evolves, and what forces drive this evolution.

This study also highlights how vocal learning is important to the survival of wild parrot populations and how this ability may serve an adaptive role in the wild. It also provides insight into the disruptive human impacts on wildlife exploitation.

"Ultimately, monitoring cultural behaviors, such as the rate of change in dialects, can help wildlife managers understand anthropogenic impacts, population dynamics and conserve species."

Source:

Christine R. Dahlin, Grace Smith-Vidaurre, Molly K. Genes and Timothy F. Wright (2024). Widespread cultural change in declining populations of Amazon parrots, Proceedings of the Royal Society B: Biological Sciences (2029) | doi: 10.1098/rspb.2024.0659