Christine Dahlin, a biology professor at the University of Pittsburgh at Johnstown, is advancing research into how wild parrots communicate. Her work focuses on Yellow-naped Amazon parrots, a critically endangered species found from southern Mexico to southern Costa Rica.
“Ultimately I really want to understand how these birds are communicating in the wild,” Dahlin said. “I want to know what they are saying, and how they are saying it.”
Dahlin and her colleagues used fieldwork, manual data sorting, and machine learning to analyze the warble duets of mated parrot pairs. Their findings indicate that these duets possess language-like features such as syntax and collocates, along with an extensive set of calls. The research was published in the Journal of Avian Biology.
Previously, Dahlin had studied simpler “standard duets” among parrots and found evidence of syntax. It was uncertain whether the more complex warble duets followed similar rules. “One hypothesis is that maybe warble duets have different notes simply to show their prowess,” Dahlin said. Yellow-naped parrots use these vocalizations during territorial disputes. “So maybe the point is just to have a lot of variety — or maybe it’s something else entirely.”
Some studies suggest that songbirds may match or avoid matching another bird’s notes during counter-duets to influence social interactions. To investigate this in parrots, Dahlin needed first to determine how many call types were present in their warble duets.
“That started this whole process.”
Over three years, Dahlin and her team conducted fieldwork in Costa Rica, observing parrot behavior in cattle pastures and recording vocalizations using video cameras and directional microphones. “The warble duets would get really fast and really loud when there was a territory dispute,” she said. Physical confrontations among birds were always preceded by these vocal exchanges.
Analyzing over ten years’ worth of data with help from undergraduate students, the team identified about 50 warble duets from 13 parrot pairs out of hundreds recorded overall. These duets included more than 450 individual calls.
Standard parrot duets involve four types of calls; however, researchers found 36 distinct call types within the more complex warbling duets. “There are actually more than 36,” Dahlin said. “Some were rare, some only appeared once, so we didn’t even put them into a category.”
To analyze syntactic structure within this larger set of calls, Owen Small (UPJ ’19) suggested using Voyant Tools—a program typically used for literary analysis—which allowed the team to examine bird vocalizations similarly to written language analysis.
“Voyant was able to run the same analysis as if it were a body of writing,” Dahlin explained. “And the results show the parallels between these complex signals the birds are giving and our own language.”
They discovered over 20 syntactic rules governing duet structure and noted that repetition within each duet was minimal despite their brief duration (5-10 seconds). “This shows that the parrots are being very precise,” Dahlin said. “They are not simply throwing random notes around.”
Dahlin believes this combination of flexibility and rule-following demonstrates intricate decision-making between paired birds: “They’re making multiple decisions,” she said. “Are they going to duet at all? If so, what kind? And what notes are they giving? All of this is happening very rapidly, and they have to do it in coordination with their partner.”
Looking ahead, Dahlin plans further study on counter-duetting behaviors among Yellow-naped parrots as well as exploring other aspects such as dialects and different vocalization types using her extensive archive of sound recordings.
“I’ve got years of sound recordings to dive into,” she said.
Photography by Tom Altany
