Black jacobin hummingbirds make unique high-frequency sounds that they may not even hear themselves, according to a new study.
The researchers heard high-pitched noises that were similar to an insect call but realized the sounds were coming from black jacobins.
“These vocalizations are fast and high pitched, and in fact, they do not sound at all like your typical bird sound,” said Claudio Mello, a co-author of the study. “They sound more like an insect, such as a cricket, or like a tree frog.”
The sounds are so high-pitched that the researchers are unsure if the birds themselves are even capable of hearing them.
In order to measure and record the frequencies of the noises, the researchers used detectors that are normally used to pick up bat sounds.
The recordings showed that the hummingbird noises were extremely complex and some of the sounds were in the ultrasonic range, which are not able to be heard by humans. The vocal syrinx needed to produce such noises is very different from other birds, according to the researchers.
“They would need to vibrate very quickly and likely have a special composition, which may be different from other birds,” said Mello.
The research team theorized that it’s likely that the sounds are used as a special kind of communication among jacobins, as they are known to live among other species of hummingbirds.
“It seems more reasonable to assume they do hear the sounds they make, but we have not yet examined whether this is true,” said Mello.
Next, the researchers hope to study whether or not jacobin hummingbirds respond to their own calls or if their inner ear is structured differently from other birds. This would help determine if the bird calls serve a specific purpose and if they can actually be heard by jacobins.
Image Credit: Ana Lucia Mello