Hummingbirds change tunes to seduce mates

The male hummingbird is a dedicated suitor, returning to the same place every day for up to eight months a year to trumpet his availability – for as long as eight hours at a stretch. He’ll repeat his song two times per second, hoping for a female to heed his call.

Hummingbirds’ songs are distinguished by more than just their duration; the birds are among a select group that learn their vocalisations (songbirds and parrots are the other two). Songs can vary by individual or by location, creating what scientists call “song neighbourhoods” and “dialects.”

Scientists had long thought that male hummingbirds learned their song while young and then “crystallised” that melody for life.

But Marcelo Araya Salas and Timothy Wright, biologists at New Mexico State University, have recently observed some male long - billed hermit hummingbirds (Phaethornis longirostris) changing their tunes in Costa Rica, suggesting they are capable of learning new songs even later in life.

Labour of love

“In most cases, this new song also matches those of neighbours,” says Wright, whose work is partly funded by a National Geographic Society grant. “But occasionally a male will develop a brand-new song type.” According to Wright, “this marks the first time such open - ended learning has been shown in a hummingbird.”

The burning question now, says Wright, is whether switching song types can help make male hummingbirds a hit with the ladies. Araya Salas, a graduate student in Wright’s lab, is now working to document more song switching events and to determine if males who do it are better able to hold territories or attract mates.

If constant singing and competing for the better part of the year sounds like a lot of work, that’s because it is. “I am continually amazed by the effort these males will put into singing, displaying, and defending a territory,” Wright said.

There are also visual aspects to the hummingbird’s display, including a flicking tail. The cues double as warnings to other males in a hummingbird’s “lek,” the term for a group of rival males all competing for the attention of certain females within the same area.

Once a hummingbird attracts a female, the male launches into a frenetic mating ritual that involves manoeuvres like the “float display,” in which the male hovers back and forth in front of his partner before mating.

“Males do a number of different display moves, and the sequence of moves can vary quite a bit from rendition to rendition, even for the same male,” said Wright. “We are still working to understand how these distinctive moves get strung together to make a full display and whether different sequences communicate more of an aggressive intent versus more of a courting intent.”

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