Hummingbirds are evolving ‘armed’ mouth with teeth for fighting

Male tooth-billed hummingbird, Androdon aequatorialis, have a strong-armed accounts, with hooked tips and rear-facing teeth. (Credit: Kristiina Hurme, Colombia)

Hummingbirds are known as strong, aggressive, and there was even referred to as “angry” by some researchers, but a certain kind of bellicose birds have their rage to a new level, she started to develop “armed” beaks used to fight and not to eat.

Some male hummingbirds in South America, which can weigh just a tenth of an ounce, have developed court bills with serrated teeth to outduel rivals for the best places to eat.

“We understand the hummingbirds all live to drink efficiently from flowers, but then suddenly we see this strange shaped rigid accounts, hooks and serrated edge, such as teeth – that make no sense, in terms of nectar collection efficiency,” said Alejandro Rico-Guevara, a Miller Postdoctoral Fellow at the university of Berkeley and a scientist on the project, in a statement.


Rico-Guevara continued: “Looking at this bizarre bill tips, which you would never expect a hummingbird, or that they would be useful for the pressing of the tongue.”

Hummingbirds have long been known to be aggressive. In some cases, they have been attacked by larger birds such as hawks or owls, but the speed at which they move is made with the tracking of their aggressiveness particularly difficult. So, Rico-Guevara and his team use a high-speed video camera and then slowed the footage down to see what actually happens as the birds fended off rivals.

“Because it happens so fast and they fly away, can’t follow you,” he said. “But people haven’t actually looked at the details of the beaks. We make connections between how tough they are, the beak morphology behind that and what that means for their competitiveness.”

The study is published in the January 2019 issue of the scientific journal Integrative Organismal Biology.

The armed beaks are not proficient for the enjoyment of nectar, Rico-Guevara said: “fuels their life,” further evidence that the evolutionary function is probably due to help fend off the competition.

“We have discovered that these properties can be related to a different strategy: instead of the run of a certain flower shape very well, some birds try to exclude everyone of a patch of flowers, even though they do not feed on them like hummingbirds without bill weapons,” Rico-Guevara said. “If you are good enough to keep your competitors away, then it does not matter how well you make use of the resources in the flowers that you are defending, you have them all to yourself.”


However, not all of the hummingbirds in the region to use to fend off competition for food. Some of the birds they have used to fight for the attention of the females on the collection of sites known as leks, Rico-Guevara was described as “a singles bar.”

“The females go to these small spaces, in the forest and choose a male to mate. If you can get a seat at the bar, it’s going to give you the chance to reproduce,” he said. “So they don’t fight for access to resources, such as in the territorial species, but actually they are fighting for a chance to multiply.”

Follow Chris Ciaccia on Twitter @Chris_Ciaccia

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