Helmeted hornbill a solid fighter

This helmeted species is the only kind of hornbill with a solid head casque, perfect for fighting
Contributor

Bec Crew

Contributor

Bec Crew

Becky Crew is a Sydney-based science communicator with a love for weird and wonderful animals. From strange behaviours and special adaptations to newly discovered species and the researchers who find them, her topics celebrate how alien yet relatable so many of the creatures that live amongst us can be.

ByBec Crew September 11, 2014 Reading Time: 2 Minutes

THESE BIZARRE CREATURES are helmeted hornbills (Rhinoplax vigil) – extremely large and colourful birds from Indonesia, the Malay Peninsula, Sumatra and Borneo.

Growing to a whopping 120cm long – and that’s not even including the tail feathers, which are 50cm on their own – these massive birds weigh an average 3.1 kg in males and 2.7 kg in females. So yep, these guys are big. And what do you do when you’re big? You battle.

Helmeted hornbills are named for the rather intimidating ‘casques’, or helmets, that emanate from the tops of their foreheads and run down the top of their impressive sunset-coloured bills.

While superficially it might look like many other hornbills are equipped with similar cranial appendages, the helmeted hornbill is the only known species in the world to have a wholly solid casque, made of bone and fused to the top of its skull. It’s thought that the helmeted hornbill’s casque could constitute 10 percent of its total body weight, which of course makes it perfect for fighting with.

Hornbills use helmet casques to fight

Helmeted hornbills are known to engage in the occasional mid-air casque-to-casque battle, which involves smashing into each other headfirst while in flight, and sometimes for two hours at a time.

If an individual engages in multiple battles throughout its lifetime, it will eventually grind its casque down to a nice, flat surface. Exactly why these birds insist on performing this elaborate ‘aerial jousting’ behaviour isn’t exactly clear, but it’s been put down to territorial disputes, resource competition, general dislike between individuals, and even intoxication from eating too many fermented figs. So yes, helmeted hornbills engage in messy, drunk battles in the sky.

A 2003 study led by Margaret Kinnaird from the Wildlife Conservation Society-Indonesia Program observed several aerial jousting matches between male and female helmeted hornbills in Thailand and Indonesia.

Describing one pair of males as gliding towards each other, crashing mid-air, and then returning to their respective perches on the separate trees, Kinnaird observed them hitting the tree branches “like a boxer punching his gloves at the corner of the ring before a fight begins”. The pair then vocalised boisterously for about half an hour before launching back into the air, jousting, and returning to their perches for a rest.

“When collisions occur, the resulting sound – a loud “CLACK!” – can be heard in the forest understory at least 100m away,” Kinnaird reported. These collisions are sometimes so powerful, they can propel one or both birds backwards in the air, and push them into unintentional but wonderfully acrobatic backflips.