Whio adaptations

The whio/blue duck has many adaptations to help it survive in its challenging fast-flowing river habitat. Even newly hatched whio ducklings can negotiate white water and dive for food. Adaptations are grouped into those that are structural, behavioural and physiological.

Whio lips

See more

The whio has rubbery soft flaps on the end of its bill to help scrape its food off the surfaces of rocks. Look closely, and you’ll also see the sieve-like structures inside the bill. It uses these to sieve larvae and insects.

Rights: Rob Suisted, Nature’s Pic Images

Structural adaptations of the whio

• Special soft rubbery ‘lips’ on the end of its bill allow the whio to scrape insect larvae off rocks. These also protect its bill from damage. It is the only duck to have this adaptation.

• Strong legs for swimming and jumping, with large claws to negotiate difficult terrain.

• Large webbed feet that collapse like a folded umbrella to create less drag when its feet are moved forwards and open when they are moved back, allowing the whio to pull itself forward through fast water and help it navigate the white water.

• Streamlined body to help water flow over it so it can effectively swim and dive.

• Camouflage – the whio is perfectly camouflaged for life in fast-flowing water. The blue/grey colour gives it the name blue duck, and it is very difficult to see in the white water. Its chestnut chest provides camouflage in the riparian zone.

• Feathers that provide insulation and waterproofing in the cold water.

Behavioural adaptations of the whio

• Roosting and nesting out of sight in overhanging vegetation, protecting it from danger and allowing quick access to the water if in danger and for feeding.

• Calling to provide warning to other birds regarding danger and also to communicate with its chicks and partner. Listen to the whio here.

• Evading threats – it can go with the water flow, submerse itself or retreat into roosts.

• Preening to distribute waterproofing oils along its feathers.

• Staying under cover in daylight and feeding most often at dawn and dusk.

• Whio are reluctant flyers but defend their territories by flying low along the river’s edge

• Defending its territory – it will fight with rival birds.

Physiological adaptations of the whio

• Production of a natural waterproofing oil to coat its feathers.

• An excretory process that produces low-toxicity uric acid that is excreted alongside faeces through a cloacal opening.