Adaptations

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The most noticeable adaptations of the Huia are:

1. The characteristic beak of the female.
2. The difference between the beak shape of the male and female.
3. Dark plumage.
4. The bright orange wattle.
5. The long tail feathers with white tips.

There are also some other important adaptations which are not so obvious, which will be discussed here.

Beaks and Feeding

The difference between the beaks in Huia is called sexual dimorphism. It is not actually all an uncommon structural adaptation (riflemen, sicklbills and even kiwi have this) but is probably most pronounced in Huia.

The reason for sexual dimporhism in beak shape and size is to reduce competition within the same species (and therefore, within the same population). Interestingly, both sexes had very similar diets, but the different beaks allowed them to find/access their food from different places.

Diet/Feeding

Huia were omnivores and considered to be experts at feeding on Huhu beetle larvae (huhu grubs), Prionoplus reticularis. They also ate a wide range of other insect larvae, as well as Weta, spiders and berries.

Huhu grubs - yum!

Accounts from early settlers describe the feeding of Huia - they would take their food to a perch, their food in their claws, strip off anything hard (like an exoskeleton), throw it into the air and catch it in their beak.

Male

• approximately 60mm long
• only slightly curved
• robust (like a woodpecker)

The male used its bill to chisel into the outer layers of decaying or live wood. To do this it had to be robust and relatively straight.

Female

• approximately 100mm long
• very pronounced curve
• fine (like a hummingbird)

The shape of the female's bill allowed her to probe areas inaccessible to the male, such as the burrows of insect larvae in living wood.

Bright Orange Wattle

The wattle either side of the beak is characteristic of the Callaeidae Family, which includes Huia, Kokako and saddleback (Tieke). The actual purpose of the wattle is a bit of a mystery, but in turkeys it is used to select a mate. It is likely this was its purpose in Huia as well.

Plumage

The feathers of Huia were black with a green tinge. This would have helped Huia be well camouflaged in the dark New Zealand rain forests, which had very tall trees limiting the amount of light getting below the canopy. With no natural predators (until the arrival of humans), this was probably more important for catching insects.

The white tip on the tail feathers was a unique feature (for New Zealand birds) of Huia. This made them a desirable commodity for both Maori and European settlers. Sadly, to collect these feathers, the birds had to be killed. The purpose of the white tip is unknown, but it is likely that it also helped break up the shape of Huia. Huia were not strong fliers (like a lot of NZ birds), so this breaking up of their shape may have helped in catching insects.

Its large tail was used (in conjunction with its short wings and strong legs) to move in long leaps and bounds through the canopy or along the forest floor. It was also used to help it balance when holding onto tree trunks (vertically. like a woodpecker). It did this by spreading the tail out.

Mating

Huia mated for life; that is, they had only one partner for mating. This is usually a disadvantage, but the lack of predators and small range of Huia meant that this was actually an advantage - they did not need to waste energy competing for mates every year. However, the arrival of humans along with their introduced predators (rats, dogs etc) led to this adaptation being a huge disadvantage for Huia populations.

Breeding and nesting usually occurred during early summer, when there was plenty of dry foliage and twigs for nest-building. The nest was built either in a hollow tree or in a mass of dense vegetation. Nesting took place in November. The clutch size was two to four eggs, which were greyish with purple and brown speckles and measured 45mm by 30mm; the colour of these eggs would help camouflage them in their nests. Most Huia nests were found near the summits of mountain ranges.

Behaviour

Huia are described as being quiet, social birds which were not afraid of humans. This made them easy to capture by hand. They were usually found in breeding pairs, but sometimes also in social groups of four (presumably two breeding pairs).

Huia had a loud distress call and were named after the sound of this call. However, it has been described as sounding more like "who-are-you" by some.

Their social, trusting behaviour is typical of animals with no natural predators, which makes it interesting that they had a distress call. It may be inferred that this distress call evolved upon the arrival of humans, but this can never be confirmed.

Summary

Huia probably developed these structural, behavioural and physiological adaptations over time due to the lack of natural predators, and to limit competition (particularly intraspecific). The fact that Huia were widespread throughout New Zealand until the arrival of Maori suggests that it could not adapt quickly enough to the introduction of predators, to human exploitation and to the introduction of competitors.