Bird time

The last two 'weekly birds' have been African and extant (not extinct), but this week's is an extinct New Zealand bird.  Along with the moa, the huia (Heteralocha acutirostris) is probably one of New Zealand's most famous extinct birds, largely due to it's aesthetic beauty.

A pair of huia on a karaka (Corynocarpus laevigatus) branch. Image: John Gould
Male huia with a shorter beak. Photo credit: Dr Paddy Ryan
The huia was unique in that the female had a much longer, more down-curved beak than the males--the most prominent beak sexual dimorphism of any bird species. This marked difference in beak size is highlighted by the fact that  John Gould first described the male and female huia as two distinct species. In addition, both parts of the binomial scientific name refers to the birds beak, the genus Heteralocha being derived from Greek and referring to the different beak sizes, and the species acutirostris from Latin referring to the sharp pointed form of the beak.

Female huia with a longer beak. Photo credit: Dr Paddy Ryan
The main hypotheses as to why the beaks differed so much between the sexes relates to feeding habits. Huia were known to be bark borers, feeding on grubs such as the larvae of huhu beetle. It was first suggested that the males used their short strong beaks to make holes in the bark and the females used their longer, more slender beaks to reach into the holes to retrieve prey. However, this cooperative feeding story is not entirely true. What is more likely is that males and females had slightly different feeding niches. This allowed males and females to exploit different food resources, thus reducing intraspecific (within species) competition.

Like so many of New Zealand's extinct birds, it was undoubtedly related to anthropogenic activity. Humans have only been in New Zealand for around 800 years, and yet in that time about 26 percent of 223 breeding birds species have gone extinct. The first settlers in New Zealand from Polynesia would have hunted birds for food and feathers and they also brought with them a predator, the kiore or polynesian rat. But, it was the successive colonisation by Europeans that was devastating. A wave of new predators including rats, cats, stoats and other mustelids and, possums accompanied the new settlers. In addition, many hectares of native forest were cleared for timber, real estate and agriculture, shrinking the habitat for native fauna. Sadly, by the 1920s the huia was extinct. There were later  unconfirmed of sightings of the bird but that was in the 1960s.

Stuffed female huia. Photo credit: John Thomas Pusateri Jr.

The image above is by John Thomas Pusateri Jr.. Check out his website for other similar images. They are great.


Post a Comment