What native animal is found in trees but can’t fly, can hold its breath
underwater and was lost longer than the takahe?
A: Niho taniwha — the riddle of the chevron skink.
It all started in the heady days of the 1970’s. While most New
Zealanders were busy growing long hair and listening to psychedelic
music, a group of dedicated conservationists in the backblocks of Great
Barrier Island were busy rediscovering the most intriguing and enigmatic
skink of them all — the Niho Taniwha or chevron skink (Oligosoma
The chevron skink is one of the most attractive and unique lizards in
New Zealand and is only known from two islands in the Hauraki Gulf —
Great Barrier and Little Barrier Islands. The chevron was first
described in 1906 but was subsequently lost to science for the better
part of last century. The chevron spent its adolescent years known as
the Great Barrier skink until a lone animal was found deep in the misty
gullies of Hauturu. Great Barrier Island continues to be the stronghold
for chevron skinks and is the location where this revered and
fascinating creature is slowly giving up clues to rangers and scientists
as to how it spends it days.
A dedicated D.o.C led research programme was initiated in the 1990’s to
learn more about the chevron skink. At that stage there had only been
100 or so records and people only had a faint idea where they lived and
how to catch them. The team was led by Keri Neilson and included current
Great Barrier Island biodiversity ranger Halema Jamieson. The team made
enormous headway into understanding some key facts about the chevron
skink with the most important discoveries being; they tend to live very
close to streams in and around debris dams because they lose water
easily; and the best way to catch a chevron is a fish trap baited with
banana placed in a stream debris dam. It sounds like simple stuff but it
has made subsequent research a walk in the park.
a crystal clear forest stream and having lunch in the dappled light I
thought to myself “these chevrons are onto it, why don’t I live down
here?” My question was answered the very next day when a huge rain bomb
unleashed over the island bringing 50mm of rain in just a few hours, and
turning the normally tranquil streams into torrents. Many of the skinks’
debris-dam homes were completely submerged and some had been swept away.
I started to fear for the chevrons. I hastily checked on 4 animals I was
radiotracking, and to my amazement 3 of them had climbed up amongst dead
fronds in the crowns of streamside silver ferns. As soon as the flood
subsided and the sun came out, the chevies were back down on the ground
in their usual retreats. A month later and the Barrier received another
torrential downpour and once again the chevrons made for the trees to
escape the inevitable floodwaters. During these flooding events I
searched in random fern crowns to see if I could find any other chevrons
(seeing as 75% of mine were up there). To my surprise I found one on my
third attempt. Two floods and eight search hours later and I had 6
chevrons ranging from just born to fully-grown adults. In comparison,
similar searches during dry episodes revealed no chevrons at all. This
discovery makes sense of their striking patterns which looks remarkably
like a dead fern frond; indeed they are very difficult to see when
hiding in the fern crowns (it’s got to be in here somewhere!). It turns
out I had no need to worry at all… these skinks have been escaping
floods for thousands of years, and have even evolved a clever disguise
that keeps them safe from our native avian predators. If worst comes to
worst they can also hold their breath as an escaping skink showed me
when he jumped into the creek and hid between some rocks underwater.
chevrons may not be so good at being undetected by introduced predators.
Two adult chevrons were found this year that had been attacked by rats -
luckily they survived but sustained some nasty head injuries. In
addition many of the chevrons in unmanaged areas have lost sections of
their tails. This is probably due to rats, as in privately owned areas
with intensive rat control (Glenfern Sanctuary) the skinks are in better
condition overall. There are also a lot more juveniles and sub-adult
skinks in these areas, which suggests a recovering population.
of the chevron skink is starting to look brighter, we now need to focus
on making sure the population on Great Barrier Island is maintained by
establishing what animals are threatening their survival. We also need
to make sure the Hauturu chevron population is alive and well as to date
there has only been two animals found there.