A river that runs backwards

So we all know that New Zealand is unstable. Literally. As anyone from Christchurch will assert. So it shouldn’t really come as a surprise that with all this up-ing and down-ing and to-ing and fro-ing of the land, that a river has changed direction. No, I don’t mean there is a river that runs uphill, but rather that the land under a river has shifted enough to make it turn around. That’s pretty crazy stuff. Like, at some stage in our geological history, the Nevis River has just stopped and then carried on in the other direction. Cooler still is that it is part of this river system: (Although the pillars of the Kings weren’t there the last time I checked).  Image

Picture from here

So how do we know this?

It’s thanks in part to these guys who I wrote about in my last blog:

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This story involves 3 rivers:

–       The Nevis (which changed direction)

–       The Kawarau (which the Nevis now runs into)

–       The Mataura (which the Nevis used to run into)

(and I suppose I should mention that the Nokomai stream is the part of the Nevis which continued flowing the same way)

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And the story involves this fish: Image

Photo from here

If there were an award for the best naming of a species, this would certainly be a contender: Galaxias gollumoides , aka the Gollum fish. There is even another very closely related species called the Smeagol fish.

Zoologists at the University of Otago have found that the Gollum fish in the Nevis have relatives in the Mataura River (to the south) but not in the Kawarau River, which the Nevis currently flows into. This supports the geologists’ evidence that in the Pleistocene (2 million-ish years ago) the Nevis used to run south through a valley between the Garvie Range and the Remarkables Range (the jagged mountains behind Queenstown).

As the mountains on either side grew, they pinched off the valley the Nevis was in. At the same time, erosion blocked off the Nevis, and caused it to run back the other way.  This isolated the Gollum fish in the Nevis from the Mataura river where it used to run. The Nevis population has since diverged from the Mataura population, but is still closely related. Image

Species that today are found in the Kawarau are not found in the Nevis, yet are found in other tributaries to the Kawarau.

P.S. If you want a closer look at the Nevis River, then this is a good way to do it!Image

Photo from here

A post about killing bunnies

When I was about 11 years old my brother and I found two rabbits. That’s not very remarkable seeing as we lived next to a farm, but these were tame lop-eared rabbits. We just walked right up to them in the paddock and picked them up. Obviously they’d been dumped, so we took them home, put them in a cage and named them Token (she was mostly black and we were insensitive) and Bob (we were also unimaginative). A couple of weeks later there were five rabbits in that cage (Token, Bob, David Brent, Gareth Keenan and Keith). So we took Bob out and gave him to the neighbours, but somehow a couple of weeks after that there were 10 rabbits in our cage. And soon there were 14. (I think the neighbours’ cage was pretty un-rabbit-proof). We were giving away baby rabbits to every kid in the neighbourhood, whether they were allowed one or not. We couldn’t get rid of them fast enough. Dare I say they were breeding like, well, rabbits.

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(Photo from here)

I’m pretty sure Central Otago is some sort of Mecca for rabbits. They gather in such numbers that if you walk into a field at dusk, it sort of explodes with rabbits running away in all directions.

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(Wikimedia commons)

Every Easter in Alexandra, there is a competition called the Great Easter Bunny Hunt, where teams compete to shoot the most rabbits in a weekend. This usually deals with about 20,000 bunnies – just the tip of the iceberg. The Central Otago bunnies are the wild brown ones – not as sweet as lops but they still have that dawww factor. That is, until you see what they do, and then bunny killing becomes quite a fun sport!

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Victims of the Easter Bunny Hunt (photo from here)

Rabbits are a massive problem because they dig holes (holes is actually an understatement – more like giant underground labyrinths) all over fields, which make them erode away. Any areas of grass that they didn’t cause to erode become their feeding grounds, leaving nothing for farmers to graze stock on.

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(Wikimedia commons)

The rabbit population in New Zealand was almost at the point where they could seriously consider world domination (aka “the rabbit plague”) in the late 90s when somehow, mysteriously a virus was introduced which made them drop like flies. The virus basically made the rabbits haemorrhage, which isn’t a very nice way to die, but it was very effective. The New Zealand Ministry of Health had previously denied the introduction of the virus, because it’s kind of dodgy to bring a deadly virus into a new area without testing it first. But somehow, two months later the virus mysteriously appeared in Central Otago, wiping out countless rabbits.  Some farmers admitted to deliberately spreading the disease by putting diseased carcasses in the blender and spreading the sludge (hopefully these weren’t their kitchen blenders), but no one knows who actually snuck it into the country. I’d say there are a few farmers out there who would gladly buy that person a drink though, if they knew who it was. Unfortunately, the virus was introduced at the wrong time of the season, just after breeding had finished. Rabbits under 2 weeks old were immune to the virus, so the next season these immune rabbits reproduced and had immune offspring. So now, almost 15 years later, rabbits are once again reaching plague numbers and are being controlled with poison, which isn’t ideal.

I may sound like a brutal and callous person (would you believe that Watership Down and Peter Rabbit were some of my favourite stories as a kid?), and don’t get me wrong I loved Token and Bob, but as for those wild Central Otago rabbits? I now consider it my duty as a road user to dispose of at least one rabbit per car trip.Image

(Wikimedia commons)