Beautiful Blue Ducks at Blue Lake - but there is trouble in paradise

The poster in the hut on the Travers-Sabine trail asked for sightings of rare birds and animals - weka, blue duck (Maori name whio, pronounced 'fee-o'), kea, kaka, black-eyed gecko, rock wren. Being observant trampers, it was with high hopes we set off to record sightings. The rushing mountain streams seemed a likely place for whio.  After three days and not a whio whistle, we came to Blue Lake or Rotomairewhenua (land of peaceful waters), surely the highlight of any tramp in this area.

Blue Lake - Rotomairewhenua

Its gorgeous clear waters are thought to be the clearest freshwater in the world (see NIWA).

Horizontal visibility in the lake is outstanding - 70-80m

We stayed in the simple Blue Lake Hut along with other trampers. In the early evening, a fellow tramper burst into the hut with the cry "There are blue ducks on the lake!" and we hastily followed her back down the short path to the lake. A pair of whio, unconcerned by our presence were feeding in the shallows.

Blue duck - Whio

They crossed the small lake a few times, moving through the water with some speed when they decided to change banks, keeping together, using their intriguing rubbery edged beaks to nibble up insect larvae from the stones.

Whio pair cruising on the lake

We stayed and watched until hunger drove us back to the hut.  How special, we thought, to see two Blue Ducks at Blue Lake.

Next morning, before we left, I went to fill my water bottle from the clear water of the lake. The two whio were still there, and one curious, perhaps because of the ripples I caused, came close to see what I was up to. I snapped some photos of it cruising around.

Early morning at Blue Lake

Then there was a sudden commotion, a rat had launched itself off a rock at the whio. Whether it was ever on the duck's back I can't be sure, but within seconds the whio was furiously lunging at it making a lot of noise. The other whio swam swiftly over and together they gave chase, right behind the swimming rat snapping at it with their beaks. Finally, the rat reached the rocks and shore and disappeared. And I was standing there powerless to do anything. One of my photos shows the rat on top of the rock, just before it jumped - I hadn't seen it through the view finder.

Rat just visible on top of the centre rock

I was sadder and wiser as we tramped back down the pretty Sabine Valley. Yes, we'd seen paradise - two rare native birds at one of the most beautiful places in New Zealand. But all was not right. The presence of the rat was a reminder that introduced mammals such as rats and stoats make it unlikely that this pair will successfully raise blue ducklings. An adult may be able to shake off a rat or stoat, but a duckling?

You can find out more about blue duck or whio at:

• NZ Birds Online website
• Department of Conservation website
• Whio Forever a project to protect blue duck

To learn more about New Zealand's introduced mammalian predators and attempts to eradicate them see:

• Predator Free NZ

The Blue Lake area hasn't been included in the Battle for the Birds campaign.

The rat incident took place on 1 March 2015. 
Thanks to Philippa Doig for photo of the Blue Duck at lake edge