Monday, April 14, 2014

The grebe hunt

Crested grebe

 Each year the Ornithological Society (that's birdology) does an assessment of the Crested grebe population. In January we checkout out the accessible lakes with not much success. Grebes are magnificent birds, worldwide but only sparsely distributed through the South Island and rare in the North Island.

There are probably about 20 grebes in Fiordland, usually seen in ones and twos. There are several good spots to tick one off it you are a bird spotter, such as Kingston, Lake Hayes, Bendigo, the lakefront at Queenstown and the Te Anau waterfront. In Canterbury there are two good places for them‚ Lake Forsythe on Banks Peninsula and Lake Alexandrina near Lake Tekako. Two of us did the walk in to Green Lake and Island Lake without success, then the next day we checked out the Rakatu Wetland off the road between Blackmount and Manapouri. This newly formed wetland has yet to develop its full potential but the shallow ponds are becoming fringed with rushes and sedges and in time will be good breeding habitat for waterfowl. Predation by cats, stoats and ferrets is an issue but there is a trapping programme in hand. There were no grebes there but a pair nested successfully at Te Anau with the help of an artificial floating nest. Later, we looked for them on Lakes Gunn and Fergus, again without success.

In the distance grebes resemble ducks but closer-up you can see the longer neck and sharp bill. The adults have a crest and a chestnut ruff and are lower in the water than a duck. Grebes don't come on to land but spend their entire lives afloat. The floating nest is made from water weeds and anchored close to the shore. The diet is fish and water insects. Grebes can fly but they are reluctant to take to the air and as nobody has ever seen one flying they must do it at night, perhaps assisted by the light of a full moon.

 Conservation is difficult with nests vulnerable to changes in lake levels and the wash from power boats. The Grebe Valley takes its name from these magnificent birds but they are rare even there. Let's hope they don't disappear from our lakes entirely. Crested grebes aren't the only ones in New Zealand. The small Dabchick is a North Island waterbird, common on Lake Rotorua. The Little grebe and the Hoary-headed grebe are vagrants from Australia although both have bred here. A pair of the latter nested on the Lagoon Creek dam near Te Anau in 1975-76 and raised a chick but they didn't persist although odd ones of both species turn up on Lake Hayes from time to time. Any reports of grebes or any other unusual birds are welcome.