We hear of vermin in paddocks, forests and nature reserves, but we seldom think of vermin in lakes and dams.
A Creswick landowner reports on the positive results he has had after ridding his dam of redfin. He reports that the unwanted fish were having a serious negative effect on the smaller creatures in the water.
Now he says life in his dam is vastly improved, with tadpoles surviving more than a day, yabbies numerous, water-boatmen "by the thousands", and lots of water bugs of all shapes and sizes.
"We have additional birds, and the water surface is rippling with tadpoles," he reported last summer, noting that any wetland with redfin is far from ideal for diversity of aquatic life. He claims that some of the local larger dams and lakes are supporting only a fraction of the biodiversity that they could, due to the presence of redfin.
"People seem generally unaware of the massive gap they create in the ecosystem," he concludes.
Redfin were introduced to Australia in the 1860s from Europe and are now found in most of Victoria's rivers and lakes.
Anglers are encouraged not to return any caught redfin to the water, according to the Victorian Fisheries Authority.
The redfin in the dam were killed with a poison. Unfortunately, it killed freshwater mussels too. The presence of the mussels was not known until their death was noticed.
It is clear that, while redfin elimination is desirable for increased biodiversity, results of any such program must be carefully considered, especially the prospect of losing a percentage of desirable aquatic life to achieve the end result.
A report of a pair of banded lapwings (plovers) in the Allendale - Clunes district resulted in several observers making a trip to see them.
While the lapwings were not found again, birds such as spotted harrier, stubble quail, black falcon and Horsfield's bushlark were welcome sightings.
Numbers of birds of prey invariably increase in summer and autumn. The recent black falcon and spotted harrier sightings were the first local reports for this year. Black kite, brown falcon, wedge-tailed eagle and Australian hobby have been seen in the area too.
The stubble quail is more of an autumn bird locally, although it can be found at almost any time of the year. One was flushed on a roadside in the Allendale - Clunes area last weekend.
The little-known Horsfield's bushlark visits the plains cropping country every year. It is smaller and stouter than the skylark and the pipit, and has a more fluttering flight.
NATURE QUERIES ANSWERED
I spotted this large and lovely moth on my walk in Nerrina. Are you able to tell me about it? M.M., Brown Hill.
Your moth is a male bardi ghost moth, Trictena atripalpis, found across southern Australia. Its wingspan is around 120mm.
It is one of several similar large moths, most of which emerge from under the ground when the autumn rains come.
They are sometimes called rain moths.
The female bardi ghost moth is paler, browner and larger (170mm wingspan), but not as clearly marked.
The caterpillars live in deep vertical tunnels in the ground, and their tan-coloured empty pupal cases are often found in bushland at about the time of the autumn rains.
The caterpillars are often known as bardi grubs.
Their cases are sometimes found half-protruding from the ground.
The moths are nocturnal and are readily attracted to lights.
They have a short adult life.
- Questions and photos are welcome. Email to email@example.com, or send to Roger Thomas at The Courier, PO Box 21, Ballarat, 3353.