Walker Swamp excursion with the Hamilton Field Nat’s yields the threatened Western Swamp Crayfish

On a beautiful Saturday morning back a few weeks ago, I had the pleasure of joining the Hamilton Field Naturalists Club for an excursion to Walker Swamp. The aim of the excursion was to provide an overview of the plans for the property and to point out some of the achievements to date. The Hamilton Field Nat’s have been a major supporter of the Walker Swamp campaign so it was very fitting that we got to stand out there, point at things and enjoy the view.

After a quick trip up the new observation tower, we all made our way to the outlet drain to have a look at the trial restoration works and get a different perspective on the wetland.

Gathering on the lookout tower (Rod Bird).

Following up from a talk I gave to the group on the Thursday night prior, I was keen to try and catch a western-swamp crayfish (Gramastacus insolitus). These crustaceans are tiny compared to their more familiar relatives – the common yabby (Cherax destructor). However, they are unique to south west Victoria’s wetlands, with a fairly narrow distribution extending from the Grampians to the border with South Australia. They are short-lived, can’t dig their own burrows and require wetland inundation to breed – so they are pretty up against it. Walker Swamp is probably one of the most reliable places to come across the species and it only took a couple of sweeps of the net before I had one, and then another. While I can appreciate that such a small yabby (the ones in the photos are fully grown males) would not usually be much cause for celebration, it was great to follow up to some of the information I presented on the Thursday night with one in the flesh.

Male western swamp crayfish (Gramastacus insolitus) underside (Rod Bird)

Distinctive markings of the western swamp crayfish (Rod Bird)

We also had a quick walk out onto the wetland fringe to inspect the recent emergence of aquatic herbs following works to flatten out the mounds from previous bluegum plantings and those with binoculars were able to do a quick count. Rod Bird sent me through a report from the day and I was surprised to see that over 400 birds across 12 different species were observed. I must have been too busy looking at water bugs and ground plants!

Tentative steps across the newly flattened wetland verge.

And for those of you who joined me on the day, you’ll be pleased to know that I found my missing dip net out there today – right where I left it! And also there were some good flows coming through the top drain so we should see a fairly full wetland over the next month.

Thanks to the Hamilton Field Naturalist’s and everyone else who came along – it was a great morning out.

Lachlan Farrington