Friday, August 26, 2011

Ever the Opportunist........Silver Gull

While my son and I were fishing the River Derwent recently, without much luck, we were heartened to see flocks of Silver Gulls, with the odd Kelp and Pacific Gull present too, working their way up river towards us. From previous experience, this can often be an indicator of fish, such as salmon or couta, chopping up bait fish, with the gulls picking up the odd morsel. Well the flock passed and despite much casting of lures, there was no sign of any fish. I took a few shots to see if I could ID what they were eating, but I couldn't resolve anything on the camera's LCD screen, but it did intrigue me.

Looking at the images on my PC, I was able to enlarge some of the shots, and realised they were eating beetles. I mentioned this to my wife, who remembered a recent story in the local daily, The Mercury, that there had recently been an "inundation" of beetles. The
story quoted Dr. Cathy Young, the Tasmanian Museum's entomologist, as saying that these 15mm beetles, Redheaded Cockchafers (Adoryphorus couloni) were particularly common at this time of year. Apparently they spend much of the year in the ground as grubs, chomping up the roots of lawn and pasture grasses and as such they are a considerable pest. "Then as soon as we get to this time of year--late winter and early spring--they emerge (from their pupal cell), mate, reproduce and then die" she is quoted as saying. They have a lifespan (as a beetle) of only a week or so.

We had noticed a large group of several hundred beetles on shore--all dead--that was swept downstream as the tide rose, but hadn't realised they were the 'target' of the gulls. Looking at the shape of some of the gulls, they had seriously overindulged!

1 comment:

Denis Wilson said...

Nature doesn't waste much.
Nice report.