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!

Gone Fishing....... Black-faced Cormorant

My son, also a keen birder, persuaded me to go fishing, and during the last week or so, we've fished various local venues with mixed results. But if you're a birder, however hard you try, you just can't help noticing the birds. So a few days ago we were fishing the River Derwent not far from the Bowen Bridge. As we arrived, my son pointed to a distant cormorant, which was silhouetted against the light from the just risen sun. It appeared to have caught a fish, which gave us some hope. The truth, as we soon discovered, was very different!
Quickly getting our lines into the water, we soon realised that there were a dozen or more cormorants apparently fishing at various spots. I opted for them being "Little-pieds", a common cormorant in the Derwent at this time of year. I had my binoculars with me, and I soon found that the passing birds were apparently carrying nesting material. I followed one as it flew up the river and landed on the bridge pontoon half a kilometre away. That seemed a very odd place for a Little-pied Cormorant to nest, as they usually nest in trees! Then the penny dropped, they were Black-faced Cormorant, (also called Black-faced Shag).

While this may not seem worthy of mention, as these birds are commonly seen in the Derwent, especially during the winter, they normally breed on isolated stacks and islets, such as Maatsuyker Island and the Hippolytes, to name two in southern Tasmanian waters. Some years back I recall visiting a colony on Little Betsy Island, close to the mouth of the Derwent. So this site, at the base of the bridge supports, is an unusual breeding site, and several kilometres 'inland' from the river mouth. I counted 16 or more nests, most with sitting birds, but as I could only see one side of the supports, I would guess that there may be twice that number in the colony.

I got the camera out of the car (I feel 'naked' without it), and I soon started taking shots of passing cormorants, which proved difficult in the prevailing light conditions, not to mention that the birds are travelling at speed. As I have mentioned, this species mainly breeds well offshore, so I suspect the activity of gathering nesting material is seldom witnessed or photographed.

The material they collected consisted mostly of seagrass, and the occasional twig, some nearly as long as the bird, which they dived for. There was a lot of it in suspension in the water, so I'm guessing that they only had to gather it up. Some dives lasted up to 40 seconds. They seemed surprisingly fussy about the material as they sometimes emerged with a bundle, which they then rejected and dived again. Mostly the material was collected by only single birds, but occasionally an apparent pair dived together. As they sped passed, I noted that some appeared to be in moult (see lower image), but thought that unlikely during breeding, as moult imposes considerable 'stress' on birds. At home, looking at HANZAB (the bible of Australasian birding), it appears that they produce these white nuptial plumes and filoplumes, (on back and neck) during the breeding season. I have to confess I've never noticed these before.

Well the fishing was ****, the birding was good and I've learnt a lot about Black-faced Cormorants!

[NB. These birds are fully protected. Some fisherman need to take note of the irritatingly frequent littering advert on TV. The amount of discarded material at many of the sites we visited, is nothing short of appalling]