Saturday, 28 February 2015

Possum Raids Figs

The Brush-tailed Possum caught raiding the fig tree

After the success of catching the cockatoo raiding the chickens' food bins last week, I thought I should try to find out who was raiding the figs and focus a camera-trap on the fig tree.

The figs are the last fruit to ripen in our Canberra garden at the end of summer and we always look forward to opening a nice ripe one for breakfast. But, not this year, some animal has been eating them before we can pick them.

At first I thought it might have been fruit bats as I have seen them on the tree in previous years. Not this time though, the thief was a Brush-tailed Possum. It was a female, probably the one that sleeps in one of our garden nest-boxes, although if it was her, she has parted with her joey. The last time I saw her a week or so ago, she had a large joey (a young marsupial) in tow, still trying to hitch a ride on her back even when it was at least half mum's size.

She will probably have a new tiny joey in her pouch already, so I suppose she will want to add a hint of fig flavour to her milk. Lucky possums.

To watch a clip of the surveillance film, as evidence of the criminal's identity, click here.

We do like the possums, but...... there are times......

Monday, 23 February 2015

Scribbly Gums

A rich mix of old and young trees in Black Mountain forest
I have noticed that there have been many more features on wildlife than wildpaces lately in the blog, so I shall try to adjust this. First off, this gave a reason to go for a walk in one of the local forests, the 500 ha Black Mountain Nature Reserve, which is only two kilometres from Canberra city centre  The woodland is dominated by two eucalyptus tree species, Scribbly Gum Eucalyptus rossi and Red Stringybark E. macrorhyncha, and the under story is mostly a sparse covering of grasses and short shrubs. The trees provide thousands of cavities for such animals as possums and parrots - especially Crimson Rosellas, while I often see swamp wallabies and echidnas working through the undergrowth.

Wild forest in the foreground - urban high-rise only a mile away
There are numerous tracks to follow through the forest and multiple variations of routes to take. On today's walk I went around the summit and looked down onto the city. And I noticed how, even the city looked green with the street and park trees shining between the buildings.

A zoomed-in view of Canberra city from Black Mountain
Now that it is late summer, some species of eucalypt trees have shed their outer layers of old bark to reveal shiny new skin. The Scribbly Gums do this but not the stringybarks.

This fine old Scribbly Gum has large and small hollows,
 it is a true veteran, yet is still throwing up young branches from its old trunk.
The cast bark lies thick on the ground in some places, giving homes and shelter to all sorts of animals, but it can build up deep enough to become a fire hazard and Canberra, as the bush capital, is well aware of the danger of bush fires. So there are regular burn-offs of the ground cover over the years to prevent such a risk.

Shards of bark lie about the base of the gum trees, their inner surface glowing red in the sunshine
The Scribbly Gum is named after the marks on its bark, which are especially noticeable when the bark is freshly cast. These scribbles are the marks of where a species of moth larvae, Scribbly Gum Moth Ogmograptis scribula, have meandered safely beneath the old bark layer, while munching on the fresh growth immediately below. To find out more on the moth and its larva, click here to a link to the Australian museum website.

The zig-zag trail left by a scribbly gum moth larva - its journey began at the thin end of the trail, where the adult moth had laid her egg. The trail ends at the thick end where the larva emerged and crawled into a crevice to form a cocoon. The  adults emerge in the autumn.

Thursday, 12 February 2015

Crafty Cockatoo

A mug shot of the robber cockatoo
A few days ago I noticed that someone had seemed to have left the lids off the bins used to store the chicken food - we have chickens roaming free-range in our back yard. Then I saw the lids off again and thought there must be something else to the tale. So, I set up a camera-trap for security surveillance.

It wasn't long before the culprit was caught red-billed. It was a Sulphur-crested Cockatoo Cacatua galerita who was raiding the bins. These are regular, daily, visitors to the garden and they often roost with us up in a high gum tree. They are well-known to be clever birds, so I was not greatly surprised to see who the villain was, but I was surprised at how quickly it adapted to overcome my defences.

Watching from atop the chicken shed

The cocky found it too easy to flip off the lids themselves, even the clip-on lid of the larger bin, so I placed bricks on top of the lids. But, still too easy. The bird simply stepped onto an adjacent bin or tree stump to gain a firm base then used its strong bill to lever open the lids, casting the bricks aside with the lever action. To watch a two minute video of the crafty cocky click here.

The bird opened the large bin first, but as that only contained chicken pellets, it wasn't too happy. It had obviously been watching me feed the chickens and wild birds, noting that I was taking seeds, especially sunflower seeds out of the bins, but which one? It didn't take long to open them all and dive into the bottom of the white bins for the sunflower seeds.

It looked like there was only one bird that had learned how to open the bins as others came and tried, but with no luck. The trick was in stepping back and using the leverage. The clever bird reaped the reward first, facing off contenders before eventually allowing more to join in the feast as it became more satisfied.

There were seven or eight in the flock at one stage, until I heard the commotion and stomped down to the far end of the garden to chase them off.

And the solution - two bricks on each bin, with the bins far enough apart to deny any leverage.

Caught in the act

Thursday, 5 February 2015

Koel fledglings

A Koel fledgling is fed by its foster parent - a Red Wattlebird

It's now late summer in Canberra and there are lots of young birds about. So when I heard some loud begging calls from a young bird outside my study window I took a quick look around the back garden, and sure enough I found what I thought I would - a young Common Koel Eudynamys scolopacea. Or rather I found two, one a couple of weeks older than the other.

Common Koels are a species of cuckoo which migrate south to Australia to breed in the southern summer. Then in the autumn, they fly back north to south-east Asia, to the Indonesian archipelago or some other islands in that region. Their full migration and range is not fully understood. With a length of about 450 mm, they are a large cuckoo, the Common Cuckoo Cuculus canorus of Europe is about 330 mm, which is about the length of this bird's foster parent, a Red Wattlebird Anthochaera carunculata (350 mm). So it is a scale up from the European cuckoo.

The older fledgling was a well marked golden bird

The older fledgling had a wonderful golden plumage, with a bold black eyestripe and yellow crown. The younger bird was much less colourful, with a dull grey eyestripe and buff crown.

The younger fledgling - showing how pale its plumage was compared with that of the older bird

Both chicks were being fed by Red Wattlebirds, but I know that another pair of wattlebirds that feed in our garden have raised two broods of their own young this year. Were the Koel chicks both from eggs laid by the same female Koel? If so, the Koel female managed to dupe at least two out of three Wattlebird pairs in our local patch.

Other species used as hosts in south-east Australia that live in the Canberra area are Noisy Friarbirds Philemon corniculatus, although there are none of those around our garden this year; and Magpie Lark Gralina cyanoleuca, but the local pair do not seem to have been parasitised. Virginia Abernethy, who is studying Koels has never found either of these host species used in Canberra either. It seems that the Koels have local specialties in which host species they use.

The younger fledgling begs for food from its busy foster parent

And it received food - of course, what parent could deny such a plea

It was a great opportunity to compare the plumages of the two birds, one older than the other, not by much, but so different in colouring. The older bird was ready to go on with life on its own. It wouldn't be dependent on its foster parents for much longer. Although as I write this a day later, I can still hear both birds calling.

The older fledgling continued to beg too, with a deeper call, and it was fed less frequently

Young Koels often walk through the branches rather than fly

The adult Koels have gone quiet recently now that they stopped breeding for this year. And as they are migratory they will soon be flying north on their annual migration, closely followed by youngsters like these two. I wonder where they will fly to, all alone with no parents to guide them, but with an innate ability to find the species' tropical habitat.

This bird was fully fledged and probably well able to feed for itself - time to go - what a splendid tail