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

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

Night watch

An adult female Tawny Frogmouth perched beside her two chicks

Now that the last summer moon is waxing to almost a quarter, it is possible to go out at night and watch the local wildlife without the aid of torchlight. I don't use spotlamps to watch animals as they ruin our night vision, and probably wreck their eyesight too. All we can see is whatever is within the light-zone, outwith that, all is black, darker than if not using a light at all. It is much better to go out at dusk and gradually let your eyes become accustomed to the dark. Anything more than a quarter moon is enough to see under and when there is a full or nearly-full moon I even use binoculars as there is enough light.

The adult delivers a grasshopper to one of the chicks

So, over the past few evenings I have been out watching a family of Tawny Frogmouths with two recently fledged chicks. These youngsters will still be dependent on their parents for about a month after leaving the nest. Frogmouth families typically all roost together during the day, then at dusk the fledglings flit to an open branch, and the adults soon begin bringing food to them. The birds leave their roost about half an hour before full darkness and it is in that first half-hour they are most active. These two adults delivered about ten items per hour for the first hour, mostly within the first half-hour. In the following hour there were no feeds and the two chicks went quiet, snuggled up together and seemed to go to sleep. Not too surprising as the prey items were mostly large grasshoppers which would have probably been more than enough to satisfy the chicks' appetites.

I last saw the adults fly off, presumably to find food for themselves before they would come back and gave the chicks more food. I have used camera traps before to monitor their food delivery times throughout the night and the pattern seems to be; they will bring occasional items during the rest of the night then a few in quick succession as dawn approaches. As with most nocturnal animals, they are more active around dusk and dawn, so those are the best times to watch for them.

At night, Tawny Frogmouths seem to become different birds from the shy ones we see by day. They are so confident under darkness and they do not seem to fear humans. Not only do they allow close approach, but I have had birds fly down to catch insects at my feet (probably stirred up by me) then carry them off to their chicks sitting on a branch a few metres away. Those are the special wildlife moments which we keep in our minds forever.

The two fledglings snuggled up together, head to tail.

Last chicks fledged

A family of Tawny Frogmouths sitting quietly in a tree. As they are nocturnal, they roost by day, relying on their cryptic plumage and minimal movement for concealment from potential predators such as Brown Goshawks. 

The last broods of Tawny Frogmouth Podargus strigoides chicks have finally fledged almost three months after the first broods to do so on 25th October 2014. These final broods fledged on the 16th and 17th January; a brood of one and the other of two, both were from relaid clutches after the adults had lost their first clutches. The pair who finally reared the single chick lost two previous clutches in separate nests to predators unknown (likely Brush-tailed Possum Trichosurus vulpecula). They built a new nest in another tree after each time the eggs were taken, while the pair who reared the twins lost their first brood of chicks after they had left the nest too early. That was possibly after the nesting birds were attacked by a predator, but as these birds are not under constant monitoring, and there was no evidence, we'll never know. They re-used the same nest for their second clutch.

The adult female is on the far left (she has reddish markings on her wings), then the male and two still partially fluffy chicks. Frogmouths usually adopt a 'stick pose' if a potential predator approaches such as a human, but these birds have seen me so often, they know me and here have only partially adopted that pose.

Now that the final results are in I have calculated the breeding success of the sample of Tawny Frogmouth pairs that I study here in Canberra, Australia. I monitored 48 territories this year, similar to most recent years, and most successful pairs (23) reared two chicks, 7 reared three, 8 reared one, another 8 reared none and there were 2 single birds; one male and one female - pity they never met up.

This chick, like so many young fledgling frogmouths, has yet to learn to adopt a protective pose like its parent, in this case mum. Her plumage colouring and posture conceal her well, but I have seen better (see some older posts).

The figure of 17% of pairs not rearing any chicks might seem a high failure rate, but I have recorded almost twice that one year. Overall the breeding success of the population (and that is what matters as all animals must eat to live, including predators) was above average with 1.6 chicks fledged per pair (avg. 1.4), or 1.9 per successful pair (avg. 1.8).

The adults close their eyes and watch one's approach through narrow slitted eyelids. That conceals their bright yellow irides which would betray their camouflage. This chick however, just cannot resist peeping around the branch to watch me with partially open eyes. It will soon learn how to behave safely.

So that ends my study season of Tawny Frogmouths for 2014. It seems a long time since the birds first began building their nests in late July, and it won't be long before July comes around again. For further details of the frogmouths over the season and in previous years click on the links to the right of the page.

What wonderful days and nights I have had with them - great birds.

The male was perched in an adjacent tree, unobtrusive and inconspicuous.

Lesser Wanderer

A Lesser Wanderer basks in the sun while perched on a low twig. 

I was out at The Charcoal Tank Nature Reserve beside West Wyalong, New South Wales, over the weekend (on a bird-banding trip) and there were several of these Lesser Wanderer Danaus chrysippus butterflies flitting about. They all flew low over the ground, landing on the tips of sedges and shrubs in open glades to bask in the sun.

This was a male - the lower wing spots are large and main one has a white centre.
The upper wing spots are also large (previous image).

The species is common and widespread over most of Australia, but not so common in the south-east, so these were just about on the edge of their main range. As they are migratory, perhaps these specimens were pushing south in the height of summer. Or they could have been the offspring of butterflies that had flown south earlier in the year, as the females can lay several sets of eggs per annum.

The head and thorax have a marvelous chequered pattern

As I stalked ever closer and closer to them I gradually realised how boldly the head and  thorax are marked. The black and white pattern is stunning, and out of our usual human scale of perception..

There was a light wind, so the butterflies had to constantly flip their wings wide open,
over-extending them to compensate for the tricky sun-basking conditions