Thursday, 31 December 2015

Last Post for 2015

My last day out in the bush for 2015 has been a trip to Tidbinbilla Nature Reserve, in the Australian Capital Territory. It is only a half-hour drive from the city and is tucked into a valley of the local hill range, the Brindabellas. This was an easy day out in a parkland type setting, and the clouds were flying high over the ridges on a clear mid-summer day.

The reserve is a great place to see the local wildlife without trailing through miles of thick scrub. A casual walk around the laid paths takes you past pools where platypus swim, in full view all day. And they are on calm water, so easy to see as their wakes ripple the flat surface. They can be tricky to spot on rivers, where they can pass unseen in the tumbling water.

As the sun was out, and quite warm, the skinks were out catching the heat. A group of Cunningham's Skinks Egernia cunninghami were conspicuous as they lay on a rock right next to the path. The main group were scurrying about in cracks in the rocks, with only their heads protruding from the shadows. They had obviously warmed up enough as they were busy clambering about. But this younger one was out in the open, basking in the dappled sunshine. It was even lying with its eyes closed, as it was so used to people walking by. When alarmed, they dart into a crevice and curl their spiny tails across the entrance. Those are sharp-edge scales on the tail, and they present a formidable barrier to any predator.

There are also some good views or plants from the path-side, such as this Mountain Spiral Orchid Spiranthes alticola which was growing on close by a pond.

Simple single orchid stems can be difficult to spot in thick cover, so it was good to just stroll along a clear path and see all these animals and plants - not to mention the two red-bellied black snakes which were hunting and sunning themselves close by on the banks of the streams.

Summer fledglings

Fledgling, or juvenile Willie Wagtails Rhipidura leucophrys are readily identified as youngsters by the cream-not-white-like-the-adults stripe above the eyes and the buff tips to the wing coverts 

The summer is now warm, the grass is high and dried out, the cicadas are singing, and the late passerine fledglings are leaving their nests. Like these two Willie Wagtails I saw perched on a log the other day while out for a walk in the local bushland.

I heard and saw the adults first, attracted by their steady chirps and flitting tails. Then I saw the youngsters sitting quietly, low amongst a pile of dead branches.

The chicks kept still until their parents arrived with food for them. Then they sat up and began to call to be fed.

This pair of wagtails lost their first clutch of eggs to a predator away back in Spring. Then they failed at a second breeding attempt, I don't know why, but now they have successfully reared a brood of chicks - two is a typical brood size. That will likely be their last attempt for this year.

Tuesday, 22 December 2015

Green Parrots

A Norfolk Island Green Parrot Cyanoramphus cookii

An almost plain green bird with just a touch of red on its head and blue in its wings might not sound like a stunning beauty, but in the case of the Norfolk Island Green Parrot, this really is an effective colour combination. They are rather endearing.

These birds are not easy to find as they tend to sit quietly in the forest, calling infrequently and softly, which is a pity as their call is the best method of locating them. That was the cue a group of us from Canberra Ornithologists' Club focused on to count Green Parrots while on Norfolk Island recently. We concentrated on listening, then watching for them. The survey was organised by Neil Hermes in collaboration with the Norfolk Island National Park staff, maximising the resource of visiting people-power for a good cause.

These parrots are listed as endangered; their main habitat of native forest is a small area of 465 ha, their breeding is hampered by cats and rats which can catch and eat them or their eggs in their tree hollow nests, they have to compete with the introduced Crimson Rosella Platycercus elegans for nest holes, and the last estimated population, in 2013, was between 42-96 birds. So how many are there now?

A pair of Green Parrots feeding in the forest of Norfolk Island National Park

We set out soon after dawn and stationed ourselves at points along transect lines in the forest of the national park, gradually picking up the birds' calls. Over a few days we found a minimum of about forty birds, and we hadn't covered all the forest, nor included birds at other outlying sites where they were known to have been recently seen. Neil and the park staff will calculate the final count, and it seems that the total will be similar to or perhaps more than that found in the last survey.

The birds' call is certainly distinctive and a clue to their whereabouts, although at first we didn't appreciate just how close we had to be to hear them. Birds in flight were loud and easily spotted, but feeding birds only gave soft contact calls to one another and were not easily heard from more than 100 m away. They are so well concealed in the forest by their green plumage and slow movement that some birds were only seen when directly above or in the body of a bush only a few metres away. On the plus side, such is their confiding nature that once they were found, we were rewarded with fine views of the birds as they nibbled at their food.

A parrot feeds on the unripe berries of Wild Tobacco Soloanum mauritianum a widespread weed,
the berries of which are poisonous to humans, but not birds

The birds I saw feeding were eating a mixture of native and introduced plant species. I watched them delicately pick out fresh shoots from between the prickly leaves of the Norfolk Pine Araucaria heterophylla and pick off the flowers of the Norfolk Island Hibiscus. There are several introduced and naturalised species that they eat and I saw them feeding on Wild Tobacco fruits - they seemed to prefer the unripe green ones - and Willow-leaved Hakea Hakea salicifolia. How they open up those rock-hard fruit casings, I just do not know. Clearly, their diet preferences and abilities are very different from ours.

The parrots also eat the flowers of the Norfolk Island Hibiscus Lagunaria Patersonia
they strip off the petals, throw them aside and eat the ovules at the base of the flower

However, as most of the native forest has been cleared, the birds have lost much of their natural food source and have compensated their diet loss with cultivated fruits and seeds, such as peaches. The parrots were once plentiful across the whole island and neighbouring Phillip Island when the European settlers first arrived in 1788. Then, within 200 years, their numbers were reduced to only about fifteen pairs. The population would have been largely reduced by habitat loss, but many birds were killed over the years, some as agricultural pests.

A parrot eats a peach in a garden 

Times have changed and the island now has a positive attitude towards the parrots; methods have been developed to protect the breeding birds from rats and cats and their numbers have recovered from the low point in the 1980s. If only their habitat wasn't so restrictive, but that is a similar tale for all endangered island endemic species.

Damage to peaches caused by Green Parrots

Those were wonderful times spent with those plain green parrots, I hope to see more of them.

How does one value a rare parrot against a peach crop

Saturday, 19 December 2015

Phillip Island

Phillip Island lies on the horizon, with Nepean Island in the middle distance - viewed from Norfolk Island

Phillip Island lies in the wide waters of the South Pacific ocean, about 6 km south of Norfolk Island. It is only 190 ha in area, being 2 km wide at most and 280 m at its highest point. It is only accessible by boat via a few landing places, the best of which is at the back of a small sheltered rocky bay. So, the island is rather remote and difficult to access, but well worth the effort.

The main landing site - the boat must be guided into the rocky bay, passengers jump ashore onto the wet slabs,
 then climb up the cliffs. The latter is aided by a rope and wooden steps in places.

For various reasons; difficulty of access, water supply, ruggedness and remoteness, the island has never been permanently settled by man and is in contrast a haven for oceanic birds. However, many of the original breeding birds were drastically affected by the introduction of pigs, goats and rabbits at the turn of the eighteenth and nineteenth centuries. The pigs would have eaten whatever birds and their eggs they could access, including digging up petrels from their burrows. Pigs would also have eaten much of the vegetation while the goats would have accessed even remote rocky ledges for food. Eventually these two species died out, probably via starvation or lack of water. But the rabbits persisted until they were finally exterminated in 1988. By then, the island was virtually stripped of vegetation and even now, in 2015 there are still large patches of ground denuded and badly eroded into gullies by water and wind. It will take many more years for the whole island to become vegetated again. But it will, for the whole Norfolk Island archipelago is volcanic in origin and would have been devoid of vegetation at first. It will simply take time.

Soil erosion from around the roots of this ancient Phillip Island hibiscus tree Hibiscus insularis have left it very exposed
but it clings on to life

Although most of the top soil has gone from the island, petrels still manage to nest in natural rocky hollows or dig shallow burrows where they can, such as in the soft weathered basalt. Species breeding there now are Providence Petrel Pterodroma solandri, Kermedec P. neglecta, Black-winged Petrel and White-necked petrel P. cervicalis, along with Wedge-tailed Shearwater Puffinus pacificus and Little Shearwater P. assimilis. The island must have been covered by these birds nesting-burrows in the past, and just how many birds bred there?

It is perhaps good timing that the island is now rabbit free, as these birds either no longer breed on Norfolk Island or many that try are eaten by rats and cats. In thirty years, Phillip Island has changed from an ecological disaster area to a potential wildlife refuge. Several species have been driven to extinction on Norfolk Island, largely because of rats and cats, and others such as the Green Parrot might in future find sanctuary on Phillip Island. Although they would probably need to be introduced to do so.

The vegetation is becoming re-established, mainly in the beds of gullies and spreading out from there.
But there are still large areas with no topsoil and badly eroded bedrock

For the present, petrels seem to fill the air at times as they whiz past, and their presence gives an optimistic outlook for the island. The eradication of rabbits from the island has been a great success story.

Black-winged Petrels Pterodroma nigripennis sweep low over the island and are ever-present,
although, as they nest in burrows they are seldom seen on land during daylight hours 

The other obvious bird on the island is the Tasman Masked Booby, a bird endemic to the Norfolk Island Group, Lord Howe Island and Kermedec Island. These birds breed in a few scattered colonies across the island, placing their nests on the ground in amongst the bushes or on the edge of cliffs alike.

Tasman Masked Booby  Sula dactylatra tasmani - distinguished from other Masked Boobies by their dark brown, not yellow irides. The seeds stuck to his breast and under the tail show how plants can be transported between remote islands by birds and barren islands can become vegetated

The boobies usually lay two eggs, but only one chick fledges, the second egg seeming to act as a reserve in case the first doesn't hatch. Incubation takes over six weeks and then the chick takes seventeen weeks to fledge. The birds on Phillip Island in December had eggs, small chicks and chicks ready to fledge, so the whole breeding season must be rather protracted on the island.

A family group of Tasman Masked Boobies, the adult female is on the left - she has a duller bill than the male

These boobies eat mostly fish and flying fish are a major prey, along with squid. Many of the chicks had both parents in close attention, so it seems that there are abundant supplies of these foods in the birds' fishing grounds.

The chicks take 17 weeks to fledge - this one still has a few weeks to go 

The chicks are soon too large for the adults to cover and brood efficiently, so they have adapted a thick growth of down and as they grow older they seem to dwarf their parents which have slim slick plumage.

The younger chicks are covered with white down - and seeds stick to that readily 

Other sea birds nesting on the island include Sooty Tern Sterna fuscata, Common Noddy Anous stolidus, Black Noddy A. minutus  and Grey Ternlet Procelsterna albivitta, all adding their chatter to what is an annually increasing population of seabirds. And another seabird there is the Red-tailed Tropicbird.  These birds are so flamboyant when flying with their pearly white wings and red tail streamers. But, when nesting, they tuck themselves quietly into niches on the cliff tops. They stand, or rather sit, their ground tightly when approached. As we walk by, they simply give a straight-in-the-eye stare.

A Red-tailed Tropicbird Phaethon rubricauda sits on its nest
typically set in a small enclave at the top of a sea cliff behind some vegetation

Although, I'm sure they could give quite a sharp peck with those bills.

A Red-tailed Tropicbird's face

This is not a comprehensive account of Phillip Island, simply a flavour of my experience from one day there. And this is a record of only some of what I saw, there is so much more. I was there as part of a team organised by Neil Hermes on behalf of the Canberra Ornithologists's Club and The Norfolk Island National Park who set up a baseline survey of the birds on the island. For more information on the island follow this link and to organise a trip there follow this link.

And all the while the petrels continue to wheel around the island

Monday, 14 December 2015

Dragon Skin

A Bearded Dragon watches as it basks in the sun

Spring is now long past in Canberra and the summer sun is hotting up. The local Bearded Dragons Pogona barbata have now passed their breeding season, so they are now shedding their skins. This one was basking on the sunny side of an old tree stump.

Eyes just above the top of the stump - watching, ever watching

The dragon was lying flat against the stump, to gain maximum warmth from the heated surface. All the while it was positioned with its eyes just above the level of the top of the stump, for it was watching all the time for any potential predators approaching. I have often watched dragons basking like this, especially when on fence-posts - a favourite basking spot - and when seen from the far side of the post they form a distinctive profile, with their pointed head peaking above the post.

The head and  tail are mostly clean of old skin

It is tricky for the dragons, with all those spiny scales, to cast their skin. It tends to come off in small pieces rather than as a whole as snakes can do. Note how this one's head is mostly clean and other shed areas are the ends of the limbs and tail.

The hands and wrists are clean of old skin

I was almost upon this dragon when I first saw it, perhaps a few metres away, and as I considered how camouflaged it was, I wondered which skin was best suited for the purpose. The old pale skin faded well in the sunshine and would conceal the animal on dusty surfaces, but on the shiny old wood I think the new black skin was a better fit. The high shine of the highlights on the dark skin, especially on a scaly skin with numerous spines, all seemed to blend with the substrate of shiny wood and dark shadows of the crack lines

Basking in the sun can be dangerous - so camouflage is important as a defence from predators

Friday, 11 December 2015

Some birds of Norfolk Island

A Masked Booby Sula dactylatra tasmani flies past a Norfolk Pine

Last week I was out on Norfolk Island, which lies at 29 degrees south, about 1400 km east of the Australian mainland and 750 km from the northern tip of New Zealand. I was with other members of the Canberra Ornithologists' Group on a bird surveying trip organised by Neil Hermes. The main surveys were of the endemic and endangered Norfolk Island Green Parrot Cyanoramphus cookii, and all birds on the adjacent Phillip Island which is slowly becoming re-vegetated following extensive denuding by pigs, goats and rabbits in the past. There are none of these on the island now, since the eradication of rabbits in the 1980s. I will post more on these topics later, this page is simply an introduction to the island's wildlife, and I'll post a page on the history of the island on ByMyEy.

The view south from Mount Pitt, with  Norfolk Pines Araucaria heterophylla in the foreground
and Nepean and Phillip Islands in the distance.

The highest point on the island is Mt Bates at 319 m and the area is 35 sq km. Most of the island is worked by small holdings growing fruit, vegetables and cattle, milk and beef, and the main income is currently tourism, serviced by flights into the airport which dominates the centre of the island. The island was once covered by rain forest dominated by tall stands of Norfolk Pines and Norfolk Island Palms Rhopalostylis baueri the best examples of which now grow in the National Park, centred around Mt Bates

A male Pacific Robin Petroica multicolor multicolor - the most colourful of the forest birds

The endemic forest birds are largely restricted to the remnant stands of the forest, while numerous introduced species populate the town, gardens and farmland and are much more obvious. House Sparrow, Starling, Greenfinch and Rock Dove are limited to these areas, but Eurasian Blackbirds, Song Thrush and the Australian Crimson Rosella are all common there and in the forest. There is even a population of feral Jungle Fowl, descendants of escaped or released domestic chickens. The various combinations of bird species that occur on different islands worldwide is fascinating, but can be threatening to their endemics, especially on small islands such as Norfolk which has already lost seven, probably now eight species.

A Grey Fantail Rhipidura albiscapa pelzelni - one of the seven forest birds unique to the island

The other main natural habitats on the island are the coastal cliffs and shores. The cliffs gird most of the coast and there are plenty of good vantage points to watch the seabirds as they glide along on the wind. There are a boulder beaches at the base of some cliffs, but they are poor for birdlife. However, the small coral reef and sandy beaches at Kingston attract migrant waders such as Ruddy Turnstone, Pacific Golden Plover and Whimbrel.

Two Sooty Terns Sterna fuscata fly overhead - mostly seen around the coasts but they fly over any part of the island at times

The whole island ecology is driven by the rich volcanic rock and the derivative soils, much of which have been enriched by the leaf litter from the forest as it developed, and by the guano of the seabirds as they brought in nutrients from the sea. All sprinkled with a splash of water carried by the winds. So, to me there was no surprise that the most vibrant birdlife was in the forests and on the sea-cliffs. One set was secluded in shade, the other basked in blue skies.

A Red-tailed Tropicbird Phaethon rubricauda a common sight along the sea cliff tops.

Friday, 27 November 2015

Millions of butterflies

A Caper White Belenois java butterfly passes through the garden

For the past week there have been white butterflies passing through our garden in Canberra, lots and lots and lots of them. They are on migration moving across southern New South Wales, heading in a broadly easterly direction. The species is Caper White and during the peak number day - last Tuesday, the 17th - I counted an average of seven per minute pass through a hundred metre long corridor between our garden and those of our neighbours, which are aligned north-south. They were flying through all day, so I reckon that there were 420 passing through per hour, which would make a few thousand during one day. The main front seemed to go through that day, but there are still a few stragglers about, some of which might be stopping locally, others are still moving east.

Almost all the butterflies were males, I maybe saw two or three that looked like they might have been female,
but they never stopped so I could not be certain. Where are the females?

There were reports of them from a wide area around Canberra, so I wonder how many were in the flock? I saw similar numbers flying in the same easterly direction as I was walking and driving around the area, so the density was possibly at the same scale over a much wider area. If so, there would have been 4200 per hour crossing a one kilometre line. The plains area of the Australian Capital Territory is about 25 km wide from north-south which could have seen about 100,000 butterflies move  through (I don't know if they passed over the forests and ridges, but if so that would bring the ACT width to approximately 90 km and approximately 400,000 of them).

A stop to re-fuel

So, if they were flying for about 10 hours that day at the same density (which they seemed to do near me) there would have been approximately a million passing through the ACT in that one day. Even if these figures are wrong, there were numerous butterflies on passage for a few days, so overall there would likely have been more than a million altogether, possibly many more. And the butterflies were flying across a wider area, hundreds of kilometres wide across neighbouring parts of New South Wales, so how many million were there on migration. Where did they come from and where did they go. I know many were seen down at the coast about 200 km to the east, and many must have stopped there, but why were they moving from west to east. My friend and local butterfly recorder, Suzi Bond will, I hope, come up with the answers. She dropped me an email about half an hour after I first noticed the unusual number in the garden. She had seen them too.

How many flowers were pollinated by so many butterflies?

This sighting reminded me of a similar butterfly day I had a few years ago while driving from West Wyalong to Canberra. That was through farming country, mostly wheat and canola oil. There was what seemed to be a miriad of Cabbage White Pieris rapae butterflies along the road verges. So I counted, well estimated, how many there were per kilometre of road and for how far along the road. It was a three hour drive and there were clouds of them for most of the way. There were x between the road and the field fences per one kilometre strip and I traveled y kilometres with them at similar densities (I forget the exact detail of the count, but I do remember the total as it was so mind-boggling). I saw at least 2,000,000 Cabbage White butterflies in one day. And there were many, many more farther into the fields, there were flickers of white all over the landscape, dotting the canola crop especially. Those butterflies weren't migrating though, there just seemed to have been an enormous synchronised emergence.

Two true wildlife spectacles, played out by common garden insects. Wonderful.

A male with ragged wing edges - how far had he flown?

Friday, 20 November 2015

A living twig

A caterpillar - or a twig
lies on a mix of fallen bark, leaves and branches
While walking through the bush a few days ago, a few kilometers from the centre of Canberra, I found this caterpillar hiding amongst some cast bark at the base of a gum tree - a Scribbly Gum. The caterpillar's camouflage was superb, and it wasn't moving, which would have given it away. But my eye was scouring the leaf and bark litter for spiders, especially peacock spiders which are magnificent if not rather tiny and very tricky to spot. But more of them in a later blog, for now follow this link to read more on them: PeacockSpider

The caterpillar is the one on the right, no the left...
The caterpillar was perched on a fallen branch lying beside fallen bark and twists of twigs which it looked just like. I think it was the distinctive caterpillar shape of a long body, hunched up and ending with two pairs of feet at the rear that attracted my eye. Then once I focused on it, of course it was obvious, yeah that would be right.

I thought it would be a moth caterpillar, and probably of the Geometridae family, and it was. It is a Fallen Bark Looper moth caterpillar Gastrophora henricaria, and it is widespread across south-east Australia. The caterpillars eat gum leaves, up in the canopy during the night, then hide in the ground litter during the day, so that all fits with what I found.

Caterpillars have six true legs as in their adult morph - and they have ten prolegs. The true legs are positioned on the thorax, as in the adults, tight behind the head. The prolegs are spread down the rest of the body and in the Geometridae  three pairs have been atrophied, leaving just two pairs close to the rear. This gap in their leg layout causes them to walk with a looping action, hence the name looper.

A looping motion as it walks and two pairs of prolegs at the very rear - a looper caterpillar
There are quite a few gum trees in the forest I was in, it is several kilometers square, so I wonder how many Fallen Bark Looper moths and their caterpillars there were in the forest - thousands, many thousands - and I only saw one. So, yes they are very well camouflaged animals indeed.

Thursday, 5 November 2015

Nest re-cycling

The male Tawny Frogmouth Podargus strigoides sits on the edge of the chough nest

Tawny frogmouths usually build their own nest, a simple platform of twigs and sprigs of greenery, although about one in forty nest records from my study of these birds in Canberra have been in old White-winged Chough Corcorax melanorhamphos nests. These are large, clay nests, which resemble bronze-age beakers set half-way along horizontal branches. In this case about fifteen metres up a Scribbly Gum tree. Frogmouth nests are often flimsy constructions, so perhaps they find these old firm structures as good bases for their nest. They add a few sprigs inside the cup, but don't fill it.

The female sits with the chicks - she has more red on her wings than the male

I have been monitoring the incubation, brooding and feeding rates of frogmouths over the years, studying differences in habitat and weather conditions. Some of this can be done by watching, but it is at times easier and less time-consuming to do this remotely with wildlife-monitoring cameras. So, with the help of Laura Rayner, who did the climbing to this nest, we set this one up, which was about fifteen metres up a gum tree. Once the camera was set and tested, we left the birds for the night and collected the camera the next night. I only approach these birds at night as I do not like to disturb them during the day when they can be vulnerable to predation. They behave so confidently at night, and these birds were feeding their chicks as we were setting up the camera a few metres away.

The chicks, at about two and a half weeks old, were beginning to fill the egg-cup nest

In this case, the adults fed the chicks seventy times overnight, so that was perhaps thirty-five feeds per chick, if they received equal shares. I don't know as I can't identify each chick in all the shots. About half the feeds were in the first two hours after dark, then the feeding rate decreased as the night progressed. And each adult only brooded the chicks for one period of about ten minutes, most of the time the chicks were alone in the nest.

Then as dawn approached the male came in to cover the chicks for the whole of the next day, for it is the male who guards the chicks all day, while the female roosts in a nearby tree. To watch some footage from the camera click here.

A chick peers over the lip of the clay nest