Sunday, 7 February 2016

A spider jewel

A female jewel spider Austracantha minax
It's late summer, spider time.

I have been busy at the desk for most of January, hence the shortage of recent posts, but that is all part of my seasonal behaviour. When the sun is out at this time of year in Canberra, it is not much fun walking about in the hot bush, so I use the time to catch up on writing and editing photographs. Meanwhile, as the summer has progressed, the spiders have been more active and I found this little beauty spinning her web this morning, before it was too hot - for me that is not her.

She is a Jewel Spider, otherwise known as a Christmas spider as they are abundant from then on, or another name is spiny spider. I like that last name as it is so apt. They have six spines set around the hind edge of their abdomen. And the jewel name is apt too, as their glossy bodies catch the light, with all those little pin-spots of colour on the abdomen. Most of those are white on the dorsal, top, side and yellowish orange on the ventral, belly side. This spider is hanging upside down as she was walking along her silk threads, and as she has such a heavy abdomen, she was belly up.

They are only about 7-8 mm long and the abdomen is so large in proportion to the rest of her body that the cephalothorax can barely be made out in these photographs. Her legs are also quite long, and in the top image, the two hairy black pedipalps can just be made out at the front, between the legs. This spider was busy spinning a new web, a circular orb-type, suspended between some grasses about a metre tall. It was nice to see a bit of colour, in the dusty sunshine.

Wednesday, 20 January 2016

Hot summer

A female Cabbage White Pieris rapae feeds on a dandelion flower

It's January, mid-summer in Canberra, and it's hot. So, I have been a little quiet recently, keeping cool and getting back into working at the desk. I try to take short sorties into the local bush, but most days I'm happy to sit on the veranda and watch the birds come and go in the garden. Then, while sitting there I counted six species of butterfly flitting between the plants, searching for food plants for themselves or to lay eggs on. So, I thought I might grab a few quick shots. No, the sunshine is so hot that the butterflies are all flying almost non-stop and at speed. They are not easy targets.

A female Common Grass Blue Zizina labradus feeds on a clover flower

The male cabbage whites were chasing one another through and over the bushes, then I spotted a female feeding on the dandelions on the lawn. One down. Next the blues, but they are so tiny and they really chase one another, fast and in unpredictable twisty flight. Fortunately this seems to take its toll on the males as they stopped every now and then to sun up and re-charge. No chance of close approach though, a long lens shot only. Similarly for the one female I saw and captured as she supped from the clover.

A male Common Grass Blue takes a short break to bask in the sun

The butterflies are certainly pretty to see, from our perspective, but the most stunning lepidorteran in the garden at the moment is a great big caterpillar, a Batwing Moth caterpillar. This one has grown to over 10 cm and the adult when it emerges has a wingspan well over that. They will emerge from their cocoons at the end of the summer, early autumn.

Batwing or White Stemmed Gum Moth Chelepteryx collesi.. Every spine hurts if it sticks into a predators skin

It is a few years since I saw one of these in the garden, which is good and bad news. Good for me as these insect larvae are protected by a mass of spines which break off into our skin if touched. And they are very irritating when they do, as they are very difficult to see and remove. A bit like pieces of very fine glass. But, then bad for the caterpillars as their main food plant in the garden, the tall red gums have been rather sickly in recent years, due to dry weather and an infestation of lerps (Google that, they are a fascinating life form and a rich source of food for birds).

Six true legs stretch forward, searching for a hold

These caterpillars have such dense spines/hairs around their thorax and head that it is difficult to discern exactly where the head is. It is a tiny section set low, beginning somewhere just in front of the legs. The best clue is their tiny black eyes which catch in the sunshine. But their mouth-parts are so swarmed by hairs, not much else can be made out. Then, of course, like so many caterpillars it is tricky to tell which end is which, as the tail resembles the head, or is it the head that resembles the tail...

A tiny beady eye looks out from beneath all those hairs

This one was not on a gum tree, but wandering across some old cut branches. I reckon that it had fed enough for that stage of its life and it was looking for a place to tuck into while it metamorphoses into an adult moth. Their cocoons are also prickly as they push those spines out thorough the casing. That is a very annoying habit for anyone like me you tends to climb trees. The cocoons are well camouflaged and too easily laid hands upon. Ouch.

So, til autumn....

Now which end was which again?

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