Skip to content

A hard head?

September 30, 2019
tags:
by

Hardhead female with grebe

An elegant female Hardhead has taken up residence on our dam this month – the first sighting here since 2013. She can often be seen gliding serenely around the dam in the company of other waterbirds, such as the Australasian Grebe and Pacific Black Duck shown here.

Hardhead female with black duck


The Hardhead is the only Australian representative of the true diving ducks or pochards. It’s an efficient swimmer and swift flyer, but a clumsy walker. It likes deep water, usually keeping well away from shore. Being a diver, it can reach food inaccessible to other ducks – its diet can include aquatic insects, crustaceans and submerged vegetation.

Hardhead male


The male Hardhead has a conspicuous white eye (see photo below), which gave rise to its previous name, White-eyed Duck. The “Hardhead” monicker was apparently given to it by shooters who considered it hard to kill due to its dense plumage and reputed stamina (from Australian Bird Names, Fraser & Gray).

It is still a permitted game species in the annual Victorian duck season, despite its conservation status in Victoria being listed as “Vulnerable”, meaning it is considered to be facing a high risk of extinction in the wild.

As they say, go figure!

Just like the Serengeti

September 27, 2019

At our house we run a 2-bay (single turn) hot composting system to convert garden waste and food scraps into soil. When one bay is full the contents are transferred into the second bay (that’s the single turn bit) and then the original bay is filled again. Last weekend was the day of the transfer and in doing so we unearthed a range of fauna that had called the compost heap home for the past year or so.

One of the most distinctive was a Slater-eating Spider (Dysdera crocata), pictured left, identifiable by its red cephalothorax and cream coloured abdomen. For its size this spider has very large fangs. This allows it to feed on most underground invertebrates including slaters, beetles, crickets and even centipedes. They are night-time hunters and spend most of the day in a silk ‘room’ which they construct in an underground crevice in leaf litter or under rocks or wood.

If you get close enough you’ll notice the spider has 3 pairs of eyes set close together. But don’t get too close – a bite will cause minor inflammation but can result in headaches and nausea. The other name for this spider is the European Garden Spider, indicative of its Mediterranean origin. Due to its aversion to ants, its distribution in Australia is limited to the south east of the continent.

As an aside, when I was a kid seeing African scenes of lions and their prey – zebra, antelopes, etc, living in very close proximity, seemingly ignoring each other, I wondered how could that be? The picture above right shows something similar, Slater-eating Spiders and slaters roaming about together. Just like the Serengeti but in microcosm.

Frog chorus

September 24, 2019

The frogs are in full voice around our dam and adjoining wetland at present, as you can hear by clicking on the audio below. It makes for a loud but strangely soothing soundscape.

Pobblebonk or Eastern Banjo Frog

Over the past week the Pobblebonk (or Eastern Banjo Frog), Limnodynastes dumerilii (left), has been the dominant caller, at least to our ears, but the Spotted Marsh Frog, Limnodynastes tasmaniensis, Eastern Common Froglet, Crinia insignifera, and Plains Froglet (or Eastern Sign-bearing Froglet), Crinia parinsignifera, have all been competing for air-time.

It’s only the male frogs that call, in order to attract females (and out-compete other males). Many of the male Pobblebonks have obviously done their job, judging by the many rafts of white frothy egg masses (spawn) that have appeared among sedges and rushes around the edge of the dam. Some of these spawn have tiny tadpoles appearing already (see below). The floating frothy spawn is typical of the marsh frogs, genus Limnodynastes. Crinia froglets in contrast lay individual eggs attached to stems of submerged vegetation, or on the substrate of a water body. For the tadpole to frog story see previous posts titled Metamorphosis.

The make-up of the frog soundscape varies from day to day, and even throughout the day. Perhaps they need a break every now and then from that hectic attention-seeking!

She who must be obeyed

September 20, 2019

This morning I was watching a Common Blackbird (Turdus merula) skip across the back lawn wondering where the neighbour’s cat was when you really needed it when WHAM, within a split-second the aforementioned Blackbird was skewered to the ground by a Collared Sparrowhawk (Accipiter cirrocephalus), see photo below. Man, it happened quickly.

The scientific name for this species is derived from the Latin words accipere meaning ‘to seize or to capture’,  kirros  meaning ‘orange-tawny’ and kephale meaning ‘head‘. Collared Sparrowhawks normally hunt in flight or by diving on prey from low, concealed perches using speed and surprise as an advantage. Small birds make up most of the diet, which can also include birds up to the size of domestic chooks. Our chooks often act as if the Sparrowhawk is around by all of a sudden scurrying with much squawking under the nearest bush and then spending the rest of the day looking skywards. Sparrowhawks  also feed on insects, lizards and small mammals including bats. The kill is taken and eaten on a nearby perch.

As for the Blackbird, if it wasn’t dead already the stare (pictured right) would be enough to stop it in its tracks. Not as deadly as the stare from ‘She who must be obeyed’ but terrifying enough.

vorare, Gk meaning ‘to devour’

September 13, 2019

Many words in the English language are derived from Ancient Greek. One of those is vorare  meaning to devour. You find it in words such as carnivore (carnis being Greek for flesh) used to describe meat eaters or omnivores (omnis being Greek for all) to describe something that eats everything. This blog post is about sporivores, creatures that eat spores.

The autumn rains have triggered the annual explosion of fungi across the landscape. Mushrooms are the fruiting body of the fungus (the same as a pear is the fruiting body of a pear tree). When the mushroom ripens it opens and releases millions of spores. These spores drop on the ground or get dispersed by the wind so the fungus can propagate. Feeding on these spores are sporivores. Knowing how big spores are (not very), these creatures are none-too-big themselves (see photo below).

Springtails (previously featured, click HERE) are small six-legged non-insects. They feed primarily on spores and hypha, the branch-like filament structure of a fungus. Some are sporivores and others are omnivorous, also feeding on animal remains and plant material. A close look at the underneath of mushrooms at the moment will reveal springtails of different colours.

Other creatures disperse spores by consuming mushrooms (fungivores) and by default consume the spores as well. These include mites, millipedes, some species of beetles and fly larvae. And finally the creatures that predate on creatures that eat spores, for example centipedes, are also known to carry viable spores which they eliminate in their faeces.

What goes in must come out…eventually.

Leaf-eaters

September 7, 2019

Young Yellow Box tree

While inspecting with dismay the considerable damage done by deer (Sambar and Fallow Deer) to revegetation plantings at the back of our place (bark stripped, defoliation and broken branches, even on well-established plants), we came across a young Yellow Box, Eucalyptus melliodora (see photo at left), with extensive damage of a different sort. Most of its leaves were severely skeletonised in patches, and in some cases eaten right through. A quick inspection of the foliage revealed many interesting-looking sacs hanging from branchlets in the tree (photo below). These we assumed were associated wih the leaf damage, and later discovered that they belong to the Ribbed Case Moth, Hyalarcta nigrescens.

Actually most of the sacs seemed to be old and inactive – one we dissected had only a dry pupa case inside, the moth having flown the coop. On closer inspection of the leaves, we noticed there were numerous much smaller cases (less than 1cm long), and these contained tiny dark larvae actively chewing and moving around, which were clearly responsible for much of the leaf damage.

The wingless female Ribbed Case Moths remain in the case for life, and lay their eggs in there. Hatched male larvae (caterpillars) leave the case and feed on the surface of eucalyptus leaves. They construct silken cases which they enlarge as they grow. Eventually they pupate and leave the case as a small hairy moth with transparent wings, as can be seen on the BowerBird website.

Larval case

Ribbed Case Moth caterpillar


The cases are built of tough silk and are incredibly strong. Unlike those of many other members of the Psychidae (case moth) family, they are not reinforced/decorated with leaves or sticks, apart from a few bits and pieces when small.
 
This young Yellow Box will no doubt survive and soon put on a new flush of growth, unlike some of the deer-damaged plants, unfortunately!

Fauna beware

August 28, 2019

Day of the Triffids by John Wyndam was one of the first books I ever borrowed from a library, and it probably had a lot to do with my following science as a career. The story describes a world where humankind, blinded after watching a spectacular meteorite shower, is at the mercy of carnivorous plants (called Triffids) which roam the country-side killing all and sundry. Even to this day, whenever I observe a shooting star I do it with one eye closed … just in case.

Some triffid-like carnivorous plants showing signs of life at the moment are plants of the genus Droseraceae (from the Greek word drosos meaning dewdrops), the Sundew plants. Though not as sexy as the well-known Flytraps, which catch their prey by snapping shut their leaves, the way in which sundews capture their food is equally interesting.

Sugar Ant trapped in Scented Sundew leaves

Each leaf of the sundew sprouts a number of tentacles that exude sweet liquid, which attracts insects (see photo above). When the insects touch this sticky liquid they become trapped and eventually die either of exhaustion in trying to escape, or asphyxiation as the sticky goo covers them. Enzymes are then released to dissolve the insects and the plant absorbs the nutrients. The picture (right) shows a mosquito trapped in the sticky tentacles. The black debris seen on the leaves are the remains of digested insects.

Scented Sundew

The commonest species of sundews in our area are the Scented Sundew (Drosera aberrans) and the Tall Sundew (Drosera peltata). In Scented Sundews, which are flowering now (pictured left), the leaves lie along the ground. In Tall Sundews these leaves are on stems (pictured below), making them look much more sinister and triffid-like. It has pale pink flowers in early summer.

Tall Sundew

These sundews won’t dissolve your leg, should you stand on one, unless you’re a mosquito. The Tall Sundews stand about 50 mm high so kangaroos and possums are safe from entrapment. But knowing evolution, it’s just a matter of time.