Damsels and dragons

No, this is not a story of days of old – sorry. It’s about two groups of insects which had a wonderful time in our recent big Wet: damselflies and dragonflies. I saw far more this year than ever before, and an online friend from Exmouth, WA, says the same.

Damselfly on grevillea
Aurora Bluetail, Ischnura aurora, a colourful little damselfly, on grevillea foliage.

Damsels are (appropriately enough) generally smaller and more delicate than dragons but both families are aerial predators, hunting on the wing. The easiest way to tell them apart is that damsels fold their wings over their abdomens when resting, whereas dragons hold them outstretched or forwards and downwards. The two groups, Zygoptera and Anisoptera respectively, make up the order Odonata. There are some 320 species in Australia, mostly in the north.

They are an ancient order – every prehistoric-nature doco seems to mention the enormous dragonflies of the late Paleozoic, 300 million years ago, when greater oxygen content in the air allowed them to reach wingspans of 70 cm.

Adults lay eggs in fresh water, where the larvae (also carnivorous) develop through several moults before crawling up into the air to split open, much as cicadas do, to emerge as adults. Adults can roam far from water but must return to breed and the abundance of dragonflies is a good indicator of a healthy ecosystem. Their mating behaviour is complex and quite strange. Read about it here if you don’t want to wait until I can find time to write about it.

Dragons and damsels have no economic significance to us but are universally loved for their beauty and agility in the air.

More about damsels and dragons

This article first appeared in a slightly different form in Kapok, newsletter of Coastal Dry Tropics Landcare, Inc., in March 2011.

Billabong: reptiles

Still at Billabong Sanctuary

Girls with snakes around their shoulders
Relaxed attitude: Woma (left) and Boa

There is a sequence of talks and shows through the day – birds, koalas, (small) reptiles, dingos and so on, culminating in the largest reptiles. The snakes and lizards show was entertaining, as well as informative, partly because of the visitors’ responses.

‘Does anyone want to put this Woma around their neck?’ Response: trepidation.

‘What about this Boa Constrictor?’ Response: consternation.

But the relaxed attitude of the staff holding the snakes did reassure the visitors, and quite a few were confident enough to step forward.

Visitors were not, however, invited to step forward and handle the snappy logs. The crocodiles were quite lethargic because of the cool weather but still not to be taken lightly. Both of our Australian species were presented:

  • The Freshwater Crocodile (Crocodylus johnstoni) can grow to about 3 m in length but are usually 1.5 – 2 m. They are primarily fish-eaters, though they will also take insects, amphibians and small mammals; they are unaggressive and are considered harmless to people.
  • The Saltwater Crocodile (Crocodylus porosus) is quite a different proposition. The world’s largest living reptile, it can grow to at least 7 m and 1300 kg, and large individuals can tackle prey up to the size of a water buffalo. There are very few fatal attacks on people but staying well away from them is strongly recommended!

The first of these two pictures shows one of the Sanctuary’s larger salties; the second shows a considerably smaller animal.

Saltwater Croc - frontal view
Saltie
Ranger feeding a Saltwater croc
Do not try this at home!

More on crocs: Wikipedia has good articles on both salties and freshies.

Billabong: waterbirds

Magpie Geese and Plumed Whistling Ducks
Magpie Geese and Plumed Whistling Ducks

Getting back to the abundant bird life at Billabong Sanctuary …
Whistling Ducks were everywhere, by twos and threes and tens, sometimes foraging alongside the Magpie Geese as in the photo on the left. The Magpie Geese were, I think, the largest birds there. The two pictured are not quite adults – they will soon lose the brown tinge to become pure white and black.

The beautiful Glossy Ibis (Plegadis falcinellus), quite a bit smaller than the common White Ibis, were new to me, but I have known Moorhens since I was a child in Victoria. Billabong also claims to host one of its close relatives, the Purple Swamphen, but we didn’t notice any during our visit.

The third of the pictures below shows a Heron, characteristically perched on a branch overhanging the water and surveying it for prey. It is grey and it is a heron but it isn’t a Grey Heron (Ardea cinerea): it’s a Pied Heron (Ardea picata). We also saw pure white Egrets, although I didn’t get any photos worth sharing.

Glossy Ibis, knee-deep in the lagoon
Glossy Ibis, knee-deep in the lagoon
Moorhen swimming amongst reeds
Dusky Moorhen swimming amongst reeds
Dark grey Heron perched on a branch overlooking the lagoon
Pied Heron overlooking the lagoon

 

 

 

 

 

 

That only leaves my puzzle picture, doesn’t it?

Congratulations to anyone who recognised the feathered football as a sleeping Magpie Goose. If you are still having trouble seeing that it really is a natural posture, this shot of a pair I had seen earlier may help:

Two sleeping Magpie Geese
Two sleeping Magpie Geese

Billabong Sanctuary

Waterbirds on the edge of the lagoon at Billabong Sanctuary
Waterbirds on an island in the lagoon

One of the nice things about having an out-of-town guest is having an excuse to revisit local attractions. Billabong Sanctuary is one I hadn’t been to for years, until yesterday. It concentrates on Australian, especially northern, wildlife, and the fact that it is centred on a large lagoon makes waterbirds a constant presence even if the large reptiles – you know, the snappy logs (and if you don’t know, you will have to wait) – are the main attraction to most visitors.

The photo above gives a hint of their numbers. Most of the bigger birds in it are the familiar White Ibis and the smaller ones are mainly Whistling Ducks, but I am sure there are other species amongst them. I saw so many different birds in our half-day at the Sanctuary that I will put them in another post, but I will leave you, for now, with the one that made me laugh:

Looks like a black and white feathered football
– ? –

 

 

 

Going Solar: David

There has been a lot of talk about domestic solar power systems in the last year or so but most of it seems to be coming from governments, suppliers and others who may have vested interests, so it’s understandable that we listen to it with a degree of scepticism.

I thought a real-life example or two may help to sort out the truth from the hype.   Sometime soon I’ll post my own story, of the installation on our own older high-set house in Mundingburra. Meanwhile, here are the experiences of David and Kate, a young professional couple living in a small modern house in the new suburb of Douglas. In David’s words (and with my thanks to him for allowing me to quote him):

Our 1.52 kW solar power system was installed by a specialist PV company in March 2011 and the entire process has been extremely smooth. The installation was performed amazingly quickly, with about six staff working together to place the panels on the roof, provide conduit from the panels to the solar inverter through our roof, and rewire our switchboard. The whole process took only a few hours to have everything in place and signed off.

After the installation, on an average sunny day, we would see generation of at least 7 kWh, even reaching 8.5 kWh on our best day. Through this, we were seeing our power usage at home more than negated, with our meter steadily going backwards. That said, we’re not a typical situation since we only have two of us at in the house, we work 9 to 5 on weekdays, have a two-storey, north-facing house with a perfectly angled roof and no trees nearby, and are extremely power efficient around the home with LED halogen-replacement lights and gas appliances in use.

After the installation, we applied to Ergon Energy for a new electricity meter so we could get the bonus feed-in tariff. Unfortunately, this process took nearly two months of waiting – but given the recent cyclone and number of people purchasing solar panel systems, that was understandable. In late May 2011, our new meter was installed and we’ve been able to watch how much we’re saving off our power bill. Because we use so little power during typical days, most of our generated power goes into the grid at 44 cents / kWh, and we’re therefore making a fair amount of money.

As a rough indication, our new meter has been in place for just over a month, we’ve pushed around 140 kWh into the grid at 44 c/kWh and we’ve only used 108 kWh at 22 c/kWh, giving us a credit of about $38 so far. This works out at around $2 per day in credit, after paying for power usage. So, since our previous year’s power bills were approximately $700, we should be looking at a net benefit of over $1200 per year (and that’s taking into account air conditioning during summer days). Our system cost was $3300, so it’ll pay for itself in no time, not to mention the value it has added to the house.

We’ve changed our lifestyle a little with the solar as we try to do washing, dishwashing and similar powered activities when the sun isn’t shining – either early in the morning or in the evening – to avoid using our solar power and losing out on the bonus. Aside from that, we just keep being electricity conscious and turning off everything we can when it’s not in use.

We’re still waiting to receive our first power bill after the new meter was installed but our previous bill (i.e. after the panels were installed but before we started getting the feed-in bonus) saw our power bill halved just by having the solar panels installed for a third of the billing period.

Kate and I are very thorough with planning so we made sure we knew what we were getting, and we made sure to have the panels in the right place, etc, etc. Aside from the slow Ergon hook-up, we’ve had no problems at all. Anything we didn’t expect? We didn’t really expect we would be saving so much!