Tilapia Terrorises the Tropics

Tilapia Terrorises the Tropics

In north Queensland we have two introduced Tilapia species. This one, Oreochromis mossambicus, Mozambique tilapia, was photographed yesterday in the Freshwater Lake at Centenary Lakes, Flecker Botanic Gardens, Cairns.

It, along with many other males have established breeding areas which they have cleaned. they have adopted their colourful breeding condition to impress the females. See the red margins to the dorsal and caudal fins, the bright red pectoral fins and the pale yellow cheek patch on the gill covers. the females are smaller, more grey and with less prominent lips. Young are pale grey with a spot on the posterior margin of the dorsal fin.

Tilapia eat detritus, live plants and prey on the eggs and fry of other fish. They can live in a wide range of habitats and reach incredible densities. They are tough fish being able to withstand unusual pH levels and low oxygen as well as high salinity and fresh water conditions. When those in the water features of a golf course in Port Douglas were killed using a fish poison something like thirteen tonnes of fish bodies had to be disposed of. These fish pose a threat to prawn and barramundi stocks and hence people's livelihoods. The beautiful endangered Oxleyan Pygmy Perch, Nannoperca oxleyana, and the vulnerable Honey Blue-eye, Pseudomugil mellis, are under threat from the expansion of this species range.

The dumping of exotic fish in our streams and lakes has made Australia one of the world's hot spots for fish invasions. Native fish and crustacea are also being spread into areas where they did not occur with the loss of local species being the result. Lake Eacham no longer has Lake Eacham Rainbow Fish. There used to be millions. When I first moved to the Atherton Tablelands I would sit on a log in the Lake and these little fish would suck on the hairs of my legs until the tickling got too much for me. Some of these introductions are by misguided people releasing aquarium specimens but others are done by people who want to fish for the species they are introducing. It is a shame that such environmental vandalism is still occurring; Tilapia have been found recently in the Walsh River Catchment and near Cooktown.

Changing of the Guard

Photo copyright Eric Preston

Lots of disruption happening with the Tree-kangaroos at my site recently but one thing sneaked under my guard. This male Lumholtz's Tree-kangaroo is superficially similar to Joan, a three and a half year old female who remained with her mother, Jill. At some stage I have started calling him "Joan" and not realised my mistake. When a strange female turned up, first near Jill's territory and then in it I wondered what was going on. That "Joan" was spending a lot of time near the new animal seemed really strange to me. Why would either of them tolerate the other if they were not closely related.

Now it makes sense that the new dominant male should let the new female know that she was welcome but he was 'the man'.

One possible cause of the disruption is the work being done by National Parks to control some of the nasty weeds which have invaded the forest. Turbina corymbosa and Aristolochia elegans are two of the culprits. Turbina is eaten by all three species of arboreal foliovores but still overgrows trees, causing their death. After the cyclone it responded to the increase in light levels by germinating throughout much of the forest. It, along with other vines, proved an important food source as the trees had lost most of their leaves. Fallen vines continued to grow, feeding the animals. A strip of land to the west of the track we use is to be re vegetated this wet season which is great. I do wonder though how much the possums, pademelons and tree-roos will allow the small trees to grow.

Below is the best picture I have so far of the new female. She has a joey in the pouch which we have seen out on three occasions. She is not yet habituated on us but is more relaxed than when she first turned up and would woof at us at the least excuse. Tree-kangaroos have this breathy but voiced woofing alarm call. It may be a threat call but I have not observed enough behaviour between animals in the wild to tell. When heard the animals were usually moving away from me but they were directing their attention in my direction.

Beetles Bite, Bugs Sux

Beetles bite but bugs suck.

If you are not sure have a look at the jaws on this curl grub, the larva of a rhinoceros beetle. The black bug below is sucking the life out of a beetle

Beetle larvae come in a variety of forms from slug like creatures to the curl grub illustrated above. The adults have two pairs of wings with the first pair hardened to form elytra which cover the flight producing and delicate hind wings. Beetles are the most common of animals, almost a third of all known species are beetles. You can see the destructive eating habits of the little glossy beetles shown below. This is the same species which lost one of its young to the tiny bug above. Like the adults in this species the larvae eat leaves and are quite active. While most beetle larvae eat leaves, some like those of fire flies feed on snails. Some beetle larvae are slow moving but the little fellow below is off looking for more food.
When I got the camera too close he climbed on board.

Big Greasy bites the dust

I am not certain that this is the Big Greasy which has been patrolling my Aristolochia vines but the circumstantial evidence is strong. Posed this dead butterfly to give you an idea of what he was like in life. Though to be honest I never saw him visit these flowers.

Spit Bug and Friend

It looked like someone with a bad cold had been spitting in this Casuarina but the animals concerned were healthy and living in this spit ball.Like all true bugs this sucker is just that, a sucker. Bugs use their rostrum, a hollow tube below the head to feed. The majority feed on plant juices but a few suck the from other insects and bed bugs suck from humans given the chance! The spit bug sucks the juices out of the plant and froths up the exudate to make this hiding place. The bug above had just moulted and you can see the old skin on the right.

Here he is getting a real move on.

As an adult they have wings. Unfortunately I did not work fast enough and this is the only photo of the adult I got.

Other small leaf hoppers can also be found around here. Many are plain green. This one shows the transparent wings which give rise to the name of the order Hemiptera, half wing.

'Little' Big Greasy's Big Day Out

'Little' Big Greasy's Big Day Out

For more than a week a male Big Greasy butterfly, Cressida cressida, has been patrolling a patch of our garden where there are some young Aristolochia vines. These vines are the host for a number of butterflies including the spectacular Cairns Birdwing.



When I wasn't watching he must have been visited by a girlfriend as eggs like this were laid on all the vines.



Yesterday one of the eggs hatched. The scale on the ruler is in centimetres. Today he was joined by another. The male is still flying circuits past these vines. Maybe he is keeping other butterflies from laying on 'his' vines. There are too many eggs for all the caterpillars to reach maturity so it will be interesting to see what happens. Related species are know to be cannibals.

This is one of the butterflies having a hard time because of the introduced Dutchman's Pipe Vine, Aristolochia elegans. The female will lay her eggs on this close relative of the host but the larvae hatch, begin feeding and die. At least this is a wide spread species with populations well away from human habitation. The Richmond Birdwing, Ornithoptera prianus pronomus, has suffered loss of habitat and the trials of the introduced garden plant killing its young.

The first specimens of this species collected for science were taken near Cooktown when Cook was forced to repair his 'Endeavour' there in 1770.

This is the same leaf as pictured at the top. Somehow I have reversed it. I'll keep you informed of progress. Below is a pupa which has over wintered. Hopefully I'll get a picture of the butterfly for you.
For more information on this beautiful butterfly have a look at http://www-staff.mcs.uts.edu.au/~don/larvae/papi/cressid.html

New Bird for Home Block #189

This morning I went outside to investigate the unusually loud trumpeting of numerous cranes and got an even bigger surprise. The Sarus Cranes were circling around to the west of the village and I was wondering if they were leaving early this year. No they were not gaining height. It may just have been the meeting of a couple of flocks.

Then I noticed one was flying very low. It was coming up from the creek and over Nick's Restaurant. It was a Great-billed Heron! It turned and flew north along Peterson Creek, giving its guttural, groaning rattle of a call.

The Great-billed Heron is a shy bird of the mangroves. I have heard reports of them being seen on the Tablelands before but this one was visible from home so it goes on the list. My home block list includes all the birds seen on or from our yard and the paddock below the house as far as the creek and wetland.

This marks the 189th species of bird to be sighted at our place in Yungaburra. Living on the edge of the village with the wetland nearby and the Curtain Figtree National Park not far away gives us the chance to have many visitors. Some like this bird may not be seen again. A Rose-crowned Fruit Dove was seen two days before Christmas last year. On the second of August 2007 I was lucky enough to see a brown coloured Golden Bowerbird fly out from under a fruiting mandarin tree, land in another tree but then it disappeared. A Satin Bowerbird visited after the cyclone in 2006 and stayed around with some Spotted Catbirds to eat our citrus! At least they eat the whole of the fruit unlike the Sulphur-crested Cockatoos.

Some of the unusual birds on our list:-
Red Goshawk. First spotted this pair over our house. they stayed around the village for a month and a half.
Pelican.
Black Swan. The wetland is a bit small for these two species.

There are not too many more that I would expect to show up but it is strange that the Australian Wood Ducks have always sat on the opposite shore on the rare occasions they have visited. Might just have to go around and herd them across next time. When the water is low I expectantly scan for waders as this is the group most liekly to add to my total.

I have twice seen birds I have seen well enough to identify if I knew them already. One was a long tailed small grey and white bird flying over with a swooping flight of a couple of wingbeats and then a glide. The other I feel may have been a northern hemisphere warbler.

Scarlet Stunner

Scarlet Stunner

This male Scarlet Honeyeater, Myzomela erythrocephala, was feeding in the yard a couple of weeks ago. The Grass Tree, Xanthorrhoea johnsonii, flowers are now finished but the scarlet honeyeaters are still here, feeding on callistemons.

Leafwing Butterfly

The Australian Leafwing, Doleschallia bisaltide, has some interesting habits as a larva and as an adult. The eggs are often laid on the flower buds of a native herb, Pseuderanthenum variabile. The young yellow to tan Caterpillar will eat one or two buds before starting on the leaves. During peak breeding season multiple eggs can be found on the one inflorescence. During the heat of the day the larvae hide under leaves. They come out in the late afternoon to start feeding. The larvae are capable of fairly rapid movement and will eat more than one plant before pupating. I have not recorded cannibalism or read of it in this species but it would not surprise me as the number of young larvae will drop dramatically when there is an over abundance. They leave their food plant before pupating in a sheltered spot about a metre off the ground, suspended head down by the cremaster.

As adults they often fly low to the ground but can be seen flying up into trees where they will hang onto a twig below a leaf, mimicking a dead leaf with their wings closed. They will more often land on the ground. When disturbed they have a strong flight but usually do not fly far before again adopting a camouflage position. The colours and patterns of the underwing are highly variable. The females have slightly more rounded wings than the males. The hindwing extends into a short tail which can resemble the leaf stem when the butterfly is at rest.

This individual has overwintered here. I can be sure that it is the same one because of the slightly deformed wings easily visible below.

Spring Song in the Lemon Tree

If anthropomorphism disgusts you turn away now!

Dramatis personae:- Two Silvereyes, Zosterops lateralis

Hey beautiful can I have a word in your ear?

Who told you that!

I don't listen to such scurrilous gossip.

Give me a kiss then.

Behave yourself!

How do you like being pecked on the neck?

Actually I prefer under the chin. Aah, that's better!

Signs of Spring

The Colours of Spring

"Signs of Spring" and you start with autumn leaves? Well no. We have winter, spring, summer and periodic deciduous trees here in the Wet Tropics of Queensland, Australia. This is Damson Plum, Terminalia sericocarpa, which is usually spring deciduous but some trees lost their leaves in winter this year, going a rich plum colour with the first frosts. The edible fruit is high in vitamin C and very tart.


One of the early spring flowering legumes is Northern Bloodvine, Austrosteenisia stipularis, a large vine endemic to the rainforests of north-east Queensland. They are able to produce spectacular shows and anyone crossing Winfield Bridge outside of Malanda is recommended to watch out for it over the next two months. This plant is just coming into flower on the bridge over Petersons Creek, Yungaburra. The flowers on this individual are about mid range with some being more purple and darker while others are a light pink. The closely related A. blackii has deep red flowers. Both vines will flower when they are partly deciduous which helps to show off their flowers. A. blackii is a very large vine up to 350mm in diameter. Two of this size can be seen at Lake Barrine after the twin Kauris. Walk to where the track divides and then another twenty metres. The vines grow between the two tracks and tie a most wonderful knot.

Cassia brewsteri comes in a variety of colours and forms but this medium sized tree with the green and red flowers is one of the best. Later in the season a beautiful small golden flowered form will flower in the median strip, Cedar Street in Yungaburra.

A number of hatchling spiders have blown in on the wind. This is a young Golden Orb, Nephila pilipes, which by the time she is fully grown will be about as large as my hand. Her abdomen will go grey, the rest of her black except for her wonderful golden knees.

We have had a bit of rain of late and that has started the frogs moving. I heard a Green Tree-frog last night but could not find it. This little Eastern Dwarf Tree-frog, Litoria fallax, was sitting on one of my dwarf bonsai plants.

Other hints of spring have been a little thunder with the rain yesterday and reports of Channel-billed Cuckoos and Koels returning. I have not seen or heard them yet but two lots of friends have reported them. With this warmer damp weather the snakes will be starting to move so please take care when travelling on the roads or in long grass.

Stinging Trees

The Stinging Tree, Dendrocnide moroides

To some overseas visitors Australia is a place of friendly people but a most unfriendly nature. We have the most poisonous land snake, the most dangerous spiders and the most painful plant. The worst of the stinging trees is not actually a tree but a bush. Of the six species in Australia there are two trees and four shrubs. While closely related to the stinging nettles, the shrubs are much worse and the worst of these is Dendrocnide moroides.

The leaves are heart shaped with teeth on the edges, a quilted appearance and a covering of fine hairs. While they can grow to seven metres it is unusual for them to exceed three. All parts of the plant carry the stinging hairs.

The leaves of the Gympie-gympie (Stinging Tree, Dendrocnide moroides) are covered in silica hairs which are like straws of glass. By brushing against the leaves the hairs penetrate the skin. Each is capable of inflicting a nasty sting like a wasp to those unlucky or silly enough to rub shoulders or any other part of their anatomy with this gem of the rainforest. The tubular hairs contain a nasty chemical which excites the nerves and causes pain for two days. Although the pain is intense the agent is not causing any damage to your body; it just feels like it is killing you! The effect is to stimulate the nerves causing a painful sensation. After this there are secondary effects which have lasted for me up to 4.5 months and can vary from person to person. None however are pleasant. They include burning sensations and electric shocks.

I discovered from one of my learned guests that this secondary reaction is a syndrome called, 'reflex sympathetic dystrophy'. Presumably this is caused by nerve damage cause by the chemical in the hairs. It seems that the pain is not reflex nor sympathetic and is not related to dystrophy. And I thought wildlife taxonomists were crazy! If you want to read more about the definitions you might like to go to http://jnnp.bmjjournals.com/cgi/content/full/71/3/291

It is not necessary to actually touch the bush to suffer its impact. Just working near the plants for some time or slashing them with a machine can be enough for the hairs to irritate the membranes of the nose and eyes. After effects vary from person to person and on the area stung but I have had them last for four months. When the area became cold I would get a little electric shock. Others suffer a burning sensation when the area is rubbed.

These plants do not lie in wait to jump out at unsuspecting bush walkers but they do often grow along tracks. For stinging trees to grow, they need good light but protection from wind. Beside roads, tracks and where trees have fallen are the best places to find and avoid stinging trees.

Prevention is always the best medicine. Find out what they look like, stay on the track and don’t touch. If one is stung, the removal of the hairs by hair removal wax or some other method will reduce the pain. Distraction by focusing on something else is often the best pain control. A severe sting will cause the release of lymph and the swelling of the gland in groin or armpit. In the case of unbearable pain or the injury of infants seek medical supervision. Do not try the bush remedies you may have heard of as the best is of negligible use and the worst, dangerous.

Below is the Mulberry -leaved or Shiny-leaved Stinging Tree, Dendrocnide photinophylla. This tree can grow as an emergent of 45 metres but by the time it is more than 5 metres tall it rarely produces stinging cells. Have a look at the hooks rather than hairs of this species. They only sting like a wasp for five to twenty minutes. The good news is there are no secondary effects. You may have noticed the holes in the leaves. These are caused by beetles. The White Nymph butterfly, Mynes geoffroyi guerini, lays its eggs in clusters on both the above species. The brownish coloured larvae are gregarious. Green Ringtail Possums, Pseudochirops archeri, also eats both of these plants. They are particularly fond of the Shiny-leaved Stinging Tree which they will eat through most of the year except the early dry season when the trees lose most of their leaves. After a prolonged dry spell the Gympie-gympie is one of the first plants to respond to a good rainfall. At this time it is possible to disturb a Green Ringtail feeding low during the day on these shrubs.

Wildlife On the Rocks, Granite Gorge

Granite Gorge is located outside the north Queensland town of Mareeba on the Atherton Tablelands. It is best known for its Mareeba Rock Wallabies which have become habituated on the hand outs they receive from tourists. This male was spotted sitting under the rock shown below. Can you see him in the second picture?

The gorge consists of huge granite boulders smoothed by millennia of water but on this excursion the Tablelands Frog Club spent its time mostly on the slopes surrounding the gorge looking for lizards.

Still cannot see the wallaby? Here is a closer view.

Under the rocks was where we were looking but the first thing I found was a case moth. It felt firm enough for something to be in the case but not as firm as to be a healthy pupa. On investigation this proved to be correct. Look at some the maggots which came out of the pupal case which was inside the structure of leaf pieces and silk built by the larva.

Not only do the animals which live on these rocks hide under them but they are camouflaged as well. This is a Zigzag Velvet Gecko, Oedura rhombifer.

And here he is in profile. Zigzag Velvet Gecko, Oedura rhombifer

This little fellow may be Nactus cheverti, but herps are not my long suit.

Skinks are often diurnal but there are nocturnal and crepuscular species as well. Carlia mundivensis (below) is a crepuscular species. That is it is most active at dawn and dusk.

Carlia schmeltzii turned up under a piece of old iron.

Tommy Roundhead Dragon and Two-lined Dragons are very similar, both have two lines along their backs and another on their flanks and both occur here. The fold on the throat gives this one away as Diporiphora australis, the Tommy Roundhead.

Back to insects now and this wonderful grasshopper is well camouflaged for its rock home.

Preying mantids are well known for their disguise but these two were on the same branch. It is likely that they emerged, some weeks before, from the ootheca or egg case shown in the second picture. You will be able to tell from the comments below that I originally posted these as stick insects. Thanks to the reader who pointed out my mistake. Mantids are carnivores with large well spaced eyes while phasmids (stick and leaf insects) are herbivores with tiny jaws and eyes close together on the front of the head. Mantids produce these oothecae with many eggs surrounded by a hard and a foamy casing. Phasmids on the other hand just pop out their eggs in a random manner. Some will emerge immediately and others will take some time; up to two years I have read.