The Townsville branch of Wildlife Queensland has resumed its monthly-except-wet-season excursions and their April trip was to Turtle Rock, an indigenous rock shelter high on Hervey’s Range. It’s a site I had known about for years but never seen, so I was very happy to be able to join the expedition.
Turtle Rock is on private land between Sharps Rd and Edward Rd; access is across the paddocks from the former, a 20 minute walk which can be shortened by driving part-way (as most of us did) or to the foot of the rock (as one of us did). The landowners, the Fryer family, are happy to have people visiting the site at any time but a courtesy phone call is a good idea and may avoid any difficulties with the access track.
Castle Hill dominates the central Townsville skyline but Mount Stuart takes over that role from anywhere further up Ross River. From Mundingburra all the way up to Kelso and across the river to the university and the hospital, Mount Stuart looms large.
That doesn’t mean people visit it very often, of course, but a road leading off the Charters Towers road just beyond the city winds up to a lookout beneath the radio masts. When I drove up a couple of days ago I was welcomed by a resident peacock (perhaps the same one who met me five years ago) and, after taking in the magnificent views over Magnetic Island, the Palm group and coastline all the way to Hinchinbrook, I wandered around the loop track.
The summit is a difficult environment for plants and animals alike: very exposed, very dry, and with only a thin covering of soil where there is any soil at all. Vegetation is ‘open woodland’ with a decent covering of tussocky grass, but most of the trees are tiny. Ants seem to be the most abundant invertebrates but there were other insects to be found as well as the spiders which prey on them.
* P.S. The ant has been identified by my friendly local expert as Meranoplus sp.
Lower down the mountain
Conditions half-way down the mountain are not quite so arid and I found more creatures per square metre than on the summit.
The two kinds of paper wasps are the two commonest around Townsville. More about them here and here.
The Spiny Orb-weaver pictured, Gasteracantha fornicata, is usually seen less often than its black cousins, Gasteracantha sacerdotalis, but outnumbered them on this trip.
“St Andrew’s Cross spider” is a common name which is applied loosely to several similar species. Argiope keyserlingi is the best known, A. picta is encountered from time to time, and this one may be unknown to science – which is a little bit exciting.
Golden Orb-weavers (Nephila sp.) are usually very big and not so brightly coloured but I have seen others around 12-15mm, like this one, in Western Queensland – at Aramac and Porcupine Gorge, for instance.
We’re well into winter, now, with the solstice only a couple of days away. We don’t get as much variation of day length or temperature as, say, Melbourne or Hobart but the change is great enough to affect the activity of ectothermic (cold-blooded) creatures such as insects. I have noted before that our butterflies tend to go to sleep by mid-afternoon at this time of year, and here are some paper wasps (Ropalidia revolutionalis) doing the same. At least they have chosen a spot where no-one is likely to bother them!
The smaller picture (just click on it for a bigger one, as usual) shows the sleeping wasps and their comb-like nest on the twigs of a spiky little conifer.
It’s not a big colony at all, and I suspect it is not getting any bigger. As I said when I wrote about paper wasps’ life cycle here, the colonies do not normally continue from year to year.
It is impossible for the adults to feed themselves and their offspring without a certain level of activity and I think these adults have been caught by the poor Wet season, which has reduced the number of caterpillars in the garden, and the shortening days, which reduce their foraging time.
Paper wasps are common around Townsville, although I don’t remember them from Victoria. They are social insects but not as social as ants or honey bees. Young adults mate, then each mated female begins her own colony by making a small nest of paper-like chewed up plant material, laying eggs and feeding the larvae on minced caterpillars. When the first generations of larvae (all non-reproductive females) emerge as adults, they join her in building and protecting the nest and in feeding their younger sisters. Males and reproductive females are produced at the end of the season, nests are abandoned and the cycle begins again.
There is a longer description of the life cycle, well illustrated with photos, here on the invaluable Brisbane Insects site, and another at zipcodezoo. Neither of them describe our Polistes stigma townsvillensis but the lifestyle is exactly the same except, perhaps, in one respect: both say that the quiet part of the cycle, between emergence of the reproducers and establishment of the new nests is ‘over winter’, which may be true in temperate climates but I don’t think it’s true here in Townsville’s monsoonal climate. My casual observations suggest nest building begins each year during the Wet, especially from January onwards, and that nests reach their maximum size (and are then abandoned) in the later part of the Dry, i.e. August and September. That would coincide pretty well with availability of the caterpillars the larvae are fed upon, but I will look out more carefully for nests later this year to make sure.
We have several species, all in the family Polistinae. The most common are Polistes stigma townsvillensis and Ropalidia revolutionalis, smaller and darker; Graeme Cocks pictures them both with more Ropalidia species here. The easiest way to identify them positively is from their nests, which are all differently constructed. A larger nest of Polistes stigma townsvillensis is here, and nests of Ropalidia gregaria and Ropalidia revolutionalis are here and here respectively. A word of warning: paper wasps are not actively aggressive but they are all perfectly willing to defend their nests and their sting is very painful.
When I was out at Porcupine Gorge recently I saw another brown paper wasp, not quite the same as our P. stigma townsvillensis but so similar that it must be another subspecies of P. stigma.
P.S. I found another different Polistes on Magnetic Island in December 2012 – photos here.
P.P.S. Feb 2013: I photographed a Ropalidia romandi in my garden today. The photo is now here … and I’m now looking out for a nest. It pays to know where they are!