Wednesday, 11 May 2016

A Visit to Greendale

A  mystery hyacinth orchid Dipodium sp. (Photo: B. Hughes)
On Sunday 17 April 2016 the Gympie and District Field Naturalists Club had the great fortune to visit Diane Kewin's Greendale nestled between Glastonbury Creek and Brooyar State Forest. The Kewins were the original settlers in the area and, while some of the scrub was cleared for farming, large tracts of vine scrub and open woodland remain almost as they were in the 1800s. Diane's father entered Greendale into the Nature Refuge Program to help insure that this area of significant biological interest is conserved.
Corymbia tessallaris looking very tessellated  (Photo: B. Hughes)
A survey by Marc Russell in 2007 identified almost 200 species of plants on Greendale and with Ric Sizer on hand to explain this botanical diversity, even the birds were given relatively short shrift. Gympie Nats in tow, Ric strode through the meadows of Kangaroo Grass and along the cattle trails to the various botanical wonders. My personal favourite was the Python Tree (formerly Austromyrtus but now Gossia bidwillii) with its smoothly patterned, twisting, trunk that takes little to imagine as a giant python. Bizarrely, the trunk reflects heat and is actually cold to the touch. Other trees of interest included Pink Bloodwood (Corymbia confertifolia), Moreton Bay Ash (Corymbia tessellaris) with its checkerboard bark, the important koala food Gum-topped Box (Eucalyptus molluccana) and Giant Ironwood (Choricarpia subargentea).
A bunyip striding through the Kanagroo Grass?  (Photo: B. Hughes)
About 45 species of birds were recorded on the trip, but apparently everyone was so interested in the plants, that no appropriate pictures were taken. There were lots of butterflies too and Ric Sizer is learning his lepidopteran host plants and helpfully pointed out several. One of the most common butterflies was the Orange Ringlet whose larvae feed on grasses, especially Kangaroo Grass. Wanderers, Glasswings, Evening Browns, grass yellows, and some white migrants also fluttered by for our entertainment. However the most interesting lepidopteran was a small 'tiger moth', so called because they are often brightly coloured to warn birds they taste very bad and to look elsewhere for a meal.
Asura cf cervicallis a Spotted Lichen Moth (Photo: DEWalter)
I think this is a Spotted Lichen Moth, so called because its caterpillars feed on lichens and it is spotted, but there are many species of Asura with similar variations on the orange and black theme and also many other small day-flying tiger moths that are similarly patterned. Such convergences in appearance among species of butterflies and tiger moths is common enough to have its own scientific term: Müllerian mimicry. It is thought that natural selection by predators (probably primarily birds in this case) tends to enforce a kind of conformity on appearances so that once a bird has learned to leave anything orange and black alone, the colourful flutters all benefit.
Staff Vine (Celastrus australis) we reckon (Photo: B. Hughes)
When a scientist isn't sure of an identification, there are several ways to communicate this. The least embarrassing is to be vague. Those of you who know your butterflies know that there are a host of similar looking grass yellows and pale migrants, but those of you who don't might just think I was being sloppy with my capitals above (current usage has been trending towards capitalising common names for all plants and animals). At the other extreme is to just admit that you don't know. So, for the mystery hyacinth orchid at the top of this post there are two competing hypotheses: Dipodium punctatum and D. roseum. Since none of us is entirely sure, the genetics of orchids is likely complex, and none of us are orchidologists (or even botanists), we are just calling it 'sp.' (for species). I am an entomologist, though, and I think it is likely that the tiger moth is an Asura but I'm not sure of cervicallis, so I've inserted a 'cf' before the species name. That's an abbreviation of conferre a Latin word that lets other entomologist know that I'm not betting the house on it.
Callicarpa pedunculata Velvet Leaf (Photo: B. Hughes)

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