The Echidna, such an iconic Australian animal and unique too being one of only two monotremes, the other being the Platypus. We’re lucky enough to have Echidnas in the local area and even venturing into our yard from time to time.
Last week I was looking out the window at home while making lunch and noticed what looked like an unusual rough clump on the ground. I went outside to have a look and it turned out to be a group of four Echidnas huddled together in the sun! They were not moving and appeared to be just relaxing. I’ve only seen lone Echidnas before, four in one place was amazing!
Some online searching confirmed that they are solitary animals but they group up during mating season which is June – September. During this time up to ten males can follow a female around for weeks at a time, she will end up mating with the one that stays following her the longest.
The group I saw wasn’t moving, must have been just a short rest in the sun. I checked again after lunch and they were gone.
There’s no shortage of sandstone in the Sydney area, almost the entire extent of Garigal National Park sits on whats known as the Hawkesbury Sandstone. The Sydney 1:100 000 Geological Sheet classifies it as “Medium to course-grained quartz sandstone, very minor shale and laminite lenses” I wanted to highlight two sandstone formations, both of which are a bit of a mystery as to how they form.
I came across these formations on a trail run on a section of single track in Belrose that runs from the end of Ralston Ave down to the Bare Creek trail next to Bare Creek.
The first formation is called tessellated pavement.
There are a number of different types of tessellated pavement. The type I came across is seen on flat sections of sandstone that have been fractured into 4-6 sided geometric shapes. Some of the blocks are surrounded by deep grooves with rounded edges. It really looks like a man made road or path the way the blocks lock together. It’s not known how this structure forms.
The second formation is even more of a mystery.
It was on the same section of trail near the tessellated pavement. Found on a gently sloping section of sandstone, it had rows of deep grooves all running in the same direction from the top of the slope to the bottom. They looked like they could have been worn over many years by the trickle of water. Above the trail was a minor gully, there wasn’t any visible creek but it looked damp and swampy. In wetter times perhaps water could have drained slowly over the sandstone. This is all guessing, I couldn’t find any information on this type of formation. The closest I came was rillenkarren or rundkarren which is the weathering of similar channels in limestone by the slight acidity of the water dissolving the rock. Rillenkarren has sharper ridges and is thought to form out in the open while rundkarren is more rounded and thought to form under a superficial covering like sandy till, peat or a layer of plants and lichen.
In the bush nearby you can often see sections of sandstone that have clusters of regular sized holes around 10mm in diameter. Sometimes these pieces of sandstone are on a walking track where they get worn down to show the internal paths these holes take. I have a distant hazy memory of being told the holes are made by native bees. A bit of the old web searching brought up some more information!
The holes in sandstone are apparently the burrows of a native bee called the Blue Banded Bee. Blue Banded bees are found all over Australia except Tasmania and the Northern Territory. They are solitary bees that build their nests in mud and soft sandstone, they are also known to burrow into the mortar of old buildings.
I’ve not seen one of these bees myself so I don’t have a picture. They are described as being 8mm – 13mm long with a furry red brown thorax and blue and black stripes on it’s abdomen. They live around 40 days, baby bees remain in their eggs over winter but several generations can hatch over the warmer months. They are meant to be common, I’ll be keeping an eye out to try and get a picture.
It was over a year ago that I first saw this flying insect that had caught a large spider and was dragging it off somewhere presumably to eat. I’d never seen anything like it and I spent a while researching to try and work out what it was. At the time I thought it was a robber fly but now I think it’s a spider wasp!
Robber flys do indeed prey on some spiders and other insects but the images really dont look anything like what I’d seen.
The spider wasp is a much closer match. I’ve seen a few now, here’s some pictures of a smaller spider wasp with another decent sized spider. This particular one was struggling a bit with it’s prey. It even tried to fly a bit and only just managed it. Looking at the picture the spider could easily weigh more than the wasp!
Spider wasps are known to chop off the legs of the spider to make it easier to carry. All the ones I’ve seen the spiders are missing their legs. Nature is brutal!