Saturday, 24 March 2018

An evening of mammals

I always check the sunrise.  Today the first sight was a strange wake mark in the Inlet.  I presume someone left overnight and the currents bent their track.
The overcast had only a small chink over Gabo Island ...
... and I missed the moment when the sun completely filled it.  But this is still not a bad snap!
When we went out for our first walk, into town along the shared path, there were still a lot of bats in the air over the colony.  They were just sorting out their perches and not looking for food.  My attempt at photography was a major fail.  I can't remember anything of major excitement along the way.

Our second outing was a drive along the Gun Club track looking for birds (highlights were a couple of very active Jacky Winters) and then to Quarry Beach.  We found a bit more land art - representing either a sea-horse, a stingray or something else.  This follows on from a couple of items we noticed on our last visit.
In the strata near the quarry itself Frances commented on the yellow band looking like ochre.
On rubbing it with a pinkie the rock was very soft and indeed resembled ochre.  So did the pink layers, but I couldn't get an image of that.
There was a fair amount of seaweed washed up including quite a lot of bladderwrack (which seems a little different to Fucus vesiculosus the usual species of that designation).  Here we have the residue of some strands on the beach.
There was also some bull kelp but not in the mounds that are sometimes on hit beach.  This may mean it has just been buried: judging by the amount of rock that has been buried I suspect about 2m of sand has been deposited on the beach.

A Shag was lonely on a rock.
After returning home for lunch I went to try to get some bat snaps.  The brown splotches here are evidence of their bowels working well.
I didn't go far into the colony as it seemed to disturb the bats and I wasn't wearing a Hazmat (see image above) suit.  I was able to get a few useful snaps from across the street.
My guess is that ground area covered by this clump was about 1 square metre.  Such clumps balance out the open areas in the creek line etc making my guess of 1 bat per 5 sq metres be reasonable.

Detail of a foot.
Here is a thumb.
A bit out of sequence but a couple of images of recently planted shrubs that have come into flower..

Just after 1900hrs the fly-out started. The light wasn't great and they move surprisingly quickly  but this silhouette shows how the bits of a bat appear in flight.
The flight against the sky.
 Just for fun I counted the number of bats in that image.  The answer was 74.  I guessed that it took a bat 10 seconds to go across the frame: ie there would be 444 (=6*74) bats go through the frame in a minute.  There was another plume, about the same size behind me and I think there was a further plume heading off to the West.  So each minute there were 1322 (=444*3) bats flying out.  This went on for at least 45 minutes - possibly longer as the bats were still flooding by after dark, with lots of noise still coming from the colony.  So (45*1322 = ) 59,940 left the colony last night.  That figure is of course VERY rubbery but is astonishingly close to the result of my guess based on the area of the colony and the density of bats.  An officer of Vic DoE has advised that the number of bats is in the 10's of thousands see previous post.

While looking at the bats I heard a rustling noise coming from one of the eucalypts next door.  Sure enough there was Fat Person.
FP had vanished by the next morning.  Possibly chased off of by the Lead-footed Furballs (aka Brush-tailed Possums) that galloped bout on the deck at 2am!

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