Getting close to NSW!

 Dale announced that he was taking a tour up the Wallagaraugh River on 26 November, and I thought this was a good chance to add a few more species to the District list, even though a trip the previous Saturday (with 17 expert birders on board) had found 65 species.  So I joined the group on the Gipsy Princess at Gipsy Point.

Here is the route marked with orange arrows (other symbols will be explained below).  The double headed arrow marks the turning point, very close to the State border.  This was not due to fears of a check point, but the presence of a small waterfall blocking the way (after dodging a few submerged rocks in the final few hundred metres).  

This is the view in the upper parts of the trip.  The area was thoroughly burnt in the Black Summer fire but has regrown densely.

We paid close attention to the vegetation at the Johnson Bridge (red arrow) as Black Bittern has been seen there in the past.  No joy on this trip.  However when we got to the point marked with '1' an unusual looking dark Bittern-shaped bird was seen on the bank, jumping up into a tree.

Much excitement ensued as we thought we had seen what the 17 experts had dipped on: the aforementioned Black Bittern.  I tried to log on to the Mallacoota Birds Facebook page (being a caring and sharing person, not gloating at all, no Sir, not me).  Unfortunately my phone didn't have coverage so that failed.

This was actually a Good Thing, as when I compared my photos (and those of others) with the paintings in The Australian Bird Guide it was clear that what we had seen was not a Black Bittern but what we would call a Striated Heron.  eBird has renamed this Little Heron - the detailed reasons for which they demand coin (although it is summarised in this which also contains a number of threats of future changes - an ominous sign that Avibase won't stop continual random changes to taxonomy).  Wikipedia links to the 34 page Masters 'thesis' as the explanation, which is also referenced in the eBird summary.  So poor connectivity saved me from making a public chook of myself.  

That is still a very good bird as the Southern limit of their range is usually around Bateman's Bay and there are only 2 eBird records West of Mallacoota.  They have not been recorded in the District since January 2024.  Another photo.

We had a few sightings of White-bellied Sea-Eagles but they showed no interest in our boat.

This pair were in the vicinity of a nest which had been occupied by young until very recently. 

On Dale's previous trip 12 Azure Kingfishers had been recorded including a bird entering a burrow with a small fish.  We saw none on the way up, but did record 3 on the return.

The weather was growing close to ordinary by the time we turned, possibly accounting for the absence of reptiles on the banks.  One Gippsland Water Dragon was seen in the upper reaches.

Overall we recorded 41 species for the trip which was quite good.  A number of very much expected species (including Lewin's Honeyeater, Pacific Black Duck, Chestnut Teal and White-browed Scrubwren) were among the MIA.

October 2025 Weather Report

 The weather recording in October was dominated by two themes:

1. The impact of the Sudden Stratospheric Warming (SSW) over the Antarctic which disrupted the expected climate drivers over Australia; and
2. The downgrade of the Bureau of Meteorology (BoM) website.

The first of these caused the dry weather experienced in September to continue into the first part of October, but appears to have gone away for the last week of the month.  There are some signs that community outrage regarding the second event is having some effect although that will probably not be known until the new Director of BoM takes up his Office later in November.  As this report is mainly concerned with data from personal weather stations (WS) this will probably have little impact on what I have to say.

Overall the month has been quite moderate: rain has ended close to median fall; temperature anomaly close to zero; and wind runs moderate.

Rain

The impact of the SSW (and its disappearance) is shown in daily rainfall for September and October 2025 compared with mean falls (2019 onwards).  This should be viewed against the situation in early September, where forecasters were suggesting that the drivers of the climate (notably IOD  and La Nina) were suggesting a wet Spring.

This is emphasised by my usual chart comparing this year, last year and median fall for months. 

As a result of the good falls in the last week of the month the rainfall for October has got to 93% of the median fall for the month (for year-to-date we are at 135% of the median fall).

The heavy falls in Autumn and Winter mean that the pro-rata estimate for annual rainfall is still holding up at a high level, having passed the annual median fall on August 24th.   

The current pro-rata estimate - 1231mm - if met would be the 8th heaviest annual fall of the 47 years for which I have records from my WS or the BoM site at the Airport.

Temperatures

The temperature anomaly for the month ended at +0.13C after a fairly variable month.

The time series for the anomaly continues as a positive and the moving average is in the same band as recent values (but the trend line is showing a drop in the last few readings).

A notable feature of the temperatures over the month - especially the first  weeks - was the great range of temperatures.  This was drawn to my attention on the 5th when the temperature range was 20.1oC and is illustrated in this chart.

Minimum temperatures

The average daily minimum was 10.13oC somewhat below the average October minimum recorded at my WS.  This continues the cool values since June.

I recorded 8 minima significantly below the monthly mean minimum and the coldest value  - +5.7oC  -was very significantly below mean.  Three days had significantly above-mean minima.

Maximum temperatures

The average daily maximum was (not a surprise, in view of the extremes graph above) well above (+1.4oC) the average for my WS.  This gets it to "the top of the heap" for recent years but still well below the 23.5oC average achieved at the Airport in October 2015.

I recorded 2 maxima significantly above the monthly mean maximyum and  days very significantly above the monthly mean.  The hottest value - +30.4oC  - was very significantly above the mean and the 6th warmest October day recorded (the hottest at my WS was 34.9oC on 31/10/2019).  Only 1 day (27th) was significantly below mean maximum.

Humidity

The chart for relative humidity at standard times shows a very orthodox pattern with afternoon values generally below those for the morning.  In both cases the series show a lot of variability from day to day.

Wind

The daily runs for the month as a whole were quite variable for October. 

Looking at the month as a whole the average daily run at my WS was very low.

I was able to locate the table of BoM observations for October and this showed that many of the observations of wind were from the ESE to S section of the compass, from which my WS is particularly sheltered.  So I believe the value shown is an egregious understatement of the windiness of this month.  This is particularly annoying as I had hoped that the wind direction would be helpful in explaining the temperature observations.

Tempest series

A friend with a weather station near the Wharf has provided access to his data published on the Tempest network.  This includes data for solar radiation and lightning strikes.

The records for solar radiation show a high level of seasonal variation so I have included a 12 month moving average which removes that effect.  The result shows the level to be very close to  constant, with a range from 165 to 178

The data for Lightning strikes relates to a circle of 40 km radius around the site ...

... and includes data from other sources (see https://help.tempest.earth/hc/en-us/articles/360046877513-Lightning-Detection).  The very high number of strikes (6941) in February 2025 cause  some issues in charting the data using a normal scale so I have used a Logscale (Log 100 = 2.0; log 6941= 3.8414 etc).

some recent birdie snaps

 From Mallacoota and Merimbula, 24 and 25 October.

Nesting Silver Gulls, Coulls Inlet.

Cattle Egrets, Seagull Island

Ibid, showing some plumes.

How to tell a Pelican from a Spoonbill.

Merimbula: Osprey on a nest.

Osprey in Flight.

A visitor

 About 2130 hrs last evening there was a loud bang outside.   This was followed by Frances telling me to bring my headlight.  We had a visitor who had climbed up a metal pole on to our railing.

We love koalas, but didn't want one climbing around the deck all evening so I shooed him off his perch and he disappeared down the garden.  10 minutes later he was back stomping up and down the deck and refusing to be further shooed.  He also seem determined to debunk the myth that they only eat a few species of eucalypt leaves, by adding my new Blundstones to his diet.  The boots were taken indoors.

I consulted our wildlife carer, who advised he was probably looking for love (or at least the physical manifestation thereof) and would probably go away eventually.

After about 30 minutes checking out the pot plants and peering through the glass door, ...

... he did wander off.  As there was no noise - in our hearing - we assume his search was unsuccessful.

Capn Steve's October 2025

 Being keen to get a good start to my list for Mallacoota in October 2025 I took my self off there on the morning of the 2nd, being joined later by Frances.  We ended with a fair list of 26 species.  The highlight was I think an immature Pacific Gull, the large bird isolated on the sand bank in this image.

The birds in the water are mainly Bar-tailed Godwits, with a few Red Knots mixed in.

A passing White-bellied Sea-Eagle stirred up the Crested Terns

September 2025 Weather Report

 The dominant feature of the weather this month has been lack of rain.  The cause of this appears to be a Sudden Stratospheric Warning event which first came to my notice in a Facebook post by cyclonesOZ on 27 September.  This article from the ABC has some detail: I haven't been able to find a definitive statement from BoM on the subject, although a spokesmeteorologist is quoted in the linked article.

Rain

With the aid of 1mm on the 30th we managed to achieve 17mm for the month.  This is the only 3rd highest September fall since my records (at the BoM site at the Airport or my WS) begin in 1975.  Here are the daily falls.

The highest daily fall was 6.6 mm: there are only 34 months (out of 570) in which the maximum daily fall was lower.  Not surprisingly the monthly total was very much below median and last year.

The pro-rata average estimated annual fall for 2025 is still high, reflecting the heavy falls in earlier months.  I note that the trend line of this series takes a major dive in September.

Temperature

My analysis of the temperature anomaly began with finding that I had used a series of averages incorporating temperatures from the BoM site rather than, as has been my recent practice, restricting the analysis to my WS data.  It is of interest that correcting this cock-up reduces the value of the anomaly from +0.65C to +0.13C! After a cold start the anomaly hovers around 0.0C for the rest of the month.

The monthly values of the anomaly are highly variable but the 12 month moving average shows relatively stable high values for the last 2 years.

The chart of daily extremes shows considerable variation especially for the maximum series, but higher values are much greater than those below the mean.

Minimum temperatures

The mean minimum temperature for the month was 8.7C, 0.57C lower than the monthly mean minimum.  The lowest temperature recorded was 4.0C, very significantly below the mean low for the month.  After running on the high end of recent experience for the first half of the year, the last three months have been on the lower side. 

There were 3 days - early in the month - significantly below average monthly low and 2 days - late in the month - significantly, or very significantly, above the mean monthly minimum.

Maximum temperatures

The mean maximum was 19.5C, 0.85C above the average maximum for the month.  The highest  temperature recorded was 25.2C on the 8th, one of 5 days through the month significantly above the mean low for the month.  The lowest maximum was 14.2C. one of 3 days significantly below average monthly high.  After running on the high end of recent experience for the first half of the year, the last three months have been variable but September is on the higher side.

Humidity

The daily readings for the standard times are reasonably 'normal' apart from 8th - 10th and 16th when the morning humidity was higher that that in the afternoon.  It is possible that these values reflect a wind shift to the South, although the phenomenon is not so evident in the BoM data.

The values for both standard times are a little lower than average.

Wind

The month was relatively calm with the maximum daily run only 127km.

Although the run is a little longer than that of August it is still well below the Average and 2024.

Tempest data

I am able to access data for a WS at the Wharf which uses the Tempest network and records some further very interesting data.  

Lightning strikes

As well as data from the WS Tempest brings in information from other sources including a tally of lightning strikes within 40km radius of the WS site.  For the Mallacoota site the raw data is made almost useless by a record of 6900 strikes (I believe real) in February 2025 dominating the chart.  It does give a good indication of relativities if plotted as log10 values (thus 6900 becomes 3.84).

The number of strikes in September was 23 (log10 =1.36).

Solar Radiation etc

The system has a range of measures of Solar Radiation and Brightness which are very relevant in these days of solar heating and power generation.  The chart below shows the value of solar radiation received and a 12 month moving average which eliminates the very obvious seasonal variation.

Applying a linear trend to the average suggests that the series is trending down, but the correlation coefficient suggests this is not significant.