Some Natural History Snaps

 The first image is of a pair of Masked Lapwings which have nested across the road - much to the joy of our neighbours on whose lawn they used to nest!

On Wednesday I drove around the Airstrip where there were 6 Scarlet Robins, in pairs.

There were 4 Kookaburras in this group, but only 3 fitted in the image.  2 singles were elsewhere.

On the 26th we went for a walk along the Narrows.  This was a nice sight with 2 Little Black Cormorants, 1 Great Cormorant and, at the back, a Darter.  They had all gone when we returned, replced by 2 Little Pied Cormorants.

The real excitement began when we spotted this seal, about half way along the Narrows.  It  was very active, I suspect attending to a school of Salmon.

It seemed to rise up and throw something - presumable a fish.  Trying to stun it?  It made a huge splash!

Then a Sea-Eagle got in the act: the ripples on the right edge are where the seal had just dived.

Then a second Eagle appeared.  It looked to have browner plumage, so possibly a young bird?

Hmmm.  Both of these look pretty adult in the images.  They were quite active so now I am wondering if there were 3!

Nightbirds

 A recent post by another blogger commented in a Note towards the end of the post, on the relative frequency of recording sightings of Nightbirds across Australia on the Birdata system.  This showed that in Birdata the Tawny Frogmouth was the most commonly reported Nightbird in Australia, with Southern Boobook in second place.

That led me to do a similar analysis for eBird records for East Gippsland (as I have the data readily to hand).  This showed a rather different outcome with Southern Boobook being the most commonly reported “Nightbird”.  Tawny Frogmouth was second.  In correspondence, the author of the original post subsequently provided Birdata information for the Birdata East Gippsland Region (East Gippsland and Wellington Shires) again showing Boobook as the most common species.  These three sets of data are shown in the page ‘cf Birdata’ in this Google Sheet and are summarised in the chart below.  Note that some of the species in the page are omitted from the chart as having relatively few records.

I concluded at the time that the difference in frequency between Birdata and eBird was  probably a reflection of the fact that a high proportion of reports of the Boobook are based on hearing the distinctive and far-carrying onomatopoeic call of the species.  The typical call of Tawny Frogmouth is a quieter and less far-carrying “Ooom”.  Once a Tawny Frogmouth is spotted at a site – not easy due to them being camouflage specialists - repeat sightings are easy, especially in urban areas, as they roost in exposed positions, often in a very tight area within their territory.  (Boobooks tend to roost in dense vegetation so are much harder to see in daylight.)  I will return to this discussion at the end of the note.

In discussion of this Frances commented that she has seen Tawny Frogmouths many times but has never seen a Boobook (although she has heard them many times).  This led me to look at the timing of sightings of Nightbirds in eBird for East Gippsland (Shire).  For simplicity I defined “daytime” as from 0600 hours until 1800 hours.  A more rigorous approach would consider the change of sunrise through the year – at Mallacoota from 0736 in June to 0537 [0437 excluding DST] in December.  (If being obsessive,  it could also adjust for the range of times in East Gippsland: on 24 July sunrise in Mallacoota is 0707 while at Paynesville it is 0716.)  Efficient implementation of such refinements is beyond my computing skill, and would not, I suspect change the outcome in a significant way.)  The following chart shows the number of eBird Nightbird sightings by the hour in which the eBird survey was started.    

I have then calculated and plotted, in the following chart, the % of records for each species that were started in “daytime”.  Tawny Frogmouth stands out as having by far the highest proportion of daytime records.

I have hinted above at the need to bear in mind observer behaviour in interpretation of these data.  I have not attempted a rigorous analysis of the possible behaviours involved (and suspect that even for the eBird data that would be a major project) but the following anecdotes might be relevant.

As a general comment I am relying on the moderators of the Birdata and eBird system having satisfied themselves that records of Barking Owl are in fact those birds and not dyspeptic Jack Russells!

As noted above most Nightbirds are hard to spot in daylight.  Some species roost in dense vegetation (eg Boobooks) or hollows (Barn Owl and kin).  Others are very hard to find due to excellent camouflage when roosting (White-throated Nightjar).  Even the Frogmouth, Powerful Owl and Owlet‑nightjar can be difficult to spot, but once a roost site is known, often on a relatively exposed perch, they can often be seen there repeatedly.  For example:

• At my previous place (near Canberra) a pair of Tawny Frogmouths had a territory in our rural yard and I included this species in every list I completed for the site over 8 years. 
• Another Tawny Frogmouth roosted in a suburban garden clearly visible from a well birded urban park (and I am fairly sure included in many lists from the park).
• A Powerful Owl – a species of interest to many observers – took to roosting in an easily accessible site in the Australian National Botanic Gardens (ANBG).  Staff of the ANBG estimated that the presence of this bird brought an extra 400 visitors to the Gardens over a 2 month period of residence.
• Also in ANBG – one of the most popular birding sites in Canberra - Owlet-nightjars roost in hollows in trees, but emerge to bask in sunlight.  They use the same hollow for some time and people visit those places to add the species to their lists.
• For Southern Boobook the data collection for the Atlas of ACT Birds was interesting.  A first tranche of data showed the bird to be entirely urban – apart from one site in the Brindabellas where some birders had camped!  This was resolved to some extent by special night-time visits to the Brindabellas in peak calling season.

While I have not recorded the details, my observation of eBird records  when compiling regular reports on the birds of Mallacoota is that a high proportion of Nightbird records arise when people are driving to Mallacoota after dark and see Owls fly across the Genoa Rd.  These are logged as ‘incidental’ records.

Most other sightings of nightbirds in Mallacoota arise from targeted outings by birders going out after dark to places where the hunting birds perch on infrastructure.  Examples are the powerlines along Watertrust Road and the fence around the Airstrip.  (Even those are not guaranteed to sight the birds: on an outing during one of our Big Weekends 20+ birders – including some nightbird experts – traversed Watertrust Rd over an hour and didn’t see or hear a single bird.)

In terms of comparison between the Australian Birdata information and the Gippsland data it must be noted that the environments covered can have an interesting effect (which I have not come close to sorting out).  Taking the example of Powerful Owl (Powl), until the bird took up residence in ANBG, on the edge of the CBD, it was considered that, near Canberra, they were only found in the forest gullies of the Brindabellas.  A Powl also appeared later, reducing the Ring-tailed Possum population of Inner North Canberra for some 18 months (and leaving the remains on pavement as an easy guide to where it was currently roosting) .  I – and many other birders - listed a bird in Carlton Gardens on the edge of the Melbourne CBD (guano again giving a good hint) while in Mallacoota most reports of the species come from a forest gully only ~500m from the town centre. 

Summary

My summary of this note is that it again illustrates the risks of single-number statistics for natural phenomena. 

For serious consideration of nightbird statistics information about the times at which data were collected is essential. If the number of nightbird records drop is it because the number of birds has dropped or because there are less night time records?   

I would also regard information about the number of sites at which records have been made is very important.  If numbers of Powerful Owl records have dropped in Mallacoota is it because people are not checking the Pumping Station Track?  If the number of Tawny Frogmouth records rises, particularly for a small area, is it because one observer is studying the birds and reporting them every day from one site?

June 2025 Weather report

 A cold and damp month overall.  At least it wasn't windy!

Rainfall

 As with every other month this year we have exceeded the median fall for the month!  For June we managed 95.4 mm, 143% of the median fall for the month.  By the end of the month our fall for the year to date is  728.6 mm or 159.8% of the median fall for that period.  (Another way of looking at that is that we have already recorded more than the annual falls for 6 of the 47 years for which I have records.)  Here is a comparison of this year, last year and the median fall or the 7 years from my Weather Station (WS) at Angophora Drive.

Most of the rain came in the first half of the month.  The very small amounts later in the month are effectively dew condensing out of very humid dawn skies.

My pro-rata estimates of the annual fall for 2025 seem to be settling down around 1400 mm for the year in total.  If we achieve anything close to that it will be in the heaviest 5 annual falls since 1975 (including falls at the BoM Airport gauge.)

Temperatures

The anomaly ended the month at -0.53oC which is the first negative value since January this year.  The start of the year was particularly chilly.

My time series of values of the anomaly is very variable, but the moving average, which removes seasonality, shows a plateau effect, at a fairly high level, over the last 2 years

Looking at the daily extreme temperatures  shows the maxima to have fluctuated around the mean values while the minima have more frequently been low.

Minimum temperatures

The average minimum temperature at my WS was 6.23oC and the coldest record here was 2.4oC while the Airport recorded a lowest reading of 2oC - a frost - on 30 June.  The average was the lowest since I started my WS in 2019.  The extreme temperatures were definitely cold, ith 9 minima significantly below the longer term mean minimum (one very significantly below) and only 2 significantly above the longer term mean,

Maximum temperatures

The average maximum temperature at my WS was 19.96oC - very close to the longer term mean - and the warmest record here was 20.6oC on the 24th - very significantly above the longer term monthly average. Overall, maximums were about normal, with 4 records significantly above average and 3 significantly below.

Humidity

The relative humidity was above average for both standard times but the afternoon reading was below last years value - not surprising in view of the rainfall last June!

The daily humidity chart shows an overall high set of readings - with afternoon levels closer than usual to the morning readings.  

The drop in humidity on the 24th is interesting.  Plotting hourly humidity and maximum temperature shows them moving in very different directions.  Both are possibly an effect of the strong NNWly winds recorded on the day.

Wind

The average wind run for the month as a whole was very low - the average of 60km being close to 20 km less than the runs in the other 6 Junes for which I have records.  In contrast the run of 243km on the 24th was longest run I have recorded in a June day.

Tempest recording

A friend whose WS is connected to the Tempest network has given me access to that system.  It includes some additional variables to those from my WS.  

The system recorded 16 lightning strikes (within a 40km radius of Mallacoota which ).  I only have records for 34 months so can't say much about that, other than noting that cooler months are less prone to lightning strikes than summer (several Summer months have over 1000 strikes recorded and February 2025 recorded close to 7,000 strikes in that area).

The system also records solar radiation in a variety of ways.  The following chart shows that recent experience is for relatively low levels of radiation as would be expected given our rain (which requires cloud!)  I shall do a separate post with more details about my interpretation of these data.

May (and Autumn) 2025 Weather Report

Frances commented on the evening of 31 May that "Tomorrow is the first day of Winter." so it behooves me to comment on the summary of the last three months representing Autumn (or as those from the Evil Empire across the Pacific call it, "Fall").

Autumnal Review

My Weather station has now recorded data from Angophora Drive for 7 Autumns.  These are summarised in the page 'Seasonal Summaries' in this Google Sheet.  Summarising further:

• The average daily minimum temperature was the warmest, by 0.3C, of the 7 seasons.  It was 1.01C above the average of the 6 earlier years.
• The average daily maximum temperature was the warmest, by 0.9C, of the 7 seasons.  It was 1.31C above the average of the 6 earlier years.  
• (In both cases the 'runner up' was 2019.)
• Although the station is not well exposed to wind it is interesting that the wind run for the three months is the second lowest of the 7 years.  (This may reflect growth of garden shrubs rather change in the weather!)
• Rainfall was the second highest (90 mm below 2022) and still 150mm above the average.

Monthly material

The month was very wet (only 3 of 46 previous Mays recorded more rain) and warm (temperature anomaly of +1.14C.   Relative humidity was at the high end of the 7 years for which I have data (but not extreme - whether examined for the standard times or for the average of the month as a whole.  Wind run was very low: possibly reflecting a higher than usual proportion of BoM wind records from the Eastern half of the compass, from which my WS is fairly sheltered.

Rainfall

In a post on 23 May to the Facebook Group I commented:

"I was a little surprised yesterday morning at how little rain was being recorded on my WS compared to what I was seeing. On going to check the WS I found that the rainfall collector was full and the filter was blocked by green slime. Never had that happen before in the 12 years I have had the device. Removing the filter let the liquid run through, tipping the cup 10 times!

Comparing the WS records with my Nylex suggests it has been missing about half the falls in the last few weeks. (I am quite happy with records to the end of April.) A comparison with BoM records for the Airport and Gabo, and information from Marty suggests that doubling my records for 18-19 May will give a fair estimate of reality so I have done that. Recording immediately started to match what I was seeing."

So it is possible my records for the month as a whole are a little understated.  I totalled 156.6mm for the month, amounting to 214% of the median for May.  For the year to end May we are at 633mm which is 176% of median falls to the end of May.  Here is a chart of daily fall, including the adjustments described above (note that there are several days early in the month with a record of 0.2mm which barely show up in the chart):

The progress of my prorata estimate for the year is interesting.  Having had falls well over median every month so far this year it is not surprising the prorata estimate is high.

I have added a section at the end of this report comparing 2025 rainfall at the BoM Airport and Gabo Island sites.

Temperatures

The development of the anomaly (difference to long-term mean) shows a cool first few days followed by a warm spell, sustained to the end of the month.

A chart of daily extremes give a pattern consistent with the above.

A time series of anomaly values resembles the Alps. Using a 12 month moving average to remove seasonal factors shows that the series is rising, but applying a trendline to that series suggests it is dropping.  I think "wait and see" is the best option here!

There were no days with both extremes significantly below long term, and only 1 day with both significantly above.

Minimum temperatures

The average minimum for the month was 10.05C, 0.73C above the average minimum for May recorded on my WS.  The lowest I recorded in the month was 5.3C on the 20th: one of only 3 days significantly below the long term average minimum for May.  The highest minimum temperature was 14.9C on the 23rd: 4 days were significantly above long term.  Overall 22 minima were above average and 9 below.

Comparing with recent years the time series for average monthly minima over financial years shows a continuation of 2024-25 as being warmer that usual.

Maximum temperatures

The average maximum for the month was 19.67C, 1.54C above the average minimum for May recorded on my WS.  The highest I recorded in the month was 27.0C on the 6th: one of 10 days significantly above the long term average maximum for May. 3 days (5th to the 7th) were very significantly above average.  The lowest maximum temperature was 11.7C  on the 18th: 2 days were significantly below long term.  Overall 23 maxima were above average and 8 below.

Comparing with recent years the time series for average monthly maxima over financial years shows a continuation of 2024-25 as being warmer that usual.

Humidity

The records for the month were reasonably normal for such a rainy period.

Wind

See comment in preamble.

Extra: Rain at Airport and Gabo

This section arose from a feeling that rainfall recordings at Gabo were lower than I expected compared to those at the Airport.  For the year to date the 2025 ( to 28 May) falls recorded by BoM at the Airport and Gabo were 682mm and 478 mm respectively.  Comparing the daily falls over 148 days there were: 

• 78 days where both sites reported the same amount (mainly 0mm!)
• On another 54 days the difference was less than 5 mm one way or the other.
• On 13 days the Airport recorded greater than 5mm more than Gabo; and 
• On 3 days Gabo was more than 5mm above the Airport.

Three days stand out where the Airport recorded much more than Gabo which I think gave rise to my feelings of doubt:

• 8 February 42.4 mm vs 4.2mm
• 10 February 73.4 mm vs 10.8 mm
• 24 May 76.2 mm vs 49.4 mm

However I think that looking at the overall series I could not conclude there was any consistent pattern I could raise with BoM.

I did also look at Green Cape (GC) but found that 14 days had missing readings and for another 5 days the falls were cumulated over more than 1 day.  One of the missing data periods, in January, included a significant rain event (27 mm at the Airport, 14 at Gabo).  I also couldn't pick a consistent pattern between GC and either of the others where data was available for all three sites. 

My conclusion was that while the differences were surprising given the 2 sites are quite close (17km in a straight line) with apparently similar exposure and neither site affected by hills (on 8 -10 February the wind at Gabo was from SE, on 24/5 it was from NW but Howe Hill is ~8km away), explaining this was above my pay grade!

May 23 rainfall

 This covers the rainfall even of 23 May 2025.  Although the rain came down the East Coast looking at a BoM map it doesn't look to me like an East Coast Low.  Here is the radar at 1150 hrs on 23 May 

.. and again at 1915hrs.

Over the whole day my Weather Station collected 77.6mm.    Here are some other local sites (neither of the Wunderground sites in Mallacoota of which I am aware are currently online, possibly reflecting the unreliable power supply at present).  I am very surprised at the low fall recorded at Gabo.

My WS shows falls through the day becoming very heavy in the evening.

The low fall at Bombala AWS suggests there will be little water coming down from the headwaters of  the Genoa River, but the worthwhile rain at Nungatta gives warning  of a good flow on the Eastern side of the ranges coming down Nungatta Creek affecting the Genoa Gorge Flood Gauge later on 24th.  At present it is well below Minor Flood level, but rising.

The fall at Nungatta may/probably also indicate rain falling in the headwaters of the mighty Wallagaraugh, to join up with the Genoa at Gipsy Point.  Together these flows  may offer interesting times for Bottom Lake in the near future.

The height peaked at 0745 on 24 May and has been slowly dropping since then.

The evening was blessed with an excellent sunset:

THis was a panoramic shot from my phone.  An idea to experiment with.

As the lightfades.

On the 25th I took a drive up to the (not close to a) flood gauge.  When I arrived it was measuring 1.12m so had dropped 0.27m (pretty close to a foot in old money) from the peak around 0800 hrs the previous day.  All was very calm upstream ...

.. but rather less so downstream.

The curious point was the state of the track from Wangarabell Rd.  Someone seems to have tried pruning some of the vegetation beside the track.  However:

• they seem to have whacked small trees at random (several species, at various distances from the track); 
• used very crude implements not an axe nor clippers or a brush cutter);
• given up after about 300m (ie about halfway to the small shed); and
• just left the material scattered across the track (thus making it more difficult to walk on).

April 2025 Weather Report

 This is starting off as a quick draft, with preparation commencing before the end of the month, focusing on a few core variables (although I have bolted down a few data-burrows in the rainfall area).  The key comments are that by the end of the period it had became a very wet and very warm month overall. Some key numbers are here.

Rainfall

For the 4th month in a row rainfall was well over the median value.  The outcome was the water level in the Inlet rising sufficiently to close Lakeside Drive.  While this is the first time I can recall that happening with the mouth open, a long-term resident has advised that "Lakeside Drive has always flooded in my memory. Closed or open to ocean Lake or not!".

The length of the period of over-median rainfall "felt" longer than usual.  On checking my long time series (including data from the BoM Airport site from May 1984 to March 2019) this seemed to be confirmed, but I am having difficulty in presenting this in a clear and rigorous manner. (The longest run is 10 months of below median falls from April 2019 until January 2020: no wonder the fire went so quickly!) 

The total fall for the month at Angophora Drive is 179.8mm (237% of median April fall at this site). I found the recorded numbers to agree well with the collection in my Nylex plastic gauge. The comparison with records from the BoM Stations at the Airport (154.6mm) and Gabo Island (146.6mm) are interesting in a number of ways.

• It is unusual for both sites to be lower than my WS.  As well as the check offered by my Nylex, other observers' records from Karbeethong and Mirrabooka correlate well with mine.
• It is difficult to compare the BoM daily falls (based on a historically based 0900hrs reset)  with my records based on a midnight reset.  However I have achieved that with some effort.

The unusual period is 22-23 April.  During that time the radar image tended to show a line of small cells heading directly up the Genoa valley between the Airport and Gabo Island.  It seemed as though the hills of the Drummer area and Howe Range were shepherding the weather.

For the year to date I have recorded 475mm (179% of the median fall to end April).  Using the records for the year to date to compile a chart of the development of my prorata estimate of the annual fall shows the continual rain in the area.  This contrasts with the rest of Victoria where anecdotes report significant dry weather, as shown in this BoM map (thanks Rob Clay for drawing it to my attention).

I suspect that the average used here is the mean rainfall rather than the median.  The mean is biased upwards by occasional months with very heavy falls in a small number of years.

The mean rainfall to the end of April is 303 mm compared with a median for the period of 265 mm.  It should also be noted that the BoM data will probably not have registered the heavy local falls described above.  Most importantly the map shows a 12 month average including several months in 2024 with very low rainfall in Mallacoota.

Temperatures

The value for the temperature anomaly in April was +1.47C.  The early part of the month was cool but after 7 April one of - or frequently both - maximum and minimum were above the average value for the date.

This continues recent experience resulting in the 12 month moving average plot of anomaly values turning upwards.  

The chart of daily extremes shows that the key contributor to the strongly positive anomaly is the high minimum temperatures.  Particularly at the end of the month maxima were close to or below the longer term average (as expected given the blanket of cloud).

There were only 2, widely separated, days on which both minimum and maximum were significantly above the average, although 12 days had both values above average (expected value 8). 

Minimum temperatures

The average minimum for the month was 13.50C, just below the highest for the District, at the BoM site at the Airport (13.54C in 2002).  It is clearly the warmest recorded at my WS.

The minimum was above average on 22 days, and significantly above average on 9 days.

Maximum temperatures

The average maximum for April was 22.6 C, well above the average for my WS since 2019.  It is below the maximum at the Airport, adjusted to be comparable with my WS which is estimated as 23.8C in 2016 and 2018.

The maximum was above average on 18 days and significantly above on 8 days.

Humidity

The average humidity at 0900 hrs (86.1%) was the equal highest recorded for an April at my WS.  For the afternoon (1500 hrs) the reading (70.9%) was above average, but below 2 of the 6 earlier years.  The daily values were not remarkable.  

Wind

The average wind run at 66.6 km was well below average.  This possibly reflects the wind coming from Southerly directions (14 of 30 readings at 0900 hrs by the Airport site came between SSW and SE) from which my WS is sheltered.