Wednesday, 23 September 2009

Hughie obliges (finally)

For the benefit of the non-Australians - and possibly the younger Ockers - I will put in this link which explains the title.
After a year of miserable rainfall - Whiskers Creek hadn't run since about February - a good shower (5mm) came on Monday (21 September 2009) evening. Tuesday started with a major dust storm and just as evening fell a thunder storm arrived and dumped another 5mm. Then about 7pm it really started and came down for about 3 hours. By 7am on the Wednesday we had accumulated another 19mm.
The dams have all risen (one to the point of overflowing) and both Whiskers Creek and the smaller creek in the top paddock are both running.
The sprinkler system for the lawns has been turned off for the duration of our trip to Peru!

Sunday, 20 September 2009

Spiky things

The chap to the left is a redback spider (possibly Latrodectus hasselti). As it only has 6 legs rather than 8 I assume it has had a hard life. It was lurking on the side of my mower trailer from where it got washed off to find a new home.

This orchid (Pterostylis curta) was given to us as a seedling and has prospered very nicely as shown by the growth. Indeed the prosperity continues with another 2 flower stems evident below the level of those shown. The impressionist background is the wattles growing, and flowering prolifically, up our drive..

Monday, 14 September 2009

Here be Dragons

When setting off for a run this morning I came across these two Bearded Dragons lying in the drive. From their later behaviour (a brawl with much biting of beards) I assumed they were 2 males discussing territorial boundaries.

Sunday, 13 September 2009

Two 'roos

This is purely here because the sight of a joey eating grass while still ni the pouch makes me chuckle.

Sunday, 6 September 2009

A tale of two trees

Frances ordered a Black Fig Tree from the Diggers Club. It arrived by post so I dug a hole, planted it and surrounded it with chook wire to keep the rodents and marsupials off of it.

We had also been offered a peach tree (and a cherry tree, but I haven't an image of that) by our friends Ros and John. They commented that "it was a bit bigger than we'd realised". Indeed - after turningup with the car we returned with the trailer.

Guess which is which (after planting).

Friday, 4 September 2009

More spring flowers

If this is boring for you, you really need to get out more!

This first image is of some of the daffs growing down our drive. I have included this to show the benefits of a '300 mixed' purchase. Note that each of these 4 blooms is very different.

Here we have some more daffs, in a massed planting under a prunus (?). These are very nice with a staged blooming pattern They are blocked from the kitchen window by some broom trees: I forsee some serious pruning/bonsai work in my future.

As well as daffs we have some tulips - which have escaped the attention of the crimson rosellas.

In an earlier post (2 years ago) I covered some direct seeding. That has been quite succesful, and some of the Acacias (possibly A. buxifolia) are now flowering.

The next two are of flowers seen on the ANPS walk on 2 September. One is a blue orchid Cyanicula caerulea and the other Dodonea viscosa, the sticky hop bush (with visiting bee). I am sure you'll work out which is which!

Brickbats and bouquets - an ongoing series

This is actually a bouquet wrapped round a brickbat. Those in Australia, and thus familiar with the term "shit sandwich" may like to reflect on whether these term are different. From my view
  • I deal out the adulterated floral products; but
  • receive the contaminated bread.

On this day I noticed that my internet connection was running very very slowly. There didn't seem to be a reason for this in the context of the setup on my 'pooter and Francie's machine was also very slow. So I checked my ISP plan. Stone the corvids, I had gone over my limit. No idea why, I usually don't get within a mile of it.

So I buy some more bandwidth (for $19.95). The fact that they didn't send out a warning email constitutes a pair of brown slices to me (and the first refractory to be placed amongst the roses).

I then start looking more around the Netspace website and find that if I switch to ADSL2 I can get 10Gb anytime for the same cost as I am currently paying for 1Gb peak time +1Gb off-peak. Another well tanned contribution to my diet!

So I ring Netspace to find out if I can swap to ADSL2 (since I don't know which phone exchange I am on). It turns out I am on the Hoskinstown exchange which has no ADSL2 ports. After a bit of muttering to the very pleasant young lady she says that I am on an old plan and I could change it to a "5gb any time" plan for the same cost!! I think this counts as a well filled, and very brown, loaf.

I did thank the young lady for pointing this out to me but asked why I wasn't automatically put on the new plan. She said that people object to being automatically upgraded - which is fair enough in some circumstances, but not when it would reduce the effective cost of the service by about 60%.

So they get a bouquet for the better plan, but it is wrapped around the bricks of their appalling information provision.

Wednesday, 2 September 2009

Getting more Superb (Fairy-wrens)

To save those of you with a busy life from reading three pages of stuff, here is the short version.

I started trying to explain why the value of A for Superb Fairy-wrens (Malurus cyaneus) drops dramatically between years 17 and 18 of the Garden Bird Survey (GBS). I didn’t explain this.

I then moved to trying to explain why the value of A for this species shows a fairly steady increase from year 18 onwards. This was more successful. It appears to be due to a number of GBS sites, active for a relatively short period with several of them joining the Survey since year 18, showing a high recording rate of a fairly large number of birds. The sites tend to be on the edge of – or outside – the urban area of Canberra-Queanbeyan.

The Detail
While doing data entry for the GBS I was surprised at the small numbers of Superb Fairy-wrens reported in some sites where I would have expected them. This led me to look at what is in the database for this species.

The key summary statistic derived from the database is denoted ‘A’, for Abundance. It is calculated as the average number of birds of a species reported per active observer week within a year. For example in the first year of the GBS observers reported 768 Superb Fairy wrens (SFW) and indicated that they were at their sites for a total of 2026 weeks. Thus A = 768/2026 = 0.3790.

Over the 27 years of the GBS for which final data has been calculated the value of A rises fairly steadily from Year 1 to Year 17 and then plummets to year 18 after which it rises again, at a slightly steeper rate than before. This is illustrated in the following graph, also showing linear trend lines for the two ‘sections of interest’, their equations and values of R2.I began to look more closely at the large drop off between years 17 (ending on 2 July 1998) and 18(ending on 2 July 2009) which is hereafter referred to as the Great Plummet. This seems to be a real change in the population, rather than an artifact of the GBS,since of the net (-)1208 difference in the number of reported birds most ((-)856 – 70%) is attributable to changes in sites reporting the species in both years. New sites added 35 birds while abandoned sites reduced the count by 387. The following table summarises these changes.
Long term research into Superb Fairy-wrens in the Australian National Botanic Gardens (ANBG) shows that numbers correlate with spring (ie August to November) rainfall. The value of A was assessed against these data from the Bureau of Meteorology for Canberra Airport. No correlation was identified: the values of R for the 27 year series was close to zero. Focusing on the period from year 18 onwards, correlating rainfall for the period August-November of year ‘n’ with the value of A for year July n to June n+1 gave a strong negative correlation (R=0.66)! Applying a lag to the values of A (using the values of rainfall in Spring for year n-1) showed a correlation coefficient of -0.04 ie no significant relationship. As well as the lack of long-term correlation, the Canberra Airport rainfall did not appear to explain the Great Plummet.

This difference in outcome is almost certainly an effect of the difference between the very systematic research in the tight area of ANBG and the far more ‘noisy’ dataset available from the GBS.

An attempt was made to examine GBS breeding data for Superb Fairy-wrens, but as is the case for many species there were relatively few (107) breeding records and 75% of these were either F (+ Fledgling, early years) or DY (Depenedent Young, later years). Possibly this paucity of data reflects SFW nests being “well concealed, close to ground and usually in live plants” (HANZAB v5 p 284) and thus hard for GBS observers to locate.

A further avenue of enquiry was whether the Superb Fairy-wrens were increasing in GBS sites as the vegetation in the gardens matured, thus providing more of the appropriate breeding sites. There is only limited habitat information provided in the GBS and certainly not enough to analyse such an enquiry on a site by site basis. However it was thought that a variable showing the time since first development of a suburb might give a proxy. Unfortunately I have not been able to find a way of analyzing the data to demonstrate any significant relationship.

A further thought was that the series may be affected by sites only in the GBS for a few years (in many cases a single year) or that less experienced birders have difficulty spotting these birds. To overcome these issues A was recalculated, restricting both the number of birds and the observer weeks to sites which have reported for a minimum of 15 years. It was then trivial to do the same for the sites in the GBS for shorter periods of time. The result is shown in the following graph. While the two series show some consistency in earlier years there appears to be a clearly higher rate of increase for the “Other” series in the years since the Great Plummet so these components of the series were examined in more detail.Looking at the linear regression equations the rate of increase is higher (shown by the ‘x’ coefficient) and more stable growth pattern (shown by the value of R2) for the ‘other sites’ series.

The next step was to examine the characteristics of ‘other’ sites contributing most to the values of A over the last 10 years of the GBS. Without being able to offer definitive proof, due to lack of GIS software (and GIS skill) it appeared that most of these sites showing large aggregate numbers of Superb Fairy-wrens were either:
* closer to the edge of the built-up area (eg Crace, Jerrabombera and Isaacs) or
* rural sites (eg Hoskinstown, Carwoola, Gundaroo).
It also appeared – on the basis of eyeballing the database records - that one of the factors was an
increased recording rate for the study species in these “high scoring sites” rather than particularly high numbers at any point in time. This tends to be supported by the review of the R-statistic below.

Of course the standard summary statistics available from the GBS are not restricted to A. The following material summarises my review of some “all sites” graphs for the variables cited. The term ‘early years’ refers to years prior to Year 18.
F: Early years show pronounced growth from approximately 50% of sites reporting the species to approximately 80% of sites. Relatively little drop between years 17 and 18. Later years show a steady rate of close to 80%.
R: Early years show pronounced growth from approximately 15% of observer weeks reporting the species to approximately 35% of observer weeks. A very pronounced drop between years 17 and 18, followed by another period of growth from 20% to low 30%s.
G: Early years show a variable Group size ranging from 2.4 to 3.6 birds, with no clear trend. After a drop between 17 and 18 later years show a somewhat fluctuating, but significant, upwards trend from 2.8 to 3.7 birds per group.