Sunday, July 11, 2010

Little Tassie Battler..........40Spotted Pardalote

A recent article in Wingspan (Birds Australia's magazine) highlighted the plight of the Forty-spotted Pardalote, a species endemic to Tasmania. In essence, the article showed that there has been a marked decline in numbers, from an estimated 3,520 birds in 1986-7, to only 1500 or so in the latest survey, conducted in 2009-10. This iconic Tasmanian bird, one of our smallest species, has long been on the endangered list.

40spots are around 10cm in length and they spend much of their life in the outer canopy of eucalypts, and anyone who has looked for them knows just how difficult they can be to find. Probably never numerous, they're found mainly in White Peppermints Eucalyptus viminalis, known as Manna Gums, a species naturally found along the coasts of south-east Tasmania. Colonies are found mainly on Maria and Bruny Islands and on the Tinderbox Peninsula south of Hobart.

The article speculates the reasons for the decline, suggesting climate change, drought and die-back disease in eucalypts.

In recent years I and many visiting birders, have looked and found them in the Peter Murrell Reserve at Kingston, south of Hobart. During my visits this last autumn, I have only occasionally seen them there, and always at the same location. To be fair, I haven't made a point of looking for them, and only found them because I heard them calling. But my overall impression is that there are very few about, and this impression is typical of other birders experience.

I am not a biologist, but my concern is that we seem to know surprisingly little about these birds. It's well known that a major food source is "manna", the conical scales spun by lerp species on the underside of eucalypt leaves. These sugary scales are known as honeydew, and are also eaten by a range of birds, including Black-headed, Yellow-throated, and Crescent Honeyeaters. These lerps are considered a pest as they skeletonise the leaves, which in turn can have an impact on the wellbeing of the tree. My observations locally suggest that there is a paucity of these insects on eucalypts this winter, so is this the "x factor"? Two winters ago the numbers of lerp 'infested" trees was considerable, and many Striated Pardalotes overwintered rather than migrate to the Mainland as they normally do. Were the numbers of lerps the reason?

Obviously the above is just my observations, and only in a small area of the state, but to my mind it does highlight some of the gaps in our understanding of what makes pardalotes 'tick'.

A much greater effort needs to be applied to the wellbeing of the 40Spot and soon. The degrading of the Peter Murrell Reserve, with ever more recreational activity and industrial and housing development on the surrounds, suggests that we're not taking this issue seriously. A more proactive approach is called for.

NB. The accompanying images were taken at the Peter Murrell Reserve about 2 1/2 years ago. I noted that these birds were regularly coming down to a bush on the side of a hill, and was grateful for a relatively easy chance to photograph them. I surmised they might be feeding nearby young, but they didn't appear to be carrying food and were unfazed by my presence. I moved away to better understand what was going on. They were in fact visiting a nest site situated behind a thick piece of bark near the base of a Manna Gum. Further watching revealed that the visiting birds were mainly juveniles, and that a family of 40spots appeared to be using this as a "funk" hole.


Penny said...

Great post on a ‘gem’ of a bird. During the last breeding season I noticed several pairs of 40 Spots on the Tinderbox Peninsular were in an advanced stage of moult prior to juveniles fledging – perhaps the wet and cold winter was also an added stress. Excellent photos BTW.

Snail said...

I saw these sweet little fellows on a property on Bruny Island a few years ago

It's unfortunate that we know so little about so many species.

BirdingTas said...

Thank you Penny and Snail.
I intended to write much more, but have been suffering from severe sinusitis, and cut it short(ish).
I pondered whether actually introducing lerps to manna gums was feasible or even deirable? Are gums under stress more likely to be attacked? More gums are being planted, but this takes time. These are issues that seem worthy of study.
Funding seems to be more likely to be forthcoming when species are endangered, rather than when decline is observed.
From my observation (first hand), biologists spend too much of their time having to chase funding, rather than on science. There is the potential for greater use of amateur birders to be seriously involved in projects, overseen by biologists. But there appears to be a reluctance to do this, possibly because of limited funds available, and a degree of antipathy between the two.