Droopy Bats

To: Richard Loyn <>
Subject: Droopy Bats
From: Chris Corben <>
Date: Wed, 12 Jun 2013 12:14:30 -0500
Hi Richard - good to hear from you!

Thanks for your comments re Pink Robins.

And for those who are only interested in things with feathers, now is the time to delete!

So here's a short history of the Gould's Wattled Bat story, from my perspective.

In the late 80s, I was doing lots of bat recording in southern Qld, and one species which I really wanted to meet was Eastern Falsistrelle (FATA). I knew they were known from some of the higher mountain areas in the border ranges. One such location was Mt Tamborine, so I went there one night in the hope of finding them, but without any knowledge of what they called like. On the highest part of the mountain, I found a largeish Bat flying repeatedly along a road, and its calls were quite different from anything I had recorded before. So I assumed this was FATA, but in the long run, it turned out I was wrong.

Subsequently, I recorded the same calls in Tasmania and at a couple of localities in Victoria where I had been told FATA could be found. One of these was Camberville. So I felt even more convinced these must be FATA, since the calls were distinctly different from any Gould's Wattled Bats (CHGO) I had recorded elsewhere, and there simply wasn't any other species known to which they could apply.

Others were mislead by my incorrect identification of these bats, and I understand that a number of records of FATA were incorrectly based on my "reference" calls. Such is life, but I personally think that if you don't make mistakes, you aren't trying hard enough! But not a common view amongst birders...

Anyway, in the mid 90s, others were getting recordings of FATA and finding they weren't consistent with my calls. This wasn't totally convincing to me at first, because the calls I was shown were all based on recordings of released, captured bats, and at a stretch might have been compatible with the calls I had associated with FATA. Now, however, I have had a great deal of experience with FATA in Tasmania and Victoria, and there is no way I would now think my weird calls were FATA, and I have often recorded them at the same place.

So what are the "Droopy" calls I recorded at Mt Tamborine? Droopy maybe an unfortunate name for a cute little bat, but it is a very good descriptor of how their calls differ from other species. So it kind of stuck, for me anyway.

I have now spent a lot of time looking for and at Droopy bats, and I have no doubt they would be identified in the hand as CHGO (but I have never seen on in the hand). But their calls are different enough from non-Droopy CHGO to make them easily distinguished in most circumstances. To put this in perspective, they are much more easily distinguished from non-Droopys than say Greater Broad-nosed (SCRU) is from FATA or Scotorepens orion. There we have three different species in three different genera which are all hard to tell apart, yet Droopys and non-Droopys are almost always easy.

Droopy Bats live in the cool, damp forests of south-east Australia. They are the only repesentatives of CHGO in Tasmania, which is especially interesting since the type locality of CHGO is Launceston! They are common in the Otways of Victoria, and I have encountered them in the few places I have looked in the mountains of Victoria, and I found them common in the forests high in the Snowy Mountains. They seem to overlap with non-Droopys at some places on the edge of their range, such as Turourong Reservoir in Kinglake ( at least they seemed to in 2004!). Tumut in NSW is an interesting case - I spent some time there in Jan 2010. Around Tumut itself, around 300m ASL, I found no sign of Droopy Bats, but recorded non-Droopys in several places. Up the road from Tumut, above 1000m, they were overwhelmingly Droopy Bats and were reasonably common wherever there were trees. Despite the altitude difference, this is only a few km from the lowlands - I seem to recall the main climb is only 8 km.

I have also searched for them in a number of other places in NSW where I thought they might be likely to occur, but without success. I did not get to the Brindabellas, but would be very surprised if they are not there. I did not find them in the Blue Mountains, for example, or Mt Kaputar or the Gibraltar Range, or Ebor, and I have never encountered them in the Border Ranges or Main Range of Queensland, or in the high country around Stanthorpe.

Despite this, I have two sets of recordings from southern Queensland, the original one from Mt Tamborine and a much more recent occurrence near Blackbutt. I have been to both Blackbutt and Mt Tamborine many times since, without any hint of Droopy calls.

So what were they doing in Blackbutt and Mt Tamborine if they don't seem to be in the main habitats between there and the Snowy Mountains? An interesting question, but one with many feasible biological explanations. They might have been vagrants or there might be populations somewhere in the higher country of southern Qld which I haven't encountered yet, or they might be like Swift Parrots and get up to Qld sometimes. But there is another possibility - it might be just a stochastic thing. Since I have done so much recording of CHGO in southern Qld compared to anywhere else, maybe these are just bats on the extreme edge of the bell curve, and I was seeing droopy calls from non-droopy bats. But it is a hell of a coincidence to have first found these calls at a known site for FATA!

Droopy calls can be recorded from non-droopy bats when flying in lots of clutter, and likewise, Droopy Bats produce non-droopy calls when in very low clutter. It isn't like you can always be certain straight away if a bat is Droopy or not, though usually it becomes obvious if you watch the bat for a short while. The calls I had from Mt Tamborine and Blackbutt stood out as very different from the calls I usually see in southern Qld. It was what the bat typically does which matters, not the extremes it can produce. This is true of most bat acoustic identification issues.

So what are Droopy Bats? In my view, by far the simplest explanation is that they are a distinct species associated with the Bassian biological region. If that's true, it means most Gould's Wattled Bats seen on the mainland are not really Chalinolobus gouldii, but something else. I do not see this idea as being far-fetched or in any way surprising, and the distribution this bat shows has close parallels with some other species, such as Vespadelus darlingtoni and FATA.

If it is not a different species, then the situation is actually a lot more interesting, because it means there is something very strange going on with the echolocation system. Variable as bat calls are, it seems to me that echolocation systems of individual species are very conservative, and when differences of this magnitude are found, it is because unrecognised taxa are involved. Several people have suggested a number of alternatives, such as the droopy calls are a response to low temperatures, or high humidity or some other local variable. But do you really think Tasmania is so consistent that the temperature is always lower than southern Qld? Of course not. It may be that my observations are heavily biased by some factor of which I am unaware, which is causing me to see things this way. But all these things can and should be tested, and I would put my money on different biological species!

Cheers, Chris.

On 06/12/2013 05:48 AM, Richard Loyn wrote:
Hi Chris, I'm not convinced that Pink Robins make the crossing, in contrast
to Flame Robins.  HANZAB says there is no evidence for such crossings, and
Tasmanian birds are subspecifically distinct (slightly longer-winged).

In Victoria (as you know) adult male Pink Robins mainly remain all year in
their breeding territories in cool temperate rainforest or wet mountain
forests with similar structure, along with some brown birds (perhaps mainly
adult females), although they  tend to forage in more open situations
(including log landings). A few adult males and lots of brown birds move
into drier habitats for the winter, in foothill forests and in shady
multi-stemmed habitats such as coastal teatree thickets, also in
box-ironbark & regrowth river red gum, etc.

It's a similar story in Tasmania.  Reporting rates go up in winter in both
states because birds are more widely dispersed and found in more accessible
places.  There are records from Bass Strait islands (King & Flinders),
apparently referring to resident populations of the Tasmanian subspecies. I
don't know of any reports of falls of Pink Robins on Bass Strait islands or
the Victorian coast, whereas such events are quite often reported for Flame

I hope this helps a bit.  I wouldn't be surprised if occasional Pink Robins
crossed the strait but it seems there's no generally accepted evidence for
it and I suspect it's the exception not the rule.  It may be worth checking
various reports of bird observations on small Bass Strait islands.

I look forward to hearing more about the boobooks and the Gould's wattled

Cheers, Richard.

Richard Loyn
Eco Insights


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