|To:||Birding-Aus Mail <>|
|Subject:||RE: Atlas Results|
|Date:||Tue, 27 Jun 2000 13:40:08 +1000|
No, Steve Clark, you are not 'completely out of line here' and thanks to Steve, Frank O'Connor and David Geering for providing some necessary criticism of this data and its analysis. I'm going to add to it: nothing personal, Rory, but this stuff is potentially misleading.
I find the list of species that are purported to have declined in reporting by >40% very interesting. I have encountered all but three of these during Atlas surveys (and since nearly all my Atlassing is done in western Qld I think I can be forgiven for not seeing Little Penguin and Red-browed Treecreeper yet). Most of the listed species I would encounter regularly and many of them commonly. From my perspective, here in western Queensland, the notion that Emu, Bustard, Singing Bushlark and Richard's Pipit are declining species is simply laughable. And the reason I make this point is that this preliminary analysis has nothing to say about the geographic area involved nor the variation in search effort over that area. Emus, for example, may well have declined in some areas where a high level of survey effort goes on (e.g. Victoria - look at the Atlas map of survey effort on the BA website to see where the best coverage is so far). In contrast, thanks to a run of three wetter-than-average years up here, Emus are doing very nicely. I recently saw a mob of 42 just east of Mitchell (about 90 km west of Roma) and see plenty throughout the west. However, I suspect that the survey effort up here does not compare with say Victoria and that Emus and other species are simply under-reported. The end result? - a distortion of the overall picture. Frank has raised similar issues about WA, where the effort is much higher this time around. As he asks, is the analysis 'standardised...to adjust for different reporting for each state'?
David's comments on sampling bias are also very important. Birders do tend to go for 'birdy' spots. I'm a bit of a grasslands freak but am the first to admit that birding them can be a bit quiet! Hence, grassland birds, especially the less conspicuous ones, will be under-reported. The problem of observer effort under the differing Atlas methodologies that David describes is spot on, too. Like David, I try to log incidentals but often don't, so birds go unreported. If I was simply writing them down at the end of the day for a 10' or even one-degree square, I'd be much more likely to record them. In case anyone's wondering - no, I didn't Atlas that mob of 42 Emus.This says as much about my level of commitment as it does about the results of analysis, but the thing is that it's an important artefact of the methodology that should be taken into account when making comparisons between the two Atlasses.
A final point - assuming the decline in ground birds is real, the cat/fox impact conclusion is drawing a very long bow in my opinion. I suspect cats and foxes have had an impact historically on ground birds of western Qld and may still suppress/eliminate some of these species, e.g. Squatter Pigeon, Flock Bronzewing, Bush Stone-Curlew, over much of their former range. But foxes have been at work for 150 years; and at least 200 in the case of cats. Why should they suddenly be having a major impact on the apparently more resilient species over the last two decades?
Why am I writing such a long-winded response to this posting? Not, as some might suggest, to make a pain in the arse of myself, but because of the potential harm this can do. This sort of material is OK if confined to a group that can examine, question and perhaps correct it. Unhappily though, this kind of stuff often gets a life of its own. I dread the thought of hearing some news announcer blithely putting this out on the airwaves then having to explain to a laughing group of farmers that: yes, the TV/radio people did get it wrong and, yes you're right, there are heaps of emus around here, but no, that doesn't mean that those city conservationists are full of it, and that there are no conservation problems out here. Get my drift?
Over to you, Rory. Sorry to be so negative and like I said, nothing personal intended. I just don't think the analysis has been demonstrably rigorous enough. Any comments?
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