Hi all
We are now one year into the Atlas Project and we have recently begun to
look at the results coming out of the data. The initial analyses has mainly
focused on comparisons with the first Atlas (1977 - 1981) by comparing
Reporting Rates for both Atlases. Reporting Rates can be seen as a crude
measure of abundance.
As we have only one years data to analyse we have only been able to look at
gross changes in Reporting Rates for the more common species. That is,
changes of greater than +or- 20% in Reporting Rates compared to the first
Atlas.
We have produced Change Maps (+ or -) of Reporting Rates for a number of
species.
Highlights for the comparison of Reporting Rates between Atlas1 and Atlas2:
Where: +ve change = increase in Reporting Rate of >20% since the first Atlas.
-ve change = decrease in Reporting Rate of >20% since the first Atlas.
Doves/Pigeons, strongly +ve change in Reporting Rates
Ibis/Herons (and some water birds), strongly -ve change
Raptors, strongly -ve change
Rosellas/Lorikeets, strongly +ve change
Thornbills/Wrens, strongly +ve change
Honeyeaters, strongly +ve change
Butcherbird/Currawong/Corvid, strongly +ve change
Sparrow/Starling, strongly -ve change
Blackbird, strongly +ve change
Richard's Pipit, strongly -ve change
Grey Fantail, strongly +ve change
Jacky Winter, strongly -ve change
Emu, strongly -ve change
Some of these findings support anecdotal evidence and we are encouraged by
these results.
What we seem to be seeing from the results is that the species still cover
their former range but the abundance (derived from the Reporting Rates)
changes.
So a -ve change in Reporting Rate for a species means that species is
'thinning' out within its range, and not necessarily a change in its range.
However, there is probably a threshold for each species at which the range
does change (contract or expand).
For many species there is insufficient data collected for proper analyses
as large areas of inland Australia (including western NSW and western QLD)
have been inadequately surveyed. This is a big challenge to adequately
survey much of inland Australia.
The current findings may be an artefact of time frame aberrations. Climatic
conditions during both Atlas periods may also have a bearing on the
results. At the time of the first Atlas eastern Australia was experiencing
one of its most intense droughts on record. Recent climatic conditions for
eastern Australia have been quite different. And of course human influences
since the first Atlas period may affect the results.
The different methodologies between the two Atlases complicate analyses.
The first Atlas used a grid block method of data collection whereas the new
Atlas uses point based surveying.
Overall the Atlas project is progressing extremely well.
Rory Poulter
Rory Poulter
Database Curator
Birds Australia Atlas Project
415 Riversdale Road
Hawthorn East VIC 3123
(Ph) 03 9882 2622
(Fax) 03 9882 2677
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