On Little Eagle breeding decline

To: <>, <>, "Harvey Perkins" <>, "Stephen Debus" <>
Subject: On Little Eagle breeding decline
From: "Philip Veerman" <>
Date: Mon, 6 Mar 2006 15:58:30 +1100
An interesting article in the CBN just out CBN 30(4)141-145, about Little Eagle decline, provides evidence of reduced breeding by the species locally. That may well be so and I would not doubt it. It is concerning. However it mentions a comparison with GBS data that supposedly doesn't support the same conclusion. I hasten to point out that they are measuring different things. Reported abundance, as surveyed in the GBS, can increase when suburbs encroach on or come closer to former nesting sites of the species. The species can still be present in the area but suffer reduced breeding. Indeed if they are spending less time at a nest, then they may well be spending more time flying over the suburbs and so be seen more often by GBS observers. So I don't see the results as conflicting at all. Indeed I suggest that is what has happened. For a species that may live for many years, there will easily be a delayed effect in breeding but not in presence. It is disappointing to see the GBS data mentioned as data not in harmony, when this approach was not at all necessary without explaining how the two sets of information fit together. Besides the GBS Report only summarised what the data shows.
As for the suggestion of misidentification, I don't agree at all. It can be argued that almost any bird in any survey can be misidentified but that is hardly helpful. In practise it is hard to confuse a Little Eagle for anything else locally, apart from a Whistling Kite and Black Kite. People would not record an ID on the GBS of something as different as the other species mentioned, if they are that unsure. The culture of the GBS has always been to be confident of the accuracy of your ID. In any case, it is obvious from the figures given in the report that the numbers of GBS observations of the Whistling Kites and Black Kites are so low, that even if every single Whistling Kite and Black Kite GBS record in the history of the GBS was in fact a Little Eagle (or indeed real Whistling Kites and Black Kites recorded as Little Eagles), then the quantitative difference would be so low it would barely impact on the statistics for the much more common Little Eagle. Besides the misidentification issue only arises on assessing trends, if relative rates of misidentification have changed over the years, (in particular in this case increased). I doubt it. With the increased number and availability of several good field guides and things like the couple of Raptor ID workshops that COG has run over the years (to which Jerry Olsen, myself and others contributed), identification accuracy rates should have improved since 1981, not decreased. This is another factor consistent with the slight suggestion of increased status for the Little Eagle in the GBS (more people able to identify them). However it is not at all inconsistent with a reduced breeding status of the species. Fair opinion that in the long term that is what is important.     
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