Tony,
I suspect the harsh response from Chris was driven by the tone of some emails that stated that because the two forms of Sooty Owl are field diagnosable than they were clearly good species and ergo C&B and the taxonomists are wrong.
Apperance is one element that can help you determine whether a group of birds is a species or not, but there are plenty of birds that look different that are in fact the same species responding to different ecological factors in a particular part of the range with very little ‘real’ difference beyond how they look. Given enough time they might be sufficiently differentiated to be called species. In a few million years you might get your wish and the Sooty Owl populations are formally split. Alternatively the ecological circumstances that might drive current variation between the appearance of the populations might level out and there will be less difference. Who knows.
At the same time there are plenty of examples of good species that are very difficult to diagnose in the field. There is an interesting case with logrunners uncovered some years back (and people keep uncovering new crossbill species!) where birds the birds in New Guniea and Australia are indistinguishable in the field but diverged millions of years ago and are genetically very different.
At the end of the day, you can of course keep your field notes and lists however you like. Species limits and individual diagnoses are always open to debate and revision in closely related populations. But I would caution against reducing the science to ‘it looks different so it must be another species’….
mjh ===============================
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