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Message: <blockquote data-quote="RoyW" data-source="post: 1934669" data-attributes="member: 71737">Personally I think that the only question in the Crossbill species debate is "where exactly do we draw the line when defining two separate species?".There is one very good example of a species that has 'sub groups' with clearly different vocalisations, and which can now be found co-habiting the same areas throughout the year - often with very limited interbreeding between the different 'groups'.I realise that it is generally considered 'politically incorrect' to even suggest that the same subspecies/race concept that we apply to other animals can be applied to humans (I think partly because the term 'subspecies' can be taken as an implication that one or more races are 'below' others), but I do think that comparisons can be made.So the crossbill scenario (as I understand it) is that there are groups that can be separated by different vocalisations but (in most cases) have been found to be practically indistinguishable genetically, and physical differences are so slight that they are of no practical use. The idea that these should be treated as different species is apparently supported by the fact that they can be found breeding in the same areas with limited interbreeding between groups with different vocalisations.The human comparison: There are groups that can be separated by vocalisations (I can recognise several languages even though I may not understand them, and there are easily distinguished regional differences even within a country). Genetic differences are apparently slight, but physical differences can sometimes be obvious - although not necessarily linked to differences in vocalisation. Finally (and this may be disputed by some), although humans from all parts of the world can be found in the same cities, there is relatively little interbreeding between groups with different vocalisations (languages). I doubt that anyone can disagree that wherever there are immigrants into a country, communities of people with the language and culture become established. There is obviously some degree of mixing between people from different countries, but I think that it is fair to say that this is clearly restricted if one person does not speak the language understood by the other.Returning to the crossbills - perhaps there is mixing, and interbreeding, between different 'vocal groups'. If this were the case, surely it would be most likely when a bird from one group learnt the calls/song used by another group and then started using these when associating with birds that use these different calls? Exactly the same as humans learning, and using, another language to allow them to communicate and mix with another group.It may well be that crossbills are best treated as a number of different species, personally though I'm yet to be convinced, and until a lot more research is available I think that it is better to be conservative with regard to the number of species (I'm not even convinced that Scottish Crossbill is really a valid species!<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink    ;)" loading="lazy" data-shortname=";)" />).</blockquote>

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