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Message: <blockquote data-quote="Scelorchilus" data-source="post: 1937931" data-attributes="member: 29410">I am a tad surprised at the discussion on learned vocalizations. Fringillids are well known to learn song, not only that they learn calls which is highly unusual in passerines. On the other hand they do some weird stuff like call matching between pairs, and seem to sort each other out into single call type flocks based on these learned calls. It is complex, and this is why crossbills have not been a shoo-in for consideration as different species. The calls are learned but at the same time they are used for identification/segregation of groups, this tendency to mix with those of your own call type may be culturally facilitating specialization. The problem is that you need only a few to mix with the wrong gang in populations to keep gene flow alive.      To get a handle on the crossbill issue it would be good to study some other related finches that show geographic variation in call type. Three in North America are Pine Grosbeak, Evening Grosbeak, and Purple Finch....I wouldn't be surprised if Pine Siskin also fits the bill (ahem). The three mentioned above have identifiable call type differences but they stay within their own separate geographic areas, at least most of the time. It would be interesting to do molecular as well as vocal playback work on these simpler systems to understand fully the role of call type in differentiation. Then these results can be applied to better understand or resolve which populations or call types in the Red Crossbill could in fact have reached species thresholds, versus some NEW type of within species variation that is yet unnamed (subspecies does not work in this case as noted above). Alvaro.</blockquote>

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