My friend told me that they were proposing to lump the Cassia Crossbill back in with the Red Crossbill. I can't find anything anywhere about this. Am I getting blown smoke or is this legit? The Cassia Crossbill is found mostly in Southern Idaho (USA), but has ventured into California at times. Anyone else heard of this possible lump with the Red Crossbills?
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Cassia Crossbill being lumped again??? (2 Viewers)
- Thread starter DHayden
- Start date
DMW
Well-known member
Yes, I've seen it mooted. There's currently a wave of re-lumping as the major taxonomic bodies conform their lists into a single unified one, and I believe both Parrot and Cassia are potentially on the chopping block. Which isn't to say they won't get un-lumped at some future point.
hookem2010
Well-known member
I know one of the primary reasons they were split is due to supposedly residing in a single patch of woods in Idaho. However, with birds being found in Colorado, I believe they are questioning if there isn't more genetic flow with other than red crossbills than previously thought.
Bismarck Honeyeater
Barely known member
And California, I believe.
raymie
Well-known member
Just an individual record from California though, whereas there appears to be a decently-sized population of the species in Colorado and Wyoming.
Mysticete
Well-known member
pbjosh
missing the neotropics
Just one guy’s opinion but it seems a dodgy split - almost as much so as Scottish Crossbill. One of the factors though is the amount and quality of work that has gone into Crossbill research in the US. It’s super cool and a lot of really neat findings and valuable knowledge come out of it. But this also perhaps sways the “is it a species” decision making while other apparently far more differentiated species, particularly in Mexico and Central America, still languish.
raymie
Well-known member
It's definitely crazy to me that we got this split before even some obvious ones in North America. Like, Steller's Jay is right there.
Farnboro John
Well-known member
So instead of being an "unusual" sedentary crossbill sp it turns out to be exactly the same as all the other Common Crossbills: irruptive and turning up "out of range". How are the birds in the new locations being determined? Call, measured dimensions or genetics? Lump it and Scottish (and Parrot if it helps) into Common where they belong and go and study something more interesting.
John
Bismarck Honeyeater
Barely known member
I wonder if all the Crossbills could have the same sort of twisted DNA (scientific term🤣) that the Redpolls have? In which case they could just be one.
hookem2010
Well-known member
I believe call
Farnboro John
Well-known member
Oh yeah, the factor that changes over time within populations and which birds can learn to mimic from less-closely related brethren.....
John
Mysticete
Well-known member
Keep in mind whether something is one or two or however many species is usually not the driving reason any scientist studies something, and is seldom the most interesting finding. Species are after all artificial bins we sort organisms that are not exist out of convenience and the human desire to categorize things, rather than being some sort of fundamental aspect of reality. Crossbills are studied because they provide a good model to understand how sympatric speciation can happen, and how slight morphological changes associated with specialization can spur the development of new species over time. That doesn't change if you think they haven't reached species level or not. From that angle, crossbills are incredibly interesting, especially given their distribution means they can be studied without long trips to poorly surveyed foreign destinations.
Farnboro John
Well-known member
Surely that is only true if they are speciating and not just demonstrating that species can do a number of things with variations and still not speciate (which I believe to be the case)?
Incidentally the holarctic distribution of what I believe is Common Crossbill - as well as its irruptive behaviour - doesn't sit well with your travel suggestion.
John
jurek
Well-known member
Actually, crossbills do precisely the opposite - they don't speciate. The lack of DNA differences proves that. Although conifer species with cones of different sizes are older than the divergence of crossbills from redpolls, and there is little doubt that different foraging efficiency associated with different bill sizes and cones is constant over time. So they are a good proof that at least one biological theory is false.
The very low difference in bill size, lack of other differences, plus the ability to change and learn calls mean that individual crossbills which change to a different form are generally indistinguishable from the new form.
As a birder, I will not miss the red crossbill lump. All red crossbills look and behave the same, so seeing different crossbills is a repetitive experience. That other birds are often almost identical, too, does not make looking at different crossbills any less repetitive.
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Kirk Roth
Rarely to be taken seriously
You can search up the paper that led to the Cassia Crossbill split - the DNA differences were precisely the justification.
What I found most interesting in that article was the inclusion of a graphic which showed Cassia in a discreet node, and also the Strickland's crossbills (Mexico and the Arizona sky islands) in their own node. Otherwise, the call types were all mixed as you imply.
What makes these so interesting is that their differentiation is so complex and dynamic. With relation to taxonomy, we don't talk about generational timing, nomadism, call types, temporary species, cultural plasticity, gene clusters, and on and on except for these and a few other finches.
Mysticete
Well-known member
Speciation is a continuous process. It's not a switch that suddenly flips and now something is a new species. You need variation to effect changes, and seeing how that variation initially evolves and changes is important for understanding how speciation works. Sometimes that variation will become the basis of a new species. Sometimes it will disappear entirely. Crossbills, showing a degree of morphological change that suggests a very early phase of speciation, is good for looking at this.
Also you don't really need to look at every single crossbill population in the world to study this stuff. It's not like Chinese Crossbills are showing up in Colorado; The North American populations are on there own separate evolutionary trajectories from Old World populations. I don't know enough about Old World Crossbills to know how much gene flow is going on between the different subspecies there.
Paul Chapman
Well-known member
WGAC are only looking at conflicts between the lists currently so I expect no change on this yet.
I looked up Cassia Crossbill records on eBird. I enjoyed the Californian extralimital ones. It seems at least as much fun as Scottish Crossbill.
Having spent some time on some of the taxonomic decision-making - Green-winged Teal & Scopoli's Shearwater - to be honest, I would probably get as sensible a discussion on an overnight twitch. On the marginal calls, some fall one side and some fall the other without any really strong difference in the underlying data in my view.
Some simply seem to have inconsistencies. Whilst the cutting edge identification articles on Scopoli's Shearwaters suggest almost one third are unidentifiable in the field, the scientific evidence shows little or no hybiridisation. How can they tell?
All the best
Paul
I looked up Cassia Crossbill records on eBird. I enjoyed the Californian extralimital ones. It seems at least as much fun as Scottish Crossbill.
Having spent some time on some of the taxonomic decision-making - Green-winged Teal & Scopoli's Shearwater - to be honest, I would probably get as sensible a discussion on an overnight twitch. On the marginal calls, some fall one side and some fall the other without any really strong difference in the underlying data in my view.
Some simply seem to have inconsistencies. Whilst the cutting edge identification articles on Scopoli's Shearwaters suggest almost one third are unidentifiable in the field, the scientific evidence shows little or no hybiridisation. How can they tell?
All the best
Paul
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