Discussion on the Evening Grosbeak and Red Crossbill

Ok, last discussion I’m going to bring up today. There’s been conflicting opinions on how we should curate the Evening Grosbeak (Coccothraustes vespertinus) subspecies.

Right now the Clements checklist only accepts 3 subspecies of Evening Grosbeak named as follows; brooksi, vespertinus and montanus. In 2018, Matt Young, finch expert, released his report that Evening Grosbeak was a species like the Red Crossbill (Loxia curvirostra) in which they have call types. These “types” are geographic variations of a species in which the flock stays together with a call only distinct to that type. These calls differ and has been deemed grounds for calling these types subspecies. Here’s the problem, Young described five different call types and as follows:

C. v. brooksi Type 1
C. v. californica Type 2
C. v. vespertinus Type 3
C. v. warreni Type 4
C. v. montanus Type 5

As you can tell there are two “new” subspecies. Young made the statement in his report that… “Our use of the subspecies names with the call types above should be considered a scientific hypothesis, yet to be established in peer-reviewed literature.”

Here’s the problem we encounter on iNaturalist. One, all of these call types are identifiable and what if an observer posts a Type 2 or Type 4. Neither of these birds fall under any subspecies besides there is no taxon to represent them. Two, since these two “new” subspecies are undescribed, that means they have not been implemented into the Clements Checklist. And three, even if a peer-reviewed paper is released and it formally described the two new subspecies, the chances of the AOS actually accepting it is slim as they have not bothered with subspecies taxonomy since the 70’s unless that subspecies had the possibility of being elevated to species level. That means the Clements Checklist won’t update with the paper.

The same thing goes for the Red Crossbill. Types versus subspecies as follows below.

Type 1 – Probably pusilla but maybe neogaea (synonymized taxon). Recommended to describe an entirely new subspecies for this type.
Type 2 – Subspecies benti is most appropriate but has been used interchangeably with Type 5.
Type 3 – Probably minor but name already attached to Type 10. Describing a new subspecies is probably best.
Type 4 – Possibly vividior but that’s currently not an accepted subspecies.
Type 5 – Subspecies bendirei is most appropriate but has been used interchangeably with Type 2.
Type 6 – Subspecies stricklandi
Type 7 – Unknown but possibly not accepted subspecies neogaea or Type 1’s pusilla.
Type 8 – Probably percna
Type 10 – Maybe sitkensis
Type 11mesamericana

Keep in mind that the only type with a confirmed subspecies in ebird is Type 11. So there is more taxonomic issues with the crossbill and grosbeak.

So when observers report these birds unto iNat, what are we going to about that. Here’s the two suggestions given.

  1. We start creating “forms” on iNat as a taxonomic level below subspecies or perhaps to replace subspecies in species like the Evening Grosbeak and Red Crossbill.

  2. We deviate from the Clements checklist and just create the subspecies that represent the forms.

Open to comments and discussion.

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Or just use an observation field for the relatively small proportion of observations where type is actually discernible? I think anything else is a bit premature without some more study into how differentiated these types really are, especially in Evening Grosbeak. I know there are documented cases of Red Crossbills switching call type to match others.

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I forgot to mention @reuvenm suggestion, it was one I had in mind but it occurred to me while discussing a totally different topic on the forum, other observations that might need “forms”. So here’s my list:

  • Evening Grosbeak Types

  • Red Crossbill Types

  • Scientifically speaking, a Brewster’s and a Lawrence’s Warbler is just a dominant and recessive form of the Blue-winged × Golden-winged Warbler hybrid.

  • Until further research is conducted, the Red-tailed Hawk subspecies abieticola should be treated as a form.

Comments, concerns?

This list of examples you have given are not really analogous to each other and I don’t think they should be treated as such.

The grosbeaks and crossbills are possibly distinct, reproductively isolated species, we just don’t have sufficient information.

The difference between Brewster’s and Lawrence’s is not a taxonomic one, it’s purely based on appearance. It doesn’t seem much different to me than e.g. light vs. dark morph buteos or jaegers - we wouldn’t use taxa to distinguish them on iNat. It’s really only historical accident that we have widely-used common names for different appearances of the same entity (hybrid GWWAxBWWA).

This subspecies doesn’t seem any worse than many other subspecies designations that nobody uses. It’s just that people try to identify them and its very unclear how viable that actually is. I’m not really sure what the downside is in continuing to call it a subspecies, when subspecies practically by definition have fuzzy boundaries. Its clearly not reproductively isolated from other hawks like the grosbeaks and crossbills seem to be, and I don’t think it should be treated the same way.

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