tomjenner
Well-known member
Discussion thread for Sharp-shinned Hawk. If you would like to add a comment, click the Post Reply button.
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Sharp-shinned Hawk (1 Viewer)
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tomjenner
Well-known member
It is a shame that these pages have now been merged. Most authors (including all field guide authors) consider the White-breasted Hawk to be a separate species and most South American field guides split them. Ferguson-Lees and Christie lumped them in their 2001 "Raptors of the World", but then changed their stance and split them in their later field guide version.
The main reason for lumping them is because the AOU is still undecided so is sticking with the status quo (based on fairly ropey evidence in a 1952 Condor paper by Storer). As a result of this there are several checklists that lump them because they follow the AOU. Yet there are many other checklists that still split them. SACC, which is the South American offshoot of the AOU (I'm not quite sure of the relationship), states on its website that the split is almost certainly valid, but that it is pending a proposal.
There are also peer reviewed journals that retain the split. The main recent paper on one of the South American forms by Seipke and Cabanne in Ornitologia Neotropical treated Rufous-thighed Hawk as a full species and my own paper on the White-breasted Hawk which is due out soon in the same journal also treats them as separate.
It seems likely that these forms will soon be officially split by the AOU (in keeping with pretty much all other organisations) and when that happens we will have to disentangle the current mix of info on this page.
Another problem we have with this is that the merged information is not clearly assigned to the relevant "subspecies". The main photo shows a juvenile without stating the subspecies, yet the juvenile plumage of White-breasted Hawk is completely different. There are differences in vocalisations of the different forms that I have tried to separate out. We now have the breeding season as starting in November, which is only true of the sedentary forms of Middle America and the Caribbean, while migratory forms have a much shorter breeding season and southern hemisphere forms are different altogether. There are major plumage differences between the different forms, both of adults and juveniles (especially the highly variable Plain-breasted Hawk) that are no longer clear in this merged format.
Until recently the pages were kept separate, but with the note "marked for merging", or something similar. I feel that this was a better situation.
Tom
The main reason for lumping them is because the AOU is still undecided so is sticking with the status quo (based on fairly ropey evidence in a 1952 Condor paper by Storer). As a result of this there are several checklists that lump them because they follow the AOU. Yet there are many other checklists that still split them. SACC, which is the South American offshoot of the AOU (I'm not quite sure of the relationship), states on its website that the split is almost certainly valid, but that it is pending a proposal.
There are also peer reviewed journals that retain the split. The main recent paper on one of the South American forms by Seipke and Cabanne in Ornitologia Neotropical treated Rufous-thighed Hawk as a full species and my own paper on the White-breasted Hawk which is due out soon in the same journal also treats them as separate.
It seems likely that these forms will soon be officially split by the AOU (in keeping with pretty much all other organisations) and when that happens we will have to disentangle the current mix of info on this page.
Another problem we have with this is that the merged information is not clearly assigned to the relevant "subspecies". The main photo shows a juvenile without stating the subspecies, yet the juvenile plumage of White-breasted Hawk is completely different. There are differences in vocalisations of the different forms that I have tried to separate out. We now have the breeding season as starting in November, which is only true of the sedentary forms of Middle America and the Caribbean, while migratory forms have a much shorter breeding season and southern hemisphere forms are different altogether. There are major plumage differences between the different forms, both of adults and juveniles (especially the highly variable Plain-breasted Hawk) that are no longer clear in this merged format.
Until recently the pages were kept separate, but with the note "marked for merging", or something similar. I feel that this was a better situation.
Tom
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Hi Tom, and thank you for this feedback and for the edits you have made to improve this page. The policy of the Opus is that the taxonomy follows Sibley and Monroe 96 but with changes made if Clements and Howard & Moore agree. Based on that policy, the merge should happen.
However, if the situation does change in the future, to a point where the two should be split again (or even a three way split as you hint), then the information you and others had entered for White-breasted Hawk will actually be fairly easy to reinstate. The history function of pages will allow the saved page just prior to the merge to be displayed again.
Cheers
Niels
However, if the situation does change in the future, to a point where the two should be split again (or even a three way split as you hint), then the information you and others had entered for White-breasted Hawk will actually be fairly easy to reinstate. The history function of pages will allow the saved page just prior to the merge to be displayed again.
Cheers
Niels
Hi Tom,
I have one more question: you seem to count the White-breasted Hawk as a monotypic species, while Clements include madrensis in this group. Where should madrensis really go, is it included as a synonym of chionogaster in your thinking or is it in the northern group?
thanks
Niels
I have one more question: you seem to count the White-breasted Hawk as a monotypic species, while Clements include madrensis in this group. Where should madrensis really go, is it included as a synonym of chionogaster in your thinking or is it in the northern group?
thanks
Niels
tomjenner
Well-known member
Hi Niels
I don't have a copy of Sibley and Monroe, but from what I have seen on the internet, they recognise the Sharp-shinned hawk complex as 4 different species - including White-breasted Hawk. Consequently, if Birdforum follows Sibley and Monroe, the species should remain separate.
A. s. madrensis is a subspecies of Sharp-shinned Hawk, not White-breasted Hawk. Indeed, the main reason for much of the confusion in whether to lump or split the two forms relates to the original description of A. s. madrensis by Storer in 1952. It has very pale underparts, which led Storer to draw a conclusion about it forming a bridge between Sharp-shinned Hawks to the north and White-breasted Hawks to the south. However, Burt Monroe (of Sibley and Monroe fame) was critical of Storer's conclusions in his book on the birds of Honduras. I don't have a copy to hand at the moment, but he quite rightly discusses the fact the Storer looks at this one feature while ignoring many others. Major differences between madrensis and chionogaster include: Yellow adult irides in madrensis and red in chionogaster, paler grey upperparts in madrensis and dark grey (almost black) in chionogaster, barred underparts in madrensis and unbarred underparts in chionogaster, plus madrensis being much larger. Almost nothing is known about madrensis, so there is no way to know what differences in behaviour exist. My recent paper in Ornitologia Neotropical highlights a number of differences between chionogaster and other better studied subspecies of Sharp-shin.
Storer's paper is the only peer reviewed publication that makes a recommendation about the taxonomy of these two forms, so with nothing else to go on many taxonomic bodies tend to follow his recommendation (specifically, many actually follow the AOU, who state that the split is probably good but no published data support the split). I have not gone into the taxonomy much in my paper. Hopefully someone will soon do a genetic study of the different forms. My guess (based mainly on plumage and structure) is that chionogaster is more related to the South American form ventralis (Plain-breasted Hawk) and that the link to northern forms is more likely to be through the West Indies than Middle America.
Tom
Jenner, T. D. (2010) Life history of the White-Breasted Hawk (Accipiter chionogaster). Ornitologia Neotropical 21: 157–180, 2010
Monroe, B. L. Jr (1968). A distributional survey of the birds of Honduras. Ornithological Monographs No. 7. AOU.
Storer, R. W. (1952). Variation in the resident Sharp-shinned Hawks of Mexico. Condor 54: 283-9.
I don't have a copy of Sibley and Monroe, but from what I have seen on the internet, they recognise the Sharp-shinned hawk complex as 4 different species - including White-breasted Hawk. Consequently, if Birdforum follows Sibley and Monroe, the species should remain separate.
A. s. madrensis is a subspecies of Sharp-shinned Hawk, not White-breasted Hawk. Indeed, the main reason for much of the confusion in whether to lump or split the two forms relates to the original description of A. s. madrensis by Storer in 1952. It has very pale underparts, which led Storer to draw a conclusion about it forming a bridge between Sharp-shinned Hawks to the north and White-breasted Hawks to the south. However, Burt Monroe (of Sibley and Monroe fame) was critical of Storer's conclusions in his book on the birds of Honduras. I don't have a copy to hand at the moment, but he quite rightly discusses the fact the Storer looks at this one feature while ignoring many others. Major differences between madrensis and chionogaster include: Yellow adult irides in madrensis and red in chionogaster, paler grey upperparts in madrensis and dark grey (almost black) in chionogaster, barred underparts in madrensis and unbarred underparts in chionogaster, plus madrensis being much larger. Almost nothing is known about madrensis, so there is no way to know what differences in behaviour exist. My recent paper in Ornitologia Neotropical highlights a number of differences between chionogaster and other better studied subspecies of Sharp-shin.
Storer's paper is the only peer reviewed publication that makes a recommendation about the taxonomy of these two forms, so with nothing else to go on many taxonomic bodies tend to follow his recommendation (specifically, many actually follow the AOU, who state that the split is probably good but no published data support the split). I have not gone into the taxonomy much in my paper. Hopefully someone will soon do a genetic study of the different forms. My guess (based mainly on plumage and structure) is that chionogaster is more related to the South American form ventralis (Plain-breasted Hawk) and that the link to northern forms is more likely to be through the West Indies than Middle America.
Tom
Jenner, T. D. (2010) Life history of the White-Breasted Hawk (Accipiter chionogaster). Ornitologia Neotropical 21: 157–180, 2010
Monroe, B. L. Jr (1968). A distributional survey of the birds of Honduras. Ornithological Monographs No. 7. AOU.
Storer, R. W. (1952). Variation in the resident Sharp-shinned Hawks of Mexico. Condor 54: 283-9.
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Tom, a small correction: Opus started with S&M, but if both H&M and Clements differ from S&M, then we follow that consensus. As you probably know, Clements basically follow AOU, and H&M also have followed the lumpers on this one. It will be interesting to see a taxonomy paper on this complex. (and also interesting to see what the next H&M does when it finally appear).
Niels
Niels
