North African Buzzard is not a Long-legged but an allospecies of Common Buzzard

By MaghrebOrnitho | 19 February 2019

The Atlas Long-legged Buzzard is more closely related to Common Buzzard than to Long-legged Buzzard according to a new study. The taxon cirtensis should be treated therefore as an allospecies of the Common Buzzard superspecies.

La Buse du Maghreb est une alloespèce de la Buse variable

Selon cette étude, la Buse du Maghreb (cirtensis) est en fait le résultat d’une hybridation entre la Buse féroce (Buteo rufinus) et la Buse variable (Buteo b. buteo et Buteo b. vulpinus). Bien que la délimitation génétique entre ces espèces n’est pas nette, l’étude a démontré toutefois que la Buse du Maghreb est plus apparentée avec la Buse variable qu’avec la Buse féroce. L’étude a donc suggéré que cirtensis soit considérée comme une alloespèce de la Buse variable. En d’autre terme, le nom scientifique de la Buse du Maghreb devrait être ‘Buteo (buteo) cirtensis’ au lieu de ‘Buteo rufinus cirtensis’.

[Les alloespèces sont des espèces à distribution allopatriques (géographiquement isolées) mais étroitement apparentées formant une super-espèce. Voir le concept de la spéciation allopatrique].

Background

The Old World buzzards of the genus Buteo are relatively a young radiation and poorly differentiated genetically. However, they are well differentiated morphologically – both within and between the recognized species. Unfortunately, morphology does not necessarily reflect the true phylogenetic relationship between species as has been shown in many groups.

The current taxonomy and subspecies arrangements of the Common (Buteo buteo) and Long-legged Buzzards (Buteo rufinus), and especially the taxonomic treatment of the Atlas Long-legged Buzzard as a subspecies of the latter were considered unjustified by many experienced raptor specialists. For example, there are some anomalies in the geographical distribution of the different taxa. First, there are Common Buzzards in the Iberian Peninsula and the Canary Islands, but separated by the “Atlas Long-legged Buzzard” in Morocco. And second, the distribution ranges of the two subspecies of the Long-legged Buzzard as currently accepted are widely separated.

The genetic relationship between three buzzard species

Jowers and his coauthors, using  different genetic markers, studied the relationship between three buzzard species: Upland Buzzard (Buteo hemilasius), Common Buzzard (buteo and vulpinus) and Long-legged Buzzard (rufinus and cirtensis). Their study has just been published in Molecular Phylogenetics and Evolution journal.

The mitochondrial (mtDNA) data showed that Upland Buzzard is clearly differentiated from the Common and Long-legged Buzzards. This species was considered as subspecies of Long-legged Buzzard in the past, and this study confirmed that the two are not the closest relatives to each other.

For the Long-legged Buzzard, the mtDNA analysis disagreed with the current taxonomy of the species: the nominate subspecies (rufinus) formed its own separate group, while the Atlas Long-legged Buzzard (cirtensis) clustered with Common Buzzard (buteo and vulpinus) in a third group. The hybridisation between cirtensis and buteo might have been the cause of this introgression (gene flow between the two taxa).

The documentation of this hybridisation in the Strait of Sicily and the Strait of Gibraltar is recent, but the phenomenon itself is not recent. In fact, this study showed that old museum samples of cirtensis from Algeria and Tunisia are intermixed with buteo, suggesting that the hybridization has been ongoing for thousands of years. It also shows that hybridisation is not restricted to the suggested contact zones between these two taxa (namely the Strait of Gibraltar area and northern Tunisia).

The historical demographic analysis showed that the effective population sizes of Upland Buzzard, Long-legged Buzzard (ssp. rufinus) and Steppe Buzzard (B. b. vulpinus) have remained relatively constant for the last 10 thousand years. In contrast, cirtensis – which has a more recent population history – has undergone a dramatic population expansion during the last 3 thousand years. This expansion is still ongoing and predicted to increase in the Iberian Peninsula as a result of several factors including climate warming (see for example Chamorro et al. 2017).

The study concluded that cirtensis should be treated as an allospecies of the Common Buzzard superspecies complex. [Alloespecies are allopatric (geographically isolated) but closely related species forming a super-species. See the concept of allopatric speciation].

What the plumage and morphology says?

Morphometric studies showed long ago that rufinus and cirtensis differ significantly in size (the former being very heavy, while the latter resembles Common Buzzard). Plumage traits also differ between the two taxa. For example, Andea Corso wrote this comment about the subject in 2010: “If you look into the plumage and morphological treats, you would never think cirtensis has nothing to do with rufinus but some similarities… However, there are many plumages that indeed are much closer to Common Buzzard….The [Atlas Long-legged Buzzard] seems to be like a mix between buteo and rufinus”. A. Corso has been researching this subject since many years, but as far as I known it hasn’t been published yet. It’s very interesting that this genetic study in some sort confirmed what has been suggested by morphological studies and experienced observers since many years.

Incomplete sampling

Unfortunately, the geographical sampling still far for complete, and some important lineages and/or regions were not included in this study:

Northern Morocco where the so-called ‘Gibraltar buzzard’ occurs is not included. However, this is probably not a big issue because the study showed that the hybridisation and introgression occurred across North Africa. No samples from the Canary Islands as well, where the local buzzard subspecies is considered a Common Buzzard (B. b. insularum).

Similarly, no samples from Cape Verde. The taxonomic status of Cape Verde Buzzard is even less clear than in the previous two regions. It’s given its own species status (Buteo bannermani) by some authors (e.g. IOC Checklist, Dutch Birding), but still considered as a subspecies of Common Buzzard by others (e.g. HBW Alive)

Suggested common names

This study confirmed that the North African Buzzard (cirtensis) is more closely related to the Common Buzzard. In my opinion, changing common names are inevitable. Here are my suggestions (comments are welcome as always!):

In English, the qualifier “Long-legged” should be dropped from the name. I think ‘North African Buzzard’ is a better and more appropriate name than ‘Atlas Buzzard’ or ‘Maghreb Buzzard’ for example. (It’s disadvantage is that it’s composed with three words).

In French, there are two names already in use: ‘Buse du Maghteb’ and ‘Buse féroce du Maghreb’. I think the first name should be used which does not include ‘féroce’ in it.

In Spanish and Portuguese, Buteo rufinus (the “parent” species not just cirtensis) is called ‘Busardo moro’ and ‘Bútio-mourisco’ respectively. In both languages, I think keeping these names which literally means “Moorish or Moroccan Buzzard” for the eastern Long-legged Buzzard would be a real misnomer. See under these two languages in this blog-post: Maghreb endemic birds.

References:

Jowers, M.J., Sánchez-Ramírez, S., Lopes, S., Karyakin, I., Dombrovski, V., Qninba, A., Valkenburg, T., Onofre, N., Ferrand, N., Beja, P., Palma, L., Godinho, R. 2019. Unravelling population processes over the Late Pleistocene driving contemporary genetic divergence in Palearctic Buzzards, Molecular Phylogenetics and Evolution 134: 269-281. doi: 10.1016/j.ympev.2019.02.004

Update:

The North African Buzzard is split from the Long-legged Buzzard by OSME (The Ornithological Society of the Middle East, the Caucasus and Central Asia) based on this study. It’s nice to see that they adopted the same English name we suggested in this blog two months ago.

The OSME List largely follows the International Ornithological Congress (IOC World Bird List), but they depart from this source when new research reveals new understanding,…etc. As anything in science, this is of course not final and can change when new information is published.

See the ‘OSME Region List Update 4.4’ at the OSME website here (PDF at the bottom of the page).

North African Buzzard / Buse du Maghreb (Buteo buteo cirtensis), Tinejdad, Morocco (Mustapha Houssaini‎)
North African Buzzard / Buse du Maghreb (Buteo buteo cirtensis), Tinejdad, Morocco (Mustapha Houssaini‎).

7 thoughts on “North African Buzzard is not a Long-legged but an allospecies of Common Buzzard

  1. Andrea Corso

    Hello,
    Interesting, and indeed truly pity I did not arrive in time to publish my long-term morphological study and taxonomic conclusions. These, as you mentioned, were briefly mooted in 2010 and in an Italian magazine even as early as 2001.

    My research in fact reported the presence, contra all literature as I already mentioned in this web-page, of grey-brown morphs: in morphometric closer to buteo but in jizz closer to rufinus. I have even a couple of personal observations of brown-black morphs, easily the products of hybridization cirtensis x buteo, with apparently even F2, F3 in Pantelleria and Tunisia, etc

    I were suggesting in my ongoing paper that cirtensis was a stable hybrid species as Passer italiae, or an emerging species still closely related to buteo and I called it as you have done: North African Buzzard.

    Would be very interesting to genetically study those cirtensis breeding in Sinai desert and Egypt, as well as those in S Israel.

    Reply
    1. MaghrebOrnitho Post author

      Thank you for your comments Andrea.

      Indeed I remember reading that article in Birding Frontiers website, but the original link as posted here in BirdForum does not function and I thought it was probably deleted.

      Mohamed

      Reply
      1. Cornelius Schlawe

        I found it funny to find this new entry on Magrehb Ornitho as just having returned from Morocco I was wondering exactly this: Is this a Hybrid that is closer to buteo really. Is shaped and sounds like a Common Buzzard (shorttailed, roundwinged), has breast markings like a common, only colorwise looks like Long-legged.

        I have a similar issue with the ravens of Morocco. To me they are more of a raven than a crow, but still they have attributes of crows accoustically (whooak whooak), in postures and in morphology. Any opinions on that?

        Reply
        1. MaghrebOrnitho Post author

          Sorry Cornelius for this long-overdue reply!

          For the first part, that’s exactly what was puzzling many observers over the years, and this genetic study brought badly needed answers. Indeed, it showed that hybridization played a role in the formation of this taxon. With the current trend of splitting (e.g. the Socotra Buzzard Buteo socotraensis, which was described less than a decade ago), it would not be a surprise if cirtensis got its full species status in the near future.

          As for the Common Raven, the taxon breeding in North Africa (Corvus corax tingitanus) is the smallest raven subspecies. The Canary Islands ravens were also considered to belong to tingitanus subspecies (e.g. they are also small,..). However, recent genetic studies (cited below) found that the ravens in the Eastern Canary Islands are genetically different from all the other Holarctic ravens.

          – Baker, J.M. & Omland, K.E. 2006. Canary Island Ravens Corvus corax tingitanus have distinct mtDNA. Ibis 148: 174-178.

          – Rösner, S., Cimiotti, D.V. & Brandl, R. 2014. Two sympatric lineages of the Raven Corvus corax jordansi coexist on the Eastern Canary Islands. Journal of Ornithology 155: 243-251.

          I don’t know, I think because they are smaller and with glossy plumage compared to the ravens in northern latitudes, they look different from them.

          Reply
  2. Joe Mac Pherson

    Is this a North African Buzzard?

    I’m hoping someone can help me identify the present name of an African Buzzard, formerly known as Buteo eximius. There are references to it living in Eritrea and Sudan, in the 1910 German publication, Journal Fur Ornithologie, on page 384. Following page 394, a full color illustration appears on Taf. VI (Plate 7). See the article at https://www.biodiversitylibrary.org/item/43496#page/406/mode/1up See the full color illustration at https://www.biodiversitylibrary.org/item/43496#page/423/mode/1up

    Another mention is in the Catalogue Of The Accipitres, Or Diurnal Birds Of Prey, In The Collection Of The British Museum. By R. Bowdler Sharpe. Volume I. Published in London, 1874. See the references on pages 176/177. https://www.biodiversitylibrary.org/item/34315#page/194/mode/1up

    Yet another mention is in A History Of The Birds Of Europe, Including All Species Inhabiting The Western Palaearctic Region. By H.E. Dresser. Volume V. Published in London, between 1871 – 1881. Page 463 is headlined, Buteo Ferox. (Long-legged Buzzard). Following this are former and associated Latin names, including Buteo eximius. See this at https://www.biodiversitylibrary.org/item/114442#page/599/mode/1up

    I know I could be wrong, but I think the current name of Buteo eximius is Buteo rufinus leucurus, or Buteo rufinus rufinus leucurus, for a subspecies of the Long-legged Buzzard.

    Or is this raptor I’m researching now defined as the North African Buzzard? Also, if anyone can tell me the present range of Buteo eximius and it’s current name, I’m so very grateful for your help!

    Reply
    1. MaghrebOrnitho Post author

      Thanks Joe for the comment!

      Firstly, the English name ‘North African Buzzard’ is not cited or suggested in the article by Jowers et al. The cirtensis taxon is still largely known as the Atlas Long-legged Buzzard. The name ‘North African Buzzard’ is suggested in this blog because the study found that cirtensis is not related to the Long-legged Buzzard (Buteo rufinus) breeding in Eastern Europe.

      For the scientific names, I think you are right. Both Buteo eximius and Buteo ferox are now treated as synonyms of Buteo rufinus. However, I don’t know their exact history (e.g. when the former names fell out of use in favour of Buteo rufinus). Also, I don’t know if the taxon leucurus is still used today (I think it was also synonymized, but when exactly?).

      An article by L. Portenko published in 1929 can give some answers. In the first page (623), the authors compared the taxonomic treatment of three major works of the time. In that comparison, we can read that the most recent work (‘Monograph of the Birds of Prey’ by Kirke Swann published in 1926) has already synonymized ferox and eximius with rufinus.

      Back to your last question. The taxon cirtensis (named here as North African Buzzard) is largely resident in North Africa, so it’s not the name of the species you are researching.

      I hope this is helpful. I will forward your query to more knowledgeable people about this subject who may have something to add.

      Mohamed

      Reply

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