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 Identification

 
Rare Birds in Spain

Identification

Some notes on the identification of Northwest African Long-legged Buzzard Buteo rufinus cirtensis

by Andrea Corso

Introduction
Plumage

Spanish birds September 2006
Acknowledgements
Editorial comment

Introduction 

While the identification of nominate Long-legged Buzzard Buteo rufinus rufinus does not show any particularly difficulties in the field, apart when we consider mainly the well marked/patterned juvenile, chiefly when bleached and abraded, compared to pale plumages of Common Buzzard (both buteo and vulpinus race) or birds to be determined just by photographs (therefore without the real possibility to judge and study silhouette, structure and behaviour), the identification of the quite different and separated North African taxon Buteo rufinus cirtensis  its still nowadays a true threat and challenge for any raptors freak.

In this short account, done as a tribute to my friend Ricard Gutièrrez, I wish to briefly summarise the main characters to at least try to identified putative cirtensis, in particular the 2 birds from Spain of the summer-autumn 2006: 

The present note is based on 9 years study of this taxon in the field in North Africa, mainly in Tunisia, and careful examination of several skins at Tring Museum (UK), Wien (A), Malmö (S), Roma and Milano (I).  An extensive and detailed article dealing with this matter is in preparation for Dutch Birding, thanks to the direct require and encouragement from my friend Arnoud B van den Berg. 

Plumage

Typical birds

  • Adults
Typically plumaged adult birds are rather easy to identify and to distinguish from Buteo buteo vulpinus, despite the small size and the more compact looking enhance the similarities between these two taxa, strengthening their similar appearance in the field and the hand, the plumage colour and pattern are still readily different.

In fact the really different silhouette of nominate give a strong help in the identification process, however, being cirtensis a smaller (sometimes as small as a vulpinus) bird with shorter wings. This great help may often result void or partially helpful only and to a very experienced eye (see further under silhouette). 

The plumage is rather richly  coloured, with a tendency to orange or orange-reddish colour even stronger than in nominate (where we note a more rufous-brownish or rufous-rusty gradient of colour); usually the breast and the neck-head is as in nominate paler, compared to vent/belly but even more usually compared to the darker the thigh-feathers and flanks (figure 1, figure 2). 


Figure 1  Adult, typical morph. A. Corso - Tring Museum


Figure 2 Adult, typical morph but slightly more reddish plumage. A. Corso - Tring Museum

The tail is very often also very rich coloured and again with same colour trend (figure 3) resulting in an immediately different bird from any vulpinus, even the most colourful fox-red-morph (sensu Forsman, 1999; Clark, 1999; Shirihai et alii). Paler more creamy bird are yet quite different from pale vulpinus being much richer coloured and yet with  quite strikingly paler head. 


Figure 3 Upperside of Tail of Adult, typical morph. A. Corso - Tring Museum.

  • Juveniles
Typical juvenile bird appear normally rather pale, with least marked underbody, chiefly an almost unmarked breast and higher belly with very narrow darker streaks, while the lower vent and thigh feathers are usually more marked, more patterned and darker (figure 4). Identification of this bird is quite difficult and could prove to be very hard, it is beyond the aims of this brief internet paper and I would deal with in the specific article in preparation.


Figure 4 Abraded Juvenile, typical morph. A. Corso - Tring Museum

Darker and more patterned birds

Here we come with the problems. In fact, contrariwise to what usually illustrated or even written in any filed guide, there is a wide spectrum of morphs, or plumages, in cirtensis too. Apart the fact that also a dark morph, even if really extremely rare (0,1%?), does in fact exist (Corso & Cardelli 1999; A. Corso, C. Cardelli, L. Maumary, O.Janni, P.Wolf, B. Caula, et alii  pers. obs.), there is a wide range of darker, more reddish or rusty plumages, some of them often tinged also brownish or soil-brown. Those plumages appear to be much closer to many plumages of vulpinus, chiefly the fox-red morph but also pale examples of the grey-brown morph or intermediate pale birds/rufous birds (figure 5)

Figure 5 Adult, rufous morph (pale example, could be more rufous). A. Corso - Tring Museum.

Interestingly, they can show a well barred tail even when full adult and fully reproductive mature (in nominate, 1st to 2nd adult plumage tail could show some kind of barring too, most often sparse, or irregular and narrow, but sometimes rather prominent yet irregularly distributed), with that barring and the tail appearing almost identical to vulpinus: a reddish-rufous or rusty-orangish tail with several darker bars, with the (sub)terminal one being wider, darker, more marked and therefore more contrasting (figure 6).


Figure 6 Barred tail of Adult, rufous morph. A. Corso - Tring Museum.

In such plumage, the best distinguish characters to be used are: 

1) a solid, rather wide and obvious dark, blackish to black, carpal patch, usually lacking in fox-red morph vulpinus (but see Corso, in prep. for further details on intermediate populations buteo-vulpinus and other morphs) or rarely visible but less contrasting. 

2) silhouette, as for nominate, even if less dramatic, differences with vulpinus: effectively,  cirtensis even if a smaller more compact bird it still does appear to have longer wing compared to body (but beware of wings or odd body  position in photographs), longer tail, a more Aquila-like field appearance. Also body more corpulent, heavier, bigger-headed, stronger, same for neck, stronger and more powerful feet (sometimes even visible on close by flying birds) and legs in general, higher, stronger and more powerful looking bill. When perched, the tail-tip project well beyond  the wing-tip while in vulpinus these are level or almost so (less in juveniles and differences in general less obvious at this age). While facing us in soaring, wing hold in a deeper V position, more than vulpinus.

3) behaviour: if the two taxa are observed while hovering, the hovering style seems to be distinctive (see Corso, in prep.). 

4) tail barring: the bars in the tail of cirtensis usually less regular, with bars themselves usually less numerous (chiefly in central feathers often- 3/6) and thicker where regular and defined or otherwise very narrow and scanty were irregular, (sub)terminal band usually less regular and with a varying width (but very variable and often identical to vulpinus). However, some birds show a tail almost identical to pale tailed, richer coloured vulpinus

5) Other minor details that will be discussed in my forthcoming paper. 

Finally, if we take into account the darkest juveniles, the matter is further complicated and some birds, often most, should be left unidentified (figure 7).


Figure 7 Juvenile, grey-brown morph. A. Corso - Tring Museum.
 

Spanish birds September 2006

Regarding the Spanish birds seen in September 2006 I can only suggest my point of view not having seen myself the birds in the field (when I would have probably been more helpful) and this is only the putative identification as I like to be conservative as very professionally and seriously our master Dick Forsman has done here

I think the Spanish birds seen at Cazalla bird observatory, Tarifa, Cádiz on 23.9 and at Guadalmesí, Cádiz on 14.9. may well be cirtensis, most probably the Guadalmesi one.  Ageing result quite hard with the Cazalla bird  looking more like and adult (more complete secondaries length and pattern, apparently 2-3 different shade of primaries bleaching indicating possibly 2-3 moult waves…but we deserve much far better photos or field view) while the Guadalmesi more like a 3rd cy retarded or an advanced 2nd cy. For this last, even if cirtensis born earlier than vulpinus and nominate rufinus, a 2nd cy in September would show  S4 with juvenile pattern, therefore with a narrower and less dark terminal bar (in this bird is already adult-like even if shorter length as normal), should show more bleached and abraded wing coverts and partially scapulars, tail should show only one moult wave while it seems to show at least 2 moult waves with different generation and length, and all of them already adult-like, not any still juvenile like, some underwing coverts should still show paler streaking etc. etc. 


Photo above: The Cazalla bird. Todor Todorov 23.9.2006

Pointing in favour of cirtensis, at least for the Guadalmesi is that the structure seems to point in favour of this taxon (see above),  though due to body and wing posture in the photos the real silhouette can not be judged easily and certainly, however the head appear to be rather strong and big, well protruding, same for the bill quite heavy and high (photo 1), facial expression of the Guadalmesi very aggressive and wild, more Aquila-like as well as showing a quite long gape, legs rather long and strong as well as looks the feet, the wing appear rather long and narrow though in the Cazalla bird (see below) the wing and body posture make them appearing too broad as an Honey Buzzard Pernis apivorus (therefore confusingly similar to vulpinus), tail rather long etc., in both birds the carpal patch is quite dark and contrasting, quite solid and extensive, the tail appears rather rich coloured with barring rather irregular, in the Guadalmesí bird (photo 1), these are very scarce being 2-3 in the T1-4,with pattern exactly alike figure 6, while in the other birds rather more numerous but thick and not as many as typical vulpinus apparently (and from below always harder to judge), the iris colour in the 3rd cy possibly to pale for a similar aged vulpinus, the general colour possibly too rusty-reddish, the undertail coverts and vent quite uniform,  not barred, especially in the Guadalmesi bird, etc..

In any case, they prove to be vary hard to be identified by using only photos and the identification is in my opinion only tentative.  Especially the Cazalla bird could well be a vulpinus and without looking it in tte field I would not be 100% sure, instead the Guadalmesi one more probably being a cirtensis, to me eyes almost certainly. 



Acknowledgements

I wish to thanks first and foremost Katrina Cook of the staff of the Tring Museum, UK, for her special kindness and courtesy in visiting the skins collection there. All photos of stiffed birds here courtesy of Tring museum

This article is dedicated to the memory of Michele Vigano’s father, a truly great man as is his special son. 



Editorial Comment

Identification of vulpinus (no accepted records in Spain yet) and rufinus cirtensis is a difficult subject hence the extreme interest of this note and also the interesting comments sent by readers on the Cazalla bird above illustrating the difficulty of this subject. We would like to thank them all and particularly Andrea Corso as well for this very interesting and instructive input:

Dick Forsman (Finland) kindly commented on the September 2006 page on the Cazalla bird what follows:  'The Buteo is interesting. I was sent excellent pictures of this same bird from
near Algarrobo, where it was photographed around Sep 6th, but I do not know what to think.  From above the tail looks very similar to vulpinus, with black barring , and to me the bird is actually more similar to vulpinus than to cirtensis.  But as I said, despite the excellent documents I have to lift up my hands at this point  with this bird. My own experience with cirtensis is too scanty. I would go for vulpinus, but I  am keen to know what other people with
more knowledge of cirtensis think'. 

Keith Bensusan (Gibraltar) on 5.10.2006 wrote us the following on the Cazalla bird: 
'I have seen a number of cirtensis, in Morocco, Southern Spain, and Gibraltar.  I have never seen an individual with tail barring, such as the bird in the photograph.  Indeed, tail barring is one of the distinguishing features of vulpinus.  I have seen vulpinus in Kenya, and the tail of the birds that I was able to observe well matched that of the bird in the picture.  Also, the darker brown colour of the head, chest and underwing coverts does not match the colour of typical cirtensis birds.  Having said this, more variation exists in the colouration of cirtensis than field guides would suggest, and one may occasionally observe cirtensis birds with the colouration of ‘intermediate’ phase rufinus, which may perhaps be younger birds.  This variation in plumage colour is shown in plates provided in Garcia (200?), which show skins of cirtensis birds kept at the museum at Tring.  If these darker birds are indeed immature specimens and/or in moult, then it would not be unreasonable to expect a certain amount of scalloping or a lack of uniformity in colour (as can be seen in the carpal patches and underwing coverts).  However, even the tails of young and dark birds that I have observed have been devoid of any markings on the tail.  I can therefore say with some assurance that the tail on the bird in the photograph does not belong to a cirtensis bird.  I must also add that the ‘jizz’ does not look right for cirtensis.  In fact, perhaps the bird also looks a little too short-winged for a vulpinus, or at least for the way that vulpinus is portrayed in many guides (which like to portray vulpinus as looking more ‘eagle-like’ than buteo).  Having said this, I also remember thinking that the vulpinus that I observed in Kenya were not quite as long-winged as I had expected.  Dick Forsman mentions in his comments that he has seen photographs of the bird from above, which show dark barring on the tail.  This would seem to confirm a vulpinus diagnosis.  However, there are no accepted records of vulpinus from Iberia. 
Although I believe the bird to be a vulpinus, I cannot say so with 100% certainty.  Furthermore, to accept an Iberian first on the basis of a debated photograph would seem somewhat rash.  In conclusion, I must say that, although I think that the bird is most likely a vulpinus, I cannot say so with absolute assurance, especially without seeing other photographs.'

- Garcia, E.F.J. (2004) Field Identification of Northwest African Long-legged Buzzards Buteo rufinus cirtensis Gibraltar Bird Report 2002: 40-46.

Michele Vigano (Italy), on discussing both birds, commented on 30.9: 
'I saw the photos of this very interesting bird on Surfbirds [the Guadalmesí bird, ed.comment] for the first time and me too I was thinking it showed something strange for a Long-legged buzzard. So I phoned Andrea Corso and discussed with him this buteo sp. and he told me after a long discussion of the caracters that this bird was more likely to be a cirtensis due to:
-very wild and aquila-like expression, tipical of long legged.
-very pale eyes. This bird is (i think) a II calendar year, in fact cirtensis usually leave the nest very soon, often in early spring, and so I guess that they moult earlier than rufinus and especially vulpinus birds.
-Well, a so pale iris in a II cy is practically impossible in vulpinus wich shows a darker colour already  when juvenile yet.
-the upper-parts coverts show a very gold and pale colour...how many vulpinus have such a pattern on upper-parts?! I think very few.
-in the surfibirds pics, wings and tail seem long
-solid carpal patch, in vulpinus usually less definite....but very variable!! 
-big bill, once again Aquila-like
-dark secondaries ecc ecc
So the bird photographed on 14.9 seems to be a cirtensis. But the bird on rare birds in Spain can't be the same: the moult is less advanced in the latter bird than in the surfbirds one...or the dates were confused or they are two different birds :-) Neverthless, in my opinion the pic taken on 23 too looks very good for cirtensis!

and later on 2.10:

'The bird on your site is in effect quite different [from the Guadalmesí bird, ed.comment], especially in shape and silhouette: the wings look shorter and rounded, the tail short and the head not that big as in the cirtensis!
There are some plumage details too, as you said, like the more marked U on the breast (but it is not impossible in long-legged complex), pale under parts coverts, less definite carpal marks and so on... But there are some caracters better for long-legged, as the well barred 
secondaries. I am more for a vulpinus-type bird after all.
I think it would be very helpful seeing some pics of the head and other pics where we can see different position of the bird...always if other pics exist :-)'

Guillermo Rodríguez (Spain) on 27.9 commented what follows on the Cazalla bird  (translated from Spanish)
'Hello all. Regarding the buzzard, to me is too shor-winged in terms of structure and too robust to be a Long-legged (even a cirtensis), and its so uniform coloration -with no pale marks- discards cirtensis too. To me it is a Steppe Buzzard more or less typical, such as those seen in Israel photos (where I've still have not gone). The secondary pattern and that of the tail is also pointing vulpinus.'






Some notes on the identification of African Long-legged Buzzard Buteo rufinus cirtensis

Summary:
Introduction

Plumage

Spanish birds September 2006

Acknowledgements
 
 



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