Eastern Black Kites in Europe: a new look
The potential presence of Black-eared Kites (Milvus migrans lineatus) in Western Europe has been on the table since a juvenile kite seen in Lincolnshire (UK) in November 2006 was considered by some to be a genuine Black-eared Kite. This bird generated both great interest and intense debate about its identity, with many birders supporting the hypothesis of it not being a Black-eared Kite, but a Black Kite of eastern origin. Looking retrospectively at the discussion, it seems clear now that it was strongly obscured by lack of clarity around the key underlying question of “what is a Black-eared Kite?”, including not just how it looks, but also its distribution range.
This question has been subsequently answered in the literature with different approaches. Shirihai (1996) discussed the presence of “Eastern populations of migrans in the Middle East”. McLoughlin (in Garner, 2008) considered Black-eared Kites to be found from western Siberia eastwards. This subject has also been covered in detail by Dick Forsman in his last book; he used the terms Black Kite for migrans and Black-eared Kite for lineatus and introduced the concept of Eastern Black Kite to describe the intergrades that extend from Western Russia to Central Siberia. Forsman showed numerous examples of these intergrades from central Kazakhstan, and a few from Mongolia.
Since the Lincolnshire (UK) bird in 2006, several kites with Black-eared features (mainly juveniles), of apparent eastern origin, have been recorded in winter in different European countries. Following the advances in our understanding of these taxa, it’s nowadays generally accepted that these birds are not true Black-eared Kites from Far East Asia, but birds from the intergradation region between migrans and lineatus located somewhere in Western/Central Asia.
Plate 1. West Siberian Black Kite, 4cy, Castilla y León, Spain (Miguel Rouco). This bird has spent every winter since 2016 at a rubbish dump in Salamanca, Central Spain. It shows obvious Black-eared Kite features, including dark iris, brownish head, dull cere, white on the base of the primaries and a solid ear-patch.
Although the previous publications are fundamentally right, the description of “a vast intergradation area” is quite coarse-grained and in my opinion can be refined. The clinal variation from the westernmost part of the range (western Europe) to the eastern extreme (Far East Asia) is gradual enough to differentiate several plumage-types that typically overwinter at different regions.
In this post I’ll try to go a bit further and describe the plumage transition across this range in greater detail, further developing the approach started by Karyakin (2017), as a necessary step to elucidating where the kites in Europe showing some typical Black-eared characters come from. In my opinion, the clinal variation is more obvious in adults (juveniles from Western Siberia already look very similar to lineatus), and therefore as a first approach to this complex identification problem, the scope of this post will be restricted to adult birds for now.
If you decide to join me for this (quite long) post, we will:
define the main plumage-types of adult Black Kites found in Eurasia based on the combination of key features;
review the gradual variation of the western populations (from Western Europe to Central Asia); and
discuss the occurrence and origin of Black Kites showing Black-eared features in Europe and the Western Palearctic.
Methods. This subject attracted my interest a few years ago, during a spring trip to Georgia when I saw many juvenile ‘Black-eared-like’ Kites on migration. I have spent lots of time studying kites since then, mainly in Spain, but also in Israel, Kazakhstan, Georgia, India, China and Japan. In order to understand the complete story, I’ve also done intensive research online, studying birds from the breeding grounds in Asia, mainly using eBird, birds.kz and other local websites. Since the number of pictures from Siberia is limited, please take this analysis as a first attempt, which will need to be revisited in the future.
1. Understanding the gradation across Eurasia
The current geographical variation within Black Kite/Black-eared Kite in Eurasia is quite complex, and it might be the result of one (or several) periods of isolation during past glaciations, followed by range expansion and interbreeding. In addition to the phenotypical differences, migrans and lineatus seem to differ in habitat selection, with migrans being more common in open and arid areas, and Black-eared more adapted to boreal forests. As a consequence, the clinal variation is mainly west-east, but it may also have a (weak) south-north component.
The separation of migrans and lineatus has been the focus of several papers (Forsman 2003, Lindholm & Forsten 2011, De Candido et al. 2013, Karyakin 2017), that described well the main differences between both taxa. In comparison to migrans, lineatus shows (in no particular order): 1. black ear-patch; 2. dark iris; 3. dull cere; 4. white on the primaries; 5. pale vent; 6. streaked body plumage; 7. brown head; 8. strong barring on inner primaries; 9. heavier structure; and 10. longer p5.
In general, these features become increasingly present as one moves eastwards, but some are quite irregular and are present in all populations (e.g. the dark iris, dark ear patch and cere color). On the contrary, the white patch on the primaries and the pale vent are only found in some populations:
White on the primaries: totally absent on European birds; present on birds from roughly c.40ºE eastwards.
Pale vent: absent on birds in roughly the western half of Eurasia, becoming obvious at longitude c70ºE but not becoming contrastingly pale until c.100ºE.
The structure of these plumage features across the cline strongly suggests four plumage-types, corresponding to the stable forms migrans and lineatus plus two intermediate populations:
‘European’ Black Kite (= true migrans) [dark primary base, dark vent]: neat rufous plumage with grey streaked head, very pale iris and bright yellow cere. These kites overwinter in Africa along the Sahel.
‘West Siberian’ Black Kite [white primary base, dark vent]: as European, but with solid white on p10-p7, a slightly browner head, darker iris, and very slightly pale vent. These overwinter mainly in the Middle East, from southern Turkey to Egypt.
‘Central Siberian’ Black Kite [white primary base, pale brown/creamy vent]: as West Siberian, but with overall dark brown plumage, no grey head, and slightly streaked body; pale vent below the legs contrasting with the belly. Wintering grounds mainly found in India.
‘Far Eastern’ Black Kite (= true lineatus, aka Black-eared Kite) [white primary base, solid pale vent area extending up to the lower belly]: very dark brown overall, with a clearly streaked/woolly belly/breast, and solid pale (creamy, not brownish) vent extending onto the lower belly. Wintering grounds found in SE Asia.
Throughout this discussion I will use this nomenclature and will refer to “Black Kite” as generic for any of the plumage-types/subspecies. “Eastern Black Kite” (following Forsman, 2017) will be used to refer to any of the West Siberian/Central Siberian/Far Eastern Black Kites. Of course this should not be understood as a rigid definition as we’re dealing with a gradual cline, but the categorization in plumage-types is quite useful to distinguish populations and analyze the plumage-type distribution in the wintering grounds.
A final comment: in the past, the definition of Black-eared Kite has been commonly based on Japanese breeders. Japanese Black-eared Kites are quite variable and strongly differ from their continental neighbours (amongst other differences, there is a rufous morph), and are likely deserving subspecies status. The ‘Far Eastern’ Black Kite as defined here corresponds to the highly migratory populations that winter as far south as Thailand and Malaysia; they are quite dark brown, with almost no contrast between the dark black ear-patch and the rest of the head. I think that, especially within the context of vagrancy to Europe, it makes more sense to focus on these birds rather than on the resident populations from Japan or S China. A typical bird representative of these Far Eastern Black Kites is depicted below.
Figure 1. Definition of the main plumage-types of Black Kite across Eurasia based on the combination of the two key plumage features: European (dark primary base, dark vent), West Siberian (white on primary base, dark vent), Central Siberian (white on primary base, pale brown vent) and Far Eastern (white on primary base, solid pale vent) Black Kites. The plumage-type represents the most common plumage of the region, but for instance birds from West and Central Siberia with dark underwing aren’t extremely rare.
Plate 2. Plumage gradation in adult Black Kite across Eurasia: representative examples of the four plumage-types defined above. From left to right: Spain (Guillermo Rodríguez), Israel (Guillermo Rodríguez), Mongolia (Simon Colenutt - TheDeskboundBirder), and Thailand (Jens Erik Nygård).
2. The transition from Europe to Central Asia
Looking at the plumage-type definitions in the previous section is enough to easily rule out both Central Siberian and Far Eastern Kites for the Black Kites of eastern origin seen in Europe. Therefore, the rest of this section will focus on the transition from European to West Siberian Black Kites, and the western limit of the latter plumage type.
Description of European Black Kites
European Black Kites in full adult plumage (5yo+) show little variation, exhibiting a quite uniform brown (cinnamon) plumage with the exception of a grey hood that usually extends to the bib. Typically, most feathers of the head and upper breast show a dark shaft, often giving a streaked appearance. The iris is most often white as the birds approach adult plumage, and the cere is always bright yellow. The underparts are likewise quite uniform, with a completely concolorous vent and dark primaries. Only extremely rarely do some birds show a small white patch on p9-p10 (noted only in one Spanish breeder out of several thousand birds studied).
Western Europe hosts areas with high densities of Black Kites, which are surely taking advantage of the numerous waste disposal sites and other human-related food resources. According to some studies, the competition for breeding territories is so high that most individuals do not breed until their fourth or fifth year of life. In the meantime, they gather in large numbers mainly at waste dumps. This has facilitated to see large numbers of the tricky young adults and understand well the variation. I have included a sample (Plates 5 & 6) of these young adult Black Kites seen at two waste sites in Lleida, Catalonia, Spain; although I can’t guarantee that every single bird is a ‘young adult’, their behaviour and overall appearance compared to birds seen at the breeding sites (supposed to be full adults) strongly suggests that most of the birds shown are <5cy.
The ‘young adults’ show variable degrees of immature traits, namely a:
darkish iris;
hint of dark patch in the ear coverts; and
browner head, lacking streaks and grey tones.
Note that all these features are also typical of adult Black-eared Kites, making the identification of Eastern birds tricky in some cases. Nonetheless, two features seem to be diagnostic of European Black Kites for 3cy+ birds:
None of the individuals show white on the under primaries (except for the single adult mentioned above).
No birds show a transition or contrast between the belly and the vent.
Note, however, that 2cy birds do show white on the primaries until they complete their first primary moult.
It seems there is little geographical variation across breeding birds in Europe (but see ‘The problematic of Scandinavian Birds’ later on). My only experience in eastern Europe is from Poland, where all the birds I saw were quite typical. eBird also shows typical European Black Kites across much of the European range, with some birds showing a hint of a white patch at the base of the primaries from eastern Ukraine eastwards, but even around Moscow many kites seem to be still quite European-like, showing all the features described above.
Plate 3. European Black Kites, 3cy+, April, Castilla y León, Spain (Miguel Rodríguez-Esteban). Adult European Black Kites show little variation, with a characteristic pale cinnamon ground colour combined with a pale grey hood. The iris in full adult birds is nearly white.
Plate 4. European Black Kites, 3cy+, Castilla y León, Spain (Juan Sagardia). Black Kites retain features of immaturity for around 4-5 years (left, middle) before acquiring the characteristic look of old adults (right). These features include brownish head, brownish iris and a hint of ear-patch.
Plate 5. European Black Kites, likely young adults (3-5cy), June-August, Catalonia, Spain (Guillermo Rodríguez). A sample showing representative examples of young adults. Despite the variation in some features such as iris color and head colour, all European birds are quite homogeneous in terms of body colour and invariably show dark vent concolorous with the belly, and dark primary base. European are lightly built kites, exhibiting an elegant silhouette due to their narrow wings and long tail. The wing typically looks pointed (much in a Montagu’s Harrier manner).
Plate 6. European Black Kites, young adults (3-5cy), Catalonia, Spain (Guillermo Rodríguez) and Castilla y León, Spain (Juan Sagardía). Two more examples of young adult birds retaining immature traits that superficially resemble birds from further east. Note however solid dark on the primary base, faint barring on the inner primaries, no contrast at all on the vent, and typical pale cinnamon plumage. The dark iris is usually brown, rather than deep red as is often shown by Eastern Black Kites.
Plate 7. Black Kite, likely European, likely 3cy, August, Catalonia, Spain (Guillermo Rodríguez). A tricky bird, quite similar to a West Siberian Black Kite. Location and early date suggest a young adult European. Confusing birds like this one are relatively rare.
Plate 8. European Black Kites, 2cy, June, Catalonia, Spain (Guillermo Rodríguez). Second-year European Black Kites superficially resemble adult West Siberian due to the combination of dark eye, ear-patch and white on the outer primaries, so ageing is important before trying to address the origin of a Black Kite. In these two birds, the pale tips to the body feathers, characteristic of the juvenile plumage, are still obvious and thus the ageing is straightforward. However, many Black Kites are hard to age, particularly in Asia where the juvenile and adult plumages are much more alike . The shape of the secondaries and an inhomogeneous wear of the flight feathers are reliable features for ageing.
Description of West Siberian Black Kites
The West Siberian Black Kite as defined here doesn’t represent a stable phenotype (as opposed to European), but roughly comprises the populations of Black Kite that generally show an overall rufous coloration and plain plumage (characteristic of European), along with at least some white on the primaries and a pale-ish brown vent. This corresponds to an extensive area from Moscow to central Kazakhstan, in which the individual variation is so high that it would make more sense to describe the distribution (frequency) for each character independently, rather than describe a typical phenotype.
The first Black-eared traits appear roughly at c.35-40ºE. For instance, a close analysis of birds from the Moscow area reveals that some birds there already show solid white on p10-p9, combined with a hint of dark ear-patch, but retain an overall look similar to European Black Kite. Many/most individuals show dark underwings and don’t differ much from a Spanish breeder.
The few pictures further east, e.g., around Ekaterimburg or western Kazakhstan, show similar birds, generally reminiscent of European Black Kite, but with increasing influence of Black-eared, including the overall colour which turns a bit more saturated, chestnut/rusty rather than pale cinnamon. In a study in the Urals, Karyakin (2017) sampled 85 individuals reporting that roughly 38% of birds do not show any white at all at the base of the primaries, and 41% only show restricted white.
The next area where the plumage variability is well described is around Astana, Kazakhstan, c.70ºE (where, however, most birds are migrants that may potentially breed quite further east). Most adults in this area show solid white on p10-p8, and a pale-ish vent (but not creamy as in Black-eared). Some birds are quite brown overall, whereas others retain the general rufous tinge of migrans. Most birds show a classic pale head contrasting with a much darker body, particularly conspicuous in the throat. A dull yellow cere and dark iris are also the norm, but birds showing a pale iris aren’t rare either. To the east of this region, Black Kites start to exhibit a more ‘streaked’ belly and solid creamy (instead of brownish) vent, acquiring a much stronger Black-eared look overall: the Central Siberian Black Kites.
As a side note, it’s noteworthy that the overall aspect of a West Siberian bird strongly depends on the sighting: if seen on the ground/perched, the black eye and dark ear-patch are very eye-catching and will emphasize a Black-eared impression, whereas if seen in flight, the uniformity and rufous tinge of the plumage may make us lean towards European.
Plate 9. West Siberian Black Kites, 3cy+, Moscow c.38ºE (Pavel Parkhaev). Birds from the Moscow area, roughly the western limit of West Siberian Black Kite as defined here. Some birds from this area already show white at the base of the primaries (left, middle) whereas most birds look like pretty standard European Black Kites (right).
Plate 10. West Siberian Black Kites, 3cy+, Astana-Almaty, Kazakhstan, around 70ºE (Guillermo Rodríguez). Birds from Central Kazakhstan (the eastern limit of West Siberian Black Kite’s range) still look quite European-like as they are cinnamon/rusty and quite neat, differing from the typical dark brown and streaked plumage of Far Eastern Black Kites. They also show a high variability in terms of extension of white on the primaries and iris colour. Nevertheless, compared with birds from Moscow or the Urals, they already show some contrast between belly and vent, although the vent typically looks dirty brownish.
3. Occurrence of Eastern Black Kites in Europe
Black Kite types wintering in the Middle East
It has long been known that kites showing Black-eared features overwinter in the Middle East, and spread as far south as Ethiopia. That’s not surprising at all, as most of the raptors seen in this region come from Central Asia and, indeed, the vast majority of kites occurring here differ phenotypically from European breeders. Amongst the Black Kites wintering along the Mediterranean coast from E Turkey to Egypt, we can find:
Birds with a solid white patch on p10-p8 are very common (c.50%), and this is usually combined with brown head, hint of ear-patch, often darkish iris, but no (or just slightly) pale vent.
Birds similar to European Black Kite are similarly present (c.40%), but usually differing from true migrans, with less extensive grey on the head and a slightly darker iris than the average migrans.
Birds with a strong Black-eared flavour, including an extensive white patch from p10 to p6, a clearly pale-ish vent, a slightly streaked appearance below, and other typical Black-eared features are not rare (perhaps 10% of birds). These birds are similar to those seen in central and eastern Kazakhstan.
The distribution of phenotypes suggests that birds wintering in the Middle East originate from a vast area with its western limit somewhere around the Urals, east to perhaps 70ºE – involving mainly West Siberian and likely some Central Siberian Black Kites.
These very same birds are seen afterwards in migration accross E Turkey, Georgia, Armenia and Azerbaijan.
Plate 11. West Siberian Black Kite, 3cy+, March, N Negev, Israel (Klaus Bjerre). A bird with a strong European feeling, but note brownish iris, grey restricted to the head, solid ear-path, and more saturated cinnamon plumage colour. It also looks bulky and broad-winged. Some of these features are subjective and depend on the light conditions, so out-of-range identification of birds like this one should be taken with caution.
Plate 12. West Siberian Black Kites, 3cy+, December, N Negev, Israel (Guillermo Rodríguez). A sample of Black Kites from Israel showing no white on the primaries. Note that, even if some of these kites are quite European-like, they typically show brownish head, variable ear-patch, and dark iris.
Plate 13. West Siberian Black Kites, 3cy+, December, N Negev, Israel (Guillermo Rodríguez). A sample of Black Kites from Israel showing extensive white on the primaries. A few more examples to get a sense of the plumage variation of the kites wintering in this region. Most birds show solid dark vent, with at most a faint contrast between belly and vent - comparison of these birds with those shown in Plate 9 (Moscow) and Plate10 (C Kazakhstan) suggests that most of the birds wintering in the Eastern Mediterranean come from the area extending between 40-70ºE.
Plate 14. West/Central Siberian Black Kite, 3cy+, March, N Negev, Israel (Klaus Bjerre). This bird, also a wintering individual from N Negev, shows an interesting combination of features: the vent is clearly paler than the belly, with a faint streaked impression on the lower belly. Birds like this individual, resembling kites from Central/Eastern Kazakhstan, are scarce but not truly rare in Israel.
Plate 15. Central Siberian Black Kites, 3cy+, December, India (Guillermo Rodríguez). Some birds from India for comparison. Wintering Black Kites in India typically show much darker plumage, faint streaking and paler vent than those wintering in the Middle East. Some birds, such as the one on the left from the Rajasthan, still show pale iris and darkish vent.
The problematic of N Scandinavian Black Kites
I first realized about the singularity of Scandinavian Black Kites when a bird wintering in Salamanca, central Spain, that looked like a classic West Siberian Black Kite (the bird depicted in the introduction), turned out to have been ringed at nest in Northern Sweden. First seen as a juvenile in winter 2016, it has returned regularly every winter since then, giving the chance to study the plumage evolution. Already as a full adult bird, it shows a white patch on p10-p8 with strongly barred inner primaries, a dark iris, a dull yellow-ish cere, a dark ear-patch, and a slight contrast between belly and vent. It usually shows up by late October, with primary moult suspended at p6 (thus retarded about 3 primaries compared to the few European Black Kites seen concurrently in the area). When seen alongside European Black Kites, it is noticeably heavier, shorter-tailed and with a squarer wing tip.
Plate 16. West Siberian Black Kite, 1cy (left, by Miguel Rodríguez-Esteban) and 3cy (right, by Miguel Rouco), Castilla y León, Spain. Bird ringed at nest in N Sweden. There is limited variation in Eastern Black Kites in juvenile plumage; this individul looks quite similar to a true lineatus - and that’s why we’ve centered our analysis on adult birds. Also compare it with this wintering bird from UK. Already in adult plumage, this well-studied bird shows brownish head, dark ear-patch, dark iris, white on p10-p8, strong barring on inner primaries, dull cere and a slightly paler vent than the belly.
Black Kite is a scarce breeder in Scandinavia, with a small population in southern Sweden and only scattered pairs in the North and neighbouring Finland. It’s more regular as a migrant, but still uncommon on both passages.
I haven’t seen any of these Scandinavian birds in the field, but Artportalen, Netfugl and Tarsiger host extensive galleries. Many of the birds shown there differ from classic migrans in several traits, even if you compare them against birds from other countries at the same longitude (e.g., Poland), and they are reminiscent of West Siberian Black Kites from a lot further east. Some of them have a strong Black-eared look, including a hint of pale vent and a faint body streaking. Although obviously many of these birds are migrants/summer wanderers from Russia (particularly the most striking ones), apparently some breed in the region, as proven by the ringed bird in Spain and some of the birds pictured in the galleries mentioned above.
It’s also worth noting that 2cy Black Kites seen in Scandinavia look unusually fresh compared to the typically extremely worn 2cy birds seen in Spain upon their arrival from the wintering grounds. This fact suggests that many Scandinavian Black Kites overwinter at temperate latitudes, and thus are not exposed to the strong sun abrasion typical of tropical latitudes.
The extensive boreal forests of Scandinavia likely look more attractive to Siberian birds than to the southern birds from the core range of migrans…
Plate 17. West Siberian Black Kite, 3cy+, May, Ämmässuo, Finland (Petteri Hytönen). A summer visitor to Finland, seen at a rubbish dump (perhaps a young adult?), showing the classic aspect of a West Siberian Black Kite. Compare how different these birds look with the Black Kites from W and S Europe (Plates 5-7), both in plumage and structure. This type of birds are often aged as 2cy, and thus ageing is a key step in the identification process. Migratory kites usually moult most of the primaries in the breeding grounds, whilst most of the secondaries are replaced in the wintering areas; consequently, a contrast between worn inner primaries and fresh secondaries is typical of adult birds in spring. In this particular individual, one can see which secondaries were moulted in the breeding grounds (worn) and which ones were replaced more recently in winter (fresh).
Plate 18. West Siberian Black Kite, 3cy+, May, Ämmässuo, Finland (Petteri Hytönen). Another example of a Black Kite seen in Finland showing a classic West Siberian appearance.
Plate 19. West Siberian Black Kite, May, Skagen, Denmark (Tonny Kristiansen). Some of the birds seen in migration in Scandinavia have a striking Eastern look, making one wonder how far East do they come from and which migration routes do they follow. This individual shows pale-ish vent and faint streaking, typical features of Central Siberian Black Kites.
West Siberian Black Kites in W Europe
Most of the Black Kites seen in Europe in winter differ from the breeding birds seen in summer, showing a variably degree of typical Black-eared features. The presence of Black Kites of eastern origin in Europe shouldn’t be surprising. Birds from Western Siberia overwinter at temperate latitudes, and even as close as Turkey, so one would expect some birds not only to reach Eastern Europe on a regular basis, but also Western countries, following a similar pattern to that of Siberian Chiffchaff or Siberian Lesser Whitethroat.
The precedent of the Black Kite ringed in Sweden that regularly winters in Spain certainly raises questions about the origin of the Siberian Kites recorded in W Europe. Do they correspond to the tiny N Scandinavian population, or they truly come from W Siberia? Although we definitely need more study to answer these questions (and hopefully this post will encourage many birders out there to study kites!), my gut feeling is that while many of the birds of suspected Eastern origin would fit the birds from Scandinavia, others look much more convincing for possibly being truly Siberian.
However, none of the kites discussed as potential lineatus I’ve seen truly match the plumage of Central Siberian or Far Eastern Black Kites, which should show solid pale vent and streaked/woolly aspect. Many juvenile West Siberian Kites look almost identical to juvenile Far Eastern (particularly in spring when worn) and this has probably pushed observers to claim some of these juveniles as true lineatus.
As I was finishing this post, a great paper by Skyrpan (2020) and colleagues came up, dealing with this very same subject. They propose that the increasing presence in Europe of kites showing Black-eared features may suggest an expansion of the latter towards the west. I have no idea whether this increase is real or just a consequence of higher coverage and greater awareness of birders, but otherwise our conclusions are very similar.
Plate 20. West Siberian Black Kite, 3cy+, February, Madrid, Spain (Delfín González). A magnificent individual of obvious eastern origin. This bird even shows a slightly pale vent and a faint streaking, in addition to other typical features of Siberian birds. Notice also the very retarded moult, still replacing p10 in February. Perhaps a high-latitude breeder?
Plate 21. West Siberian Black Kite, 4cy+ (returning individual), December, Catalonia, Spain (Thomas Kuppel). Note that this bird lacks the outer primary coverts, and thus more white than usual is visible. This isn’t the most obvious Eastern Black Kit seen in Europe, but still exhibits obvious traits supporting an Eastern origin, including dull cere colur, dark ear-patch, brownish plumage including head. In the field it also looks stonker and with broad wings when seen alongside European Black Kites. Most of the Black Kites seen in Europe in winter show this combination of features.
Check out two more examples of West Siberian Black Kites seen in winter in Europe here or here.
Acknowledgments
I would like to thank all the photographers who kindly allowed me to post their pictures here. Miguel Rodríguez Esteban has provided interesting discussion over the years and kept me posted about the Black Kite seen in Salamanca. Lo Chun Fai shared with me his extensive gallery of Black Kites from Hong Kong. Sabrina Hepburn helped me disentangling this quite intricated post.
References
De Candido, R., Subedi, T., Siponen, M., Sutasha, K., Pierce, A., Nualsri, C. & Round, P. D. 2013. Flight identification of Milvus migrans lineatus ‘Black-eared’ Kite and Milvus migrans govinda ‘Pariah’ Kite in Nepal and Thailand. Birding ASIA 20: 32-36.
Forsman, D. 2003. Identification of Black-eared Kite. Birding World 16: 156-160.
Forsman, D. 2016. Flight Identification of Raptors of Europe, North Africa and the Middle East. Helm, London, 2016.
Garner, M, 2008. Frontiers in Birding. BirdGuides Limited, UK.
Karyakin, I. 2017. Problem of Identification of Eurasian Subspecies of the Black Kite and Records of the Pariah Kite in Southern Siberia, Russia. Raptors Conservation, 49 (67).
Lindholm, A. & Forsten, A. 2011. Black Kites Milvus migrans in Russian Altai. Caluta 2: 1-6.
Shirihai, H. Birds of Israel. Academic, London, 1998.
Skyrpan, M., Panter, C., Nachtigall, W.et al. KitesMilvus migrans lineatus(Milvus migrans migrans/lineatus) are spreading west across Europe. J Ornithol (2020).
