Basic Principles

The sight of a ghostly Rough-legged Buzzard is the highlight of any winter day, but a regular problem facing observers and county records committees is that of separating these Scandinavian visitors from Common Buzzard, the not infrequent pale examples of which can closely resemble their much rarer cousin.

Common Buzzard

One of the major ornithological success stories of the last 20 years has been the eastward march of Common Buzzard. For decades confined to traditional strongholds in the upland west and north, it has spread relentlessly east across the Midlands, the SouthEast and East Anglia.

Almost unknown in these areas in the 1980s, it is now an everyday sight there; indeed this is now Britain’s commonest diurnal raptor. Significant movements of Common Buzzards are today recorded in eastern England, both in spring and autumn, but these are poorly understood and the degree of interchange with the Continent (if any) remains unknown.

Rough-legged Buzzard

By contrast, the status of Rough-legged Buzzard has changed little over recent decades. This tundra and taiga breeder has always been a scarce, irruptive visitor to eastern England, particularly East Anglia and Kent. Its arrivals from Scandinavia are triggered by shortages of its small mammal prey (mostly voles) and are therefore erratic and unpredictable.

In years with plentiful food in the home range hardly any reach Britain, but very occasionally when food sources collapse significant irruptions can occur. In most years, however, just a few arrive, typically in October, and take up winter territories, departing the following spring.

This occurrence pattern in eastern England (and the fact that Rough-legged Buzzard is rather rare in Scotland) indicates that our birds probably arrive through northern Germany and The Netherlands rather than undertaking the long sea crossing from Norway.

Wintering English birds often choose rough coastal grassland, and certain sites are favoured time and again. No site is occupied every winter, however, and some are empty for years on end. Birds can also penetrate a little inland, where they can be harder to find in the patchwork of copses and agricultural land. Their relatively sedentary habits in winter, spending long periods just sitting about, also make them harder to find.

Identification

Common Buzzards come in a bewildering variety of plumages, ranging from relatively dark through medium to pale. Most fall somewhere in the medium range, but some are much paler, a few strikingly so. While the species’ new abundance provides ample opportunity for familiarity, it also means that there are more of these pale birds in circulation, thereby increasing the chances of confusion with Roughlegged Buzzard.

Pale Common Buzzards can be almost white about the head and underbody, with bright white underwings and white in the tail base. However, they will always show a number of features never seen in Rough-legged Buzzard. For example, the central belly is often white, the dark ‘wrist patches’ on the underwing are often reduced to narrow commashaped marks, and the white in the tail base is usually diffuse, ‘bleeding’ into the dark tail. The rump is often white, too, and the scapulars and inner wing coverts can also be contrastingly whitish. Any buzzard showing one or more of these characters will be a pale Common Buzzard.

In North America, Rough-legged Buzzards come in both dark and pale morphs, but European birds are all pale. The key feature is the tail pattern, best appreciated f rom above as it can be a little blurred and difficult to interpret from below.

Juveniles show a white tail with a broad solid dark tip (occasionally covering most of the tail), while adults have several thin black subterminal bands close together and a white tail-tip. Neither pattern is shown by Common Buzzard.

Ageing is also key to understanding the other plumage features of Rough-legged Buzzard. The more frequently encountered juveniles show a pale head and upper breast but a large dark belly patch; the underwings are white with prominent, almost rectangular dark ‘wrist’ patches. A whitish upperwing ‘flash’ is often present in the inner primaries. Adult females are rather similar to juveniles, but lack the upperwing flash and show the adult-type tail pattern described above.

Adult males look rather different, being darker headed and darker breasted and having a less striking belly patch, in this respect being more like Common Buzzard, especially when perched. However, they still look ‘cold’ and greyish overall, never warm or rusty brown. In flight things get easier, with the tail pattern, as ever, the clincher.

Plumage is, however, not necessarily the easiest way of separating this pair, especially at range. In reality, the two species are decidedly different in both structure and flight action. Common Buzzard is typically rather compact and short tailed. It also looks somewhat short winged and has a distinctive stiff wing action. It can, however, hover quite well, sometimes for lengthy periods.

By contrast, Rough-legged Buzzard is a much more elegant bird, larger, longer tailed and usually appearing strikingly longer winged. These proportions give it a notably fluid, relaxed wing-beat (sometimes rather harrier-like) and further enhance the impression of a large, powerful, almost eagle-like raptor. Just like Common Buzzard, it can spend long periods at rest, but when hunting it is a habitual and proficient hoverer.

Finally, any claim of Rough-legged Buzzard should be subject to a ‘reality check’. Outside the October to May period and away from eastern England, the chances of this species are extremely low. Pale Common Buzzards are, however, present throughout the year and can be found across the whole of the country.

THREE: Rough-legged Buzzard (Flevoland, The Netherlands, 12 March 2011). This bird also shows a pale head and, helpfully, a solid dark chocolate brown patch is present on the lower breast, belly and flanks. Such an extensive and solidly dark area on the rear underparts is never shown by Common Buzzard and this bird can therefore confidently be identified as a Rough-legged. Though the tail looks extensively dark, this is consistent with some juvenile Rough-leggeds. In flight this bird would still show some white in the tail base.

TWO: Common Buzzard (Gigrin Farm, Rhayader, Powys, 26 May 2012). With its pale ‘frosty’ head, this bird might attract attention as a Rough-legged Buzzard candidate. However, a pale-headed appearance is typical of pale Common Buzzards and everything else visible here is entirely consistent with that diagnosis. The underbody pattern – a particularly useful feature – is not visible in this image, but one look at the wholly brown, finely barred tail seals the deal.

FIVE: Rough-legged Buzzard (Grindale, East Yorkshire, 27 November 2014). By contrast, this bird shows all the classic features of a juvenile Rough-legged Buzzard – a ‘frosty’ pale head combined with a solid dark belly patch, shining white underwings, extensive ‘wrist patches’ and a white tail with dark terminal band. The structure can be appreciated here too – rather long winged and ‘rangy’ with a prominent head and a longer-tailed outline than is ever shown by Common Buzzard. In life, Roughlegged Buzzards have a soft, fluid flight action more akin to a harrier or a small eagle than a Common Buzzard.

SIX: Common Buzzard (Seaforth, Lancashire, 2 April 2011). This rather typically plumaged Common Buzzard is showing its underwing pattern well. No Rough-legged Buzzard shows such extensive brown in the underwing coverts, while the tail can be seen to be uniform pale brown below and finely barred. Also obvious is the typically short-winged and short-tailed appearance of Common Buzzard, a structure which translates in real life into a distinctive stiff, rather rapid wing action.

FOUR: Common Buzzard (Falsterbo, Sweden, 5 September 2010). This bird looks extremely pale and eyecatching. It is, however, an entirely typical example of a very pale Common Buzzard. The structure – short, broad wings and short, broad tail – is classic Common Buzzard, while the plumage detail is typical too. Note the reduced, comma-shaped dark ‘wrist patches’ (these are much more extensive in Rough-legged) and, most obviously, the wholly white underbody – a pattern never shown by any Rough-legged Buzzard of any age.

SEVEN: Rough-legged Buzzard (Pyhäjoki, Finland, 17 April 2008). This Rough-legged Buzzard lacks the prominent dark belly patch of juveniles and females, showing instead a rather more Common Buzzard-like pattern. This pattern is, however, typical of adult male Rough-leggeds, an identification that can be confirmed by its shining white underwings, extensive dark ‘wrist patches’ and, best of all, a white tail with a dark band. As confirmation of this bird’s age, and therefore its identity, note the detail of the tail pattern. Instead of the broad dark terminal band of a juvenile, it shows a narrower dark subterminal band with further thin dark lines along the inner edge – the classic adult pattern.

EIGHT: Common Buzzard (Gigrin Farm, Rhayader, Powys, 7 March 2010). With such extensive warm brown hues on the underbody and underwing, this is an ‘easy-to-identify’ Common Buzzard. Indeed the brown in the underwing coverts is so extensive that the dark ‘wrist patches’ barely stand out. The tail can also be seen to be uniformly coloured, while the short wings and short tail are again characteristic of our commonest raptor.

NINE: Rough-legged Buzzard (Hokkaido, Japan, 12 February 2012). This lovely snow-lit portrait of a hovering Rough-legged Buzzard, accentuating its white ‘frosty’ head, underwings and inner tail, reminds us that this is a real Arctic species. On such a close view it is also possible to see its greater feather density or ‘fluffiness’, an adaptation to colder climes shared with other Arctic inhabitants such as Arctic Redpoll. This bird also shows a clear white ‘flash’ in the upper primaries – a feature shown by many (though not all) Roughleggeds.

TEN: Common Buzzard (Texel, The Netherlands, 28 November 2012). The short-winged and short-tailed outline of this Common Buzzard is beautifully shown here, as is a complete suite of diagnostic plumage features, most notably uniform warm brown hues in the head, upperparts and upperwing, and a concolorous brown uppertail with fine barring throughout its length.

ELEVEN: Rough-legged Buzzard (Porvoo, Finland, 6 February 2006). This bird, by contrast, shows a complete set of juvenile Roughlegged Buzzard characters – a pale, ‘frosty’ head, a bright white tail base and a broad dark brown terminal band. Although this is sufficient to nail its identification, the white ‘flash’ in the upper primaries is a useful confirmatory feature. Note, again, the rather more elegant, long-winged and long-tailed, almost harrier-like outline of this species.