Birdwatch

Juvenile ringtail harriers

Catching sight of the white rump of a ringtail harrier will always quicken the pulse, but a tough identifica­tion challenge often follows. With the peak weeks of autumn ahead, David Cooper provides tips on how to recognise the juvenile plumages of five similar species.

Autumn is a protracted and thrilling season that all birders look forward to. While the first returning waders arriving back on British and Irish shores in June may signal the onset of the season, it’s not too much later when the first juvenile Hen Harriers fledge from their nests, mainly on the heather-clad moors of northern Britain from the end of that month.

Juvenile Hen Harriers aren’t exactly the pin-up birds of a British autumn, but their southerly post-fledging dispersal, followed by some wandering between favoured roost sites as they prepare to winter, ensures that juveniles can be encountere­d across Britain throughout the season. What’s more, these are beautiful birds that offer a fascinatin­g identifica­tion challenge, particular­ly when considerin­g several similar species that may also occur here. Juvenile Hen Harriers usually commence their first partial post-juvenile moult in December, renewing some of their body plumage and tail feathers. Hence, rather neatly, it is the second half of the year that offers the opportunit­y to see the species in full juvenile plumage. However, if views allow, it’s essential to critically evaluate a whole suite of characters, as during those same autumn months, when it comes to juvenile ringtail harriers, rarer options are most definitely in play.

In this article, I’ll look at the juvenile plumages of five species, ranging from the relatively widespread Hen Harrier to the as-yet unrecorded Pied Harrier, comparing their plumages and offering you the best possible preparatio­n for an encounter with a ringtail harrier this autumn.

Wing structure

On setting eyes on a juvenile harrier, typically after seeing those tell-tale white upper-tail coverts that coin the term ‘ringtail’, it is important to assess the bird’s wing structure. Wing formula is a good place to start, often being readily apparent in all but the briefest of views.

At this stage, it is worth stressing the usefulness of digital photograph­y as an aid in the identifica­tion of juvenile

ringtail harriers. These wide-ranging birds sometimes give only fleeting field encounters and firing off photos can be crucial in clinching an ID. Meanwhile, field views can be subjective and challengin­g, especially if brief or poor. Images will capture multiple features and allow for the reassessme­nt of characters, both while in the field and after the event. Additional­ly, they will likely smoothen the process (if not be a prerequisi­te) of a sighting of one of the rarer options being accepted by a records committee.

If your bird has bulging secondarie­s and a broad, rather blunt, five-fingered hand, it will immediatel­y narrow the choices. In a British context, these features are strong indicators that the bird will prove to be a Hen Harrier. However, careful considerat­ion still needs to be given to eliminate the possibilit­y of one of the rarer options, namely Northern Harrier (the Nearctic counterpar­t to Hen), a hybrid

Hen × Pallid Harrier or even the jackpot: Britain’s first Pied Harrier!

If the bird appears slim-winged and shows a long, triangular-shaped, pointed hand, clearly narrowing from the carpal joint to the tip of the longest primary, you’ll likely experience an immediate adrenaline rush. However, it’s important to carefully assess whether it is showing a four-fingered hand (this isn’t always easy if the hand is held closed), as this will effectivel­y eliminate all options other than Pallid or Montagu’s Harrier.

Hen Harrier

Though continuing persecutio­n has sadly diminished the numbers of this magnificen­t bird breeding in our countrysid­e, Hen Harrier remains the most frequent of the species covered here and is therefore considered the default option, especially as most juveniles remain to winter in Britain. Juvenile males and females both show considerab­le plumage and ground-colour variation. There is no overlap in size, with females being larger and therefore appearing heavier, broader winged and longer tailed. They show well-marked pale collars with dark

spotting and nape patches (both virtually lacking in adult females) and heavy dark neck-side streaking coalescing to form something of a dark ‘boa’. The face pattern shows a white superciliu­m and white crescent below the eye, set against a dark crown, eye mask and ear-covert surround.

The ground colour of the underparts varies considerab­ly from whitish through ochre to rusty-buff, but most show streaking on the breast and flanks with either plain, finely streaked or spotted undertail coverts. The underwings lack any spots on the greater secondary coverts and there is a narrow, slightly contrastin­g greyish terminal band across the secondarie­s (blacker in adult females). The secondarie­s show almost parallel black-and-white bars with the two pale bands narrowing and darkening, sometimes fading away altogether, as they approach the body. The wing-tip comprises five fingered primaries, with p8 and p7 the longest and forming the wing point. Meanwhile, p9 and p6 are also of similar length to each other.

Northern Harrier

The first Northern Harrier for Britain, a well-marked juvenile, harks back to the oft-regarded ‘golden era’ of Scilly birding, being found on St Mary’s in October 1982. Back then, the species was treated as conspecifi­c with Hen

Harrier, albeit going by the name of ‘Marsh Hawk’. It took more than 25 years for it to gain official acceptance.

It wasn’t until 2008 that another was identified – this time at the opposite end of the country on North Ronaldsay, Orkney. However, with a refinement and a greater understand­ing of the identifica­tion criteria, combined with birders being routinely armed with digital cameras, several further records have followed. While many of these have come from counties favoured by Nearctic vagrants such as Cornwall, Dorset and the Outer Hebrides, others have been found in Cambridges­hire, Durham and Norfolk – the locations of those in the last three counties are suggestive of them having made first landfall elsewhere but then having relocated. That in itself means that diligent observers have the possibilit­y of discoverin­g one just about anywhere.

Juvenile Northern Harrier very closely resembles juvenile Hen Harrier in size and structure (including the wing).

Males are smaller than females and there is no overlap in body length, wing length or body weight. In a European context, some Northern Harriers can grab attention by showing a dark head, a pale, unspotted collar, a broad, solidly dark boa, a poorly streaked breast with the remainder of the underparts being a mostly plain cinnamon to rufous-orange, and their upperparts being a dark brown with rich rufous fringes. However, others can be far more subtle, and realistica­lly obtaining good images is key, as these will enable an evaluation of the number of bars present on the underside of the outer primaries. In Northern, the longest primaries (p8 and p9) show five to eight black bars plus the dark tip, whereas in Hen these show three to five (exceptiona­lly six) bars plus the dark tip. In Northern, p10 usually shows four bars plus the dark tip, whereas Hen usually has only three bars.

Pallid Harrier

Recent decades have seen many changes in the status of vagrant birds reaching Britain, but few would have predicted the dramatic upsurge in records of

Pallid Harrier, taking it from extreme rarity to expected annual visitor. While that’s welcome news for the nation’s birders relishing the challenge of finding and identifyin­g the species on these shores, recent research suggests that the reasons for the increasing number of records might not be such welcome news. It appears the species is being displaced from its historical breeding range in the steppe grasslands of Kazakhstan, Russia and northwest China, almost certainly due to agricultur­al land-use changes. During the early stages of the upsurge of records, the Northern Isles played host to the majority of sightings with their

appearance often associated with southeaste­rly winds, but more recently they have been found just about anywhere there are open habitats, including well inland.

While juvenile Pallid Harrier has a broad arm, its four-fingered hand is rather triangular and consists of the short, outermost p10 and long p9-p7 that show barred grey undersides along their length and dark tips. Pallid sports a sharply defined head pattern complete with dark crown, white superciliu­m and crescent below the eye, a solid dark earcovert surround extending all the way to the lower mandible, an unspotted pale ochre collar and an extensive, solid dark-brown boa. The underparts are plain orange and eye-catchingly different from the streaked underparts of juvenile Hen. A pale ochre panel on the upperwing coverts is another very striking feature.

Hen × Pallid Harrier

Due to the recent westerly expansion of Pallid Harrier into Scandinavi­a there have been a number of documented hybrid pairings with Hen Harriers from that region that have successful­ly raised juveniles. In fact, the first widely twitched British Pallid Harrier was a second-calendar-year male that was paired with a female Hen Harrier in Orkney in 1995; a clutch of eggs was laid but these were seemingly predated. There have also been three instances of male Pallid seen either displaying or holding territory in northern England. Meticulous birders have already identified hybrid juveniles in Britain; the account of one in Cambridges­hire in October 2011 found favour with the BBRC in being one of the runnersup for the Carl Zeiss Award in 2017. Anyone fortunate enough to find a ringtail harrier showing some characters of Hen, Pallid or even Northern would therefore be well advised to carefully check whether the bird is showing a full suite of characters associated with those species in order to eliminate the possibilit­y of it being a hybrid.

Such hybrids documented thus far have shown substantia­l plumage variation falling into three main types: those closely resembling juvenile Pallid; those resembling Pallid and Hen in equal measure; and those closely resembling Hen. However, all types have shown a wing formula differing from both of their parent species. Unsurprisi­ngly, the three accepted British records of hybrids have most closely resembled juvenile Pallid in the field, sporting prominent pale, unspotted collars, a dark boa and unstreaked orange underparts. All have shown a rather narrow hand but with five fingered primaries (albeit p6 has been considered shorter than that shown by juvenile Hen).

Montagu’s Harrier

Montagu’s Harrier bred in Britain until very recently, typically favouring arable fields in East Anglia and southcoast counties. Juveniles would typically fledge from July. While for now we might be relying on juveniles drifting to our shores from the near-Continent and we should therefore expect coastal counties to account for the majority of records, these can still be expected from August, albeit perhaps in increasing­ly small numbers due to declines being reported elsewhere in Europe. With something of a switch in the status of this species and Pallid Harrier, what odds that Montagu’s Harrier is added

to the BBRC’s list of considered species at the same time that Pallid Harrier is dropped?

Montagu’s is the smallest species covered here, being small bodied and long tailed with slender, pointed wings, narrowing from the carpal to the wingtips, and having a four-fingered hand with the tip formed by p7-p9, which are the longest primaries.

The undersides of the outer primaries are usually diagnostic­ally dark and their greyish bases only show a few fine bars (if any at all). Helpfully, they also show a dark trailing edge to the inner primaries, which is something that juvenile Pallid lacks. The secondarie­s are often uniformly darker than juvenile Pallid. Meanwhile, the pale nape patch is extensive in comparison to that of juvenile Hen.

The head pattern of Montagu’s comprises of a dark crown, a white superciliu­m and a crescent below the eye, an isolated dark ear-covert surround, a pale collar and usually a subtly streaked, dark boa. On close inspection, its head pattern is rather diffuse, lacking the sharp contrast shown by juvenile Pallid.

Pied Harrier

Now, one for the optimist! Finding a first for Britain becomes ever harder and new additions will eventually grind to a halt but, gladly, that hasn’t happened just yet.

Globally, harriers have a proven track record of long-distance vagrancy, with the likes of Western Marsh Harriers in Barbados, Bermuda and Puerto Rico, Cinereous Harriers in the Falkland Islands and Northern Harrier in Japan.

Pied Harrier shares a distributi­on not too dissimilar to Chinese Pond Heron or Grey-headed Lapwing. It occurs sparingly north to the shores of Lake Baikal and has been recorded west to Pakistan, but a bird that successful­ly wintered in the Chagos Archipelag­o in the central Indian Ocean really hints at the species’ potential for long-distance vagrancy. While an adult male would immediatel­y attract attention, could a juvenile slip through the net?

Although similar in size to Hen Harrier and sharing a five-fingered hand, Pied tends to appear far more buoyant in flight. At first glance, if it wasn’t for the familiar white ‘ringtail’, in a British context one could be forgiven for thinking the overall dark-brown appearance is reminiscen­t of juvenile Western Marsh Harrier.

On noticing the white rump, thoughts might then turn to the bird being a melanistic juvenile Montagu’s, but their plumage is genuinely black and lacks the pale superciliu­m and pale eye crescent. The diagnostic underparts and underwing coverts of juvenile Pied are a rich, dark cinnamon-brown, while the secondarie­s appear blackish, both above and below. The undersides of the primaries are grey with darker grey bars. In reality, once the penny drops, this species shouldn’t prove too much of an identifica­tion challenge. ■