ABOVE: Can nightjars be  identified when they are not in the hand? I promise that if you summon all your energy, give me 2 hours of your time, and wade all the way through this exhausting article, you will be able to tell that this is a male European Nightjar! Whether it’s worth the effort you’ll have to decide. Photo by Joe Grosel.

A few years ago Ronel and I found ourselves on a bird ringing camp at Ndumo in northern Zululand, South Africa. The first thing that we learned about a bird ringing camp, is that there really isn’t much actual camping. Several hours before dawn you’re up and unfurling nets already. And after supper you’re out catching nocturnal birds the whole night long. On one evening the team caught a nondescript nightjar, and perhaps not unexpectedly, a massive argument about its identity ensued. Huddled in a little circle, headlamps trained on our quarry, and constantly flicking off moths and beetles, I remember thinking ‘I wish there was a proper reference to the field ID of southern African nightjars, without all this messing about with measurements, ratios and feather emarginations’.

About a decade later, I tackled this question again, which resulted in an article entitled ‘Spot the difference – a guide to correctly identifying a quiet nightjar’ in the July/August edition of African Birdlife magazine. However, that article was only a shortened, reader-friendly version of the original…which is far more technical, confusing, poorly written and tedious. I present it to you here in full! All the specimen photographs are by my friend Jason Boyce. Enjoy!

The identification of nightjars is arguably one of the most challenging dilemmas faced by birders. In the words of Cramp et al. (1985), “nightjar identification is as much a matter of fortune as of effort or knowledge; all species are essentially crepuscular and observation is difficult even in occasional diurnal discoveries, as the birds use astonishingly cryptic plumage to disappear against many backgrounds, even at point-blank range”. Fortunately, most species have highly distinctive and diagnostic songs that are a characteristic component of Africa’s nocturnal soundscape and facilitate reliable identification. However, singing is usually performed only by males, and is mostly restricted to the breeding season.

Identification of non-vocalising nightjars presents a considerable problem, and is traditionally based virtually exclusively on careful in-hand evaluation of plumage details, morphology, and structural ratios. In particular, the size, position and number of the contrasting white or buff spots on the outer primaries and the pale apical patches on the two outer rectrices of most species are useful in identification. Additionally, characters such as wing length, length of the emargination on the outer web of the ninth primary (P9), position of P9 spot relative to the emargination, relative ratios of the primaries and rectrices, and even bill and foot length may need to be examined. This methodology has given rise to a number of dichotomous identification keys e.g. Jackson (1986, 2000) and Maclean (1993), or technical identification diagrams e.g. Newman (1983) and Chittenden (2007). However, in the vast majority of cases, observing such intricate details requires having the bird in the hand, or examining road-killed specimens.

As nocturnal visual hunters, nightjars have excellent eyesight and consequently, they are easily blinded with a spotlight and captured by hand or netted. This, together with their habit of resting on roads at night has ensured that catching nightjars has become somewhat of a “sport”, and this activity is frequently performed by scientists, game rangers and birders, even within conservation areas. Research into the potential adverse effects of prolonged exposure to strong artificial lights on nightjars’ eyes is limited. Nevertheless, it is likely that temporarily blinding nocturnal animals may negatively affect them physiologically, and interferes with their foraging efficiency, predator avoidance, behaviour and even breeding cycles. Several conservation and ethics agencies recommend that spotlighting be kept to a minimum, and that red filters and indirect lighting will help reduce discomfort to the subject.

So, if a nightjar is not singing and cannot be examined in-hand, is it possible to identify it to species-level? We set out to answer this question by examining approximately 400 study skins of the seven southern African nightjar species in the collection of the Ditsong National Museum of Natural History (DNMNH):

• European Nightjar, Caprimulgus europaeus
• Fiery-necked Nightjar, Caprimulgus pectoralis
• Freckled Nightjar, Caprimulgus tristigma
• Rufous-cheeked Nightjar, Caprimulgus rufigena
• Square-tailed (Mozambique) Nightjar, Caprimulgus fossii
• Swamp (Natal) Nightjar, Caprimulgus natalensis
• Pennant-winged Nightjar, Macrodipteryx vexillarius

Jackson (2000) cautioned that nightjar plumage patterns evolved for camouflage and not as species-specific characters, and varies greatly within species, geographically and individually, to the extent that identification keys placing too much emphasis on plumage are unreliable. Nevertheless, we set out to determine whether any reliable and easily observable identification characters exist to separate southern African nightjars, without having them in the hand. We recognise that subspecific variation is pronounced in several species (notably the migratory European, and resident Fiery-necked; see table, opposite), and that individual, age-related, sexual, and feather wear variations also complicate the picture, but we feel that all these issues have not been sufficiently researched and are unlikely to be of major concern to the average field birder.

TABLE 1: Nightjar subspecies, following Chittenden et al. (2012).

As several species may occur in close proximity (indeed, six species occur in sympatry in e.g. northern Limpopo or parts of KwaZulu-Natal), we do not place too much emphasis on habitat preference and distribution, for which readers are referred to Fry et al. (1988), Harrison et al. (1997) and Hockey et al. (2005). In terms of movements, European, Rufous-cheeked and Pennant-winged are summer visitors (but may occasionally overwinter), while Fiery-necked, Freckled, Square-tailed and Swamp also undergo local altitudinal, regional or nomadic movements. As mentioned above, nightjar songs are diagnostic and easily recognisable, although alarm, contact and threat calls may be similar between species.

We focus primarily on characters that can be readily observed with binoculars at a distance of 5-10 m, or on photographs of birds at rest (i.e. with the wings folded). With practice, even subtle details such as placement of wing spots, size of patches on outer tail feathers and scapular patterns should be apparent in such situations. We also discuss structural features that do not require actual measurements, such as primary projection, tail:wing ratio, posture, size and body shape. Readers are advised to familiarise themselves with the nightjar morphology diagram (Fig. 1) and the annotated images for each species (Fig. 8-21).

Of these seven species, we focussed primarily on European, Fiery-necked, Rufous-cheeked and Square-tailed Nightjars, which provide most identification pitfalls, overlap widely in habitat and distribution, and are common and widespread. Identification of the remaining three species (Swamp, Freckled and Pennant-winged), which are either highly range-restricted, or have sufficiently distinct plumage to facilitate confident identification, is addressed briefly. Characters are first assessed individually, followed by a summary for each species.

FIGURE 1. Nightjar morphology; example species is Fiery-necked Nightjar. Lower left image shows upperside of tip of right wing. Lower right image shows underside of tail. Total wing length and relative lengths of the various primaries were taken by sliding a stopped ruler under the carpal joint, and flattening the primaries. Wing spot and tail spot length was measured as the maximum dimension parallel to the rachis (shaft). Tail length was taken from the skin at the unfeathered base of the feather shaft (calamus) to the tip of T1 (central tail feather), unless otherwise specified. Primaries are measured from the inside of the wing, i.e. the longest primary is P9.

Juvenile plumage is undocumented or only described very superficially in most Afrotropical nightjars, and few museum specimens are available. The active and semi-precocial hatchlings are initially covered in fluffy down, but this is rapidly replaced by the first suite of true feathers, i.e. juvenile plumage. Indeed, within days of hatching the quills of the juvenile plumage feathers begin appearing, and in the second week of life the juvenile plumage progressively replaces the nestling down (Holyoak, 2001). Juvenile plumage is generally paler, plainer and more rufous- or buff-toned than adult plumage, but in some species is very similar to adult females. Generally, juveniles have softer, looser plumage that is more fluffy in texture, and the remiges and rectrices are narrower and more pointed than in adults. Juveniles may also lack the characteristic tail and wing spots of adults, or have much fainter versions of these markings. Young birds, already independent and capable of flight, are often noticeably smaller than their parents.

Juvenile plumage is not retained for long, and the partial moult into adult plumage may begin within a few weeks or at most a few months after leaving the nest (Holyoak, 2001), and even as early as at c. 50 day old in Square-tailed Nightjars (Cleere & Nurney, 1998). The post-juvenile moult is partial, involving the body feathers and wing coverts but not the remiges or rectrices. Retained juvenile wing and tail feathers may thus assist in separating first-years from the otherwise similar adults. However, the post-juvenile moult is complex and the timing and extent varies within and between species. Young birds also tend to moult later than adults. Once the first adult-type plumage is attained, there is usually a single complete post-breeding moult per year (Holyoak, 2001). Migratory species (e.g. European, Rufous-cheeked) often commence moult on the breeding grounds, suspend moult during migration, and finish on the wintering grounds.

FIGURE 2. Ageing of nightjars. Young but independent nightjars are often noticeably smaller than their parents. They tend to have more rufous or buffy plumage, with a more fluffy texture. This sequence illustrates age progression of Rufous-cheeked Nightjar. A) is a recently fledged bird in fresh juvenile plumage; December. B) is an immature that has started a partial moult in which some body feathers and wing coverts will be replaced, but still has (by now worn) juvenile wing and tail feathers; April. C) is an adult in fresh plumage at the onset of the breeding season; October.

Traditionally, southern African nightjars are typically divided into two groups: large species with a wing length of more than 176 mm viz. European, Freckled and Pennant-winged, and small species with a wing length below 176 mm viz. Fiery-necked, Rufous-cheeked, Square-tailed and Swamp. Note that wing length varies within species, and that there are some overlapping cases (e.g. a small European and large Rufous-cheeked can be similar in size). Also important is the length of the tail relative to the wing: see tail:wing ratio in Table 2, below.

TABLE 2. Wing and tail lengths (in mm) of Caprimulgus nightjars, with species arranged by increasing wing length. Swamp Nightjar has the smallest dimensions, as well as the smallest tail:wing ratio; indeed, its tail appears noticeably short in the field. Square-tailed, Fiery-necked and Rufous-cheeked all have relatively similar tail and wing lengths, and tail:wing ratios, and it is doubtful whether these three species can be distinguished in the field based solely on structure. In contrast, the wing of European appears considerably longer and more pointed in the field; although it has the longest tail of any species, it has a relatively small tail:wing ratio, because the wing tips extend so far along the tail when at rest. Freckled is a large and long-winged, but short-tailed species, as reflected in its small tail:wing ratio. Data from Jackson (2000).

Another useful character to assess is relative primary projection, i.e. the distance that the primaries project beyond the tips of the tertials on the folded wing (see Fig. 1). Being a long-distance Palearctic migrant, it is not surprising that the European Nightjar has longer and more pointed wings than the other species (see Fig. 4), with a very long primary projection of c. 39% of the total wing length. In some cases this can be useful in distinguishing this species from the similar Rufous-cheeked (primary projection c. 32%) and the small Square-tailed Nightjar (c. 33%), but the primary projection values do overlap with Fiery-necked (c. 38%).

Identifying nightjars solely by their shape or giss is risky, but a few general pointers may still be kept in mind. European Nightjars typically, but not exclusively, roost lengthwise on diagonal or horizontal tree branches during the day, and then appear particularly flat-crowned, sleek and elongated (emphasised by the long, pointed wing). At night, e.g. when sitting on a road, they often look large with bulky and broad but flat heads, that seem to “blend smoothly” into their shoulders. Fiery-necked Nightjars have heavy heads and broad necks, giving them a front-heavy, bull-necked look. Square-tailed Nightjars typically appear small and rather delicate, with small heads; one observer compared the giss of this species to a “tennis ball into which a tail has been stuck”. Rufous-cheeked Nightjars are intermediate in shape.

Swamp Nightjars are stocky and squat, but tend to sit high on their long legs; they also have noticeably shorter tails than other nightjars (but beware of shorter-tailed juveniles). Freckled Nightjars are large and powerfully built, with long wings but relatively short tails. Pennant-winged Nightjars appear to be “all wings” with relatively small heads and weak, pointed bills; they often hold the wings slightly drooped, with the carpal joint (i.e. “shoulder”) projecting forwards. Interestingly, this is the only species in which the outer tail feather (T5) is longer than the central tail feather (T1); in effect, its tail thus appears square-ended or even forked instead of slightly rounded (despite the deceiving name of the “Square-tailed Nightjar”).

Given exceptional views or a good photo, a nightjar’s wing formula, i.e. the differences in length of the various primaries, may also prove informative. Although most species have very similar patterns, the more pointed wing of European is notable in Fig. 4; this is sometimes apparent in the field as well. In contrast, Pennant-winged has an equally long but blunter or club-shaped wing. Most other species have P9 and P8 longest and about equal, and P10 and P7 close.

FIGURE 3 (ABOVE). Total wing length vs. primary projection beyond the tertials. While Fiery-necked, Square-tailed and Rufous-cheeked all cluster close together, European is obviously longer-winged than any of these species. However, there is considerable overlap in terms of the exposed section of the primary feathers visible beyond the tertials (i.e. primary projection) on the folded wing, between all four species. Large individuals of European Nightjar have considerably longer primary projection than the other species depicted. Primary projection on smaller Europeans exceeds most Rufous-cheeked and Square-tailed, but does overlap extensively with Fiery-necked.

FIGURE 4 (ABOVE). Simplified nightjar wing formulae diagram. Only P6-P10 are shown (in reality P5 may also be over 120 mm, but is not depicted here). Most species have the outer edges of P9 and P8, and less noticeably P7, emarginated, but this is not illustrated here. Note that wing moult can drastically affect the wing formula.

On resting birds, the scapulars are often the most visible plumage feature (see e.g. Fig. 7), and usefully, show distinct differences between most species. The scapular feather tracts consist of two parallel rows of broad feathers on the outside of the mantle, which together form a large, isolated oval patch on each side of the body. The scapulars often cover the top section of the folded wing, and may be mistaken for the “shoulder” i.e. the lesser coverts, but are situated further down along the body (more or less above the middle of the folded wing), being attached to the skin at the base of the humerus, not the radius (see Fig. 1). The most useful identification characters related to the scapulars are:

• The shape of the blackish centre of each feather.
• The extent of cream or off-white markigns on the outer web.
• The presence of a large dark oval formed by the inner webs of the lined-up scapulars.

Fiery-necked: Apparently regardless of race, feather wear or sex, the scapulars always look distinctly black-spotted on Fiery-necked Nightjar (Fig. 5, A). This is because each individual scapular feather has a very large and prominent black area on the outer web, but relatively little cream colouration. The black may be in the shape of an oval, pointed spearhead or star, but does not look like a black streak. Conversely, the cream colour is usually restricted to small paired spots on the tip of the feather or a narrow wavy basal band. A few scapular feathers may show broader cream outer edges reminiscent of other nightjar species, but the overall impression is not of a neatly lined-up cream band running parallel to the wing. Inner webs are grey-brown and finely vermiculated. Many individuals, particularly of the fervidus race, also show much rufous or brown on the outer webs. The back contrasts relatively little with the scapulars. At a glance, the black-spotted pattern is most reminiscent of Swamp Nightjar, although less coarsely marked.

Rufous-cheeked: In this rather subtly marked species, each scapular feather has three colour patterns: a narrow plain cream line on the outer web; a black, sharply pointed black central streak; and a dark grey-brown or faintly rufous-mottled inner web. When neatly lined-up, the scapulars thus forms a thin cream line, bordered above by a large dark oval. This dark patch often contrasts strongly with the pale grey and rather plain back and mantle, which have only thin black shaft streaks and nearly invisible grey mottling (Fig. 5, D). In darker individuals the mantle is more prominently mottled and streaked, thus reducing the contrast with the dark scapular patches.

European: Due to the polytypic nature of this species, the scapular pattern is highly variable. However, most individuals are almost indistinguishable from Rufous-cheeked (compare C and D, Fig. 5); thus, a contrasting cream band on the outer web, a black central streak, and a dark brown inner web. Likewise, twin dark oval patches are also discernible on the side of the back/mantle, as in Rufous-cheeked. On the darkest birds (mostly europaeus), the cream outer colour is darker and richer, thus contrasting less with the black feather centre; also, because of the generally darker dorsal plumage, the black oval patches are less striking. Conversely, on palest birds (plumipes) the pattern is less clear: the black central streak is often narrower and more undulating, and the inner webs are paler and more mottled (Fig. 5, B).

Square-tailed: In keeping with the rest of its attractive plumage, the scapulars of Square-tailed Nightjar are vividly and boldly marked. Each feather has an extensive black centre contrasting strongly with a very broad and extensive cream or golden orange band. The pale band covers most of the outer web, extending to the feather tip, and may even extend partly up the inner web as well (thus isolating the black centre). In effect, this striking and strongly contrasting black and cream pattern is quite reminiscent of the upperparts of a Gallinago snipe (Fig. 5, E-F), a useful analogy to remember when in the field. The scapulars contrast fairly strongly with the grey back with its granite-like appearance.

Other species: In order to effectively camouflage in its rocky haunts, Freckled Nightjar lacks any distinctive contrasting patterns above, although it may show a few scattered greyish buff flecks on the scapulars. Swamp Nightjar looks distinctly black-spotted above (in this respect recalling Fiery-necked), on a straw-coloured background heavily mottled and spotted with darker grey. The large black spots are often star–shaped, with white fringes or tips. Finally, Pennant-winged Nightjar is rather plain brown above, overlain with fine dark mottling; it usually shows a few broad buff slashes on the scapulars.

FIGURE 5. Patterns of scapular feathers of A) Fiery-necked Nightjar; B) European Nightjar race plumipes; C) European Nightjar race europaeus; D) Rufous-cheeked Nightjar; E) Square-tailed Nightjar female; F) Square-tailed Nightjar male. Left scapular tract shown, i.e. birds face to the left of the image. Fiery-necked appears black-spotted, with relatively little cream colour. European is variable, but in many birds almost identical to Rufous-cheeked, with neat cream-edges on the outer webs and a large black wedge contrasting with the grey back. Square-tailed has vivid and broad, snipe-like bands.

Most nightjar species show white or buffy brown spots on the outer primaries. These marks, together with the apical tail spots, probably play an important role as an intraspecific visual signal in this nocturnal family. When the wing is folded as when a nightjar is at rest on the ground, these spots are almost invisible, but in flight the spots are conspicuous and striking. Traditional identification methods typically rely heavily on the size, colour, extent and placement of such wing spots, but for accurate adjudication, the bird needs to be captured and examined in-hand. Nevertheless, some identification clues may still be discernable through careful observation of birds at rest, especially if the wing is slightly drooped. The most important characters to verify are:

• The number of spots visible on folded wing (thus on the outer webs of the primaries).
• The placement of the spots relative to the emargination on the outer webs, especially on the longest primary, P9.
• The placement of the spots relatively to the tertials.
• The approximate size, shape and colour of the spots.
• If visible, the size of the spot on the underside of P10 on the “back” wing.

Square-tailed: Of the four problem species, Square-tailed shows the most extensive white in its wings, creating a striking pattern in combination with the completely white or buff outer tail and diagnostic pale bar on the trailing edge of the secondaries. In extreme cases, males may show white patches on the six outermost primaries (P5-P10). However, most males show obvious, rather rectangular white spots on the outer webs of at least four feathers on the closed wing (P6-P9), unlike the other species discussed here. P5 may also show white on both webs, but this is more often restricted to the outer web only, and the spot is faint and infused with rich orange-buff. A small percentage of males also show a <1 mm wide white edge on the outer web of P10, but this is quickly worn off after moulting. Inner webs of P6-P10 (and sometimes P5) have white patches, largest on P7 and P8. The white spot on the inner web of P10, as visible on the inside/underside of the closed wing, is fairly large, usually reaching across the entire inner web to the rachis: 13.1 mm (range 11-16) in males, 10.3 mm (range 8-12) in females. In females, at least three and sometimes four wing spots (on P6-P9) are visible on the closed wing; spots are rich buff on the outer webs, but white on the inner webs. P10 has a prominent white spot on the inner web. P5 may show a faint spot pattern. Of all the species, the wing spots of Square-tailed are situated the furthest inwards (proximally) of the emargination; as a rule of thumb, the distance between the point of flexure of the emargination and the start of the wing spot is about the same as the length of the white spot itself.

Rufous-cheeked: In most males three white patches are visible on the folded wing (P7, P8, P9). About 27% of males also show an additional 1-3 mm wide white area on the outer edge of P10, rarely covering the entire outer web up to the rachis. There are four approximately equal-sized white patches on the inner webs (P7-P10), and rarely a faint whitish or buff mark on the inner web of P6 too. The white mark on the inner web of P10, i.e. the spot visible on the outermost feather on the underside of the “back” wing, is large: 18.4 mm (range 14-22) in males, 13.5 mm (range 9-18) in females; this spot is thus considerably larger than in either sex of Fiery-necked, and unlike that species, usually extends across the entire inner web all the way to the rachis (especially in males; usually covers at least 60% of the inner web in females). The female’s pattern is a buff-toned version of the male’s: she typically shows three buff or rufous spots on the outer webs of P7-P9 on the folded wing, and four large spots on the inner webs of P7-P10; the inner web spots are off-white close the rachis, shading to rufous-buff towards the outer edge. The spots are situated well inside of the emargination on P8 and P9, thus lacking the distinct “pinched” appearance of Fiery-necked’s spots.

Fiery-necked: The wing spot pattern is similar to that of Rufous-cheeked in that (both sexes of Fiery-necked) show white spots on the outer webs of three feathers (P7-P9) and on the inner webs of four feathers (P7-P10). Thus, likewise, three white patches are normally visible on the folded wing. However, the outer web white patches are placed right on the emarginated feather edges, so that they are thinner distally than proximally, i.e. they look “pinched”, especially on P9. In addition, the white patches clearly become progressively larger towards the inside of the wing (more so than in Rufous-cheeked). In fact, the outermost white spot on the inner web of P10 (visible on the underside of the folded wing), is considerably smaller than in male Rufous-cheeked, though similar to some female Rufous-cheeked: 10.5 mm (range 6-14) in males, 8.4 mm (range 4-11) in females, extending only about halfway from the outer edge across the inner web of P10. The female’s wing spots are basically identical to the male’s but may be slightly more buff-tinged.

European: This long-winged species has the least distinctive wing spots (indeed, many females lack any hint of wing spots altogether). Males have large, rounded, approximately equal-sized white patches on the inner webs of three feathers, P8-P10. The white spot on the inner web of P10 is large: 21 mm (range 16-26), extending all the way across the inner web. However, the amount of white visible on the outer webs when the wing is folded varies considerably. On the darkest birds (especially of subspecies europaeus and sarudnyi) the outer webs of P8 and P9 have only small, strongly buff-washed and rather inconspicuous white wedges. In fact, many dark males seem to lack white spots on the folded wing completely, or show only one spot on P8. However, paler males (especially of subspecies plumipes) can show two fairly distinct white spots, on P8 and P9. Only P9 is obviously emarginated in this species (P8 very gently), and the spots are situated inside (proximally) of the emargination. Given the long primary projection of this species, the white spots are often, but not always, placed far down along the wing, i.e. about a third to halfway between the tertials and the wingtips (unlike the shorter-winged species, in which the white spots are usually more or less directly below the tertials). Females usually lack distinctive wing spots, but some birds show indistinct dark buff, speckled patches covering 50-70% of the inner webs of P8-P10; no buff patches are discernable on the outer webs.

Swamp: This species has prominent white spots on inner and outer webs of three feathers (P7-P9), and also on inner web of P10. White spots on outer webs are inside (proximal to) the emargination. There is quite often a pale band or fringe along a large section of the outer edge of P10; this is broadest (2-3 mm) opposite the wing spots. There is sometimes also a mottled buff spot on P6 (both webs). Spots are white in males and buff in females.

Freckled: Both sexes have white wing spots on P7-P10: there might be tiny white spots on the outer webs, but the white is mostly restricted to the inner webs. This creates the impression of the bird having an unmarked wing when at rest, but white spots suddenly becoming visible when it takes flight (especially if seen from below).

Pennant-winged: Even without their extravagant trailing pennants on P2, male Pennant-winged Nightjars are instantly identifiable by the very broad white mid-wing band. This band is situated just outside the primary coverts (thus about a third of the way along the folded wing, and much “higher up” than in any other species). The band becomes progressively broader to culminate in the long pennant on P2. In addition, the outer primaries and secondaries are white-tipped to form a white trailing band on the wing, and the outer edge of P10 is also extensively white. It also has a unique wing shape, in that P10 is longest, and that the inner primaries become progressively longer towards the P2 pennant; this gives the wing a strange flared shape. Females lack distinct, isolated white or buff spots in the wing, having instead a series of rufous spots along the entire length of the primaries. In this respect they resemble female European, but have richer rufous instead of yellow-buff blotches. In addition they have buff-tipped secondaries that create a pale trailing band.

FIGURE 6. Wing spots on outer webs (<) and inner webs (>) of P5-P10. White circles represent white spots (mostly males), and orange circles represent buff or rufous spots (mostly females). Large circles represent conspicuous and consistently present spots; small circles denote cases in which spots are small, inconspicuous or only present on some individuals. Diagonally divided circles represent spots that grade from buff to white, or are either buff or white.

Most species have strongly contrasting white or buff apical tail patches on the outer two rectrices (T4 and T5). While very conspicuous in flight, these patches are difficult to see properly when the tail is closed and viewed from the side. Fortunately, nightjars often sit with the tail slightly flared, which makes it possible to see a portion of the tail pattern. Note that juveniles may have reduced or absent tail patterns. The most important characters to check are:

• Whether the tail has pale outer patches or not.
• The length of the pale patch / panel, relative to the total length of the tail.
• If there are dark markings on the tail corners.

Figure 7. Position of scapulars, wing spots and tail spots on European Nightjar. The scapulars have broad creamy outer edges, a dark central streak and dark inner webs, neatly arranged on this bird. In terms of the wing spots, P10 is not visible, but P9 shows a small buff-washed spot on the outer web (inner web not visible), while P8 shows a buff outer web and part of the white inner web. The white tail spots are barely visible on T5. Photo by Joe Grosel.

Square-tailed: This species and Swamp Nightjar are the only two in which (virtually) the entire outer web of T5 is white in males or buff in females. This creates a diagnostic narrow but obvious pale panel that extends all the way along the outer edge of the tail. In male Square-tailed the entire outer web is white, as is the tip of the inner vane; the white may extent as a narrow fringe partway up the inner edge of the inner web too. Females have a similar pattern in buff. There is no white or buff on T4. Juveniles have buff on the outer web of T5, with black mottling near the rachis, but lack pale colour on the tip of the inner web.

Swamp Nightjar: Males of this species have the most extensive white panels in their tails of any southern African nightjar. The entire outer web of T5, plus about two thirds of the inner web is white, and most of the outer web and about half of the inner web is white on T4. This creates a very striking pattern when the bird is flushed. Females have a more subdued pattern, with a 3 mm wide buff outer edge on T5 and T4, and a faint 5 mm wide buff tip on the inner web. The remainder of T4 and T5 is coarsely barred black and buff.

Rufous-cheeked: This species has relatively small patches on T4 and T5, almost equal in size. In males the spots are white, and cover only about the terminal quarter of the tail (or terminal third of the tail visible beyond the undertail coverts). Conversely, in male Fiery-necked the white tail spots cover nearly 40% of the tail, so that in the field it looks like half the tail is white in Fiery-necked. However, female Fiery-necked Nightjars have smaller white tail spots that are very similar to those of male Rufous-cheeked; however, Rufous-cheeked lacks the dark infusion on the outer webs that is virtually always present in Fiery-necked, and unlike the latter, the white areas on the outer and inner webs are about equal in length (not shorter on the outer web). Female Rufous-cheeked has much fainter greyish buff to dull white tail tips; while these patches are fairly obvious in some birds, they are mottled or nearly absent in others.

Fiery-necked: Both sexes have white apical tail spots on T4 and T5. In males the spots are very extensive, essentially encompassing about half the length of the tail. In females the spots are restricted to the last third of the tail (cf. Rufous-cheeked, above). In most individuals, of both sexes, the tips of outer webs of T5 have “dirty” corners, being clearly infused with dark grey. The white patch is
c. 7.3 mm (4-12 mm) longer on the inner web than the outer web.

Freckled: Males recall Fiery-necked in having very extensive white patches on T4 and T5, and in having the outer webs and often the tip of the inner web mottled darker (“dirty corners”). Females lack any white or buff on the outer tail.

European: Males have small to medium-sized white patches on T4 and T5. Unlike the similar Rufous-cheeked Nightjar, the T5 spot is noticeably larger than the T4 spot (average difference 6.8 mm in European, 0.9 mm in Rufous-cheeked). The white on the outer web of T5 is on average 2.9 mm shorter than on the inner web (cf. Fiery-necked). Female European lacks any white or buff on the tail; however, in some females the tip of T5 lacks a dark crossbar and is slightly less mottled than the ground colour of the tail, creating the impression of a faintly buff tail tip (but never as clearly grey-white as in female Rufous-cheeked).

Pennant-winged: Neither sex shows any indication of a buff or white patch on the tips of the square-ended tail.