Field Identification of Orange-Breasted and Bat Falcons

C O T IN G A 4 Orange-breasted and Bat falcons Field identification of Orange-breasted and Bat Falcons Steve N. G. Howell and Andrew Whittaker Introduction extent on chest of Bat Falcon); definite coarse The Bat Falcon Falco rufigularis is a wide buff barring on black vest (not fine white spread, small, generally quite common edging); and proportionately much stronger Neotropical falcon resident from Mexico to larger feet.” Other guides13,18 echo these fea South America, west of the Andes to Ecuador, tures, in particular the orange chest, buff east of the Andes to Brazil1. Over much of its barring on the narrower black chest band, and range the Bat Falcon is sympatric with the the proportionately larger feet of Orange larger and much rarer Orange-breasted Fal breasted. However, many Bat Falcons show con F. deiroleucus, which is resident from orangish to bright orange across the chest south-eastern Mexico to South America, east above the black vest (as cautioned by Ridgely of the Andes to Brazil1. These two species are & Gwynne16), the barring on the black vest can remarkably similar in plumage (Figure 1), but be whitish or buffy in both species, and judg the field identification of Orange-breasted, a ing the relative size of bill or feet on a lone near-threatened species6, is poorly treated in bird can be difficult. Becoming thoroughly many guides. Here we discuss characters that familiar with the structure and plumage vari can be used to help correctly identify Orange ation of the much commoner Bat Falcon is breasted Falcons. This paper is based on field desirable before identifying an Orange observations by SNGH at traditional sites in breasted Falcon. Belize and Guatemala (1984, 1990–1995) and one bird seen in eastern Ecuador (July 1994), Geographic variation and six birds seen by AW in Amazonian Brazil The races of Bat Falcon, and their characters, (1988–1993)20 and one in Roraima, northern have been the subject of some debate: this has Brazil (Nov 1994), plus examination of mu a bearing on field identification. Numerous seum specimens. We also have seen at least authors (for example 3,4,9,11,14) recognise nomi 400 Bat Falcons in the field (1981–1995) from nate rufigularis (or albigularis, now considered Mexico to Ecuador and Brazil, including birds a synonym8) throughout most of the Bat Fal virtually alongside Orange-breasteds in Belize con’s range, and petrophilus of north-west and Guatemala. Mexico. Wetmore19, however, pointed out that Middle American birds were separable as The problem petoensis (described by Chubb5), and other Most literature inadequately treats the field more recent authors2 have followed this separation of Bat and Orange-breasted fal course; the race petrophilus is at best weakly cons, often perpetuating equivocal characters differentiated, and the race pax described from supposedly diagnostic for Orange-breasted, Bolivia5 is generally not recognised. such as the orange chest. For example, for In summary, adult Bat Falcons from Mexico, Peterson & Chalif15 state simply “… Mexico to north-western South America like a large, big-footed, heavy-billed version (petoensis) tend to be bluish grey above and of the Bat Falcon. The bright orange breast have a whiter throat (e.g. Figure 1, no. 1c) below the white throat identifies it.” For Co versus the darker, blackish grey upperparts lombia, Hilty and Brown10 note the following and buffier throat of most South American differences for Orange-breasted compared birds east of the Andes (rufigularis) (Figure 1, with Bat: “black vest narrower (usually), cross no. 1a). The Orange-breasted Falcon is ing only lower breast and upper belly (not considered monotypic, but note the entire breast); rufous wash on chest and up apparent geographic plumage variation de per breast (rufous also often present to some scribed below. 36 C O T IN G A 4 Orange-breasted and Bat Falcons Identification features breasteds (especially females) show more Size and structure strongly pronounced shoulders than Bat Fal Orange-breasted Falcons (length 13.5–16", cons. 34.5–40.5 cm; wingspan 30.5–35.5", 77–90 cm) These overall structural differences paral are larger than Bat Falcons (length 9–11", 23– lel those between a Peregrine Falcon and a 28 cm; wingspan 24–29", 61–73.5 cm)12. While Merlin F. columbarius or European Hobby F. lengths of the two species do not overlap, judg subbuteo and, with experience, enable identi ing size of a lone bird perched high on a bare fication of birds at long range when plumage snag against the sky can be difficult. Using features are not visible. A recent illustration size as a primary identification character “it of Orange-breasted Falcon (del Hoyo et al.7, was large so it had to be Orange-breasted” — Plate 27) quite wrongly shows Orange is circular reasoning akin to “I wouldn’t have breasted Falcon with a long tail projecting well seen it if I hadn’t believed it”. Measurements beyond the wingtips. of length and wingspan, however, do not con The feet of Orange-breasted are proportion vey the significantly greater bulk of ately larger than on Bat Falcon (Figure 1). Orange-breasted compared to Bat Falcon: However, Bat Falcon, like most falcons, has male Orange-breasteds weigh around 350 g, long toes so its feet may look quite large (e.g. and females 550–650 g; Bat Falcons are much Figure 2), although its toes may appear slen lighter, with males about 110–150 g and fe der relative to the toes of Orange-breasted. males 180–240 g4. Some observers have noted that the large feet Linked to bulk, the overall shape of of Orange-breasted Falcon can create the im Orange-breasted and Bat falcons differs no pression in flight that the bird is carrying prey ticeably, something that has been generally (P. Jenny pers. comm.); however, a Bat Falcon overlooked (Figure 1). Orange-breasted is a carrying prey is going to give the same im more heavily-built bird with a proportionately pression. In Middle America, SNGH has found larger, blockier head; in flight its wings ap the proportionately larger, heavier beak of pear relatively broader-based and its tail Orange-breasted Falcon to be as useful a char proportionately shorter and broader-based acter as the feet size, and often easier to see than on Bat Falcon; this is more pronounced in the field when the feet can be partly cov in females than males. Thus it has a thickset, ered by belly feathers or hidden by a branch. powerful shape likely to remind observers of Correctly judging the size of beak and feet in Peregrine Falcon F. peregrinus, as noted by the field, however, can be difficult, and re Ridgely & Gwynne16. In contrast, the Bat quires critical experience with Bat Falcons. Falcon is more slightly built, with a propor tionately smaller head, narrower-based wings, Plum age and a longer, narrower-based tail than Basically, both species have dark upperparts, Orange-breasted Falcon; thus, in flight, Bat a pale throat, a pale-barred blackish “vest” Falcon can suggest a White-collared Swift across the underparts, and rufous thighs and Streptoprocne zonalis. At rest, the wingtips of undertail coverts (Figure 1). The sexes are Orange-breasted are equal with (mainly similar in appearance although differing males?) or often project noticeably beyond markedly in size (see above). Adult plumage (mainly females?) the tail tip. On Bat Falcon appears to be attained by a complete, first the wingtips of females tend to be about equal prebasic (“post-breeding”) molt within a bird’s with, or very slightly longer than the tail tip, first year. Thus, there is only one immature whilst those of males usually are slightly plumage stage to consider. The juvenile shorter than the tail tip. Orange-breasted Falcon is distinctive if seen The tail shape of the two species differs well, and is not discussed in detail here: note also: Orange-breasted Falcon has a somewhat the extensive dark chevrons on its pale (cin graduated tail tip like Peregrine; whereas the namon to whitish) thighs (e.g. Plate 6 of outermost rectrices of Bat Falcon are not much Howell & Webb12). The following features are shorter than the rest, and its tail often appears important to note when distinguishing adult slightly cleft (see flight shapes in Figure 1). Orange-breasted from adult and juvenile Bat AW has noted that some perched Orange- Falcons. 37 C O TIN G A 4 Orange-breasted and Bat falcons Upperparts On most Middle American and wash of cinnamon or orange along the border some eastern South American adult Bat Fal with the black vest and on the sides of the neck cons the blackish head (especially the sides of (Figure 1, no. lc; also Hilty & Brown10, Plate the face) often is contrastingly darker than the 5; Ridgely & Gwynne16, Plate 7; Howell & slaty blue-grey upperparts (Figure 1, nos. 1c/ Webb12, Plate 6). However, on many birds the d); the back feathers have blackish shaft- sides of the neck and the chest above the black streaks, while the upperwing coverts are ish vest have a distinct cinnamon or orangy blackish-centred and edged blue-grey; birds in wash; on some birds this can be bright orange, north-western Mexico (the described race as bright as Orange-breasted Falcon (Figure petrophilus, Figure 1, no. 1c) tend to be paler 1, no. 1d). In such cases, the orange colour above and whiter-throated. On most South tends to be more extensive than on Orange American and a few Middle American adults breasted and suffuses into the throat which there is often little or no head-back contrast appears buffy white, often with a buffy-cinna- since the upperparts are darker and on some mon band or patch across the lower or median birds can be blackish, narrowly edged grey, throat; the throat can, however, look fairly similar to Orange-breasted (Figure 1, no.

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