«The Occurrence and Identification of Red-necked Stint in British Columbia Rick Toochin (Revised: December 3, 2013) Introduction The first confirmed ...»
The Occurrence and Identification of Red-necked Stint in British Columbia
Rick Toochin (Revised: December 3, 2013)
The first confirmed report of a Red-necked Stint (Calidris ruficollis) in British Columbia
was an adult in full breeding plumage found on June 24, 1978 at Iona Island (see Table
1, confirmed records item 1). Recently another older sighting has been uncovered that
fits the timing of occurrence for this species in BC and may be valid (see Table 2,
hypothetical records item 1). Since the first initial sightings in the late 1970s, there has been a slow but steady increase in observations of this beautiful Asian shorebird in British Columbia and, indeed, across the whole of North America. With an increase in both observer coverage and the knowledge of observers, this species is now known to be of regular, and probably annual, occurrence during fall migration in coastal British Columbia. Additionally, this species is now recorded occasionally during spring migration, indicating that at least a few individuals may be successfully wintering farther south in the western hemisphere.
Identification of this species is straightforward when presented with a full breeding- plumaged adult, but identification of birds in juvenile and faded breeding plumage can be very complicated due to the close similarities to other small Calidris shorebirds. This paper describes the distribution and occurrence of the species in B.C., and also examines the similarities of all plumages of Red-necked Stint to species with which it might be confused, most notably Little Stint (C. minuta), Semipalmated Sandpiper (C.
pusilla), and Western Sandpiper (C. mauri). It is hoped that the discussions presented here will fuel further interest in this species among birders in British Columbia and hopefully allow more people to be fortunate enough to lay eyes on this elusive shorebird gem.
Distribution The Red-necked Stint breeds across the high arctic regions of Siberia Russia, ranging from the Taimyr Peninsula west across northern Siberia to the Chukotsky Peninsula. In North America, the breeding range of this species is limited to northern and Western Alaska, particularly along the coastlines of the Seward Peninsula and the coastal regions around Point Barrow. The Red-necked Stint winters widely throughout Southeast Asia, occurring from southern China and Myanmar west through Malaysia, Indonesia, coastal New Guinea, and Australia to New Zealand. The primary migration routes used in spring and fall bring large numbers of this species to Korea, Japan, Hong Kong and the Philippines (Veit and Jonsson 1984).
1 Away from their limited breeding range, Red-necked Stints in North America are regular (albeit rare to uncommon) as migrants only in the Aleutian Islands and through the Bering Sea of Alaska. Vagrants have been recorded along both coasts of North America, as well as in Hawaii, South America, Europe and South Africa (Veit and Jonsson 1984;
Rosair and Cottridge 1995). There are 17 confirmed records for British Columbia, all from coastal regions, with 12 coming from the lower Fraser River Valley (Boundary Bay, Iona Island, Sea Island, Reifel Bird Sanctuary) (see Table 1, confirmed records 1-5, 8-14 and 16). Elsewhere in Canada, this species has been recorded once in Alberta and once in Saskatchewan (Escott 1995, Godfrey 1986).
Identification and Similar Species It is crucial for observers to be aware of the fact that before attempting to identify any unusual shorebird one must determine the age of the bird in question. Thorough familiarity with all plumages of the more common species in the area, Western and Semipalmated Sandpipers, is critical for those attempting to identify stints since the variation within the species often exceeds the differences between the species. It must be stated that, even if the identification seems confirmed, it is highly recommended that photographs be obtained (if possible) to completely eliminate any other similar species.
For juveniles and faded adults, photographs may be necessary for full confirmation of the sighting.
The following structural clues will apply to all individuals, regardless of age or plumage:
The Red-necked Stint has a shorter, thicker-based, and more sharply tapered bill than Western Sandpiper, even when compared to shorter- and straighter-billed male Westerns. When compared with Semipalmated Sandpiper, the more strongly tapered bill of Red-necked Stint is an important field mark as Semipalmated is generally known for its straight, nail-like bill with little taper towards the tip (sometimes even appearing slightly bulbous at the tip). The bill of Little Stint is similar to that of Red-necked Stint but slightly longer and noticeably finer, especially at the tip (See Figures 1a-h).
The head of Red-necked Stint typically appears squarer than Little Stint, Western Sandpiper or Semipalmated Sandpiper, and usually shows a rather steep angle between the forehead and base of the bill. The body of Red-necked Stint often appears rounderbellied than Western or Semipalmated Sandpipers, while at the same time showing a longer, more attenuated rear end due to the bird’s longer primary projection (the primaries extending past the tip of the tail when folded). The belly of Little Stint also appears rounded, with the attenuated rear-end appearance even more pronounced. Of
The legs and feet of Red-necked Stint are blackish in all plumages, as in Little Stint and both Western and Semipalmated Sandpiper (although some juvenile Semipalmated Sandpipers can have paler olive legs), with the legs typically appearing slightly shorter than in Little Stint. The feet, however, lack the partial webbing between the toes that is present in two sandpipers. Although requiring a very close look, this mark can help distinguish Red-necked Stint from Western and Semipalmated Sandpipers, although it should be noted that it does not help in differentiating individuals from Little Stint as that species also lacks this partial webbing. It should be noted that this field mark requires extremely close scrutiny to determine and is best left to photographs to confirm.
Figure 1: Adult Plumaged Stints and Sandpipers
The Identification of adults in bright breeding plumage anywhere in B.C. should present few problems, particularly when compared to similarly-plumaged Western and Semipalmated Sandpipers, but this species can be highly variable with regard to the extent of red on the throat and face and care may be required when confronted with individuals with reduced red, particularly when compared with Little Stint (See Figure 1a compared to Figure 3b). When in full breeding plumage, such as those individuals seen on the coast in late June and July, the red throat and face of Red-necked Stint should catch the observer’s eye immediately and allow for quick identification (See Figure 1c and Figure 1d).
The following additional field marks should prove helpful when confronted with a faded or worn adult (such as in mid- to late summer) and a thorough knowledge of these additional features may be necessary for identification in some cases.
The Red-necked Stints seen on the coast in late June and through July are often in full breeding plumage, at which point the entire head, throat, and upper breast are rich rusty-red (except for narrow blackish streaks on the crown and a small pale area around the base of the bill), eliminating confusion with any other species. Spring Red-necked Stints in very fresh breeding plumage have extensive red on the face and throat, as in full breeding plumage, but the red colouration is often paler and more washed out and the narrow blackish crown streaks are edged with frosty-white. From mid-July through August, however, observers may be confronted with worn, faded breeding adults which 8 may appear superficially similar to our other small sandpipers, most notably breeding Little Stint, although the reddish colouration on the head and breast of Little Stint is slightly more orange-tinged than in Red-necked Stint. When worn, the throat and supercilium of Red-necked Stint become gradually whiter and the red colouration becomes less extensive, until at the extreme it is reduced to a pale reddish wash across the upper breast and on the crown, nape, and auriculars (Lewington et al. 1991). As well, the auriculars and lores become increasingly dusky, eventually appearing to form a narrow dark mask across the face. The pale supercilium often splits up the forehead, a feature shared with (and even more prominent in) Little Stint but not Western or Semipalmated Sandpipers (Lewington et al. 1991). Breeding-plumaged Western Sandpipers throughout the summer have all reddish tones on the head restricted to the auriculars, crown, and upper nape, never extending anywhere onto the throat or upper breast as in Red-necked Stint (See Figures 1g and 1h and compare to Figures 1c and d).
Breeding-plumaged Semipalmated Sandpipers generally lack any reddish tones on the head, making separation from adult Red-necked Stint straightforward (See Figures 1e and f and compare to Figures 1c and d).
A critical feature for separation of adult Little and worn adult Red-necked Stints is the distribution of dark speckling on the breast. In Red-necked Stint, these dark speckles are below the pure reddish breast, even when worn, whereas in Little Stint the reddish colouration across the upper breast is peppered with dark speckles throughout (Lewington et al. 1991) (See Figure 1b and compare to Figure 1c).
In Red-necked Stints, the dark spots below the red throat form a necklace across the upper breast, extending only slightly down the upper sides. In both Western and Semipalmated Sandpipers, these dark spots extend further down the sides to the upper flanks, often appearing as more extensive streaks (Compare Figure 1c-d and 3a-b to Figure 1e-f and Figure 1g-h).
Both Red-necked and Little Stints are separable from Western and Semipalmated Sandpipers by upper part colouration, as the scapular feathers of both have bold, rounded black centres, distinct reddish edges, and whitish tips (Lewington et al. 1991, Veit and Jonsson 1984). Western Sandpipers also have rusty-red scapular feathers, but in that species the red colouration is located near the base of each feather, separated from the whitish featheredge by an anchor-shaped black band. Semipalmated Sandpiper also has black feather centres, like Red-necked and Little Stints, but largely lacks the reddish colouration (although some have a slight reddish tinge along the edges) and the black centres are less rounded. The mantle on Red-necked and Little Stints shows a 9 series of blackish lines with two whitish lines along the edge of the scapulars forming a whitish “V” when viewed from behind (Lewington et al. 1991). Although a similar field mark is shown by Western and Semipalmated Sandpipers, it is much more noticeable in the stints. With Little Stints showing bold mantle “V” markings and Red-necked Stints showing softer less defined mantle “V” markings (Lewington et al. 1991, Grant et al.
1984). Additionally, even in the brightest breeding plumage, the wing coverts and tertials of Red-necked Stints are always grayish or brownish with paler feather edges (some tertials occasionally with reddish edges in the brightest adults) (Veit and Jonsson 1984). This feature is a good field mark for separating adults from adult Little Stints, which show extensive rufous feather edges on the upper wing coverts and tertials in breeding plumage (Veit and Jonsson 1984)(See Figure 1c and compare to Figure 1b).
The Identification of juvenile Red-necked Stints in British Columbia is very difficult given the similarities to other juvenile peeps, especially juvenile Semipalmated Sandpipers, and extreme caution is necessary when attempting to identify such a subtly distinctive plumage. Variation within the small Calidris sandpipers is very extensive, often confusing even shorebird experts, and a cautious approach must be taken with vagrants such as Red-necked Stints. Juvenile Red-necked Stints can vary from dull-plumaged birds resembling Semipalmated Sandpipers to brighter, rustier birds more similar to Little Stints, with the brightest and freshest-plumaged birds occurring earlier during migration with the brightest juvenile Western and Semipalmated Sandpipers (the latter is a particularly important pitfall for those not familiar with the plumage). The subtle structural differences of individual Calidris species becomes even more important than when confronted with adults, and as a result it is highly desirable that photographic evidence be obtained of suspected juvenile Red-necked (or Little) Stints (See Figures 3ce and Figure 3f).
One feature of the two juvenile stints that may help separate them from juvenile Western and Semipalmated Sandpipers is the “capped” appearance of the head which is created by the brighter, rusty crown contrasting sharply with the grayish nape. This collared pattern is most obvious when viewed from behind or above and is much more prominent in Red-necked and Little Stints than the two sandpipers, although those species can also show a suggestion of the pattern (See Figures 2a-b along with Figure 2c and compare to Figures 2g-h and 2k-l). As well, the sides of the crown of Red-necked Stint tend to be paler and more finely streaked than the centre of the crown, a feature that can be used to separate such individuals from juvenile Semipalmated Sandpiper with its usually more uniform crown (Lewington et al. 1991). Another feature that is shared by the two stints but is not as prominent on the two sandpipers is the split 10 supercilium. On Red-necked Stints and, especially, Little Stints, the whitish supercilium splits in front of the eye, with a narrow spur running up the side of the forehead and, often, along the side of the crown in addition to the supercilium (Lewington et al. 1991).
This forehead pattern is best observed when viewing the bird head-on or from above, although it is not nearly as prominent as on juvenile Little Stints (See Figure 2b). In Western and Semipalmated Sandpipers this feature is absent or much reduced and is never as prominent as in the two stints. Additionally, the supercilium of Red-necked Stints is usually interrupted above the eye by a diffuse, dusky area, a feature typically not shown by the other species with which it can be confused (Lewington et al. 1991).