Wing and tail moult of American Golden-Plovers Pluvialis dominica on wintering grounds in Uruguay, with confirmation that juveniles replace all primaries during their first non-breeding season Joop Jukema1 , Oscar W. Johnson2, Joaquin Aldabe3,4 & Pablo Rocca4 1Haerdawei
62, 8854 AC Oosterbierum, The Netherlands.
[email protected] of Ecology, Montana State University, Bozeman, MT 59717, USA 3Centro Universitario de la Región Este, Universidad de la República, Rocha, Uruguay 4Aves Uruguay, Canelones 1164 Montevideo, Uruguay 2Department
Keywords: American Golden-Plover, Pluvialis dominica, wing moult, primaries, secondaries, remiges, rectrices, juvenile, first-year, age criteria There is considerable variability among shorebirds as to when juvenile primaries are moulted. In some species, juveniles replace all or a few of these feathers during their first year, in others the pattern is to retain juvenile remiges until the second prebasic moult (O’Brien et al. 2006, Prater 1981, Prater et al. 1977, Remisiewicz et al. 2010). The latter timing has been documented in three of the four Pluvialis plover species (Black-bellied Plover P. squatarola, Eurasian Golden-Plover P. apricaria, Pacific Golden-Plover P. fulva; Johnson & Johnson 1983, Paulsen 1995, Byrkjedal & Thompson 1998). In the fourth species (American Golden-Plover P. dominica), accounts differ: Johnson (1985) collected specimens during northward migration in Minnesota and concluded that young birds (identified from remnant cloacal bursae) replaced their juvenile primaries during the first non-breeding season (also see Pyle in Johnson & Connors 2010), whereas Byrkjedal & Thompson (1998) stated the opposite (i.e., dominica retains
juvenile primaries until the second non-breeding season like its three congeners) but with a caveat based on Johnson’s findings that further study was needed. We are now able to resolve the lingering question as to which of these two moulting strategies is correct. Our findings agree with Johnson (1985), and substantiate that the timing of juvenile primary moult differs between first-year American Golden-Plovers and their near relatives. The moult data reported here were obtained coincident to banding American Golden-Plovers on non-breeding grounds in the Laguna de Rocha region of SE Uruguay. Plovers were captured in early austral summer from 18–28 Nov 2010, and in late austral summer from 8–16 Feb 2011. The samples were caught on grazed natural grasslands at 34.66°S, 54.32°W (Nov), and at 34.69°S, 54.35°W (Feb). During the November period, adults and also juveniles (the latter typically migrate southward later than adults) had arrived in the non-breeding
Fig.1. Wing of a juvenile American Golden-Plover on non-breeding grounds in Uruguay, Nov 2010. Primary moult is underway with juvenile remiges P1 and P2 new, and P3 and P4 growing. Although this individual’s juvenile primaries are relatively fresh (only about 4–5 months old) they will all be replaced before northward migration. Wader Study Group Bulletin 118(2): 129
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range; the February period coincided with the start of northward migration. Northward movements of American GoldenPlovers begin relatively early in South America (Isacch & Martinez 2003; JA, D. Blanco, PR unpubl. data), followed by gradual passage through mid-continental U.S. and Canada while en route to breeding grounds. Young birds in November (4–5 months old) were easily recognized from distinctive juvenile body plumage. However, after prebasic body moult is completed during the non-breeding period, the separation of young individuals from adults becomes much less certain (see Pyle in Johnson & Connors 2010). Therefore, based on the wing and tail features described below, we divided our February sample into presumptive first-year individuals (7–8 months old) and presumptive adults. For additional details concerning timing of migrations, migratory behaviour, and also photographs of juvenile plumage, see Johnson & Connors (2010). Birds were captured with the classic Dutch “wilsternet”, a large clap net to which birds are attracted by decoys and imitated plover calls (see Jukema et al. 2001). Primary moult was scored on the right wing according to the system described by Ginn & Melville (1983): 0 = an old feather, 1 = a missing feather or one in pin, 2–4 = progressive stages of growth, 5 = a fully-grown feather that has lost its sheath. This species has 10 functional primaries, thus the score of a fully-grown new set is 50. Primary moult in both adult and young birds was descendant from P1 outwards to P10. In addition to primaries, the 11 secondaries and 12 rectrices also were examined. For these tracts we recorded the progression of moult (number and position of new or growing feathers) along with the presence of old feathers. The November sample consisted of 156 birds (113 adults and 43 juveniles); the total in February was 63 birds (26 presumptive adults and 37 presumptive first-years). If our ageing criteria are correct (see below), the high proportion of first-year plovers in February suggests the northward migration of this age group tends to be somewhat later than that of adults. November observations Adults were well into primary moult with an average score of 33.3 (SD = 3.9, range = 19–44, n = 113). Of these, 88 individuals (78%) had at least six fully grown new primaries, plus one or two growing primaries at various stages, and the moult of secondaries was coincident to that of primaries. Replacement of secondaries was irregular and often asymmetrical between right and left wings. Some birds had replaced all or nearly all secondaries, others had barely started with only one or two growing. Rectrix moult began at the time of the loss of P7. Tail moult was centripetal (from each side toward the center), and often asymmetrical and irregular. Juveniles also were moulting their primaries, but at a much earlier stage and with greater individual variation; their mean score was 8.7 (SD = 9.2, range = 0–27, n = 43); 29 (67%) had started to moult primaries, the remaining 14 (33%) had not. In those that were actively moulting, the progression of feather loss varied widely from a single primary (P1) to birds with two to four fully grown new primaries and an additional one to three growing primaries (Fig. 1). The foregoing difference between adult and juvenile primary moult scores clearly reflects the timing of southward migration and the later arrival of juveniles on non-breeding grounds. February observations All birds had either completed or nearly completed primary moult and had not yet started prealternate body moult. Based
on a possible age-related difference in moult of secondaries and rectrices, we divided the sample into two groups: those birds that had replaced all secondaries and rectrices were considered to be Presumptive Adults (hereafter PAs), and birds that had moulted only some or none of these feathers were classed as Presumptive First-year Birds (hereafter PFYs). The primary moult score of PAs averaged 49.9 (SD = 0.27, n = 26); the slight deviation from an overall score of 50 was because P10 in two individuals was at stage 4 and thus not yet completely grown. Comparable figures for PFYs were 48.7 (SD = 1.43, range = 41–50, n = 37); of the PFY sample, 32 birds (86%) had either a complete set of fresh primaries or nine new feathers with P10 at stage 4, and five individuals (14%) had new primaries through to at least P7 with P8–P10 at various stages of growth. At this point in the moulting cycle, the fresh primaries of both PAs and PFYs were essentially identical in appearance, and the later onset of primary moult among juveniles was no longer apparent. As mentioned above, PAs had completely replaced their secondaries and rectrices during the period between November and February. By contrast, all PFYs had variable numbers of faded secondaries, most had at least some faded rectrices, but a few had replaced all rectrices. Presumably, the faded feathers were retained juvenile plumage. Of the 37 PFY birds, 8 (22%) showed no moult of secondaries thus all feathers were faded; and 29 (78%) had replaced from one to eight of these feathers with moult beginning at the outer margins of the secondary tract and progressing towards the center. As a group, PFYs averaged eight faded secondaries (SD = 2, range = 2–10, n = 37). Conclusions By examining plumages and moult in American GoldenPlovers during a large-scale banding project in Uruguay (the first such effort on the non-breeding grounds of this species in South America), we confirmed the loss of juvenile primaries during the first prebasic moult. Presumably, this finding in Uruguay is characteristic of the entire non-breeding range; however it should be verified at other locations. American Golden-Plovers are known for a gradual northward passage through North America during which they acquire much of their alternate feathering (Johnson & Connors 2010). Such continued moulting post-departure from Uruguay raised the possibility that the retained faded secondaries and rectrices we found in our February sample might yet be replaced in the same season. However, this does not appear to occur as Jukema (unpubl. data) found essentially the same pattern of feather retention in April 2009 when he examined plovers captured for banding at a stopover site in Indiana and again in June 2010 among nesting birds in western Alaska. It appears likely that faded secondaries (sometimes in combination with faded rectrices) are characteristic only of first-year plovers; however we cannot rule out possible misleading variation among both first-year and adult birds. Conclusive tests of the relationship between secondary moult and age could be carried out in at least two ways: 1) Unique colour-banding of adults and juveniles during arrival on non-breeding grounds with follow-up recapture (or collection) late in the austral summer before birds depart on northward migration. Whether such an approach might be feasible depends on individuals being site-faithful during the non-breeding season, a behavioural feature that is presently uncertain in American GoldenPlovers. 2) Collection of specimens before departure from South America or along the flyway in North America during northward migration for careful dissection to reveal presence or absence of remnant cloacal bursae (Johnson 1985). Con-
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sistent correlations (i.e., small bursa plus variable numbers of faded secondaries = first-year bird; no bursa plus all new secondaries = adult) would essentially resolve the question. Notably, Pyle’s description (Johnson & Connors 2010) of first basic plumage in this plover mentions only occasional retention of 1–4 juvenile secondaries. This further signals the need for additional studies to clearly identify first-year birds and also to examine moult in other regions of the nonbreeding range. During a trip to Argentina by OWJ in 1999, Jorge Navas at the Museo Argentina de Ciencias Naturales, and Carlos Darrieu of the Museo de Ciencias Naturales de La Plata kindly allowed him to view plover specimens in their collections. Various of the birds examined appeared to be first-year individuals that were in primary moult when collected. These observations prompted the more conclusive investigation of live plovers reported in this paper. Fieldwork was mostly funded by the Canadian Wildlife Service, Manomet Center for Conservation Sciences, and the Southern Cone Grassland Alliance (BirdLife International initiative). Javier Vitancurt from the National System of Protected Areas provided additional logistical support. We are grateful to Martín Segredo and Tropicalia Farm for housing and access to the study areas. Catharinus Monkel, Héctor Caymaris, Verónica Correa, Macarena Sarroca, Diego Caballero, Daniel Sosa, Sofía Cortizas, Mariana Illarze, Nestor Leal, Andrés Sosa Huelmo, and Joaquín Lapetina assisted us in the field. Pablo Isacch helped to access the museum specimens in 1999, and more recently suggested contacts that led to Uruguay as the location for this study. We thank Charles Duncan and Diego Luna for ongoing support of shorebird studies and conservation at Laguna de Rocha. Helpful editorial suggestions from reviewer Les Underhill substantially improved the manuscript.
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Byrkjedal, I. & D. Thompson. 1998. Tundra plovers: The Eurasian, Pacific and American Golden Plovers and Grey Plover. T & AD Poyser Ltd., London. Ginn, H.B. & D.S. Melville. 1983. Moult in Birds. BTO Guide 19. Tring, UK. Isacch, J.P. & M.M. Martinez. 2003. Temporal variation in abundance and the population status of non-breeding Nearctic and Patagonian shorebirds in the flooding pampa grasslands of Argentina. J. Field Ornithol. 74: 233–242. Johnson, O.W. 1985. Timing of primary molt in first-year Golden-Plovers and some evolutionary implications. Wilson Bull. 97: 237–239. Johnson, O.W. & P.G. Connors. 2010. American Golden-Plover (Pluvialis dominica). In: The Birds of North America online, No. 201 A. Poole (ed.). Cornell Lab of Ornithology, Ithaca, NY. (doi:10.2173/bna.201). Johnson, O.W. & P.M. Johnson. 1983. Plumage–molt–age relationships in “over-summering” and migratory Lesser Golden-Plovers. Condor 85: 406–419. Jukema, J., T. Piersma, J.B. Hulscher, E.J. Bunskoeke, A. Koolhaas & A. Veenstra. 2001. Golden Plovers and Plover Netters: a Deeply Rooted Fascination with Migrating Birds. Fryske Akademy, Ljouwert and KNNV Uitgeverij, Utrecht, The Netherlands. (in Dutch with English summary). O’Brien, M., R. Crossley & K. Karlson. 2006. The Shorebird Guide. Houghton Mifflin, New York. Paulson, D.R. 1995. Black-bellied Plover (Pluvialis squatarola). In: The Birds of North America online, No. 186 A. Poole (ed.). Cornell Lab of Ornithology, Ithaca, NY. (doi:10.2173/bna.186). Prater, A.J. 1981. A review of the patterns of primary moult in Palaearctic waders (Charadrii). Pp. 393–409 In: Proceedings of the Symposium on Birds of the Sea and Shore. J. Cooper (ed.). African Seabird Group, Cape Town. Prater, A.J., J.H. Marchant & J. Vuorinen. 1977. Guide to the Identification and Aging of Holarctic Waders. BTO Guide 17. Tring, UK. Remisiewicz, M., A.J. Tree, L.G. Underhill & P.B. Taylor. 2010. Rapid or slow moult? The choice of a primary moult strategy by immature Wood Sandpipers Tringa glareola in southern Africa. J. Ornithol. 151: 429–441. (doi: 10.1007/s10336-009-0473-4).
The occurrence of the Javan Plover Charadrius javanicus in Sumatra, Indonesia Muhammad Iqbal1 , Iwan Febrianto2 & Hilda Zulkifli3 1KPB-SOS,
Jalan Tanjung api-api km 9 Komplek P & K Blok E 1, Palembang 30152, Indonesia.
[email protected] 2WCS-IP, Jl. Burangrang 18, Bogor 16151 – Indonesia, Indonesia.
[email protected] 3Department of Biology of Sriwijaya University. Zona D FMIPA Biology, Universitas Sriwijaya, Jalan raya Palembang-Indralaya km 32, Indralaya, Ogan Ilir, Sumatera Selatan, Indonesia
Keywords: occurrence, Javan Plover, Charadrius javanicus, Sumatra, Indonesia The taxonomic status of the Javan Plover Charadrius javanicus (Chasen 1938) is unclear, and it may not merit the status of a full species. However, different authors associate it with different species, and it has sometimes been treated as a race of Kentish Plover C. alexandrinus, or Red-capped Plover C. ruficapillus or Malaysian Plover Charadrius peronii (Piersma & Wiersma 1996). Tentatively Javan Plover is a distinct species (Piersma & Wiersma 1996), and this treatment has been followed by most recent authors (e.g. BirdLife International 2011, Inskipp et al. 1996, Mackinnon et al. 1998, Sukmantoro et al. 2007, Wetland International 2006). We follow this treatment, but whatever its taxonomic status, it is a distinct form that deserves to be fully monitored and conserved in its own right.
The entire population of the Javan Plover has been estimated at about 2,000 individuals and the species is endemic to coastal habitats on the islands of Java and Kangean and possibly also on Bali (Centurioni 2010, Mackinnon et al. 1998). There are no data on population trends (Wetland International 2006), but it may well be in decline as its habitats are subject to heavy disturbance by humans, especially during the breeding season; it is classified as Near Threatened (BirdLife International 2011). Kennerley et al. (2008) reported that Javan Plovers breed at Penet, in Lampung province, Sumatra, which is information that was provided by second author (IF). Here, we report further detail on the occurrence of Javan Plovers at Penet, and an additional record for Sumatra from Bangka Island.
