ORNITOLOGIA NEOTROPICAL 15: 17–30, 2004 © The Neotropical Ornithological Society

THE TUMACO (SPOROPHILA INSULATA, EMBERIZIDAE): A SPECIES THAT NEVER WAS ?

F. Gary Stiles

Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Apartado 7495, Bogotá, Colombia & Department of Ornithology, Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103, USA E-mail: [email protected]

Resumen. – El Espiguero de Tumaco (Sporophila insulata, Emberizidae): ¿Una especie que nunca la era? – El Espiguero de Tumaco, Sporophila insulata, generalmente se considera una especie endémica de Colombia y en peligro crítico de extinción. Con base en un reconocimiento breve de los plumajes de los machos en una población silvestre y la colección de tres ejemplares (los primeros desde la colección de la serie típica hace 80 años), examinación de esta serie típica y de series largas de ejemplares de los Espigue- ros Golicastaño (S. telasco) y Menudo (S. minuta), dos posibles parientes, concluyo que S. insulata debe con- siderarse como una subespecie o morfo del primero y que no está emparentado con el segundo. En S. telasco la extensión del castaño del plumaje ventral parece no cambiar con la edad, y lo mismo probable- mente ocurre en insulata; el plumaje dorsal parece un mejor indicativo de la edad. Hembras de las dos son indistinguibles, y no hay indicios confiables de aislamiento reproductivo. Por lo tanto, fenotipos interme- dios (los cuales se constituyen en la mayoría de los machos en las poblaciones cerca de Tumaco) deben representar el resultado de entrecruzamiento libre, lo cual posiblemente se ve facilitado por los hábitos nómadas de estas poblaciones. Abstract. – The Tumaco Seedeater (Sporophila insulata) is generally considered to be a critically endangered, endemic species of Colombia. On the basis of a brief survey of plumage types in a wild population and collection of three specimens (the first since the type series was taken 80 years ago), examination of the type series and extensive series of possible relatives (Chestnut-throated Seedeater, S. telasco and Ruddy- breasted Seedeater, S. minuta), I conclude that S. insulata is best considered a race or color morph of the former, and is not closely related to the latter. The amount of chestnut color below in males of telasco apparently does not increase with age, and evidence that the same is true in insulata is presented; dorsal col- oration is a better indicator of age. Females of the two are indistinguishable, and no solid evidence of reproductive isolation exists. Thus, phenotypes intermediate between the two (which constitute the bulk of males in populations of “insulata” near Tumaco) most likely reflect free interbreeding that may in turn be facilitated by nomadic population movements. Accepted 15 May 2003. Key words: Colombia, conservation, , , Tumaco Seedeater, Sporophila insulata, Sporophila telasco.

INTRODUCTION son on Isla Tumaco and the next time the was seen by an ornithologist. During this The Tumaco Seedeater (Sporophila insulata) has interval Isla Tumaco was engulfed by the city long been one of Colombia’s most enigmatic of Tumaco and recent searches there for the . Eighty-two years elapsed between the seedeater were unsuccessful. The meager data collection of the type series by W. B. Richard- were summarized by Collar et al. (1992) who

17 STILES feared that it might be extinct. Recent treat- (width 10–50 m) of low vegetation dominated ments have considered it to be critically by the bunchgrass Uniola pittieri (shown in the endangered (e.g., Renjifo 1998). However, foreground of Salaman’s (1995) photo, with stunted vegetation flanked by mangroves like scattered low shrubs and stunted mangroves. that described by Richardson (in Chapman I found seedeaters only in this habitat, as did 1917) on Isla Tumaco occurs widely on Salaman and Giles. However, I would esti- islands and mainland along the coast of mate the total extent of bunchgrass-scrub on Nariño, such that the rediscovery of S. insulata the island to be 3–5 ha, rather than á1 ha as at Isla Bocagrande, c. 15 km west of Tumaco, stated by Salaman (1995). The western half of in September 1994 by Salaman and Giles the island is broader and includes a small set- (Salaman 1995), while exciting news indeed, tlement with various rustic resort hotels, was not wholly unexpected. In March 1995, I mostly unoccupied at the time of my visit, as made a brief visit to Isla Bocagrande, where I well as areas of taller scrub and second observed a flock, captured several birds in a growth on the landward side. The entire sea- mist net and collected three specimens, the ward side of the island consists of a broad, first since the type series. The taxonomic sta- very gently sloping sandy beach. tus of the Tumaco Seedeater has also been somewhat uncertain. When he described insu- Field work. I arrived on Isla Grande at 14:00 lata, Chapman (1921) compared it only with on 14 March 1995. Late that afternoon, fol- the Ruddy-breasted Seedeater (S. minuta) lowing a period of light rain, I located a loose because of the extensively chestnut under- flock of seedeaters c. 200 m east of the settle- parts of the males. However, Ridgely & Tudor ment, evidently going to roost in some small (1989) reexamined the type series and sug- bushes scattered among the bunchgrass. Poor gested that the closest relative of insulata is the light prevented detailed observations, but I Chestnut-throated Seedeater (S. telasco) which spent over 3 h the next morning observing occurs along the Pacific coastal lowlands this flock, and capturing five birds in a mist from extreme southwestern Colombia to net. I spent the rest of the morning making a northern Chile (Meyer de Schauensee 1966). census of all seedeaters on the eastern two- They suggested that insulata might represent thirds of the island and attempting to classify simply a race of the latter species, or even all males seen according to the following hybrids of telasco and minuta. I therefore exam- scheme: Type A = “good” insulata with dark ined all specimens of S. insulata and series of chestnut underparts and only a small area of S. telasco and minuta to try to determine the buffy white on the abdomen; type B = “pale” taxonomic status of this striking bird. insulata with underparts mostly paler chestnut with more extensive buffy to white on the METHODS AND MATERIALS belly; type C = underparts chestnut back to the midbreast, buffy to white posteriorly; type Study area. Isla Bocagrande is basically a sand- D = entire throat chestnut but little to none spit c. 3 km long, separated from the man- on breast, belly or flanks; rest of underparts grove swamps of the adjacent mainland by an buffy-white to white; and type E = “good” estuary some 100 m wide, along which exten- telasco with only upper throat dark chestnut, sive mudflats are exposed at low tide. The rest of underparts white. These classes are not eastern half or more of the island is narrow discrete but intergrade to some extent. How- and uninhabited; the landward side consists ever, I found that they could be applied rap- of low dunes, covered by a narrow strip idly in the field. Strong winds after about

18 STATUS OF THE TUMACO SEEDEATER Sporophila telasco Throat chestnut; remaining chestnut; Throat sometimes underparts white, or (flanks) grayish buff tinged than paler to white 32 (Chestnut); buff) 118 (Warm this extend- gray, throat Sides of ing medially throat across lower widely usually a narrow band, as incomplete medially Mostly gray; and crown midback streaked distinctly to vaguely lower across band pale blackish; rump Near 85 (Lightneutral gray), oftenbrownish washed White Bases of 3–5 central pairs of rec- white trices sides buffy (paler than Breast and Yellow buff or 123C, 118, Warm throat,ochre); belly and crissum whitish Sporophila insulata Throat and varying amounts of Throat and varyingamounts and flanks sides breast, chestnut, rest (sometimesonly center of abdomen crissum) white to and buffy 35 (Hazel); to 32 (Chestnut) buff) white to near 118 (Warm this extend-Sides of throat gray, throat ing medially across lower incom- usually band, narrow a as plete medially and crown gray;Mostly midback streaked distinctly to vaguely lower across band pale blackish; rumprump entire pale) (rarely Near 85 (Light neutral gray), often washed brownish Whitish, morewith or less mixed to entirely rusty(near 36, Amber); paler than underparts rec- of pairs central 3–5 of Bases trices white (118, sides buffy and Breast Yellow buff to 123C, Warm but paler);ochre throat, belly and whitish crissum insulata and Sporophila minuta Entirely uniformrufous, includ- ing bellyand crissum 240 (Kingfisher rufous) to 340 rufous)(Robin Immaculate rufous and head immaculate gray- Back rumpbrown; and upper tail- rufous coverts horn)Near 91 (Grayish Concolor with underparts No white in tail Uniform, immaculate dull tawny buff (near 39, Cinnamon, to Tawny) 223D, Sporophila minuta, telasco Pattern of underparts underparts of Color pattern Throat Pattern of upperparts Ground color of upperparts Color of rump (or rump-band) pattern Tail underparts of color and Pattern Feature Adult males Adult females TABLE 1. Plumage features of TABLE

19 STILES Buffy-brown, streaked faintly to faintly streaked Buffy-brown, broadlyespecially with blackish, on midback brown Sayal Near 223C, Bases of 3–4 central pairs of rec- male) than (less white trices dusky breast on streaked Variably and sides Buffy-brown, streaked faintly streaked to Buffy-brown, broadly with blackish, especially on midback brown Sayal Near 223C, rec- of pairs central 3–4 of Bases tricesmale) white (lessthan breast on dusky streaking Some sides and Sporophila minuta Sporophila insulata Sporophila telasco Unpatterned dull buffy-brown color) (Clay 26 Near No white in tail Unstreaked Pattern of upperparts Ground color of upperparts pattern Tail Pattern of underparts Feature Juveniles TABLE 1. Continuation.TABLE

20 STATUS OF THE TUMACO SEEDEATER

TABLE 2. Measurements (in mm) of parameters of external morphology, and body masses (in g) of adult males of Sporophila minuta, insulata and telasco; sample sizes, means, standard deviations and ranges given, as well as results of analysis of variance (F, P) and Tukey a posteriori tests. Means (M = minuta, T = telasco, I = insulata) are presented in order of magnitude; lines below connect means that do not differ significantly.

Parameter S. minuta S. insulata S. telasco F, P Tukey N 27 7 46

Exposed cul- 7.98 ± 0.25 8.54 ± 0.17 8.49 ± 0.32 28.80 M T I men (7.5–8.5) (8.3–8.8) (7.8–9.3) P < 0.001 ------

Bill length from 5.96 ± 0.19 6.16 ± 0.18 6.29 ± 0.19 14.01 M I T nostril (5.5–6.3) (5.7–6.6) (6.0–6.6) P < 0.001 ------

Bill depth at 6.32 ± 0.20 6.60 ± 0.17 6.61 ± 0.24 15.35 M I T nostril (6.0–6.6) (6.4–6.8) (6.1–7.1) P < 0.001 ------

Chord of closed 49.91 ± 1.31 52.16 ± 1.30 52.90 ± 1.35 41.60 M I T wing (47.6–52.5) (50.5–54.0) (50.2–55.6) P < 0.001 ------

Tail length 34.43 ± 1.19 37.30 ± 1.00 37.20 ± 1.54 35.87 M T I (32.2–36.5) (36.4–38.9) (34.5–40.1) P < 0.001 ------

Tarsus length 13.64 ± 0.47 14.39 ± 0.29 14.49 ± 0.39 39.50 M I T (12.5–14.2) (13.9–14.8) (13.4–15.3) P < 0.001 ------

Length of wing 3.84 ± 0.86 5.58 ± 0.60 5.62 ± 0.84 60.79 M I T speculum (1.6–5.1) (4.1–6.4) (3.1–7.4) P < 0.001 ------

Body mass (g) 8.38 ± 0.40 9.27 ± 0.62 8.91 ± 0.61 4.57 M T I (7.8–9.2) (8.6–10.1) (8.0–9.9) P < 0.05 ------N = 9 N = 4 N = 8 ------

08:30 prevented further mist netting, and exposed culmen, bill length from the nostril, avian activity declined to virtually nil after bill depth at the nostril, chord of the closed about 10:30 due to wind and hot sun. I left wing, and lengths of the tail, tarsus, and the the island at 13:00 on 15 March. white “speculum” at the base of the primaries (see Stiles 1996). All measurements were Museum work. I measured series of S. minuta made to 0.1 mm with a Mitutoyo dial caliper. I and my specimens of insulata in the collection measured body mass of the insulata I captured, of the Instituto de Ciencias Naturales, Bogotá, and compared these with masses of telasco series of telasco in the Academy of Natural Sci- supplied by M. Marín from the collection of ences of Philadelphia and the American the Museum of Zoology of Louisiana State Museum of Natural History, and the type University, as well as masses of minuta from series of insulata in the latter museum. For my own field work in Colombia. I also took each specimen I measured the length of the notes on plumages of specimens examined,

21 STILES

TABLE 3. Measurements (as in Table 2) of adult females of Sporophila minuta, insulata and telasco, with val- ues of t-tests and corresponding probabilities for comparisons between means for minuta and telasco (except for body mass, where the nonparametric Mann-Whitney U is used).

Parameter S. minuta S. insulata1 S. telasco t, P N 22 2 26

Exposed Culmen 8.16 ± 0.22 8.5, 8.9 8.53 ± 0.28 4.97 (7.8–8.5) (8.0–9.0) P < 0.001

Bill length from 5.93 ± 0.24 6.0, 6.2 6.25 ± 0.22 4.18 nostril (5.5–6.6) (5.8–6.7) P < 0.001

Bill depth at nostril 6.34 ± 0.23 6.4, 6.5 6.53 ± 0.22 2.68 (5.9–6.8) (6.1–7.0) P < 0.05

Chord of closed 47.54 ± 1.06 48.5 (molting), 49.8 51.04 ± 1.40 9.62 wing (45.5–50.5) (47.4–53.4) P < 0.001

Tail length 34.37 ± 1.09 38.1, 35.7 36.01 ± 1.36 4.50 (32.6–36.6) (33.0–38.2) P < 0.001

Tarsus length 13.60 ± 0.50 14.6, 13.9 14.37 ± 0.34 6.33 (12.6–14.5) (13.7–15.0) P < 0.001

Body mass (g) 8.30 ± 0.68 —, 9.0 8.93 ± 0.90 U = 7 (7.1–9.2) (8.0–9.8) P > 0.10 N = 8 N = 3 and made color comparisons with reference the presence of a partial grey throat band to Smithe (1975, 1981). (rarely complete in insulata, at least suggested on many telasco), streaking on the upperparts, RESULTS the progression of dorsal plumages from brown to grey (see below), the presence of Relationships of S. insulata. Before considering white in the tail. Insulata differs from telasco in the field observations in detail, I will try to having more extensive chestnut below determine whether telasco or minuta is the clos- (although some individuals may be almost est relative of insulata. Because only a single indistinguishable on this basis) and the rusty female specimen of insulata exists, I base my color in the rump; the posterior (non-chest- quantitative analysis on male plumages. nut) underparts of this form are usually more Numerous features of color and pattern are or less strongly tinged buffy whereas those of similar or identical between telasco and insulata telasco are white (Table 1). An interesting mark but differ from the corresponding features of present in males of all three forms but absent minuta: the presence of white or buff on the from those of most Sporophila is a white spot abdomen, the shade of reddish color below, beside the base of the mandible; this area is

22 STATUS OF THE TUMACO SEEDEATER diffusely white in S. plumbea, and extended 2001, Cadena et al. in press). The main ques- into a broad moustachial stripe in S. lineola tion remaining after these analyses is to what and bouvronides, but its taxonomic significance extent insulata is separable from telasco: is it a is uncertain. The female of insulata is essen- species, a race or merely an erythristic mutant tially indistinguishable in color and pattern phenotype? from those of telasco, but differs in numerous respects from that of minuta. A further resem- Plumages of S. telasco. Accepting a very close blance between insulata and telasco is streaking relationship between insulata and telasco, I below in juveniles, also unknown in minuta decided that a closer study of the plumages of (Table 1). the latter might help me to interpret those of The analysis of variance of measurements the former. In all, I examined over 60 male of males of the three forms produced equally telasco from Ecuador and Perú, the majority clear-cut and concordant results (Table 2). taken between January and April of different Highly significant variation between means years. Most of those with gonad data also had was found in all measurements; in all cases enlarged testes and slightly to moderately minuta differed from telasco and insulata, which worn plumage, suggesting that these months did not differ between themselves except that included at least the latter part of the breeding insulata was significantly heavier (and thus season (as juveniles were also taken). Small even more different from minuta). However, numbers of specimens taken between March this probably reflects the fact that all insulata I and August of different years were molting; collected and dissected were fat and molting; birds from September through December especially given the small sample size, I see no were mostly in fresh plumage, some with reason to conclude that a real difference in slightly to moderately enlarged testes. mass between these forms exists. Females of I was able to distinguish three or four minuta and telasco differ significantly in virtu- more or less discrete plumages in this sample ally all parameters except body mass; the two of males. The juvenile plumage is female-like, female insulata measured are either more or being warm buffy-brown above with dusky less internediate or much closer to telasco streaking on the back; the throat and center of (Table 3). Thus, the overall conclusion is that the abdomen are whitish, the breast, sides and insulata is very similar to telasco, but its resem- flanks rather bright buff; dusky streaking blance to minuta is only superficial at best and occurs on the sides and flanks and in some, probably does not indicate close relationship. across the breast as well. The remiges, wing Similarly, it seems most unlikely that insulata coverts and rectrices have brown borders. represents hybrids between telasco and minuta: Within a few weeks or months after fledging, only in the extent of chestnut below is there this plumage is replaced over much of the any hint of intermediacy. Contact between body: I tentatively call the resulting plumage telasco and minuta prior to the collection of the basic I. Ventrally, chestnut feathers enter on type series of insulata seems impossible: the throat and the general coloration becomes Tumaco was entirely surrounded by forest much whiter, the streaking nearly or quite and thus inaccessible from inland to open- obsolete. Dorsally, grey feathers, usually more country birds like seedeaters. Moreover, or less edged with brown, enter on the back minuta was absent from the Pacific slope of and crown. Some wing coverts and rectrices Colombia or Ecuador until very recently, may be replaced as well but apparently most when it undoubtedly arrived following corre- or all juvenile remiges are retained until the dors of deforestation (Ridgely & Greenfield first annual molt. In this molt, the males

23 STILES

FIG. 1. Specimens of Sporophila telasco: four males and (bird on far right) one female. Note variation in the extent of chestnut and the development of the gray band on the throats of the males, as well as the scat- tering of chestnut feathers down the right side of the breast of the fourth male from the left; also the streaked breast of the female. acquire more grey above, although still some- (occasionally with a buffy tinge), the throat is what mixed with brown; usually a fairly dis- chestnut, sometimes with a few whitish feath- tinct brownish nuchal collar separates the ers mixed in. I tentatively call this plumage grey of back and crown, and the rump-band basic II. During the next (second?) annual is mixed with tawny. The edgings of the rem- molt, the definitive (basic III) plumage is iges, wing coverts and rectrices are light attained. In this plumage the entire dorsum is brownish-grey; the underparts are white slaty grey with distinct blackish streaking on

24 STATUS OF THE TUMACO SEEDEATER the crown and back; the rump-band is white; chestnut area may become darker and more the edgings of the wing-coverts and flight solid (in fact, ANSP 9384 is in nearly full juve- feathers are pale grey; the throat is solid chest- nile plumage with a wholly chestnut throat). nut, the remaining underparts clear white Moreover, c. 10% of basic II and III males except for some greyish clouding on the have one or a few chestnut feathers posterior flanks. I should note that a postbreeding to the caudal margin of the throat. These plumage in which the chestnut throat is lost feathers occur irregularly and not symmetri- has been reported in captive birds (R. Restall cally: for example, ANSP 83672 has a broken pers. com.), but I found no suggestion of this line of chestnut down one side of the breast, in any specimen I examined. Because molts only one or two chestnut feathers on the and plumages can be strongly influenced by other side (see Fig. 1). the hormonal state of the birds, which in turn may depart from normal rhythms and levels Field observations. About 20 birds comprised due to conditions of captivity, such data from the flock that I spent most time observing, captives should be interpreted very circum- including 12–15 males and c. 5 birds in female spectly. The most doubtful point in this plumage. When located at c. 16:45 on 14 hypothesized plumage sequence concerns the March, the birds were evidently going to roost distinctness of basic I and basic II, due to a in small dense shrubs scattered in a flat area scarcity of specimens taken during the molt dominated by bunchgrass (Uniola) to the land- period of June through August or September, ward side of the dunes of the upper beach. which clearly show a transition between the The following dawn, they left their roost two. It is possible that only a single, variable bushes and gathered in a loose flock to begin basic I plumage exists (which would imply at feeding on seed heads and fallen seeds of Uni- least some flight feather replacement during ola, which appeared near the end of its fruiting the first year, for which I found no clear evi- season. The birds appeared to be postbreed- dence) and that the definitive plumage is basic ing, and many showed evident signs of molt. I II. The latter would more closely approximate heard no song and saw no evidence of territo- the sequence in some other species of Sporo- riality or reproductive behavior. Indeed, the phila (Stiles 1996), although for yet others strongly male-biased sex ratio in both flocks (e.g., luctuosa, torqueola) at least two years may suggests that most females and young had left be required for attainment of the definitive the area, perhaps reflecting a decline in avail- male plumage (R. Restall pers. com.). ability of Uniola seeds. Several other Sporophila Regardless of this uncertainty, two main seedeaters may show more or less nomadic points stand out: first, the chestnut feathering behavior in response to changes in seed avail- of the throat is acquired early, during the first ability (see Stiles & Skutch 1989 for S. schista- year; second, the most notable changes there- cea). Most striking was the array of male after concern the dorsal plumage, where at plumages present, including at least one type least two distinct stages (year classes) may be A male insulata and 1–2 male telasco (type E), recognized, and in which males may breed but most birds appeared to be more or less (enlarged testes). A further point of interest is intermediate between the two. The birds cap- that the extent of chestnut of the throat varies tured included three such intermediates which in males in both basic II and III; in some only I collected, a type A male insulata and a juve- the anterior throat is chestnut, in others, the nile in female-like plumage, which I measured entire throat – the extent of chestnut does not and released. appear to increase with age, although the I also encountered one other flock of c. 15

25 STILES

FIG. 2. Specimens of Sporophila insulata collected in the present study, in March 1995 at Isla Bocagrande. The two males on the left are classified as type C, that on the right as type D (see text). All had ossified skulls and were completing molt. Note the variability and asymmetry of the chestnut on the breast. seedeaters in Uniola scrub some 300 m east of assuming that a casual observer would place the first flock, plus two lone birds near the type B birds with the former and type D with eastern end of the island (one of which flew the latter, fully half of the males seen were of across the estuary to similar-appearing Uniola the most intermediate plumage type. habitat flanking the beach on the adjacent mainland). In all, I obtained good looks at Specimens of S. insulata. My specimens (Fig. 2) some 25 males (including the four captured); include two (ICN 32303, 32304) with exten- the census of plumage types gave the follow- sively rufous-chestnut throats and breasts and ing results: Type A = 2, type B = 3 or 4, type buffy-white posterior underparts, flecked C = 10–12, type D = 5+, and type E = 3 or 4. with chestnut in one; in the other (ICN Clearly only a minority of the birds seen were 32305), the chestnut is nearly confined to the unequivocally “good” insulata or telasco; even throat but is more extensive than in most

26 STATUS OF THE TUMACO SEEDEATER

FIG. 3. The type series of Sporophila insulata in the American Museum of Natural History, taken in July 1912 at Tumaco, Nariño, Colombia. The left-hand male is the holotype; its plumage is type B (tending towards A); the next two birds are males in plumage types B and C, respectively; the right-hand bird is a female. Note the worn, molting plumage. telasco. ICN 32303 and 32304 are type C (the are in mostly fresh plumage, just finishing former tending toward B), while 32305 is type body molt; that with only the throat chestnut D, tending toward E (telasco). All have partial is in fairly heavy molt – but the incoming to complete bands of grey across the throat, feathers on the breast and belly are buffy- and the chestnut varies from fairly dark to white, not chestnut. This latter bird has the pale [the lower photograph in Salaman (1995) dorsum brown with some grey feathers com- depicts a male with distinctly paler chestnut ing in; in the others the dorsum is grey, plumage below and a partial grey throat- washed with brown. In all, the back is band]. A narrow band across the rump streaked with dusky, much more heavily in the includes chestnut and white feathers inter- third bird. The two former birds had moder- mixed in nearly equal amounts to mostly ately enlarged testes (4–4.5 mm long), while buffy-white, roughly in proportion to the the third bird had very small testes; all three amount of chestnut feathering on the breast. had fully ossified skulls and considerable sub- The two birds with half-chestnut underparts cutaneous fat. The bird with the most exten-

27 STILES sive chestnut (ICN 32303) had a distinctly DISCUSSION paler, more yellowish bill than did the others, whose bills were dusky to horn color. In There are basically two possible interpreta- terms of the plumage sequence worked out tions for the observed variation in male plum- above for S. telasco, I would place ICN 32303 age in insulata: a) the variation reflects age of and 32034 as molting from basic II to basic males within insulata; or b) the variation III (a further indication that the extent of mostly reflects intrinsic (genetic) differences chestnut is not an indicator of age is the fact between males. I feel that the available evi- that the former, with more extensive chest- dence supports the second alternative. nut, has more brown dorsally). ICN 32305 Although the most chestnut bird is also the appears to be molting from basic I to II. This oldest, I do not find clear evidence that the male therefore may be at least one year old, amount of chestnut increases with age in the others at least two years old. either group of specimens; Chapman’s inter- The birds of the type series of insulata pretation that the intermediate birds are (Fig. 3) were described by Chapman (1921) “immatures” lacks a firm foundation. This as in worn plumage, but in fact are also in also agrees with the situation in telasco, in heavy molt. The holotype male, AMNH which the chestnut is acquired early and 118412, is in definitive plumage (fully grey shows no appreciable increase in extent there- dorsum) and is extensively chestnut below, after. This follows from my interpretation of but less than what I would consider type A, the plumages of telasco, in particular that the “good” insulata as in the darker bird photo- dorsal plumage gives the best estimate of age. graphed by Salaman and two I saw (one cap- However, the only fully conclusive test would tured and released), which had only a small involve banding young birds to follow their buffy-white area on the lower abdomen. The subsequent plumage changes. other two males, AMNH 11841 and 11843 If the second interpretation is correct, the (labeled “female?” and “male?” by the collec- plumage variation could reflect interbreeding tor), have chestnut throats and breasts, with between insulata and telasco, which in turn the lower breast and upper abdomen blotched would cast strong doubts upon the status of with chestnut in the former and nearly enti- insulata as a species. Given that Salaman and rely buffy-white in the latter. The former res- Giles also observed apparent type C males in embles ICN 32303 except for having more September (as well as those of the type series extensive chestnut blotching posteriorly; I taken in late July), seasonal plumage change would call it type B, tending toward C. The also seems unlikely (and would be very second is like ICN 32304 and I would call it unusual in Sporophila). Thus, the evidence for type C. Both appear to be molting from basic species status of insulata boils down to the II to III; the former has more brown feathe- observation by Salaman and Giles of singing ring above than the latter and in neither do males of this form (although in several plum- chestnut feathers appear to be replacing age types, including intermediates or “imma- buffy-white ones. The fourth specimen, a tures”) and telasco in apparent sympatry at Isla female, is simply replacing its plumage with Bocagrande. another of similar appearance. It appears no All of these data and observations are at different from females of telasco in compara- least as compatible with a hypothesis of free ble plumage and, had it been taken alone, it interbreeding between insulata and telasco. The would undoubtedly have been classified as the range of male phenotypes resembles that latter. found in an undoubted zone of hybridization

28 STATUS OF THE TUMACO SEEDEATER of two other species of Sporophila (Stiles 1996). ever, further field work in this area suggests Neither Salaman and Giles nor I noted any that the insulata-type birds are in fact minuta, differences among females that might suggest which may be invading (J. C. de las Casas pers. the existence of two good species; Salaman com). A report by L. G. Olarte of insulata-like (1995) reported no obvious differences in and telasco seedeaters still further north also song between the two forms. At best slight requires verification. He noted the distinctly habitat differences were noted between the different songs of the two, but if the former forms by Salaman and Giles (a greater predil- were in reality minuta this would be expected. iction of insulata for bushes amid the Uniola) Unfortunately, Olarte apparently did not col- but I found free intermixing of all plumage lect specimens or photograph any birds. types in the same flocks. I also could not con- Hence, at this point there is no solid evidence firm the suggestion by Salaman (1995) that that insulata occurs north of Tumaco (and so insulata forages lower in the vegetation than far no insulata have been seen or collected in telasco – in fact, the first type A male I saw was Ecuador). plucking seeds from a tall seed head of Uniola. In conclusion, I consider Sporophila insulata The much greater numbers of birds reported to represent a form of S. telasco and not a dis- by Salaman and Giles, including many more tinct, endangered species. Its exact taxonomic “pure” ( ?) telasco apparently in flocks, may status cannot be defined without more indicate a partially nomadic population with detailed study of populations north and south insulata-like birds being perhaps more seden- of the Tumaco area. If it were found that the tary, but this in itself says nothing regarding type A plumage does increase northwards, possible reproductive isolation and could in insulata might be considered a race of telasco, fact facilitate interbreeding. As noted above, it possibly reflecting differentiation of an iso- seems probable that the type C plumage of lated population at the northern extreme of two of the ICN males is indeed the definitive the species range, which is now in secondary plumage; these individuals show no sign of contact with concomitant interbreeding. In immaturity. Whether the type D plumage of the absence of clear geographic structure of the third specimen is definitive is more con- phenotypes, it would simply constitute a color jectural, but the very fact that this individual is morph. Hence, I would not recommend undergoing a complete molt implies that it is “urgent conservation measures” at this time, at least one year old, as young male Sporophila particularly on Isla Bocagrande (given pres- typically do not molt their flight feathers until sures for development there and the interme- after their first breeding season (Olson 1981, diate, possibly nomadic nature of the Stiles & Skutch 1989; Stiles unpubl. data). seedeater population). The available evidence There have been at least two reports of S. further suggests that the insulata phenotypes insulata much further north along the Pacific represent one or several mutations increasing coast. In December 2000, Felipe Estela dis- the amount of chestnut and replacing white covered a population of seedeaters in Parque areas with buff in the ventral plumage of the Nacional Natural Sanguianga, in extreme males. Plumage types B through D might northern Depto. Nariño (c. 2º40’N), c. 100 represent distinct genotypes or heterozygotes km northwest of Isla Bocagrande and or backcrosses between insulata and telasco. Tumaco. This population included both If birds could be captured, genetic analysis insulata-like and telasco male phenotypes; one should be performed on samples of males of the former was captured and photo- with different phenotypes, to shed light graphed; it had a wholly chestnut rump. How- on the origin of insulata. It would be most

29 STILES interesting to institute a banding program anonymous reviewer made helpful comments to follow plumage sequences in known on the manuscript. individuals, and to conduct laboratory breeding and genetic studies. While the REFERENCES Tumaco Seedeater might no longer fall within the sphere of action of BirdLife Inter- Chapman, F. M. 1917. The distribution of bird-life national, it represents an interesting biological in Colombia. Bull. Am. Mus. Natl. Hist. 36: 1– phenomenon that is clearly worthy of further 729. study. Chapman, F. M. 1921. Descriptions of proposed new birds from Colombia, Ecuador, Peru and ACKNOWLEDGMENTS Brazil. Am. Mus. Novit. 18: 1–12. Collar, N. J., L. P. Gonzaga, N. Krabbe, A. I am grateful to Paul Salaman for communi- Madroño N., L. G. Naranjo, T. A. Parker III, & cating to me his and Robert Giles’s rediscov- D. G. Wege. 1992. Threatened birds of the Americas. ICBP, Cambridge, UK. ery of the Tumaco Seedeater on Isla Olson, S. L. 1981. A revision of the subspecies of Bocagrande, thereby making possible the Sporophila (“Oryzoborus”) angolensis (Aves: present study. Logistic support was provided Emberizidae). Proc. Biol. Soc. Wash. 94: 43–51. through the “Biological Inventory of the Renjifo, L. M. 1998. Especies de aves amenazadas y Río Güiza Watershed, Nariño” project casi amenazadas de extinción en Colombia. Pp. funded by INDERENA and carried out by 416–426 in: Chaves, M. E., & N. Arango (eds.). the Instituto de Ciencias Naturales in March Informe nacional sobre el estado de la biodi- 1995. I am grateful to Tito Holguín and versidad. Volume I. Instituto A. von Hum- David Paredes for transport and hospitality boldt, Bogotá, colombia. in Tumaco and Isla Bocagrande, to the “Fun- Ridgely, R. S., & P. J. Greenfield 2001. The birds of dación Los Colibríes” (FELCA) for logistic Ecuador. Volume 1: Status, distribution and taxonomy. Cornell Univ. Press, Ithaca, New support in Nariño, and to Arturo Rodríguez York. for curatorial assistance in the Instituto de Ridgely, R. S., & G. Tudor. 1989. The birds of Ciencias Naturales; Juan Carlos de las Casas South America. Volume 1: The Oscine passe- and Felipe Estela supplied interesting field rines. Univ. Texas Press, Austin, Texas. observations. Examination of specimens in Salaman, P. G. W. 1995. The rediscovery of the the American Museum of Natural History Tumaco Seedeater, Sporophila insulata. Cotinga was made possible by a Chapman Memorial 4: 33–35. Fellowship; I thank Paul Sweet and Mary Smithe, F. B. 1975, 1981. Naturalists’ color guide. LeCroy for facilitating my work there. I also American Museum of Natural History, New thank Leo Joseph and Nathan Rice for help York, New York. and support while studying the Academy of Stiles, F. G. 1996. When black plus white equal gray: the nature of variation in the Variable Natural Sciences collection. J. Van Remsen Seedeater complex (Sporophila, Emberizidae). and Manuel Marín A. provided information Ornitol. Neotrop. 7: 75–107. on S. telasco in the collection of Louisiana Stiles, F. G., & A. F. Skutch. 1989. A guide to the State University; Gerd Kraus supplied mea- birds of Costa Rica. Cornell Univ. Press, Ithaca, surements of specimens in the Museum of New York. Natural History of Vienna. Leo Joseph and an

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