Avian Range Extensions from the Southern Headwaters of the Río Caroní, Gran Sabana, Bolívar, Venezuela
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Cotinga31-090608:Cotinga 6/8/2009 2:38 PM Page 5 Cotinga 31 Avian range extensions from the southern headwaters of the río Caroní, Gran Sabana, Bolívar, Venezuela Anthony Crease Received 7 December 2005; final revision accepted 25 December 2008 first published online 4 March 2009 Cotinga 31 (2009): 5–19 Este artículo se refiere a mis observaciones de aves durante más de ocho años de residencia en la región de las cabeceras sureñas del río Caroní en la parte sur de la Gran Sabana, en el Estado Bolívar de Venezuela. Para 145 especies, presento nuevos registros que están significativamente distantes de los publicados o fuera de los rangos altitudinales establecidos para Venezuela al sur del Orinoco. La gran cantidad de observaciones ha sido resumida en una tabla para proveer información sobre la magnitud de las extensiones aparentes dentro de Venezuela, una indicación aproximada de la abundancia y distribución detallada dentro del área de estudio y sus diferentes tipos de hábitat. Se proveen descripciones más completas, incluyendo detalles de distribución en zonas circundantes, para algunas especies seleccionadas, para las cuales la distancia a los registros establecidos son mayores o donde existe evidencia respecto a movimientos estaciónales. Las especies tratadas incluyen Poecilotriccus fumifrons, conocida previamente en Venezuela de un solo espécimen colectado en el extremo sur del país en 1992. The Gran Sabana in south- east Venezuela, in itating the arrival of lowland savanna species from Bolívar state, comprises a remnant of a band of Roraima state in Brazil. elevated savannas that once separated the The study area (Fig. 1), a strip of land c.80 km Amazonian and Guianan lowlands. In its southern × 15 km, refers to that part of the southern part, the río Cukuenan crosses east–west from near headwater region accessible via the limited road the border with Guyana to the junction with the río system, in particular the Paují road linking Santa Caroní, forming the southern border of Canaima Elena to Icabaru, which is mentioned in birders’ National Park, which is dominated by savanna. guidebooks6,18,25. I refer to this accessible part as the Four tributaries (Uairén, Surucún, Uaiparú and Paují road area. Ornithological exploration was Icabarú) drain the more forested area south of the initiated here by Phelps in 194519, specifically Cukuenan from the Orinoco / Amazon watershed on around Santa Elena and Pauraitepuy. Although the Sierra de Pacaraima, which marks the border much of the forest habitat along the roads is now with Brazil. I refer to this area as the southern disturbed by slash- and- burn agriculture, the area headwaters of the Caroní. As a resident of the still possesses several extensions of largely region since 2000, I have discovered avifaunal continuous forest, notably in the Uaiparú Valley diversity to be much greater than previously (c.200 km2) and the Surucún basin (c.400 km2). The recognised (>500 species). Here I detail the forests of the Uairén basin are more fragmented numerous range extensions I have documented, in and disturbed due to the proximity to Santa Elena order to promote ornithological interest in the area. (c.25,000 inhabitants). Forested areas in the Most of the area lies at 800–1,000 m with tepuis to 1,600 m (Chirikayén) and valleys at c.650 m (río Uaiparú) and 500 m (río Icabarú). With annual rainfall of c.2,000–2,250 mm, the three main bioclimatic types in the area are savanna, wet premontane forest and, at lower elevations in the Uaiparú and Icabarú valleys, tropical humid forest5. Savannas, mostly in the elevation range 850–1,000 m, exist in the form of islands, up to 100 km2, surrounded by forest. The savannas around Santa Elena, at the east end of the study area, form the southern tip of the much more extensive savanna occupying the north- east Gran Sabana and were bordered to the south until recent times by unbroken forest. The forest border along the Figure 1. Map of the southern Gran Sabana, showing the steep southern flank south of Santa Elena is now Paují Road area. being breached by slash- and- burn agriculture, facil- 5 Cotinga31-090608:Cotinga 6/8/2009 2:38 PM Page 6 Cotinga 31 Avian range extensions from southern Venezuela headwaters of the Icabarú (c.500 km2), although Species inclusion largely untouched, are inaccessible. Most published records for Venezuela, until to year 2002, were mapped as points by Hilty7. A more Methods recent guide to the northern South America Since 2000, I have devoted on average about one region15 shows updated expected distributions but morning per week, mostly from first light until c.11 no actual records, presumably in part due to the am, to field work, with the aim of compiling an very small scale of the maps. Since 2002 to date, no avian inventory. Frequent opportunistic observa- further specimen or sighting records have been tions have also been made, particularly around published for the Paují Road area. The limited Paují village and along the Paují road during trips number of published records, together with the to Santa Elena. Observations are recorded in a deliberate omission from the Hilty guide7 of database1. unpublished and unconfirmed sightings, means Sight identification, using binoculars and that the presence of many species in the area is not telescope, was based on Meyer de Schaunesee & reflected. Although the paucity of records was Phelps9, Ridgely & Tudor for passerines16,17, latterly compensated, to some extent, in Hilty7 by marking Hilty7 and, even more recently, Restall et al.15. expected distributions, derived from actual records Photography, using a digital camera hand- held to using habitat distribution and elevational contours, the telescope, has been used in the last three years the necessity of consolidating the actual record base to document sight records. Photographs have been remains. I used the following criteria for inclusion deposited at VIREO (Philadelphia, PA). in Table 2: (a) observed outside the expected distri- Recording of vocalisations has been used butions7 >50 km from the nearest actual record; (b) increasingly, particularly for forest interior and observed within the expected distributions7 but other hard- to- see species, by comparison with >100 km from the nearest actual record; (c) commercial CDs2,22, the voice descriptions in Hilty7 observed significantly outside the altitudinal and recordings posted on the website www.xeno- ranges of the guide7; and (d) evidence of seasonal canto.org. A digital voice recorder with external movement obtained. Based on these criteria, 146 microphone is used for recording field notes and species are included in Table 2. As my main purpose readily audible vocalisations, and a Sony MZ- R37 is to present new range information with respect to Minidisc recorder with a Sennheiser K6 / ME67 the Hilty guide7, systematic order and species microphone for better quality recording. Recordings nomenclature follow the latter. evidencing species occurrence in the area have been deposited at the British Library Sound Archive Range extensions (London, UK). I have registered 79 species in the Paují area at Altitudes were obtained from three sources: elevations well above published altitudinal limits of contour maps of the area published by Cartografía these birds south of the Orinoco7. However, many of Nacional in the 1: 25,000 and 1: 100,000 series, a these limits evidently understate altitude range, GPS or a watch altimeter. The study area has been since the maps actually show an expected presence divided into eight sub- areas, with roughly or records at locations considerably higher than the homogeneous habitats (see Table 1), to permit stated limits. In reality, apparently most species observations (Table 2) to be associated with a that occupy lowland forest or ‘edge’ habitat predominant habitat type and to permit more adjacent to the Gran Sabana have also occupied all precise localisation. areas of contiguous forest or ‘edge’ up to at least 900 m in the same area. A similar observation was made for the nearby Mt. Kopinang, in the Table 1. Details of Paují Road sub-areas. Sub-Area Elevational Coordinates of sub-area Habitat types Code Description range midpoint a El Paují area 800–1,000 m savannas, scrub, white-sand woodlands, some narrow gallery 04°28.5’N 61°35.4’W b Savannas west of El Paují 800–1,000 m forests, forest islands, conucos and edge of forests of rio 04°27.6’N 61°38.9’W c Savannas north-east of El Paují 800–1,000 m Icabarú basin 04°33.9’N 61°31.7’W savannas, morichales, narrow gallery forests and forest d Savannas around Santa Elena 800–1,000 m 04°36.2’N 61°06.4’W islands, conucos, forest edge, ponds e Tepui summits 1,050–1,600 m white-sand woodlands, savanna scrub 04°36.5’N 61°27.3’W f Río Uaiparú Valley forest 650–850 m 04°32.0’N 61°37.3’W primary and degraded forest, conucos and clearings along g Río Cinco Ranchos forest 800–950 m 04°32.5’N 61°31.5’W road, forest edge (including forest rivers and ponds) h Río Surucún basin forests 800–950 m 04°37.0’N 61°23.8’W 6 Cotinga31-090608:Cotinga 6/8/2009 2:38 PM Page 7 Cotinga 31 Avian range extensions from southern headwaters of río Caroní, Venezuela Table 2. Summary of range extensions. Inclusion. Rationale. R = outside expected distribution per Hilty7 and at least 100 km from nearest known published record in Venezuela; r = less- surprising range extension, see text; h = outside Hilty’s7 altitudinal range; M = evidence of migratory movement. Categories R and M detailed in Selected species accounts.