Discovery of a population of the endangered Red Siskin (Carduelis cucullata) in Guyana

ABSTRACT.-A heretofore unknown population of the endangered Red Siskin (Carduelis cucullata) was discovered in southwestern Guyana, ~950 km from populations along the Venezuela coastal cordilleras. Most Venezuelan populations have been greatly reduced by the pet trade during the past 150 years, thus the newly discovered Guyana population represents an opportunity to insure the survival of this highly endangered species in the wild. Breeding of Guyanese siskins coincides with both breeding periods (May to early July and November-December) that have been documented in Venezuela. Breeding behavior, vocalizations, feeding habits, and immature plumages are described. Received 12 November 2002, accepted 22 April 2003.

RESUMEN.-Se descubrio una poblacion hasta ahora no conocida de Carduelis cucullata en el suroeste de Guyana, localizada a ~950 km de poblaciones que se encuentran a lo largo de las cordilleras costeras de Venezuela. Durante los ultimos 150 anos, la mayoria de las poblaciones venezolanas han sido diezmadas por los traficantes de mascotas, por lo que la poblacion descubierta recientemente en Guyana representa una oportunidad para garantizar la sobrevivencia de esta especie fuertemente amenazada en su ambiente natural. Los periodos reproductivos de C. cucullata en Guyana coinciden con los dos periodos reproductivos reportados en Venezuela (mayo a comienzos de julio y noviembre a diciembre). En este estudio se describen el comportamiento reproductivo, las vocalizaciones, los habitos de forrajeo y los plumajes de individuos inmaduros.

THE RED SISKIN (Carduelis cucullata) has been the object of intense trapping for the international cagebird trade for over 150 years (Coats and Phelps 1985, Collar et al. 1992). Though it once occurred naturally from extreme eastern Colombia across the northern coastal cordilleras of Venezuela (Fig. 1), the latest summaries of its status suggest that most wild populations have been extirpated, with remaining wild populations highly fragmented and consisting of no more than a few hundred individuals per population in extreme eastern Colombia and western and central Venezuela (Coats and Phelps 1985, Collar et al. 1992, Lopez-Lanus 2000, S. Hilty pers. comm.). The species was introduced into Puerto Rico, probably in the 1930s (Raffaele et al. 1998), and there were a handful of records up until 1960 for Trinidad (ffrench 1991), although natural origin of those birds is open to question due to extensive finch trade. In spite of being legally protected in Venezuela since 1940 (Coats and Phelps 1985), birds continue to be captured and smuggled out of the country (V. Patterson, American Federation Aviculturists, pers. comm.). Collar et al. (1992) listed the species as category 2 of endangered ("situation serious: action urgent").

On 12 April 2000 in southwestern Guyana, while observing a mixed-species flock at the edge of forest and savanna, M.B.R. heard a small flock of Carduelis-like birds fly overhead. Recognizing that no Carduelis was known from the region, he located the flock a few minutes later, and was stunned to see three adult male and two adult female Red Siskins perched ~15 m above the ground in the top of a leafless tree. During the next hour, he located an additional 7-8 birds (three pairs and at least one female) in an area of ~1.0 x 0.25 km. Here we document the discovery of that new population of an endangered species and provide natural history data that may help in the conservation of the species in the wild.

STUDY AREA AND METHODS

Because of the relentless pursuit of this species by the cagebird trade, we have not listed precise localities. To date, the newly discovered siskin population appears to be restricted to the Rupununi savanna of southwestern Guyana (Fig. 1). The Rupununi savanna of Guyana (~13,000 km^sup 2^; Hills 1976) is a low-lying plain, 100-200 m in elevation, divided by the western portion of the Kanuku Mountains south of the border town of Lethem (03[degrees]23'N, 59[degrees]48'W). The savannas continue for many kilometers to the west in the state of Roraima in Brazil (also known as the Roraima or Rio Branco savanna), and indeed the total area of savanna there is considerably more than in Guyana (Eden 1964, Cole 1986). Interspersed throughout the Rupununi, and adjacent Brazil, are isolated granite mountains that range from small dome-like hills with sparse, semihumid vegetation to relatively tall mountains that cover several square kilometers with more mesic forest (Fig. 2). The rolling plains are covered by grasses, dominated by the perennial bunch grass Trachypogon plumosus (Poaceae) that are interspersed with the dominant savanna tree, Curatella americana (Dilleniaceae; known in Guyana as "caimbe" or "sandpaper tree"). Within the savanna there are pockets, ranging from a several square meters to a few square kilometers, of isolated forest that are known as "bush islands." The entire fringe of the savanna interdigitates with extensive humid forest. Eden (1973) provides details on Rupununi savanna geomorphology and vegetation.