Notes on the Rediscovery of the Baudó Oropendola Psarocolius Cassini In
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Notes on the rediscovery of the Baudo Oropendola Psarocolius cassini in Chocó , Colombia Ralf Strewe Cotinga 12 (1999): 40– 43 Psarocolius cassini es conocida solamente en tres lugares del Darién colombiano, en el departamento del Chocó, donde había sido registrada por última vez en 1945. En julio de 1997 y abril de 1999 la especie fue encontrada nuevamente cerca del parque Nacional Ensenada de Utría. La observación de los individuos ocurrió en el dosel del bosque primario, al nivel del mar, a 1 km de la costa. La vegetación de la planicie costera está constituida por bosque tropical húmedo con una estructura del dosel peldonado, donde sobresalen arboles altos con abundantes epífitas. Las observaciones arrojaron también las primeras informaciones sobre la vocalización, el comportamiento y la ecología de la especie. La poca abundancia y las preferencias de un habitat singular hacen de Psarocolius cassini una especie muy sensible a la destrucción del bosque primario en su área restringida de distribución. Introduction Field observations Baudo Oropendola Psarocolius cassini is endemic On 17 July 1997, c. 4.5 km north of the Ensenada to the lowlands of dpto. Choco, north-west Colom Utriá National Park boundary (at 06°04'N 77°23'W), bia, where it is known from four specimens and a I noticed two unusual oropéndolas foraging high in sight observation of a flock. Birds were recorded the canopy with a flock of c. 25 Chestnut-headed from the middle río Truando (07°07'N 77°23'W) in Oropendola Psarocolius wagleri. They were larger 1858 (adult male; type-specimen), upper Río Baudó than the P. wagleri with bare cheeks and bicoloured (05°32'N 76°59'W) in 1940 (two specimens), and Rio not pale ivory-coloured bills. When one perched in Dubasa (05°19'N 76°57’W) in 1945 (a female col the open, the presence of bright chestnut on the lected from a group of 10 birds)2,3,6. Additionally closed wings, flanks, upper back and rump indicated Rodriguez11 mentioned that the species occurs along that they were P. cassini, based on the description the río Jurado (07°06'N 77°46'W), but presented no in Hilty & Brown6. Having consulted additional evidence for this. There have been no confirmed literature7,10, I was doubtful of the identification due records of Psarocolius cassini since 19457. to bill and cheek patch colorations. I concluded that The species is considered very rare and classi this observation was not sufficiently detailed to fied as Endangered2,3. Collar et al.2 noted that the confirm the rediscovery of P. cassini. rediscovery of the Psarocolius cassini is of highest In April 1999, I again visited the El Valle and priority and that details of the species’ ecological the Ensenada Utría National Park areas. After requirements are urgently required if an effective seven days of fieldwork in the park, on 23 April 1999 conservation plan is to be developed. Here, I report along the path from El Valle to the National Park the rediscovery of P. cassini just north of the boundary, I encountered the same oropendola as I Ensenada Utría National Park and provide the first had observed in July 1997. At 13h35, six individuals descriptions of its behaviour, vocalisations and ecol of P. cassini were observed feeding on fruits in the ogy. canopy of primary forest at 06°04'N 77°22'W. Figure 1. Baudo Oropendola Psarocolius cassini, Ensenada Figure 2. Forest along the río Valle, Ensenada Utría Utría National Park, Colombia, 23 April 1999 (Ralf National Park, with the Serranía de Baudó in the S trew e) background, April 1999 (Ralf Strewe) 4 0 Cotinga 12 Notes on the rediscovery of the Baudo Oropendola in Choc ó , C o lo m b ia They were obviously larger than P. wagleri. The canopy. Once, the two males — an adult and an im distinct bare cheek patch was entirely pink. The mature, which had a completely black bill — met on mantle, flanks and closed wings were wholly rich a large horizontal branch: the adult called inten chestnut; only the primary tips were blackish and sively to the immature, while bowing forward, the wings appeared solid chestnut when closed. The cocking its tail upward and spreading its wings bill was largely black, tipped orange-red. The tail while singing, comparable to the bow-display of was lemon-yellow with the central tail feathers Montezuma Oropendola P. montezuma or P. blackish. Females were similar to males, but guatimozinus7. distinctly smaller and duller in coloration. On 24 April 1999, I visited the locality again Among Psarocolius species, P. cassini is and at 14h05 four birds were present in the same sympatric only with P. wagleri, which is relatively emergent. Unfortunately the weather conditions common in the area with two breeding colonies were extremely bad with thunderstorms and heavy along El Valle path. P. wagleri is noticeably smaller rain throughout most of the day. The birds stayed than P. cassini and is almost entirely black, does only a few minutes before departing to the south. not possess a cheek patch and has a pale bill. The My observations of P. cassini provide no closely related Black Oropendola P. guatimozinus indication of when the species breeds. Interestingly, is distributed through eastern Darién, around the a nearby breeding colony of P. wagleri (06°04'N Gulf of Urabá (north-west Colombia), the upper 77°23'W) with 62 nests was active as the females reaches of the río Sucio and east along the north were constructing nests. In another colony of P. ern base of the Western and Central Andes to the wagleri with 26 nests, close to the boundary of the middle Magdalena Valley; the ranges of P. cassini national park, females were already feeding young. and P. guatimozinus are not known to overlap5,7,10. P. guatimozinus is distinguished from P. cassini by Habitat preferences its largely black plumage with the exception of the My three observations of P. cassini are from humid lower mantle, rump, crissum and secondary coverts, lowland forest and forest edge in at 100–365 m. As which are dark chestnut but not rich bright the río Dubasa and río Truando specimen localities chestnut. The upper mantle, flight feathers and are beside rivers, it was supposed that the species tertials are black contrasting with the chestnut preferred forest on sand deposits2. This preference wing-coverts, secondaries and tertials. The bare is apparently confirmed by my records of P. cassini cheek patch is blue and only the wattle and culmen just 800 m (July 1997) and 1.2 km (April 1999) from base is pink6,7,10. As the photograph (Fig. 1) confirms, the Pacific coast. The narrow coastal plain, under the oropendolas I observed had the all-pink face lain by the sandy deposits of historical beaches and patch and bright chestnut closed wings, flanks and alluvial sediments, extends north from the mantle characteristic of P. cassini. Following my Ensenada Utría to the mouth of the río Valle where detailed observations in April 1999, I am positive the plain is wider8. Its natural vegetation is wet that the birds encountered in July 1997 were of the tropical lowland forest. same species. In July 1997, P. cassini was observed close to the path from the bay of the Ensenada Utría to the B e h a v io u r village of El Valle. Outside the National Park In July 1997, P. cassini was only observed briefly. boundaries the path passes through pastures, The pair foraged on major horizontal branches laden clearings, second-growth woodland and patches of with epiphytes and moss at or near the canopy, and primary forest. The area between the path and the principally near the trunk. In contrast, P. wagleri beach is largely more heavily disturbed than that preferred the outer tree canopy. to the east, where primary forest occurs within 100 In April 1999, the six birds (two males and four m of the track. The species was observed in a patch females) foraged in a canopy tree (Leguminoseae). of relatively undisturbed forest with huge After a few minutes, they moved to a clearing with emergents and a natural structure. In April 1999, I Cecropia stands and foraged in dense leaf clusters. found the species just 850 m from the first locality They associated with Black-chested Jay Cyanocorax and 750 m east of the path. The observation was affinis. No P. wagleri were present. Subsequently made in primary forest at the base of a 200–300-m- the birds visited the canopy of a tall emergent high ridge. Interestingly, I did not record the species (Bombacaceae), where the males, especially, in in these hills, although two days of fieldwork were spected the undersides of large horizontal branches conducted there. for insects by leaning beneath them (in the manner The structure of the lowland forest consists of a of many Tangara species). Usually the males re rather open canopy (crowns of taller trees usually mained closer to the trunk and used larger branches not touching), allowing sunlight to penetrate to the while feeding, presumably because they are heavier forest floor, although denser locally. The canopy is and less agile than females, which are better able broken by tall emergents and the majority of the to forage on thinner branches and in the outer larger trees have many epiphytes. 4 1 Cotinga 12 Notes on the rediscovery of the Baudo Oropendola in Chocó, Colombia As my, and previous, records demonstrate, The principal threats to the area of Bahia Solano closed-canopy forests are not the preferred habitat and El Valle are indiscriminate felling of trees, of P.