In recent decades, there has been a dramatic increase in knowledge of the Bolivian avifauna, progress reflected in the significant rise in the number of species known in the country between 1989 (1,274) (Remsen & Traylor 1989) and 2003 (1,398) (Hennessey et al. 2003). By 2016, 1,437 species had been registered (Herzog et al. 2016). Four years later, following such additions as Laughing Gull Leucophaeus atricilla (Brady et al. 2019), Common Ground Dove Columbina passerina and South American Painted Snipe Nycticryphes semicollaris (Aponte et al. 2022), and the description of Inti Tanager Heliothraupis oneilli to science (Lane et al. 2021), the number had reached 1,446 (Herzog 2021). Here, we present three new bird records (two species and one colour morph) for Bolivia, from dptos. Beni and Santa Cruz.

BISCUTATE SWIFT Streptoprocne biscutata

Found in eastern Brazil and northern Argentina, with one record in eastern Paraguay (Capper et al. 2001, Pearman et al. 2010, Pearman 2012, Bowe 2020), the species frequents waterfalls and caves for roosting and nesting, but forages over tropical evergreen and deciduous forests, mountainous areas, and scrublands (Chantler 2000, Pichorim 2002, Bowe 2020).

On 5 January 2023, GAP & CR observed three S. biscutata on the ground (Fig. 1) inside a humid cave in Reserva de Vida Silvestre Tucabaca, Santa Cruz (18°20'46.32”S, 59°33'2.01”W; 835 m), c.250 m from the rock paintings of Miserendino cave, with pools on the ground and a small amount of water falling from the ceiling. Another, dead, individual was nearby. Abundant excrement, probably from bats and the swifts, was visible inside the cave. Subsequently, on 21 March 2023, c.20 swifts were seen exiting the same cave (RSMS). Tucabaca protects a portion of Chiquitano Dry Forest, as well as cerrado vegetation with many endemic and threatened plant species. Near the cave is a waterfall with permanent water year-round. The area supports tree ferns of the genus Cyathea, abundant Myrtaceae, terrestrial ferns, and mosses.

Our photographs match Biscutate Swift Streptoprocne biscutata, particularly the ‘white patch on the nape and chest, forming a broken white collar around its neck’, which is the main characteristic differentiating it from the similar and partially sympatric White-collared Swift S. zonaris (Kirwan 2007). Our records are 510 km south-west of the nearest documented site in Brazil (E. Pennington et al.,  https://ebird.org/checklist/S120438283), and thus the westernmost record ever, as well as the first in Bolivia. The area appears very suitable for the species, but further work is needed to confirm or deny its regular presence there.

Figure 1.

Biscutate Swift Streptoprocne biscutata, Santiago de Chiquitos, Santa Cruz, Bolivia, January 2023; the first documented record for Bolivia (Germaine Alexander Parada)

BUCKLEY'S FOREST FALCON Micrastur buckleyi

Locally common in far western Brazil, Amazonian Ecuador and Peru, with a single record in south-east Colombia (Hilty & Brown 1986, Whittaker 2001, Bierregaard et al. 2020), the species is present mainly in lowland forests, although it has been recorded up to 1,800 m in Ecuador (Robbins et al. 1987, Solano-Ugalde & Real-Jibaja 2010) and 1,350 m in Peru (Schulenberg et al. 2007). M. buckleyi is morphologically similar to Collared Forest Falcon M. semitorquatus, but has proportionately longer wings and a smaller bill (Whittaker 2001).

On 31 October 2022, MAM recorded a M. buckleyi in the Área Protegida y Reserva Natural Aquicuana (10°51'39.63”S, 65°58'24.15”W; 140 m), Beni. Initially, a Micrastur was heard giving a three-note song, which was recorded using the Birdnet app (Fig. 2). After three minutes, playback was used and the bird responded by flying into view and moving between trees (Fig. 3), before it eventually disappeared. The original recording was deposited on Xeno-canto ( https://xeno-canto.org/782173), but was subsequently resampled using the Raven programme and the edited recording (volume increased and insect sounds removed) was deposited in Macaulay Library ( https://macaulaylibrary.org/asset/538470551). It was made in a narrow strip of flooded forest on the alluvial plain of a white-water river adjoining flooded forest of white stagnant waters (Navarro 2011).

MAM's recording involves a territorial call, identical to that described by Whittaker (2001), typically consisting of two (EEOK, OOW) or three loud notes (EEOK, OOW, ... AW) (Fig. 2). This vocalisation is the easiest means of differentiating M. buckleyi from M. semitorquatus (Whittaker 2001, Schulenberg et al. 2007). This is the first record in Bolivia, c.390 km from documented records in Peru (F. Schneider,  https://ebird.org/checklist/S59580879; A. Wiebe,  https://ebird.org/checklist/S48351775). Possibly, the species will be found at other sites in Bolivia, e.g., in dpto. Pando, as the species is easily overlooked except when vocalising.

Figure 2.

Sonogram of Buckley's Forest Falcon Micrastur buckleyi, with territorial song of three notes in the first part and, at eight seconds, a territorial song of two notes (spacing natural).

Figure 3.

Buckley's Forest Falcon Micrastur buckleyi, Área Protegida y Reserva Natural Aquicuana, near Riberalta, Beni, Bolivia, October 2022; the first documented record for Bolivia (Pia Handke)

DARK-THROATED SEEDEATER Sporophila ruficollis ‘caraguata’ morph

S. ruficollis is distinguished from other Sporophila in Bolivia by the male's black throat and moderately distinctive female plumage (Herzog et al. 2016, Jaramillo 2020). However, a colour morph dubbed ‘caraguata’ was described from Corrientes and Entre Ríos in northeast Argentina, with a black throat and nape, otherwise grey head, reddish-brown back, rump and ventral patches, and blackish wings and tail (Areta et al. 2011). S. ruficollis breeds in northern Argentina, parts of southern Brazil, Paraguay, western Uruguay and extreme south-east Bolivia, but moves north and west as far as central Brazil in the non-breeding season (Jaramillo 2020). In Bolivia, the nominate subspecies has been seen in La Paz, Santa Cruz and Beni, where it is considered fairly common in flooded savanna, lowland swamps, cerrado, and natural and artificial grasslands (Herzog et al. 2016).

Figure 4.

Male and female Dark-throated Seedeater Sporophila ruficollis ‘caraguata’ morph, near Riberalta, Beni, Bolivia, October 2022 (Miguel Montenegro-Avila).

On 30 October 2022 in a grassland (11°09'57.3”S, 65°45'47.7”W; 152 m) 36 km southeast of Riberalta, Beni, MAM recorded a large flock of c.300 S. ruficollis, some of which had a grey crown, black neck and rufous back (Fig. 4), matching the ‘caraguata’ morph. Due to the overall numbers of Sporophila present (including some Double-collared Seedeater S. caerulescens), the precise number of the ‘caraguata’ morph could not be established. The presence of this morph in October along with ‘normal’ individuals of S. ruficollis indicates that they spend the winter together, and also suggests that it is migratory, as this record is 2,500 km from the breeding areas in north-east Argentina (Areta et al. 2011).