We report the first record of Lesson's Seedeater Sporophila bouvronides, a South American species, in Costa Rica. It was seen at Tortuguero, in the lowlands of north-east Costa Rica in June 2022. The record is perhaps explained by the passage of a tropical storm that moved north-west from off northern South America.
The genus Sporophila comprises c.40 species, distributed from Texas in the USA to Argentina (Machado & Silveira 2010, Rising 2011). Most species live in grasslands, but a few inhabit forest interiors (Ridgely & Tudor 1989, Areta et al. 2013). Due to urban development and the expansion of agricultural monocultures (e.g., pineapple, banana or soybean), the areas inhabited by these species (especially grasslands) have been declining, which may explain changes in their distributions (Silva 1999).
Although the majority of Sporophila species are sedentary, approximately 25% perform migrations between the breeding and non-breeding ranges (Rising 2011). One species with long-distance movements is Lesson's Seedeater Sporophila bouvronides, which breeds in north-east Colombia, northern Venezuela, Trinidad & Tobago and the Guianas, and migrates to western Amazonia, reaching northern Bolivia, western Brazil and eastern Peru during the non-breeding season (Ridgely & Tudor 1989, Rising 2011). It inhabits shrubby savannas, forest edges, cultivated areas and grasslands near water (Rising 2011). Clearly, the species is capable of moving long distances, although the only previous evidence of vagrancy is a few records in eastern Panama (Angehr & Dean 2010). Here we present the first report in Costa Rica.
First record in Costa Rica
The observation was made at Tortuguero (10°32′23.9″N, 83°30′06.1″W), Pococí, Limón province, in the lowlands of north-east Costa Rica (Fig. 1) on 25 June 2022, on a private property with an open area and lawn, and involved an adult male (Fig. 1) with a flock of Variable Seedeaters Sporophila corvina, near the beach and foraging under a tropical almond Terminalia catappa. It immediately drew our attention, because the two species' plumages are very different, and the bird remained alert and wary. The observation lasted c.7 minutes, during which time it stayed with the Variable Seedeaters, then flew c.10 m from the other seedeaters, before flying further and disappearing.
We separated the Lesson's Seedeater from other Sporophila in Costa Rica as follows. Male Morelet's Seedeater S. morelleti has a white collar and white wingbars, a white spot below the eye, and the lower underparts are off-white or cream. Males of the Caribbean subspecies of Variable Seedeater are all black, whilst the Pacific subspecies (not recorded or expected in the area) has a white collar. Male Lined Seedeater S. lineola, an accidental species in Costa Rica (Garrigues & Dean 2014), has a white median crown-stripe (Rising 2011).
There are no previous reports of Lesson's Seedeater in Costa Rica. The closest records are in Darién, Panama, where an eBird ( https://ebird.org/checklist/S56064460) report in May 2019 also involved a bird in the company of Variable Seedeaters. Our record is c.615 km north-west of this and 760 km from the closest area where the species breeds (Fig. 2). The date of our sighting coincides loosely with the species' return to the breeding range (from April but mainly May or June; Ridgely & Tudor 1989, Rising 2011). With the passage of tropical storm Bonnie that began on 25 June in the southern Caribbean, then moved east to west, and on 1 July impacted Barra del Colorado north of Costa Rica with gusts of wind of 75 km/h ( https://cap-sources.s3.amazonaws.com/cr-imn-es/2022-07-01-17-56-34.xml; https://www.nhc.noaa.gov/archive/2022/al02/al022022.discus.018.shtml), the bird could have been blown off course to eastern Costa Rica. Potentially similar vagrancy has occurred in a closely related species, with a male Lined Seedeater found on the Pacific slope of Costa Rica in October 2013 (Obando-Calderón et al. 2013).