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Evidence for longitudinal migration by a “sedentary” Brazilian flycatcher, the Ash-throated Casiornis

2016; Association of Field Ornithologists; Volume: 87; Issue: 3 Linguagem: Inglês

10.1111/jofo.12159

1557-9263

Alexander Charles Lees,

Animal and Plant Science Education

The digitalization of museum collections and concurrent increase in citizen-science initiatives is ushering in an era of unprecedented availability of primary biodiversity data. These changes permit a reappraisal of phenological patterns of tropical species. I examined spatio-temporal variation in the distribution patterns of an ostensibly sedentary endemic Brazilian flycatcher, the Ash-throated Casiornis (Casiornis fuscus), using both specimen data from museums and sighting records and rich media data from citizen-science initiatives. I found compelling evidence for partial intratropical longitudinal migration to Amazonia and the Cerrado biomes from the species' core range in the semi-desert Caatinga biome and adjacent ecotones. These records from outside of the Caatinga were distributed during the height of the dry season from April to October, although the Caatinga is not entirely vacated at this time. This pattern of partial migration leads to a doubling of the distributional range of Ash-throated Casiornises and strongly suggests that the species is a breeding near-endemic of the Caatinga biome. This pattern was potentially previously not apparent because of significant biases in specimen collection between biomes, giving a false sense of abundance in the Brazilian Amazon. La digitalización de las colecciones de museos y el aumento simultáneo de las iniciativas de ciencia ciudadana está marcando el comienzo de una era sin precedente de la disponibilidad de datos primarias de biodiversidad. Estos cambios permiten una reevaluación de los patrones fenológicos de las especies tropicales. Examiné la variación espaciotemporal de los patrones de distribución de un tiránido endémico de Brasil, y cual se cree que es ostensiblemente sedentario, el burlisto gorgigrís (Casiornis fuscus), utilizando ambos datos de especímenes de museos y registros de avistamientos, y también, datos de medios por iniciativas de ciencia ciudadana. He encontrado pruebas concluyentes de migración longitudinal intratropical entre la Amazonía y la bioma Cerrado desde la área núcleo de la especie en el semi-desierto bioma, la Caatinga, y en los ecotonos adyacentes. Los registros al exterior de la Caatinga se estaban distribuidos durante la altura de la estación seca, de abril a octubre, aunque la Caatinga no fue desocupado por completo en esa temporada. Este patrón de migración parcial conduce a una duplicación de la área de distribución de Casiornis fuscus y sugiere firmemente que la especie es cercano a ser un ave reproductora y endémico de la Caatinga. Este patrón potencialmente no era previamente aparente debido a sesgos en la obtención de muestras entre los biomas, dando una falsa sensación de abundancia en la Amazonia brasileña. Table S1. Full list of records and accession numbers for records of Ash-throated Casiornises used in the analysis. Table S2. Number of transects allocated to each land use in each region, number in parentheses is the total number of records of Ash-throated Casiornises (if there are records). Table S3. Full list of specimens, associated metadata, and habitat preferences from Parker et al. (1996) for series of birds >10 individuals co-collected with Ash-throated Casiornes in Amazonia. Figure S1. Spatiotemporal distribution of eBird checklists within the range of Ash-throated Casiornis (the Brazilian states of Pará, Maranhao, Ceara, Piaui, Rio grande do Norte, Paraiba, Bahia, Tocantins, Alagoas, Pernambuco, Sergipe and Minas Gerais). Figure S2. An Ash-throated Casiornis (Casiornis fuscus) photographed in a young Amazonian secondary forest in the municipality of Paragominas in Pará state (2°54′S, 47°40′W) on 13 August 2010 (Alexander Lees). Figure S3. An Ash-throated Casiornis (Casiornis fuscus) photographed at the border of an Amazonian natural campo limpo and terra firme forest ecotone in the municipality of Moju in Pará state (2°14′S, 48°50′W) on 14 September 2013 (Alexander Lees). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.