Status of Nearctic and Austral migratory birds in the Brazilian state of Acre, Southwestern Amazon: insights from citizen science contributions

Alnizia Galdino Pereira; Kaylane de Oliveira Silva; Luana Alencar; Ighor Dienes Mendes; Edson Guilherme

doi:10.56178/eh.v41i1.1531

Articles Published 31 March 2026 https://doi.org/10.56178/eh.v41i1.1531

Status of Nearctic and Austral migratory birds in the Brazilian state of Acre, Southwestern Amazon: insights from citizen science contributions

Amazonia birds citizen science migratory route

Alnizia Galdino Pereira Laboratório de Ornitologia, Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, Rio Branco, Brazil

Kaylane de Oliveira Silva Laboratório de Ornitologia, Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, Rio Branco, Brazil

Luana Alencar Laboratório de Ornitologia, Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, Rio Branco, Brazil

Ighor Dienes Mendes Laboratório de Pesquisas Paleontológicas, Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, Rio Branco, Brazil

Edson Guilherme Laboratório de Ornitologia, Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, Rio Branco, Brazil | Laboratório de Pesquisas Paleontológicas, Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre, Rio Branco, Brazil

Abstract

Migratory birds undertake seasonal movements between breeding and non-breeding areas in search of favorable climatic and food conditions. In South America, two major migratory systems are recognized: Nearctic and Austral. The Brazilian state of Acre, located in the southwestern Amazon, serves as a strategic stopover for both groups, yet increasing anthropogenic pressures threaten these corridors. Understanding migration dynamics is therefore essential for conservation planning. This study analyzed temporal patterns of Nearctic and Austral migratory bird species in Acre and assessed their degree of temporal overlap. Data was obtained from citizen science platforms, with photographic records filtered by species and month and visualized through heatmaps. Records were classified into reproductive and non-reproductive months, and differences tested using the non-parametric Mann-Whitney U test (p < 0.05). A total of 1554 images representing 61 migratory species (31 Nearctic and 30 Austral) were analyzed. Solitary Sandpiper (Tringa solitaria) showed the highest frequency of records among Nearctic migrants, whereas Vermilion Flycatcher (Pyrocephalus rubinus) prevailed within the Austral group. Phenological analysis revealed distinct seasonal windows: Nearctic migrants occurred mainly from September to March, whereas Austral migrants were recorded from March to September, with minimal overlap. Some species, such as Chivi Vireo (Vireo chivi) and Crowned Slaty Flycatcher (Empidonomus aurantioatrocristatus), were observed nearly year-round, suggesting complex strategies including partial migration or coexistence of resident and migratory populations. These findings highlight Acre’s role as a dynamic migratory corridor and demonstrate the value of citizen science in monitoring avian biodiversity in remote regions, reinforcing its importance for conservation strategies.

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References

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Alnizia Galdino Pereira, Kaylane de Oliveira Silva, Luana Alencar, Ighor Dienes Mendes, Edson Guilherme (2026). Status of Nearctic and Austral migratory birds in the Brazilian state of Acre, Southwestern Amazon: insights from citizen science contributions. El Hornero, Vol. 41 No. 1 (2026), 63-74. https://doi.org/10.56178/eh.v41i1.1531

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[1] Acre, Governo do Estado (2014) Caderno das Unidades de Gestão de Recursos Hídricos do Acre / Secretária de Estado do Meio Ambiente. Rio Branco: SEMA

[2] Acre, Governo do Estado (2015) Zoneamento Ecológico-Econômico do Estado do Acre, Fase II. Rio Branco: SEMA

[3] Alves MAS (2007) Sistemas de migrações de aves em ambientes terrestres no Brasil: exemplos, lacunas e propostas para o avanço do conhecimento. Revista Brasileira de Ornitologia 15(2):231-238

[4] AviList Core Team (2025) AviList: The Global Avian Checklist, v2025. https://doi.org/10.2173/avilist.v2025

[5] Barbosa KVC, Develey PF, Ribeiro MC, Jahn AE (2021) The contribution of citizen science to research on migratory and urban birds in Brazil. Ornithology Research 29:1-11. https://doi.org/10.1007/s43388-020-00031-0

[6] Billerman SM, Keeney BK, Kirwan GM, Medrano F, Sly ND, Smith MG (2026) Birds of the World. Cornell Laboratory of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow

[7] Campos CEC, Naiff RH, Araújo AS (2008) Censo de aves migratórias (Charadriidae e Scolopacidae) da Porção Norte da Bacia Amazônica, Macapá, Amapá, Brasil. Ornithologia 3:38-46

[8] Canassa GG (2022) Migração austral do Príncipe (Pyrocephalus rubinus: Aves): uma avaliação através da ciência cidadã. Universidade Estadual Paulista, Rio Claro. [URL: http://hdl.handle.net/11449/216499]

[9] Carmi O, Witt CC, Jaramillo A, Dumbacher JP (2016) Phylogeography of the Vermilion Flycatcher species complex: multiple speciation events, shifts in migratory behavior, and an apparent extinction of a Galápagos-endemic bird species. Molecular Phylogenetics and Evolution 102:152-173. https://doi.org/10.1016/j.ympev.2016.05.029

[10] Carroll C, Furrow RE, Gerhart LM (2025) Consistency and Validity of Participatory Science Data: A Comparison of Seasonality Patterns of Northern California and Nevada Birds Across eBird and iNaturalist. Citizen Science: Theory and Practice 10(1):1-14. https://doi.org/10.5334/cstp.825

[11] Cestari C (2015) Coexistence between Nearctic-Neotropical migratory shorebirds and humans on urban beaches of the Southern Hemisphere: a current conservation challenge in developing countries. Urban Ecosystems 18:285-291. https://doi.org/10.1007/s11252-014-0399-3

[12] Chesser RT (1994) Migration in South America: an overview of the austral system. Bird Conservation International 4(2-3):91-107. https://doi.org/10.1017/S0959270900002690

[13] Daly DC, Silveira M (2008) Primeiro catálogo da flora do Acre, Brasil. Editora da Universidade Federal do Acre – Edufac. Rio Branco, Acre. Pp. 42

[14] Dennis EB, Diana A, Matechou E, Morgan BJ (2025) Efficient statistical inference methods for assessing changes in species’ populations using citizen science data. Journal of the Royal Statistical Society Series A: Statistics in Society 188(3):641-657. https://doi.org/10.1093/jrsssa/qnae105

[15] eBird (2025) eBird: An online database of bird distribution and abundance (web application). eBird, Cornell Lab of Ornithology, Ithaca. [URL: http://www.ebird.org]

[16] El Hindi TS, Jahn AE, Tuero DT, Pizo MA, Silveira NSD (2023) Projected population- and season-dependent impacts of climate change on a migratory songbird in South America. Frontiers in Bird Science 2:1214458. https://doi.org/10.3389/fbirs.2023.1214458

[17] Ellison KS, Wolf BO, Jones SL (2021) Vermilion Flycatcher (Pyrocephalus rubinus), version 1.1. In: Poole AF (ed) Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.verfly.01.1

[18] Farmer A, Holmes RT, Pitelka FA (2020) Pectoral Sandpiper (Calidris melanotos), version 1.0. In: Billerman SM (ed) Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.pecsan.01

[19] Fuentes M, Van Doren BM, Fink D, Sheldon D (2023) BirdFlow: Learning seasonal bird movements from eBird data. Methods in Ecology and Evolution 14(3):923-938. https://doi.org/10.1111/2041-210X.14052

[20] Guilherme E (2001) Comunidade de Aves do Campus e Parque Zoobotânico da Universidade Federal do Acre, Brasil. Tangara 1(2):57-73

[21] Guilherme E (2012) Birds of the Brazilian state of Acre: Diversity, zoogeography, and conservation. Revista Brasileira de Ornitologia 20(4):393-442. [URL: http://www.revbrasilornitol.com.br/BJO/article/view/0149]

[22] Guilherme E (2016) Aves do Acre. Editora da Universidade Federal do Acre – Edufac. Rio Branco, Acre. Pp. 897

[23] Hammer Ø, Harper DA (2001) Past: paleontological statistics software package for education and data analysis. Palaeontologia Electronica 4(1):1-9. [URL: http://palaeo-electronica.org/2001_1/past/issue1_01.htm]

[24] Humple DL, Cormier RL, Richardson TW, Burnett RD, Seavy NE, Dybala KE, Gardali T (2020) Migration tracking reveals geographic variation in the vulnerability of a Nearctic-Neotropical migrant bird. Scientific Reports 10:5483. https://doi.org/10.1038/s41598-020-62132-6

[25] iNaturalist (2025) iNaturalist: an online social network of people sharing biodiversity information to help each other learn about nature. [URL: https://www.inaturalist.org/] (10/09/2025)

[26] Jahn AE, Levey DJ, Smith KG (2004) Reflections across hemispheres: Austral migration is key to a system-wide approach to New World bird migration. The Auk 121(4):1005-1013. https://doi.org/10.1093/auk/121.4.1005

[27] Jahn AE, Levey DJ, Cueto VR, Ledezma JP, Tuero DT, Fox JW, Masson D (2013) Long-distance bird migration within South America revealed by light-level geolocators. The Auk 130(2):223-229. https://doi.org/10.1525/auk.2013.12077

[28] Jahn AE, Seavy NE, Bejarano V, Benavides Guzmán M, Provinciato ICC, Pizo MA, MacPherson M (2016) Intra-tropical migration and wintering areas of Fork-tailed Flycatchers (Tyrannus savana) breeding in São Paulo, Brazil. Revista Brasileira de Ornitologia 24(2):116-121

[29] Jahn AE, Cueto VR, Fontana CS, Guaraldo AC, Levey DJ, Marra PM, Ryder TB (2020) Bird migration within the Neotropics. The Auk 137(4):ukaa033. https://doi.org/10.1093/auk/ukaa033

[30] Jahn AE, Tuero DT (2020) Fork-tailed Flycatcher (Tyrannus savana), version 1.0. In: Schulenberg TS (ed) Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.fotfly.01

[31] Johnston A, Hochachka WM, Strimas-Mackey ME, Gutierrez VR, Robinson OJ, Miller ET, Auer T, Kelling ST, Fink D (2021) Analytical guidelines to increase the value of community science data: An example using eBird data to estimate species distribution. bioRxiv:574392. Diversity and Distributions 27:1265-1277. https://doi.org/10.1111/ddi.13271

[32] Joseph L (1996) Preliminary climatic overview of migration patterns in South American austral migrant passerines. Ecotropica 2(2):185‑193

[33] Kelling S, Johnston A, Bonn A, Fink D, Ruiz-Gutierrez V, Bonney R, Fernandez M, Hochachka WM, Julliard R, Kraemer R, Guralnick R (2019) Using semistructured surveys to improve citizen science data quality. BioScience 69(3):170-179. https://doi.org/doi/10.1093/biosci/biz010

[34] Kirwan GM (2020) Chivi Vireo (Vireo chivi), version 1.1. In: Schulenberg TS, Keeney BK, Billerman SM, Rodewald PG (eds) Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.chivir1.01.1

[35] Koh J, Opitz T (2024) Extreme-value modelling of migratory bird arrival dates: Insights from citizen science data. Journal of the Royal Statistical Society Series A: Statistics in Society 188(3):674-699. https://doi.org/10.1093/jrsssa/qnae108

[36] La Sorte FA, Fink D, Hochachka WM, Kelling S (2016) Convergence of broad-scale migration strategies in terrestrial birds. Proceedings of the Royal Society of London B 283:20152588. http://dx.doi.org/10.1098/rspb.2015.2588

[37] Leal Filho W, Dinis MAP, Canova MA, Cataldi M, Silva da Costa GA, Enrich-Prast A, Symeonakis E, Brearley FQ (2025) Managing ecosystem services in the Brazilian Amazon: the influence of deforestation and forest degradation in the world’s largest rain forest. Geoscience Letters 12:24. https://doi.org/10.1186/s40562-025-00391-9

[38] Linscott JA, Basso E, Bathrick R et al. (2024) The Amazon Basin’s rivers and lakes support Nearctic-breeding shorebirds during southward migration. Ornithological Applications 126(4):duae034. https://doi.org/10.1093/ornithapp/duae034

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