A Vagrant Black-Headed Gull (Chroicocephalus Ridibundus) Documented from Saint Peter and Saint Paul Archipelago: Brazil’S First Record
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Ornithology Research (2020) 28:263–266 https://doi.org/10.1007/s43388-021-00036-3 SHORT COMMUNICATION A vagrant Black-headed Gull (Chroicocephalus ridibundus) documented from Saint Peter and Saint Paul Archipelago: Brazil’s first record Antônio Coimbra de Brum1,2 & Renata Brentano1 & Rosalinda Carmela Montone3 & Maria Virginia Petry1 Received: 23 July 2020 /Revised: 13 January 2021 /Accepted: 14 January 2021 /Published online: 8 February 2021 # The Author(s) 2021 Abstract We report the sighting of a specimen of Black-headed Gull (Chroicocephalus ridibundus) in Saint Peter and Saint Paul Archipelago (SPSPA), Brazil, in the mid-Atlantic Ocean. Chroicocephalus ridibundus is a Palearctic species that breeds through- out Europe. Part of the population spends winters in the Mediterranean and coasts of Africa, and a small breeding population remains in the northeast coast of North America. The specimen was on the island for 27 days, between 09 February and 06 March 2020. The gull was identified as a first-winter bird based on its plumage. We conclude that the vagrancy of yet another Old World species at the oceanic SPSPA in the western equatorial Atlantic Ocean was caused by the southwesterly trade winds of the Intertropical Convergence Zone. To our knowledge, this is the first documented record of C. ridibundus in the Brazilian territory. Keywords Laridae . Oceanic island . Palearctic bird Bird vagrancy (i.e., outside their regular range) is a ubiquitous Paul Archipelago (SPSPA) and Fernando de Noronha global phenomenon (Gauthier-Clerc et al. 2002;Petersenetal. Archipelago (FNA). Well-known as support to both Palearctic 2015; Miskelly et al. 2017). Inexperience, navigational errors, vagrants and intertropical African migrants, SPSPA already has changes in the environment, and adverse climatic conditions are hosted several vagrant birds such as the Western Reef-Heron among the main factors that divert animals from their routes (Egretta gularis) (Fedrizzi et al. 2007; Whittaker et al. 2019), (Woehler 1992; Bencke et al. 2005; Petry et al. 2013; the Common Kestrel (Falco tinnunculus) (Bencke et al. 2005), Carpenter-Kling et al. 2017). In this context, oceanic islands andtheBlackKite(Milvus migrans)(Nunesetal.2015). Here, can be important resting and feeding areas for vagrants or gen- we present a new record of an Old World species for Brazil, the eral migrant species (Ferreira et al. 2019; Whittaker et al. 2019). Black-headed Gull (Chroicocephalus ridibundus). In the Neotropical region, several Palearctic vagrants from the The Black-headed Gull was recorded at the SPSPA Old World have already been documented on oceanic islands (Fig. 1), in the mid-Atlantic Ocean (0° 55′ N; 29° 20′ W) (Murphy 1992;Ingelsetal.2010; Behrstock and Kenefick between the African and South American continents, approx- 2012; Olmos and Burgos 2013; Whittaker et al. 2019). The imately 1100 km from the Brazilian coast and 1860 km from two major vagrant refuge of Brazil are Saint Peter and Saint the Cape Verde Islands (Fig. 1). The closest land to SPSPA is FNA, approximately 630 km away. With a total area of 17,000 m2, SPSPA is formed by a complex of ten small islets, Communicated by Marcos P. Santos and Belmonte Island is the largest one. Only three bird species reside at the SPSPA, the Brown Booby (Sula leucogaster), * Maria Virginia Petry Brown Noddy (Anous stolidus), and the Black Noddy [email protected] (Anous minutus) (Both and Freitas 2004). 1 Laboratório de Ornitologia e Animais Marinhos, Universidade do The specimen was first spotted in Belmonte Island (Fig. 2) Vale do Rio dos Sinos, Unisinos, São Leopoldo, RS, Brazil by A.C.B. and R.B. on 09 February 2020 and was last seen on 2 Programa de Pós-Graduação em Biologia, Universidade do Vale do 06 March, by the same authors. The gull lingered in the island Rio dos Sinos, Unisinos, São Leopoldo, RS, Brazil for 27 days. It was observed frequently foraging in small tide 3 Laboratório de Química Orgânica Marinha, Instituto Oceanográfico, pools and sometimes flying offshore toward a fishing boat that Universidade de São Paulo, São Paulo, SP, Brazil remained close to the archipelago, where it was occasionally 264 Ornithol. Res. (2020) 28:263–266 Fig. 1 Location of Saint Peter and Saint Paul Archipelago, between the South American and African continents. The closest point to the archipelago where the Black-headed Gull (Chroicocephalus ridibundus) regularly occurs is the African island Cape Verde, highlighted on the map fed fish by the fishermen onboard. At night, the gull used the and size. Regardless of the similarities with the Black-headed same spot for roosting, next to single brown boobies and a Gull in size and structure, Brown-hooded Gull juveniles have flock of twenty Black Noddies. black primaries with white spots on the tips; they also have the The bird plumage was whitish, with pale gray upperparts color white restricted to the external primary coverts and parts (Fig. 2A); the wings and tail, however, were still typical of of the two external primaries. Comparatively, Black-headed juveniles: tertiary feathers were brown with a broad, light Gull juveniles have white stripes extending from the base of border, and the tail had a dark terminal band (Fig. 2B). primary coverts, and the tips of primaries are black. Moreover, Primary feathers were mostly dark; however, the outer the Brown-hooded Gull also has a black band on the tail, feathers were white in the middle, near the rachis, and dark which is more distal compared with that of the Black-headed on the tips (Fig. 2C). The bill was orange with a black tip, and Gull (Howell and Dunn 2007). Conversely, the first-winter the legs were shaded orange (Fig. 2D). The covert feathers on plumage of the Gray-hooded Gull is similar to that of the the wings had small brown spots (Fig.2E). These characteris- Black-headed Gull because both have extensive blackish- tics indicate a juvenile gull with first-winter plumage (Fig. brown outer primaries; however, the outer primaries of the 2A), as described by Olsen (2010). Black-headed Gulls with former are longer (total length 39–45 cm) and have a pale iris this plumage are expected to be found between August and (Olsen 2010). The species recorded at SPSPA also differs April. from other Chroicocephalus species that might reach the ar- The species is a small gull (total length 34–39 cm) (Howell chipelago from North America. The Slender-billed Gull and Dunn 2007) and can be distinguished from the two resi- (C. genei), recorded in the Caribbean as a vagrant (Holland dent Chroicocephalus species that occur in Brazil, the Brown- and Williams 1978), is larger (total length 40–44 cm) than the hooded Gull (C. maculipennis) and the Gray-hooded Gull Black-headed Gull. Moreover, its first-winter plumage is char- (C. cirrocephalus), because of differences in the plumage, bill, acterized by a longer bill, paler eyes, and the weak gray ear- Ornithol. Res. (2020) 28:263–266 265 contribute to the dispersion of birds over long distances (Brum et al. 2018); however, ship-assistance in gulls is unlikely. Therefore, the first occurrence of the Black-headed Gull in Brazil may be due to inexperienced young birds misled by the easterly trade winds. This phenomenon has already been attrib- uted to other migrant species occurring in Europe and intertrop- ical Africa that were documented in the SPSPA, such as the Little Egret (Egretta garzetta), Eurasian Kestrel, Lesser Moorhen (Gallinula angulata) (Bencke et al. 2005), Western Reef-Heron (Fedrizzi et al. 2007), and the Black Kite (Nunes et al. 2015). It is noteworthy that several Palearctic vagrants recorded for the first time in Brazil, in either FNA or SPSPA, were first documented in either Central America, e.g., the Common Cuckoo (Cuculus canorus) (Whittaker et al. 2019)orinother South American countries, e.g., the Eurasian Kestrel (LeDref and Raynaud 1993; Bencke et al. 2005). According to Whittaker et al. (2019), vagrants documented in other islands in the middle of the Atlantic, Caribbean region, or Trinidad and Tobago or from other continental countries of South America may become future vagrants in Brazil. Black- headed Gulls have been reported in the Caribbean region (White 1997;Valdésetal.2003), Trinidad and Tobago (Kenefick and Hayes 2006), French Guiana (Tostain and Dujardin 1989), and Suriname (Davis 1979). To our knowl- edge, SPSPA is the southernmost point in South America Fig. 2 Black-headed Gull (Chroicocephalus ridibundus) in the Saint where the Black-headed Gull has already been reported, Peter and Saint Paul Archipelago between February and March 2020. a confirming the prediction of Whittaker et al. (2019). first-winter plumage; b dark band at the end of the tail; c details of the outer primaries, dark with white parts; d orange legs and bill; E wings coverts with small brown spots Acknowledgments We would like to thank the Programa Arquipélago de São Pedro e São Paulo (PROARQUIPELAGO) and the Brazilian Navy for logistical support; the ornithologist Glayson Ariel Bencke, for spot is considerably smaller in the Slender-billed Gull com- confirming the Black-headed Gull identification; the biologist Carlos pared to that in the Black-headed Gull (Olsen 2010), thus, Eduardo Agne and Dr. Claudio Dias Timm, for helping with the identi- ruling out this species. fication; all members of the Birdwatchers Club of Rio Grande do Sul, for Chroicocephalus ridibundus is found across the entire the enthusiastic discussion and about the identification; Mr. Andrew Whittaker, for revising the manuscript for language and helpful com- Palearctic; however, it is a vagrant to the Nearctic and ments; Júlia V.G. Finger, for translating the manuscript; and Marlon Neotropical regions. The species is rare in most North Ferraz, for helping us with the map.