A new breeding site for the gull-billed tern (Gelochelidon nilotica) in Central Sinaloa, northwestern Mexico

Nuevo sitio de anidación de la golondrina marina piquigruesa (Gelochelidon nilotica), en el centro de Sinaloa, noroeste de México

Un nouveau site de reproduction de la sterne Hansel (Gelochelidon nilotica) dans le centre du Sinaloa, nord-ouest du Mexique

Erick González-Medina* & Miguel Guevara-Medina

Recibido: 16 de octubre del 2007.
Revisión aceptada: 12 de febrero del 2008.
Editor asociado: Borja Milá.

Abstract

We discovered a new breeding site for the Gull-billed Tern (Gelochelidon nilotica) in central Sinaloa, Mexico. We recorded the presence of this species in an abandoned salt pan at Bahía Ceuta since 2004. A nesting record was made in 2006, an adult incubating among several nest of Least Tern (Sternula antillarum). Our observation indicates that despite the intensity of the survey by Palacios and Mellink, inventorying of Gull-billed Tern colonies in western Mexico has not been fully completed, and some small colonies might still be found.

Keywords: Gull-billed Tern, Gelochelidon nilotica, Sinaloa, new breeding site, Bahía Ceuta.

Descubrimos un nuevo sitio de anidación para la golondrina marina piquigruesa (Gelochelidon nilotica) en la región central de Sinaloa, México. Registramos la presencia de esta especie en una salina abandonada en la Bahía de Ceuta desde el 2004. Registramos su anidación en 2006, un adulto incubando entre varios nidos de charrán mínimo (Sternula antillarum). Nuestra observación indica que a pesar de la intensidad de los monitoreos de Palacios y Mellink, el inventario de colonias de la golondrina marina piquigruesa en el oeste de México no ha sido terminado completamente, y algunas colonias pequeñas aún pueden ser encontradas.

Palabras clave: Golondrina marina piquigruesa, Gelochelidon nilotica, Sinaloa, nuevo sitio de anidación, Bahía de Ceuta.

Rèsumè

Nous avons découvert un nouveau site de reproduction de la sterne Hansel (Gelochelidon nilotica) dans le centre de l'état du Sinaloa, Mexique. Nous avons enregistré la présence de cette espèce dans une saline abandonnée de Bahía Ceuta depuis 2004 et sa nidification en 2006, quand un adulte incuba au milieu de plusieurs nids de petite sterne (Sternula antillarum). Notre observation indique que malgré l'intensité des échantillonnages par Palacios et Mellink, l'inventaire des colonies de sterne Hansel dans l'ouest du Mexique n'est pas encore complet et quelques petites colonies pourraient encore être trouvées.

Mots cléts: sterne Hansel, Gelochelidon nilotica, Sinaloa, nouveau site de reproduction, Bahía Ceuta.

Gull-billed Terns (Gelochelidon nilotica) are found in all continents, except Antarctica (Parnell et al., 1995). There are 6 recognized subspecies, of which the vanRossem's Gull-billed Terns (G. n. vanrossemi) breeds in southern California and western Mexico (Howell and Webb, 1995; Parnell et al., 1995). The breeding status and the distribution of vanRossem's Gull-billed Terns along the western coast of the Mexican Pacific were recently assessed by Palacios and Mellink (2007) who reported 13 colonies in Mexico, ranging from the delta of the Colorado River to Laguna Cuyutlán, Colima. There are also two colonies in southern California, U.S.A. (Patten et al., 2003; Unitt, 2004).

On 8 and 9 July 2004 MGM observed eight adult Gull-billed Terns and two fledged juveniles, which were being fed by some of the prior, by a pond in Bahía Ceuta. They were together with several Least Terns (Sternula antillarum) and three Forster's Terns (Sterna fosteri). In this same area, on 6 June 2006 we recorded two Gull-Bill Terns flying over an abandoned salt pan (Figure 1), and one adult on a nest among several nests of Least Tern. This Gull-billed Tern was in typical incubation position (breast down, rump up). The nest was in a cattle footprint, and contained one egg. In 2007, Clemens Küpper (pers. comm.) recorded chicks of Gull-billed Terns in the same area.

Bahía Ceuta (24° 06' to 24° 15' N and 107° 11' to 107° 24' W) is a large coastal lagoon in Central Sinaloa, that covers about 50 hectares of saltflats, which was formerly used for salt production (Figure 2). The area supports a large colony of breeding Least Terns (average of about 170 nests during the last 5 years) and Snowy Plovers (Charadrius alexandrinus, average of about 30 nests during 3 years, Muñoz del Viejo and Vega, 2002). Ceuta was recognized as an important site under the Western Hemisphere Shorebird Reserve Network and has been declared a nesting preserve for sea turtles (especially Olive Ridleys, Lepidochelys olivacea) by the government of Mexico.

There seem to be no direct threats from humans to the ground-nesting waterbirds nesting in Bahía Ceuta, but the area becomes flooded both by high spring tides and by irrigation spillage from the nearby agricultural fields, and Peregrine Falcon (Falco peregrinus) is a common predator of shore and waterbirds in the area. Also, cattle crossing the saltflat often disturb the birds nesting on it. Bahía Ceuta is located between the colonies of El Rancho, to the north, and Laguna Caimanero, to the south (Palacios and Mellink, 2007), and our observation indicates that despite the intensity of the survey by Palacios and Mellink, inventorying of Gull-billed Tern colonies in western Mexico has not been fully completed, and some small colonies might still be found.

Acknowledgments

Work on Playa Ceuta in 2004 was funded by the Sonoran Joint Venture, administered by Pronatura-Sinaloa. Work in 2006 was funded by the authors. Clemens Küpper provided data from 2007, Alfredo Castillo helped with comments and Eric Mellink assisted with editorial comments and English translation. We appreciate helpful comments on the manuscript by Eduardo Palacios and an anonymous reviewer.

Howell, S.N.G. y Web, S. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, Oxford.         [ Links ]

Muñoz del Viejo, A. y Vega, X. 2002. Efectos de disturbios en la reproducción del charrancito americano (Sterna antillarum) en ecosistemas costeros de Sinaloa, noroeste de México. Ornitologia Neotropical 13: 235-245.         [ Links ]

Palacios, E. y Mellink, E. 2007. The colonies of vanRossem's Gull-billed Tern (Gelochelidon nilotica vanrossemi) in México. Waterbirds 30: 214-222.         [ Links ]

Parnell, J.F., Erwin, R.M. y Molina, K.C. 1995. Gull-billed Tern (Sterna nilotica). Eds. A. Poole and F. Gill. In The Birds of North America. No. 140. Birds N. Am., Philadelphia. Pp. 1-20.         [ Links ]

Patten, M.A., McCaskie, G. y Unitt, P. 2003. Birds of the Salton Sea; status, biogeography, and ecology. University of California. Berkeley, Los Angeles.         [ Links ]

Unitt, P. 2004. San Diego County Bird Atlas. San Diego Natural History Museum. San Diego, California.         [ Links ]