Reproductive ecology of the black-necked swan Cygnus melancoryphus in a marine wetland of southern Chile
By Jaime A. Cursach, Jaime R. Rau, Claudio N. Tobar, Jonnathan Vilugrón & Francisco Brañas
The Black-necked Swan Cygnus melancoryphus is an endangered species in Chile. After the Río Cruces ecological disaster in Valdivia in 2004 (due to installation of a new pulp mill), the Black-necked Swans that survived were mostly dispersed to marine wetlands of the large island of Chiloé, passing from continental wetlands to the marine environment.
Locations and characteristics of Black-necked Swan Cygnus melancoryphus nesting areas in the marine wetland of Caulín Bay, Chiloé Island, southern Chile. Caulín Bay is located at the northern end of Chiloé Island, within the Los Lagos Region, southern Chile (insets, bottom right).
The objectives of this study were to provide the first observations of nesting Black-necked Swans in the marine wetland of Chiloé Island, and to identify factors that may affect the survival of their cygnets. Our study was carried out in Caulín Bay (41°49ʹS; 073°38ʹW), Chiloé Island, during austral winter and spring of 2011 and 2014. During both years, the Black-necked Swan nested in different sectors of Caulín Bay.
Black-necked Swans Cygnus melancoryphus nesting at Lacaos Island, Caulín Bay, Chiloé Island, southern Chile: (A) active nest; (B) nest grouping; (C) nests with four eggs and a clam shell; and (D) nest with two cygnets and an egg.
The construction of nests began in mid-July, and the first hatchings were recorded in September. In 2011, 23 nests were found in the stone promontories sector and 39 nests were found at Lacaos Island. In 2014, the Black-necked Swan, nesting only in Lacaos Island, occupied 47 nests. We discuss the need to evaluate potential factors that affect the survival of this species’ cygnets in the marine wetland of Caulín Bay.
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