Inca Terns Larosterna inca

Unlike other species of terns, the Inca tern displays elaborated and colorful facial ornaments that are used for mate selection (Velando et al. 2001). They nest inside small crevices among boulders or in burrows in the guano deposits. Two similar-sized eggs are laid per clutch, but some pairs can breed successfully twice a year. Active nests at different stages of the breeding cycle can be found from March to June and from late September to December, but two main peaks of egg-laying occur in April-May and October. Nests with eggs or chicks during the winter (July-August) or during the summer (January-early March) are scarce. Adults at different molting stages have been found during the summer. Reproductive failure occurred during El Niño years, but when food supply is abundant two chicks per clutch can be raised. They feed mainly on Peruvian anchovies, but other species of fish such as silversides, mote sculpins and South Pacific sauri may be consumed. One adult was banded in 1992 and was sighted alive  nesting in the same site in 1999.

Inca terns may compete with commercial fisheries for same anchovy stocks and are affected by guano harvest, which reduces nesting substrate. Actual numbers of Inca terns are currently unknown for the Peruvian coast. Main breeding sites in Peru: Isla La Vieja, Islas Chincha, Isla San Gallán and  isla Pachacamac.

Recent literature on Inca terns:

Velando, A., And J.C. Márquez. 2002. Predation risk and nest-site selection in the Inca tern. Can. J. Zool 80:1117-1123

Velando, A., Lessells, C.M. and Márquez, J.C. 2001. The function of female and male ornaments in the Inca Tern: evidence for links ornament expression and both adult condition adn reproductive performance. J. Avian Biol. 32:311-318.

Zavalaga, C. 1997. Ecología reproductiva del zarcillo (Larosterna inca) en Punta San Juan, Perú. tesis de Licenciatura, Universidad Peruana Cayetano Heredia, Lima, Perú.