Fenología reproductiva y tamaño poblacional de cuatro especies de aves marinas (Sula granti, S. nebouxii, S. sula y Fregata magnificens) en Isla La Plata, Parque Nacional Machalilla.

摘要

La Plata Island is an important site for marine birds, who use it to reproduce and feed in its surroundings. Sula granti, Sula nebouxii, Sula sula, and Fregata magnificens are four of the six species of marine birds that are found in the Island; these four are the objective of this study, developed between August 2008 and August 2011, with the purpose of understanding their population and reproductive situation. The observed reproductive phenology was similar amongst these species, showing a greater seasonality for Sula nebouxii, and almost no seasonality for Sula granti. Prolonged reproductive cycles were observed for Sula sula and Fregata magnificens. During the three years of study, a reproductive success between 5 and 18% was observed for S. granti, and between 3 and 40% for S. nebouxii. Population size for S. granti was of approximately 2175 individuals, 1436 individuals for S. nebouxii, 62 individuals for S. sula, and 5106 individuals for F. magnificens. The results obtained in this study show an availability and abundance of food year round in the surrounding areas of La Plata Island. The data obtained show important information that can be used to expand the knowledge of these four species in relation to their reproductive behavior and situation, but also in relation to abundance of fish stocks, influence of oceanographic phenomenon such as El Niño and La Niña, and even the relation and impact of human activities such as fisheries in the reproduction and population sizes of these.