Ecologia reprodutiva de Sterna hirundinacea Lesson, 1831 e Thalasseus sandvicensis (Lathan, 1787) (Aves, Sternidae) na ilha dos Cardos, Santa Catarina, Brasil
Fracasso, Hélio Augusto Alves
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Despite being widely distributed in South America, the South American Terns (Tierra del Fuego to Bahia and all around the Pacific coast to Peru), and Cayenne Terns, (from the Caribbean Islands to the region of Deseado Port), and having relatively large populations, little is known about the ecology of these species in the Neotropical region. The present study is a contribution to the knowledge of the reproduction and trophic ecology aspects. Samples were taken daily on the Cardos island, SC, Brazil, along 2003, 2005, from 2006 to 2008, aiming to characterize the reproductive ecology of these species. The season of 2003 began with the arrival of the first adults in mid-May, and in 2005 and 2006 occurred in late April, with the departure of adults in early October. 2486 nests of S. hirundinacea were recorded in 2005 to 1,852 in 2006, with average clutch size ranged from 1.45 in 2006 to 1.19 in 2003 and the hatching success in 2006 was estimated at 82.16%. While for Thalasseus sandvicensis in 2003, it took on average 23.5±0.2 days for the hatching of chicks, and success of 83.33%. Was recorded 6,248, 5,140 and 4,006 preys transported by S. hirundinacea and 1157, 628 and 98 by Thalasseus sandvicensis for the colony during seasons of 2003, 2005 and 2006, respectively. The delivery of food to the chicks occurred since the early hours of the morning until late afternoon. The first chicks hatched in July 2003 and June 2005 and 2006, with reproductive success for S. hirundinacea of 50.94%, 35.96 and 53.47%, and Thalasseus sandvicensis of 48.00, 29.94 and 5.00%, respectively. The highest growth rate for S. hirundinacea occurred in the first 20 days of life with small increments until the flight and subsequent abandonment of the island around 46 days in 2003, 45 in 2005 and 42 in 2006. The small size of the island, the human low pressure and little activity of the gull (Larus dominicanus), considered the main predator on the Brazilian coast, during the egg laying period, allowed the regular occupation, making it an important site for the conservation of these species.