Parámetros reproductivos del caracolero (Rostrhamus sociabilis) (Aves: Accipitridae) en Santa Fe, Argentina

Abstract

Reproduction is a fundamental process in the history of bird life and one which demands greater energy expenditure in bird life cycles. The reproductive biology of the R. sociabilis was studied in the lagoon of the Santa Fe. All nests (N = 46) were built on Solanum glaucophyllum at 1.10 ± 0.26 m water level, recording per nest 2-3 (2.76 ± 0.43) eggs, an average the length, width and weight were: 43.18 ± 1.53 mm, 35.52 mm and 28.05 ± 1.23 ± 2.86 g, respectively. The size of the eggs was not affected by the amount of the eggs in the nest (nests with two eggs vs three eggs). If differences between the height of the nests were observed as were higher which contained two eggs. The reproductive suc- cess was 49.0%, 41.0% the brood, hatching the 67.0% (N = 94) and 63.0% of fledging. Of the total monitored 19 nests failed (N = 46), six did so by environmental factors and six by intrinsic factors of the species. The crude death rate was 57.0%, the rate of age-specific mortality 33.0% (egg) and 36.0% (chicks). The daily mortality rate of nests was 12.4%, the holding period of the chicks in the nest was 24.17 ± 5.08 days and the average number of fledglings per nest was 2-3 (2.0 ± 0.6). These data provide new input on the environmental and intrinsic factors that presumably influence the reproductive parameters of R. sociabilis .