Seasonality of Reproduction in Amazon River Dolphins (Inia geoffrensis) in Three Major River Basins of South America

Authors

McGuire, T.

Additional Authors

Aliaga-Rossel, E.

Year

2007

Volume & Issue

39(1):129-135

Pages

7

Country / Region

Peru, Venezuela, Bolivia

Document Type

Peer-reviewed journal article

Species

Amazon river dolphin

Science Keywords

Reproduction

Conservation Measure

Species knowledge and understanding

Abstract

Reproduction of Amazon River Dolphins, Inia geoffrensis, is generally reported to be highly seasonal; however, this conclusion is based on studies from only one area of Inia distribution from throughout the Amazon and Orinoco river basins. Our observations of live dolphins from the Orinoco, Amazon, and Mamoré river basins (in Venezuela, Peru and Bolivia, respectively) indicate that reproduction in Inia often occurs year-round, with seasonal peaks varying according to geographic location. Inia neonates in Peru and Bolivia were seen in all seasons, and were observed most often in falling water (season was defined by relative water level). Conversely, neonates in Venezuela were seen at the end of low water and in rising water, yet were never observed during falling water. Inia mating behavior in Peru was observed in all seasons, while mating was observed only during falling and low water in Bolivia. Our review of the literature from throughout the range of Inia indicates variation in reproductive seasonality, with year-round reproduction in some areas. Seasonality of peaks in births varied according to study area, and may be more closely associated with local environmental and prey conditions than with taxonomic relatedness, relative seasonal differences in water levels, or broad geographic distribution.