The use of hydroelectric lakes by giant ottersPteronura brasiliensis: Balbina lake in central Amazonia, Brazil

Abstract

Data on the occurrence and habitat use of giant ottersPteronura brasiliensisin the 4,437 km2of Balbina hydroelectric lake in central Amazonia, Brazil, were collected from September 2001 to December 2005. Twenty-nine groups of giant otters were recorded in an area corresponding to 10% of the total reservoir. Despite the fact that it is a hydroelectric lake, the water level can vary annually by up to 3.5 m with the Amazonian seasonal flood pulse. A total of 210 dens, communal latrines and campsites of giant otters were located. An average of 37% of the dens observed were classified as in use, and the species was recorded in the lake throughout the year. Giant otters started their daily activities between 05.23 and 08.05. The average height of den openings was 28.77 ± SD 10.00 cm, with an average width of 56.11 ± SD 19.17 cm. Births in Balbina occur mainly during the period of high and receding water level, as reported for giant otters in other Amazonian areas. There are at least two conditions that enable the species to inhabit hydroelectric reservoirs: (1) presence of the species in the area before dam construction and (2) absence or low numbers of human communities around the reservoir. The potential use of hydroelectric lakes for the conservation of the giant otter in the Amazon is discussed.

Riqueza e composição de vertebrados em latrinas ativas e inativas de Pteronura brasiliensis (Carnivora, Mustelidae) na Amazônia Oriental, Brasil

“…A marcação do território é feita através de latrinas ("communal latrines") e estações de cheiro ("scent stations") (duPlaix, 1980;carter & rosas, 1997;leucHtenBerger & mourão, 2009). As latrinas são locais onde membros do grupo defecam e urinam (duPlaix, 1980;carter & rosas, 1997;rosas et al, 2007;leucHtenBerger & mourão, 2009) e são caracterizadas pela presença de remanescentes de escamas e ossos de peixes (groenendijk et al, 2005). Ariranhas constroem latrinas em margens de rios, áreas abertas de fácil acesso a áreas fl orestais, regiões alagadiças ou igarapés, próximos a grandes rios e com pouca ou nenhuma vegetação de cobertura (Duplaix, 1980;Groenendijk et al, 2005).…”

“…Ariranhas constroem latrinas em margens de rios, áreas abertas de fácil acesso a áreas fl orestais, regiões alagadiças ou igarapés, próximos a grandes rios e com pouca ou nenhuma vegetação de cobertura (Duplaix, 1980;Groenendijk et al, 2005). A frequência de uso das latrinas varia de acordo com o nível dos rios e sua localização, sendo que algumas podem ser ativas por longos períodos, enquanto outras são abandonadas, tornando-se inativas (duPlaix, 1980;rosas et al, 2007;leucHtenBerger & mourão, 2009).…”

Cub biometry, litter size and reproductive period of giant oters (Pteronura brasiliensis) at the Balbina Hydroelectric Reservoir, Amazonas, Brazil

“…The group sizes are quite flexible, and are usually composed by two to 16 individuals, but having only one dominant breeding pair (alpha couple) that is apparently monogamous (Duplaix, 1980;Evangelista and Rosas, 2011;Oliveira et al, 2011). Solitary individuals (transients) can be observed, and are usually young adults that have reached sexual maturity or adults that have lost their mate (Duplaix, 1980;Carter and Rosas, 1997;Staib, 2005;Rosas et al, 2007;Evangelista and Rosas, 2011).…”

“…The gestation period varies from 65 to 70 days, and the birth peak occurs from the end of the flood period to the beginning of the low-water period in the Amazon region (Duplaix, 1980;Rosas et al, 2007;Evangelista and Rosas, 2011).…”

“…However, until recently, no long-term studies had been carried out with giant otters in dams, and hydroelectric dams have been mentioned as a threat to the species 1 . According to Rosas et al (2007) giant otters use the Balbina Lake throughout the year and display an annual reproductive cycle. Cabral et al (2010) described the feeding habits of P. brasiliensis in Balbina Lake and observations on predation, mortality, behavior, internal layout of giant otter dens and detailed characteristics of the habitats used by the species in that reservoir have also been described by Rosas and De Mattos (2003a, b), Rosas et al (2008; and Bozzetti (2011).…”