Reproductive parameters and nesting behavior of the Amazon turtle Podocnemis expansa (Testudinata: Pelomedusidae) in Brazil

Abstract

The Amazon River turtle Podocnemis expansa was studied during the nesting and hatching seasons (October and December of 1978, 1979, and 1980) at a protected site in a Biological Reserve on the Trombetas River, a tributary of the Amazon. Mean carapace length of nesting females was 66 cm and mean carapace width 59 cm. Mean clutch size was 91.5 eggs (with 95% hatching success) and was positively correlated to carapace length, carapace width, plastron length, and plastron width. Carapace width was positively correlated to egg chamber height, and egg chamber diameter was positively correlated with nest depth, clutch size, and plastron width. There is a synchronization between low water and nesting.

Nesting ecology of Podocnemis expansa (Schweigger, 1812) and Podocnemis unifilis (Troschel, 1848) (Testudines, Podocnemididae) in the Javaés River, Brazil

“…Podocnemis expansa nested in the upper areas of the beach near the riparian forests, whereas P. unifilis nested in areas closer to the river channel, preferably close to the base of the dunes (Ferreira-Júnior et al, 2003). Lowest river level is a basic requisite for P. expansa nesting activity on the Trombetas River, as pointed out by Alho and Pádua (1982) and Ferreira-Júnior and Castro (2003) for the varied among the beaches. In general, the beaches could be divided into sandbanks consisting of well-selected medium sand (Jaburu, Comprida, Murici, Marreca, and Goiaba Beaches) and poorly selected medium and coarse sand (Canguçu, Bonita, and Coco Beaches).…”

“…The concentrated nesting in P. expansa was a consequence of the gregarious habit of the species, members of which usually climb up the beach in large groups during nesting activity (Alho and Pádua, 1982). Although P. unifilis does not form groups to lay its eggs, nesting peaked in August, when 50% of the eggs were laid within nine days (Figure 1) Mean height of egg placement from the level of the Javaés River differed between the two species (n = 860, p < 0.001).…”

“…Flooding is common in the case of P. expansa, P. unifilis, and P. sextuberculata nests found along the beaches of Peruvian (Mitchell and Quiñones, 1994;Soini, 1995), Colombian (Hildebrand et al, 1988), and Brazilian rivers (Alho and Pádua, 1982;Pezzuti and Vogt, 1999;Ferreira-Júnior and Castro, 2003;2006b). Floods are also the main cause of nest loss of Trionyx muticus (Plummer, 1976) and Emydoidea blandingii (Standing et al, 1999).…”

“…In general, factors such as flooding (Alho and Pádua, 1982;Pezzuti and Vogt, 1999;Ferreira-Júnior and Castro, 2005;2006b), shade cover, nest depth (Wilson, 1998;Valenzuela, 2001), incubation temperature (Bobyn and Brooks, 1994;Öz et al, 2004), soil moisture (Packard et al, 1987), and type of soil (Packard and Packard, 1997) may affect hatching success.…”

Management and relocation of nests of Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) on the Crixás-Açu river, Brazil

“…During the period of receding water, sandy beaches are formed on the riverbanks. These beaches are utilized as nesting areas by P. expansa (Alho and Pádua, 1982), P. unifilis Troschel (Ferreira Júnior and Castro, 2010), P. sextuberculata Cornalia (Pezzuti and Vogt, 1999), P. lewyana Duméril (Correa et al, 2010), and P. erytrocephala Spix (Batistella and Vogt, 2008). In the search for the most suitable beaches for nesting, females must choose sites that are topographically high enough to prevent the flooding of nests at the start of the rainy season.…”