Richard C. Vogt

Seasonal Movements of Podocnemis sextuberculata (Testudines: Podocnemididae) in the Mamirauá Sustainable Development Reserve, Amazonas, Brazil

ABSTRACT We studied the linear home range and seasonal movements of Podocnemis sextuberculata from September 1996 to December 1998 in the Mamirauá Sustainable Development Reserve located in the middle Solimões River, near Tefé, Amazonas, Brazil. We collected data on turtle movements and home range through mark and recapture and radiotelemetry, focusing on seasonal differences between periods of high and low water levels. Based on radiotelemetry of 6 females in the Jarauá River system, linear home range varied from 16.52 to 44.5 km. Nesting migrations from the Jarauá to the beaches of the Japurá River averaged 18.04 km. Males did not move significantly between captures. For conservation purposes, it is of critical importance to protect both the canals that the turtles use to travel between the lakes and the river as well as the deep holes in the river where mature turtles congregate during the dry season. RESUMO Nos pesquisamos o tamanho da área de vida e movimento de iaça (Podocnemis sextuberculata) de setembro de 1996 a dezembro de 1998, na Reserva de Desenvolvimento Sustentável Mamirauá. A Reserva está situada no médio Solimões, perto da cidade de Tefé, Amazonas, Brazil. Os movimentos das iaçás foram estudados através dos métodos de marcação-recaptura e telemetria. Rádio-transmissores foram instalados em 9 fêmeas. O registro e a medição dos deslocamentos de seis fêmeas, indicou que a área de vida linear no Sistema Hidrológico do Jarauá varia de 16,52 a 44,50 km. O deslocamento desde o Sistema Jarauá para as áreas de nidificação no rio Japurá foi em média 18,04 km. A distância percorrida pelos machos até a primeira recaptura não foi significativamente correlacionada com o comprimento da carapaça. No entanto esta relação foi significativa para as fêmeas. A proteção dos canais que usa a iaçá para se movimentar, e os remansos nos rios, onde a população reprodutora permanece durante a vazante, são medidas importantes para a preservação desta espécie.

Nesting Ecology of Podocnemis erythrocephala (Testudines, Podocnemididae) of the Rio Negro, Amazonas, Brazil

ABSTRACT We studied reproductive ecology and egg survivorship of Podocnemis erythrocephala (Spix 1824) in 4 campina habitats on the Ayuanã River, Santa Isabel do Rio Negro, Amazonas, Brazil. There were 2 nesting periods, the first in early October and the other in the beginning of December, separated by a period of flash floods. A total of 117 nests were recorded, with a nest density of 19.9 nests/ha, a mean clutch size of 8.7 eggs, and a mean egg volume of 14 cm3. Females chose to nest in the most open sites, with plant cover of up to 50%. Nest loss reached 100% for the season: 70% was from flash floods, 12% was from predation by the weasel Eira barbara (Mustelidae), 9% was by the lizard Ameiva ameiva (Teiidae), 5% by humans, 2% by Crocodilurus lacertinus (Teiidae), and 1% by Daptrius ater (Falconidae).

Diet of Podocnemis unifilis (Testudines, Podocnemididae) During the Dry Season in the Mamirauá Sustainable Development Reserve, Amazonas, Brazil

ABSTRACT Stomach contents of Podocnemis unifilis sampled in white water varzéa forest during the dry season in the Mamirauá Sustainable Development Reserve (Middle-Solimões River) had plant material in 100% of cases, with Poaceae and Bombacaceae the most frequently recorded. Poaceae leaves (67.7% frequency) and seeds (21.5% frequency) were common, as were fibers of the fruit Pseudobombax munguba (Bombacaceae; 38.5% frequency), with fruits in general contributing 45.9% of volume. Animal material was consumed in much lesser quantities—only 0.8% of total volume—but had a 37% frequency.

Sound Communication and Social Behavior in an Amazonian River Turtle (Podocnemis expansa)

Abstract:  The social behavior of turtles during the nesting season can be attributed to a series of functions such as reducing predation, increasing hatchling survivorship, and information exchange between nesting females. However, the mechanism(s) used to remain in a group during the different phases of nesting behavior has yet to be explained. The objective of this study is to document the sounds produced by Giant South American River Turtle, Podocnemis expansa, during the nesting period, and identify how acoustic mechanisms might facilitate social behavior and group aggregation during this period. From September 2009 to October 2011, the sound repertoire of P. expansa was identified during the nesting period, which begins with the migration of the turtles from the flooded forests to the nesting beaches and terminates when the hatchlings emerge and the females migrate with the hatchlings to the flooded forests. Sounds were recorded when the turtles were active in different behavioral patterns (1) migrating; (2) aggregating in front of the nesting beaches before basking; (3) nesting at night; (4) waiting in the water without nesting or after they have nested; and (5) waiting for the arrival of the hatchlings. We observed six types of sound in the recordings of turtles made during the nesting period. These data indicate that this species is social, and that sound plays an important role in the synchronization of the activities of groups during the nesting season.

First Evidence that Hatchlings of Chelonia mydas Emit Sounds

Hatchling green turtles (Chelonia mydas) were recorded emitting sounds at Ascension Island, South Atlantic Ocean, on 19 May 1978. Analysis revealed that the 70 sounds recorded could be separated into four sound categories. The sounds were complex and characteristic of a contact call, and were similar to those recently reported in other species of aquatic turtles. The relationship between the structure and frequency of the sounds and levels of predation on turtle eggs and hatchlings, especially by ghost crabs (Ocypode spp.), warrants further study.

Chelonian Vocal Communication

Recently it was discovered that freshwater turtles communicate underwater by sound. The vocal repertoire of the Western Australian longneck turtle Chelodina colliei includes complex and percussive calls which are harmonically structured and frequency modulated, with dominant frequencies below 1 kHz and a range from around 100 to 3.5 kHz. Sounds with similar characteristics are used by the females of the South American river turtle Podocnemis expansa when migrating to nesting beaches and during communal nesting. Near term embryos inside eggs vocalize, and hatchlings emerging from nests and scampering across the beach and into the river continue to vocalize. In the water the adult females respond and the hatchlings then migrate with the females down the river, presumably to the flooded forests where they feed. Many unexplained aspects of aquatic turtles social behavior may eventually be explained when their vocalizations have been studied.

First Evidence of Leatherback Turtle (Dermochelys coriacea) Embryos and Hatchlings Emitting Sounds

Abstract There are only a few studies documenting acoustic communication in chelonians; here we provide additional evidence that sound plays an important role in the interchange of information in this group. We recorded 12 nests of Dermochelys coriacea during March 2012 at Barra de la Cruz Beach, Oaxaca, Mexico. Four types of sounds were identified from recordings of nests after 51 d of incubation; our results reinforce the idea that sounds are important to coordinate group behavior in turtles.

First Evidence of the Pig-nosed Turtle (Carettochelys insculpta) Vocalizing Underwater

Recent research has demonstrated that some freshwater turtles vocalize underwater, but the taxonomic breadth of this mode of communication in freshwater turtles is unknown, hindering our understanding of its evolution. The Pig-nosed Turtle (Carettochelys insculpta), a monotypic genus inhabiting tropical Australia and New Guinea, is a likely candidate for producing underwater sounds because it exhibits social behavior while feeding, nesting, and thermoregulating. We tested the hypothesis that C. insculpta vocalizes using an omnidirectional hydrophone. We recorded C. insculpta emitting sounds underwater in the field and in captivity in northern Australia in May 2014. Analysis revealed that the 182 sounds produced by seven individuals could be separated into three sound categories. The sounds were simple and characteristic of a contact call, and were similar to those recently reported in other species of aquatic turtles. Further research should focus on the role of sound production in social activities.

MORPHOLOGY OF THE DIGESTIVE TUBE OF THE PODOCNEMIDIDAE IN THE BRAZILIAN AMAZON

Abstract:  We describe the morphology of the digestive tube of Podocnemis expansa, Podocnemis unifilis, Podocnemis sextuberculata, Podocnemis erythrocephala, and Peltocephalus dumerilianus. The esophagus in these species has two distinct regions: the anterior region has esophageal papillae and the posterior has longitudinal folds. Esophageal glands are absent but goblet cells occur in the mucosa of esophagus. The stomach in P. expansa, P. unifilis, and P. erythrocephala has two regions: the anterior region consists of cardiac and fundic regions and is without glands; the more-posterior pyloric region contains gastric glands that extend into the lamina propria. In P. sextuberculata, the stomach is a J-shape, and in Peltocephalus dumerilianus the stomach is a C-shape with a larger curvature to the left side. The stomachs of these two species have numerous gastric glands in all regions. The small intestine (SI) in all species is a long, coiled tube and has folds and villi that appear different in each region. In P. expansa, P. unifilis, and P. erythrocephala, there is a dilatation in the anterior region of large intestine (LI), followed by a straight and tubular region of smaller diameter. In P. sextuberculata and Peltocephalus dumerilianus, the dilatation is absent and the LI is tubular and of uniform diameter along its entire length. The LI has a larger quantity of goblet cells than the SI. The digestive tube of the turtles in the family Podocnemididae demonstrates differences in the morphology between species, and these differences could be related to the diet of each species. Resumo:   Foi descrito a tubo digestório de Podocnemis expansa, P. unifilis, P. erythrocephala e Peltocephalus dumerilianus. O esôfago das espécies analisadas apresenta duas regiões distintas: a região anterior com presença de papilas esofágicas e a região posterior com pregas longitudinais. Glândulas esofágicas foram ausentes, mas células caliciformes ocorreram na mucosa do esôfago. O estômago em P. expansa, P. unifilis, e P. erythrocephala apresenta duas regiões: a região anterior que é formada pelas regiões cárdica e fúndica e é ausente de glândulas; e a região posterior, considerada a região pilórica, com glândulas gástricas em sua lâmina própria. Em P. sextuberculata o estômago teve forma de “J” e em Peltocephalus o estômago tem formato de “C” com a curvatura maior do lado esquerdo. O estômago dessas espécies apresenta numerosas glândulas gástricas em todas as regiões. O intestino delgado em todas as espécies é um tubo longo e enovelado e com pregas e vilosidades que se diferenciam em cada região. O Em P. expansa, P. unifilis, e P. erythrocephala, existe uma dilatação na região anterior do intestino grosso (IG), seguindo de uma região retilínea e tubular de menor diâmetro. Em P. sextuberculata e Peltocephalus, a dilatação é ausente, o IG segue como órgão tubular de diâmetro constante. O IG apresenta grande quantidade de células caliciformes. O trato digestório dos quelônios da família Podocnemididae demonstra diferenças na morfologia entre as espécies, e essas diferenças podem estar relacionadas com a dieta de cada espécie.

Diet of Amazon river turtles (Podocnemididae): a review of the effects of body size, phylogeny, season and habitat

Amazon rivers can be divided into three groups (black, white and clear waters) according to the origin of their sediment, dissolved nutrient content, and vegetation. White water rivers have high sediment loads and primary productivity, with abundant aquatic and terrestrial plant life. In contrast, black water rivers are acid and nutrient-poor, with infertile floodplains that support plant species exceptionally rich in secondary chemical defences against herbivory. In this study, we reviewed available information on the diet of Amazon sideneck river turtles (Family Podocnemididae). Our aim was to test the relationship between water type and diet of podocnemidids. We also took into account the effects of season, size, age, sex and phylogeny. Based on our review, turtles of this family are primarily herbivorous but opportunistic, consuming from 46 to 99% (percent volume) of vegetable matter depending on species, sex, season and location. There was no significant correlation between the maximum carapace size of a species and vegetable matter consumed. When the available information on diet, size and habitat was arranged on the podocnemidid phylogeny, no obvious evolutionary trend was evident. The physicochemical properties of the inhabited water type indirectly influence the average volume of total vegetable matter consumed. Species with no specialised stomach adaptations for herbivory consumed smaller amounts of hard to digest vegetable matter (i.e. leaves, shoots and stems). We propose that turtles with specialized digestive tracts may have an advantage in black water rivers where plant chemical defences are more common. Despite limitations of the published data our review highlights the overall pattern of diet in the Podocnemididae and flags areas where more studies are needed.