. Recent studies have shown that acoustic signals play an important role in turtle social behavior and reproduction. We recorded embryos and hatchlings of Lepidochelys kempii inside the nest and underwater in June 2016 in Playa Santander, Veracruz, Mexico, and detected 189 sounds that were classified into 6 types according to their aural and spectral characteristics. Our results show that acoustic communication appears to be widely used in all species of sea turtles in aquatic environments, probably because of the high efficiency of this signaling modality in water compared with air.

. Mesoclemmys raniceps is a medium-sized aquatic turtle widely distributed throughout the northern Amazon Basin in South America. Little information has been published about its reproductive biology. Because there is a significant problem identifying juveniles of this species found in the wild, and a controversy concerning the taxonomic status of the Mesoclemmys nasuta group, we incubated eggs from known females from known localities at controlled and ambient temperatures. We describe the hatchlings produced. The eggs hatched after an incubation period of 249 d at 28°C. Incubation experiments found both M. raniceps and Mesoclemmys heliostemma phenotypes hatching from the same clutch of eggs, suggesting that these taxa are conspecific. Mesoclemmys wermuthi had been incorrectly synonymized with M. nasuta and later absorbed by M. raniceps when M. raniceps was elevated to species status, resulting in the confusion of M. raniceps being different from M. heliostemma . Mesolemmys wermuthi is a distinct species separate from M. raniceps ; however, M. wermuthi is preceded by Hydraspis maculata , which was synonymized with M. raniceps and is available for this species as Mesoclemmys maculata .

Adult Podocnemis unifilis were monitored using VHF radio tracking from September 2013 to September 2014 in the Rio Trombetas Biological Reserve, Pará, Brazil. Our aim was to analyze the use of space by this species near the nesting beach base by describing size and overlap of estimated home ranges. Transmitters were attached to 10 males and 10 females. The mean home range size calculated through the fixed-kernel (FK) method with 95% of the fixes was 79.28 ± 77.08 ha (0.56–215.07 ha; n = 13). The mean of overlapping areas was 14% with FK95% (0.02%–81%; n = 13) and 5% with FK50% (0.1%–23%; n = 9). There was a significant difference in the mean overlapping areas between females and males. The analysis of the overlap of activity centers estimated by FK50% is extremely important for the establishment of conservation strategies in the management plan for this species in the reserve. We were able to identify 2 critical areas for the maintenance of this population where there was a frequent overlap of activity centers: the first, identified during the dry season, was composed of small overlaps among 7 turtles and was near the nesting areas on the clay banks within the Lago Jacaré; the second, identified during the rainy season, was composed of a concentration of overlap areas of larger size among 6 turtles and was an open area in the flooded forest. It is important not only to protect the nesting areas during the dry season but also to protect flooded forest areas with the major intensity of use along with the canals that link the flooded forests to the lakes in the rainy season. For conservation purposes, it is necessary to continue the protection of the nesting beaches throughout the savannas inside the lake where the species nests in the dry season. The flooded forest areas that are zones of intense use during the rainy season, and the canals where the turtles can move between lakes must be protected throughout the year.

We present a review and analysis of the conservation status and International Union for Conservation of Nature (IUCN) threat categories of all 360 currently recognized species of extant and recently extinct turtles and tortoises (Order Testudines). Our analysis is based on the 2018 IUCN Red List status of 251 listed species, augmented by provisional Red List assessments by the IUCN Tortoise and Freshwater Turtle Specialist Group (TFTSG) of 109 currently unlisted species of tortoises and freshwater turtles, as well as re-assessments of several outdated IUCN Red List assessments. Of all recognized species of turtles and tortoises, this combined analysis indicates that 20.0% are Critically Endangered (CR), 35.3% are Critically Endangered or Endangered (CR+EN), and 51.9% are Threatened (CR+EN+Vulnerable). Adjusting for the potential threat levels of Data Deficient (DD) species indicates that 56.3% of all data-sufficient species are Threatened. We calculated percentages of imperiled species and modified Average Threat Levels (ATL; ranging from Least Concern = 1 to Extinct = 8) for various taxonomic and geographic groupings. Proportionally more species in the subfamily Geoemydinae (Asian members of the family Geoemydidae) are imperiled (74.2% CR+EN, 79.0% Threatened, 3.89 ATL) compared to other taxonomic groupings, but the families Podocnemididae, Testudinidae, and Trionychidae and the superfamily Chelonioidea (marine turtles of the families Cheloniidae and Dermochelyidae) also have high percentages of imperiled species and ATLs (42.9–50.0% CR+EN, 73.8–100.0% Threatened, 3.44–4.06 ATL). The subfamily Rhinoclemmydinae (Neotropical turtles of the family Geoemydidae) and the families Kinosternidae and Pelomedusidae have the lowest percentages of imperiled species and ATLs (0%–7.4% CR+EN, 7.4%–13.3% Threatened, 1.65–1.87 ATL). Turtles from Asia have the highest percentages of imperiled species (75.0% CR+EN, 83.0% Threatened, 3.98 ATL), significantly higher than predicted based on the regional species richness, due to much higher levels of exploitation in that geographic region. The family Testudinidae has the highest ATL (4.06) of all Testudines due to the extinction of several species of giant tortoises from Indian and Pacific Ocean islands since 1500 CE. The family Testudinidae also has an ATL higher than all other larger polytypic families (≥ 5 species) of Reptilia or Amphibia. The order Testudines is, on average, more imperiled than all other larger orders (≥ 20 species) of Reptilia, Amphibia, Mammalia, or Aves, but has percentages of CR+EN and Threatened species and an ATL (2.96) similar to those of Primates and Caudata (salamanders).

Podocnemis sextuberculata (Pleurodira: Podocnemididae) is widely distributed throughout the Amazon drainage basin in Brazil, Colombia, and Peru. Telemetry and previous molecular data suggest that P. sextuberculata lacks population structure in the central Amazon basin of Brazil. Generalization of these results, however, requires much-broader sampling across a range of habitats of this broadly distributed species. For this reason, we tested the hypothesis of panmixia in P. sextuberculata , analyzing a total of 319 specimens sequenced for the mitochondrial control region. Our sampling included localities from 16 areas in the Amazon basin from rivers characteristic of the Amazon basin (whitewater), clearwater rivers of the Guiana shield (Branco, Trombetas, and Nhamundá rivers), and the Brazilian shield (Xingu River). The hypothesis of panmixia was rejected because the results of analysis of molecular variance, pairwise Ф ST , and Bayesian analysis of population structure indicated population structure in the group of individuals from the locality of Xingu which was not correlated to a pattern of isolation by distance. We suggest that the populations of P. sextuberculata of the Brazilian Amazon basin are composed of 2 management units, one represented by populations restricted to the Xingu River and the other represented by all other populations. The population of the Xingu should be viewed with attention and concern, especially considering the direct and indirect impacts of damming the Xingu River.

In contrast to the other Podocnemis species, Podocnemis erythrocephala (Pleurodira: Podocnemididae) is restricted to blackwater and clearwater rivers and lakes, including the Negro River basin, and several other tributaries of the eastern Amazon River basin. In order to test the effects of geographic barriers on genetic connectivity of P. erythrocephala , 10 localities sampled throughout the Brazilian Amazon basin were studied. Two hundred and forty-six specimens were sequenced for the mitochondrial control region. Analysis of molecular variance confirmed the existence of population subdivision (Φ ST = 0.28, p < 0.001). In pairwise comparisons, the values of the fixation index Φ ST were significant in almost all comparisons involving the São Gabriel da Cachoeira (Negro River), Jaú National Park (Jaú River), and Barreirinha (Andirá River), indicating that these populations are genetically differentiated. Genetic differentiation is most likely explained by the presence of rapids and waterfalls separating the São Gabriel da Cachoeira (Negro River) and Jaú National Park (Jaú River) populations from the remaining populations. Populations from Barreirinha (Andirá River) were also genetically differentiated, providing support for the hypothesis that the Amazon River is a geographic barrier for this species. Although distributed over a large geographic area, the remaining 7 localities were not differentiated from one another ( p > 0.005), suggesting that these localities are part of a panmictic population distributed throughout the central Amazon basin. We recommend that the 4 structured populations be treated as separate management units.

In the Rio Negro, the third-largest tributary of the Amazon, many turtle species have been important commercial and protein resources for centuries for populations of humans living in the region. For many years, this had been a sustainable activity, but nowadays the outlook for turtle populations in the Amazon is unfavorable due to increasing hunting pressure. Based on 20 yrs of conservation work in the Amazon, we report on the pressure faced by turtle populations in the area and report a sustainable chelonian exploitation alternative developed in the Rio Negro region. We describe the materials and the hand processing artisans use to transform natural resources into artworks. Based on this community program model, we discuss the current government support to local communities of the Rio Negro and provide insights on the application of this economic alternative to substitute for turtle commercialization in the Amazon. The outcomes of this manuscript have direct applications for environmental managers, nongovernmental organizations, and policymakers in Brazil and aim to call government and environmental managers to promote turtle conservation in the Amazon, securing economic safety for local communities.

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.

We studied the population structure, sex ratio, and abundance of a locally endangered species of freshwater turtle, the red-headed river turtle ( Podocnemis erythrocephala ), in the Unini River in Negro River Basin in Brazil with capture–recapture of marked individuals in 1 yr, including both dry and rainy seasons. We used trammel nets of 3 different inner mesh sizes in the lakes. The nets were revisited at 3-hr intervals from 0600 to 1800 hrs each day. All turtles were released after being marked, measured, and sexed. During the study, 352 individuals were marked including 162 males, 150 females, and 40 immatures. The majority of the turtles (79%) were captured in the dry season when the water level of the river was declining. Mean ± standard deviation straight-line carapace length was 210 ± 14 mm (range 163–262 mm) for males and 251 ± 18 mm (221–303) for females. Most turtles captured were in the intermediate size classes: 200–210 mm for males and 230–270 mm for females. The sex ratio of adults in this population was 1.05 males per female, not significantly different from 1∶1. Only 12 turtles were recaptured, each once: 5 males, 5 females, and 2 immatures. The population showed recruitment and the adults are in equilibrium; however, few turtles were captured in the smallest or largest size classes.

We studied reproductive parameters and noted predation of Phrynops geoffroanus nests along the Guaporé River of the Brazilian and Bolivian Amazon during the beginning of the falling water level season ( vazante ) in July 1989 and 2008. We searched for nests on the banks of the Guaporé River every morning navigating by outboard along the Guaporé River between Divisa sector state of Rondônia in Brazil and Versalles village, Department El Beni in Bolivia. We found 10 nests in 1989 and 46 nests in 2008. Clutch size ranged from 7 to 16 eggs and was larger in 2008. There was no relationship between egg size and nest size or the size of eggs between year 1989 and year 2008. The predation rate in 2008 was 89.1%, all depredated by the lizard Tupinambis teguxin. Habitat loss for the lizard may be creating habitat utilization shifting and increased turtle nest depredation rates.

Although turtles are well protected by laws in Brazil, the laws are not enforced in some places and ignored in others. Based on 15 years of work in the Rio Negro Basin, we describe the history of turtle exploitation in this region, comment on their current conservation status, and suggest practical conservation alternatives that are necessary to preserve stable populations.

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 cm 3 . 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).

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.

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.