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Daily activity peaks of Red-eared Sliders (Trachemys scripta elegans) per season. All turtles showed diurnal activity. Turtles were active throughout the day during spring, but only early in the morning during summer. In winter months, they tend to be more active during midday.
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Overland movement is an important aspect of freshwater turtle ecology. Turtles make overland excursions searching for mates, to find new aquatic habitats, in response to drought, or during nesting. Here, we tested how environmental factors may influence the excursion events of adult Red-eared Sliders (Trachemys scripta elegans). We found that 85% o...
Citations
... We also observed changes in activity for T. dorbigni; this species exhibited higher activity in October (2016), August (2017) and September (2017), differing from previous records in its original distribution range: February and March (Fagundes et al. 2010) and November andDecember (Bager et al. 2007, Bujes et al. 2011). In contrast, T. scripta elegans followed a pattern already recorded in its natural distribution, closely related to the summer season (Morreale et al. 1984, Mali et al. 2016. ...
Urbanization may significantly impact wild population dynamics, even in protected green spaces. From 2016 to 2018, we accessed an assemblage of freshwater turtles isolated in an urban remnant of the Atlantic Forest, southern Brazil. We captured turtles by active search, hookless fishing, and funnel trap, and we marked them individually. Using a capture-mark-recapture method, we estimated population density, and movement, including home range size and habitat selection. Home ranges were estimated using the 100% minimum convex polygon method and habitat selections through eigenanalysis. We captured 41 specimens of Phrynops geoffroanus (Schweigger, 1812), 35 Trachemys dorbigni (Duméril & Bibron, 1835), and 20 Trachemys scripta elegans (Wied-Neuwied, 1839). The invasive T. dorbigni showed the highest density (1.72 individual/ha), followed by the native P. geoffroanus (1.36 individual/ha) and the invasive T. scripta elegans (0.87 individual/ha). Home range sizes for P. geoffroanus and T. dorbigni ranged between 0.04-0.48 ha, with the latter species covering the longest distance (525.8 m). All three species showed a preference for habitats influenced by human presence (walkways). Our findings highlight the anthropic influence on the movement of the freshwater turtle assemblage and underscore the need for enhanced protection of native species and control of invasive turtles. This study provides essential baseline data for future researches and management of urban areas.
KEYWORDS: Anthropic pressure; chelonians; hotspot; habitat selection; home range; invasive alien species
... Population monitoring of semiaquatic freshwater turtles traditionally involves invasive trapping with baited or unbaited hoop nets (Brown et al. 2011), deployment of basking traps (Gamble 2006), or less invasive visual encounter surveys using spotting scopes and binoculars (Lindeman 1999). Sampling turtles across large, dynamic, ephemeral wetland complexes with these traditional monitoring methods can be time-consuming and expensive, but camera traps have recently become a cheap, efficient, non-invasive, automated alternative to studying turtle movements and basking (Mali et al. 2016;Unger and Santana 2019), nesting and aestivation (Geller 2012; Bowers et al. 2021b), and detection/survival (Bluett and Schauber 2014). Herein, we assess the efficacy of a relatively inexpensive camera-trap basking array designed to move up and down with the changing water levels of ephemeral wetlands occupied by Western Chicken Turtles (Deirochelys reticularia miaria; Fig. 1A, B), a subspecies under review for protection under the U.S. Endangered Species Act (USFWS 2011). ...
... Sex-biased road mortality in turtles is evidenced by male-skewed populations (Steen and Gibbs 2004, Steen et al. 2006, Patrick and Gibbs 2010, although some studies question the strength of this phenomenon (Dorland et al. 2014, Carstairs et al. 2018, Bowne et al. 2018, resulting in controversy (Bowne et al. 2019, Lambert andSteen 2019). In addition to nesting migrations, primarily aquatic turtles move through terrestrial habitats in response to habitat changes such as pond drying (Gibbons et al. 1983, Aresco 2005, Mali et al. 2016, for dispersal or mating opportunities (Tuberville et al. 19395582, ja, Downloaded Bowne et al. 2006), or, for semi-terrestrial species, to exploit seasonal resources within a multi-patch home range (Edge et al. 2010). In particular, natal dispersal could bring juveniles into terrestrial habitats and contact with roads. ...
Adult mortality is often the most sensitive vital rate affecting at‐risk wildlife populations. Therefore, road ecology studies often focus on adult mortality despite the possibility for roads to be hazardous to juvenile individuals during natal dispersal. Failure to quantify concurrent variation in mortality risk and population sensitivity across demographic states can mislead the efforts to understand and mitigate the effects of population threats. To compare relative population impacts from road mortality among demographic classes, we weighted mortality observations by applying reproductive value analysis to quantify expected stage‐specific contributions to population growth. We demonstrate this approach for snapping turtles (Chelydra serpentina) observed on roads at two focal sites in Ontario, Canada, where we collected data for both live and dead individuals observed on roads. We estimated reproductive values using stage‐classified matrix models to compare relative population‐level impacts of adult and juvenile mortality. Reproductive value analysis is a tractable approach to assessing demographically variable effects for applications covering large spatial scales, nondiscrete populations, or where abundance data are lacking. For one site with long‐term life‐history data, we compared demographic frequency on roads to expected general population frequencies predicted by the matrix model. Our application of reproductive value is sex specific but, as juvenile snapping turtles lack external secondary sex characters, we estimated the sex ratio of road‐crossing juveniles after dissecting and sexing carcasses collected on roads at five sites across central Ontario, Canada. Juveniles were more abundant on roads than expected, suggesting a substantial dispersal contribution, and the road‐killed juvenile sex ratio approached 1:1. A higher proportion of juveniles were also found dead compared with adults, and cumulative juvenile mortality had similar population‐level importance as adult mortality. This suggests that the impact of roads needs to be considered across all life stages, even in wildlife species with slow life histories, such as snapping turtles, that are particularly sensitive to adult mortality.
... North American turtle assemblages are speciose and interspecific competition, especially for basking habitat, can be important for determining assemblage composition (Cadi and Joly, 2004;Moll and Moll, 2004;Luiselli, 2008;Lindsay et al., 2013). Trachemys scripta elegans are known to migrate for mates (males), nesting habitat (females), new aquatic habitat, or in response to drought, and quickly colonize areas where competition is low (Mali et al., 2016). ...
Ecological communities are becoming more typified by generalist species in conjunction with anthropogenic activities. Using a long-term dataset (1968-2019), we documented the expansion of a native generalist species, the red-eared slider ( Trachemys scripta elegans ), into a river community, and studied the subsequent population changes that occurred in conjunction with short- and long-term changes within the ecosystem. Trachemys scripta elegans was able to expand into a new geographic area following a harvesting-induced population decline of a native competitor, the northern map turtle ( Graptemys geographica ). The population of T. s. elegans remained small for approximately 2.5 decades, then significantly increased in conjunction with habitat degradation in the form of increased silt/sediment deposits and nuisance aquatic vegetation growth. Our results demonstrate how a generalist species can expand and establish a population in an area impacted by multiple anthropogenic stressors. This research reveals how ecological communities become characterized by more generalist species following anthropogenically-induced competitive release caused by harvesting of native competitors, habitat degradation, and extreme flooding associated with land cover and climate change.
... Furthermore, although Miguel Hidalgo and Bosques de Saloya localities are distant from each other, they belong to a geographical landscape consisting mainly of lacustrine and palustrine wetlands (areas with lagoons of more than 100 ha) ( Barba-Mac ıas et al., 2006). This type of landscape is very important for freshwater turtles as it helps maintain the regional stability of turtle populations (Mali et al., 2016). The individuals from La Venta Park Museum originate from seizures carried out by the Federal Attorney of Environmental Protection of Mexico (PROFEPA, by its Spanish acronym) which confiscates illegally trafficked animals. ...
The Meso-American slider turtle (Trachemys venusta) is a freshwater turtle that is widely distributed from Mexico to Colombia. Due to the overexploitation of populations of this species in Mexico, it has been placed within the "subject to special protection" category formulated by the Official Mexican Standard NOM-059-ECOL-2010. In the state of Tabasco, Mexico, Management Units for the Conservation of Wildlife (UMA) were created to reduce the impact of overexploitation of freshwater turtles bred in captivity. However, no genetic management plan was considered. The present study was carried out in an UMA in the state of Tabasco. We obtained the level of genetic diversity of the founder individuals of the UMA in order to develop a management plan which will optimize reproduction in the UMA. Genetic diversity was compared between captive (n = 86) and wild (n = 45) individuals using 14 microsatellite molecular markers. The genetic diversity parameter determined in this study was slightly higher for captive than for wild population (H e = 0.606 and H e = 0.594 respectively), reflecting the mix of genetic sources in captive group (founding individuals from different localities) and demonstrating that the captive population contains a diverse subset of alleles from representative populations. The analysis of genetic structure revealed a relationship between captive and wild populations, indicating the influence of the two principal river basins in this region on the populations structure of freshwater turtles. Finally, according to the results obtained from the relationship analysis, we recommend the use of 19 females and 13 males to constitute the appropriate breeding group, generating a potential of 247 dyads with no relationship. However, in order to improve breeding program and the genetic diversity of captive population, we suggest to introduce wild-caught individuals. These results are the first regarding genetic management in a Mexican UMA and demonstrate the importance of molecular approaches in the management and conservation of captive species.
... Furthermore, although Miguel Hidalgo and Bosques de Saloya localities are distant from each other, they belong to a geographical landscape consisting mainly of lacustrine and palustrine wetlands (areas with lagoons of more than 100 ha) ( Barba-Mac ıas et al., 2006). This type of landscape is very important for freshwater turtles as it helps maintain the regional stability of turtle populations (Mali et al., 2016). The individuals from La Venta Park Museum originate from seizures carried out by the Federal Attorney of Environmental Protection of Mexico (PROFEPA, by its Spanish acronym) which confiscates illegally trafficked animals. ...
The Meso-American slider turtle (Trachemys venusta) is a freshwater turtle that is widely distributed from Mexico to
Colombia. Due to the overexploitation of populations of this species in Mexico, it has been placed within the “subject
to special protection” category formulated by the Official Mexican Standard NOM-059-ECOL-2010. In the state of Tabasco,
Mexico, Management Units for the Conservation of Wildlife (UMA) were created to reduce the impact of overexploitation
of freshwater turtles bred in captivity. However, no genetic management plan was considered. The present study was carried
out in an UMA in the state of Tabasco. We obtained the level of genetic diversity of the founder individuals of the UMA in
order to develop a management plan which will optimize reproduction in the UMA. Genetic diversity was compared
between captive (n=86) and wild (n=45) individuals using 14 microsatellite molecular markers. The genetic diversity
parameter determined in this study was slightly higher for captive than for wild population (He=0.606 and He=0.594
respectively), reflecting the mix of genetic sources in captive group (founding individuals from different localities) and
demonstrating that the captive population contains a diverse subset of alleles from representative populations. The analysis
of genetic structure revealed a relationship between captive and wild populations, indicating the influence of the two
principal river basins in this region on the populations structure of freshwater turtles. Finally, according to the results
obtained from the relationship analysis, we recommend the use of 19 females and 13 males to constitute the appropriate
breeding group, generating a potential of 247 dyads with no relationship. However, in order to improve breeding program
and the genetic diversity of captive population, we suggest to introduce wild-caught individuals. These results are the first
regarding genetic management in a Mexican UMA and demonstrate the importance of molecular approaches in the
management and conservation of captive species.
The impacts from urban areas may result in alterations in environmental characteristics and wild populations dynamics. Therefore, we aimed at assessing population size, density, home range, maximum range of movement and habitat selection of native and aliens freshwater turtles in a Brazilian urban park ( Phrynops geoffroanus- PG, Trachemys dorbigni- TD, Trachemys scripta elegans -TSE). We applied capture-mark-recapture procedures from July/2016 to August/2018. Home ranges were estimated from trap locations using a 100% minimum convex polygon (MCP) method, and habitat selections using eigenanalysis. We sampled 41 PG, 35 TD, and 20 TSE. Population size was estimated as 59 ± 7.6 (PG), 36 ± 1.4 (TD), and 20 ± 0.5 (TSE) individuals (± SE), with a density estimates of 1.36 (0.34), 1.72 (0.36), and 0.87 (0.25) individual/ha (± SE), respectively. Home ranges size ranged between 0.04 ha and 0.48 ha, the highest distance was reached by D'Orbigny's slider (525.8 m). Our results indicate that habitat preferred for all species is clearly influenced by human presence, and the turtle assemblage exhibit strategies as temporal segregation to coexist on this small, closed park. Both the presence of two established populations of invasive alien species and the changing movement of freshwater turtles reflect anthropic pressure on wild population dynamics and the lack of effectiveness of environmental policies and inspection in Brazil. The understanding that wild populations are being affected even in conservation units could be considered by the managers implement monitoring of target wild populations, control of exotic species, insertion of educational signs and actions, and control of visitors.
Researchers and managers often need vehicular access into areas fenced to protect wildlife, but commonly used vehicle crossings often are cumbersome, cost‐prohibitive, or inadequate at restricting target taxa. We describe a cost‐effective method using partially buried conveyor belt, which is flexible and sturdy enough to allow convenient and frequent vehicular passage across wildlife fencing while not compromising the integrity of the barrier or harming the target species. We have no evidence of any target taxa (i.e., tortoises, freshwater turtles, toads) breaching a conveyor belt barrier from projects in central Florida (2005–2012), Guadalupe County, Texas (2014–2018), or Robertson County, Texas (2014). The proposed technique is unlikely to prevent large‐bodied, saltatory, climbing, or arboreal taxa from crossing a wildlife barrier. However, this technique is applicable to many small vertebrates and any taxa for which silt‐fencing or other similar semipermanent barriers are appropriate. © 2018 The Wildlife Society.
