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Journal of Herpetology publishes on the biology of amphibians and reptiles, emphasis on behavior, conservation, ecology, evolution, morphology, and physiology.
We report on nesting phenology, nest success, and life history traits of Green Salamanders (Aneides aeneus) in DuPont State Recreational Forest on the Blue Ridge Escarpment in North Carolina during 2011–2022. We examined relationships between weather (i.e., maximum temperature, precipitation, relative humidity) and (1) onset of ovipositing; (2) egg hatching; and (3) nest success. We conducted 3,429 surveys of 276 nests. Nesting phenology and life history traits were comparable to those previously reported in 1949–1950 and in 1970 from the same region as our study. Initiation of oviposition and egg hatching was associated with lack of precipitation and higher temperature, respectively, during the 24-h period of the event. No relationships were found for weather and nest success during July and August during the study period. Nest success ranged 44–96%, and failure was attributed to predation and animals that compromised integrity of eggs. These results suggest that environmental conditions outside brood crevices influence initiation of ovipositing and egg hatching. Our findings also suggest that nesting phenology and fecundity of Green Salamanders have remained stable on the Blue Ridge Escarpment between 1949 and 2022. In addition, these findings do not support the assertion that seasonal drought during the brooding period is a factor in breeding failure. Further research is needed on environmental cues related to onset of oviposition and egg hatching in terrestrial-nesting plethodontids.
Over nearly two decades, I observed and amassed a capture-mark-recapture study to estimate maximum natural lifespan and lifetime distance moved in a population of Common Side-blotched Lizards (Uta stansburiana). The focal population, near the high-latitude margin of their geographic distribution (43.4 °N), was characterized by reduced abundance and diversity of predators. During 12 study years between 2004 and 2017, I marked 5,298 individual animals and annually attempted to recapture the same lizards. Of these, 2,989 were determined to be one year old at the time of first capture, with 359 (12%) recaptured in at least one subsequent year. After allowing sufficient time for animals to age out of the population naturally, I estimated that the maximum lifespan for this species is at least 7 years, which is longer than previously reported. I determined that 34 (1.1%) of these lizards survived to be at least four years of age, potentially representing a significant demographic influence for populations at higher latitudes. Moreover, I detected a significant male-bias in the sex ratio of survivors by age two. Using GPS coordinates for each annual capture, I determined that males and females did not differ in movement distances from their initial capture location as adults. Rather, individuals generally moved very little over the course of their adult lifetimes (average between first and last coordinates = 27.9 m; median = 14.4 m). Long, sedentary lives may be the norm, rather than the exception, in rangeedge populations of lizards with less abundant predators.
Several aspects of orientation, spatial navigation abilities, and use of space in amphibians have received some attention in research analyses in natural environments. However, given the lack of information on spatial cognition of terrestrial toads (Rhinella arenarum) in the wild, we collected data on space use dynamics in their natural habitat. Sampling was conducted around the Chascomús Lagoon, Argentina, for two spring-summer seasons (from October to March). Toads were marked, their locations GPS-recorded, and the type of shelters used was identified. Results indicated that most toads exclusively used drain-type shelters, while a smaller proportion used field-type shelters. Those toads that shared a shelter had a greater overlap of home ranges than those that did not. There was no association between size of home ranges and sex, or type of shelter used. No differences were found in distance from shelter to home range centroid between different groups of toads. Data revealed that toads were inconsistent in directions moved and distance traveled. In addition, as expected, toads were more active on days of higher maximum temperatures and rainfall, and when fewer days had elapsed since rainy days. This basic information on space use of this species in their natural environment promotes future spatial orientation studies to allow comparisons with previous results on use of reference cues obtained under controlled laboratory conditions.
Pre-Pleistocene fossils of Anolis lizards from the mainland of the Americas are exceedingly rare: only two specimens referred to a single species have been described previously. Here we report on a third specimen, preserved (as are the other two) in Miocene amber from Chiapas, Mexico, and consisting primarily of the anterior vertebrae of the caudal sequence. Despite the fragmentary nature of the fossil, it preserves key osteological characters that permit confident referral to the Anolis clade and further suggest placement within the Dactyloa subclade in a clade of three extant species within the Anolis aequatorialis series. The Chiapan provenance of the fossil indicates that the geographic distribution of the Dactyloa clade (and possibly that of the A. aequatorialis series) extended considerably farther north during the Miocene. Although the new fossil represents a different part of the body than the two fossils representing the fossil species Anolis electrum, its inferred phylogenetic relationships are the same as one of the several possible phylogenetic relationships of that species and thus allow for the possibility that all three specimens belong to the same species.
Road mortality is a widely recognized, but rarely quantified threat to the viability of amphibian populations. This paper summarizes road mortality during the spring migration for a northern Common Toad (Bufo bufo) population in Norway for 10 of the last 22 years, in addition to assessing where on the road (which wheel-track) toads were most exposed to mortality risk for 2 observation years. Percentage of observed dead toads for all observation years ranged from a mean of 56.9% in 2001 to 83.2% in 2006. The highest annual number of migrating toads was 1,082 in 2006, of which 764 were killed. When adjusting for effective counting days with positive toad activity, average number of toads per day decreased from 40.5 in the years 2001–2007 to 24.2 in 2020–2023, an average decrease of 40%. As a global mean for all 10 counting years, 69.4% of toads were killed on the road. When assigning dead toads to the closest wheel-track, the highest mortality in numbers was found at the start of the road, at wheel-track 1, for both years. Fractional risk of mortality was highest at the fourth wheel-track in 2007, with 47% of toads entering this track being killed, whereas the first wheel-track had the highest fractional death in 2023, with 43% dead animals. Among live migrating animals in 2023, there were 3 females and 56 males, indicating a highly male-dominated migrating population of toads.
Little is known about the natural history of Sandfish Skinks (Scincus scincus), despite a range spanning two continents. In arid and hot environments across North Africa and the Arabian Peninsula, these lizards are uniquely adapted to a sand dune environment. However, much about the basic biology of this species remains unknown, especially concerning adaptations to its thermal environment. With this study, we compiled a robust suite of thermal biology parameters to assess within-individual trait covariation in Sandfish Skinks (n = 8). We found one of the highest recorded critical thermal maxima for a vertebrate ectotherm (mean: 48.2 °C), suggesting a large thermal safety margin. We quantified thermal preferences and documented use of sand horizons to thermoregulate. We monitored individual body temperatures day and night for one week and found significant differences in active and inactive thermoregulation. Additionally, we quantified thermal dependence of performance by recording sprinting speed and diving speed, important for prey capture and predator avoidance, across a range of temperatures. Finally, we measured the critical thermal minimum (CTMIN) and maximum (CTMAX), allowing us to build a complete thermal performance curve (TPC) for two behaviors, which we used to estimate optimal temperatures for performance. We then tested the relationship between thermal preferences and performance, finding no support for the thermal coadaptation hypothesis in the context of hunting or predator avoidance. Overall, these data provide understanding of how this unique ectotherm survives in the extreme thermal conditions of a hot desert.
Autecology studies provide essential information on species' life history and natural history, improving our knowledge of evolutionary processes vital for effective biodiversity conservation. Herein, we describe the autecology of Micrablepharus atticolus with emphasis on morphometry, diet, and reproduction. We collected specimens from two municipalities (186 km apart) within the state of Rondônia, Brazil, during the dry season (between July and September). M. atticolus showed sexual dimorphism in body size and shape. As observed in other gymnophthalmids, females were larger (size dimorphism) and longer, whereas males had larger heads (shape dimorphism). Additionally, males from our study sites had relatively long hind limbs when compared to females. The most important (average of percent numeric, volumetric, and frequency) prey categories were Araneae, Blattodea, and Orthoptera, corresponding to more than 80% of the total prey number. Females had a fixed clutch size of two with more than one clutch per reproductive season. Egg volume was positively correlated to snout-vent length, which might contribute to the sexual dimorphism observed where relatively large females produce relatively large eggs and, therefore, larger offspring. All adult individuals were reproductively active, suggesting high reproductive activity during the dry season. Reproduction in the dry season can be related to the species' dependence on solar incidence to court and copulate. It can also be related to higher availability of oviposition sites, which are limited during extended periods of rain, especially for egg-burrowing species.
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