Colin Strine

Sexual dimorphism of tropical green pit viper Trimeresurus ( Cryptelytrops ) macrops in Northeast Thailand

Total body size for arboreal vipers is normally biased toward small males and larger females. We evaluated sexual dimorphism in adult and sub-adult Trimeresurus macrops , a small, arboreal green pit viper commonly found in Southeast Asia, but severely understudied. We evaluated morphological characters of 139 adult T. macrops obtained by active and opportunistic searches at Sakaerat Biosphere Reserve in northeast Thailand, from May 2012 to October 2014. We compared 7 external characters including residual index (R i ) and scaled mass index (SMI) between male and female T. macrops . Body length measurements and mass differed between males and females. Females had greater snout-vent length, body mass and head length and width, while males had greater tail lengths. A postocular stripe was always present on males, but never on females. Male head size was negatively correlated with SMI, which may reveal intersexual competition in T. macrops . Sexually dimorphic characters in T. macrops may have evolved through intraspecific resource partitioning.

Using dynamic Brownian Bridge Movement Models to identify home range size and movement patterns in king cobras

Home range estimators are a critical component for understanding animal spatial ecology. The choice of home range estimator in spatial ecology studies can significantly influence management and conservation actions, as different methods lead to vastly different interpretations of movement patterns, habitat selection, as well as home range requirements. Reptile studies in particular have struggled to reach a consensus on the appropriate home range estimators to use, and species with cryptic behavior make home range assessment difficult. We applied dynamic Brownian Bridge Movement Models (dBBMMs) to radio-telemetry data from Ophiophagus hannah, a wide-ranging snake species. We used two focal individuals at different life stages (one juvenile male and one adult male) and sought to identify whether the method would accurately represent both their home range and movement patterns. To assess the suitability of dBBMMs, we compared this novel method with traditional home range estimation methods: minimum convex polygons (MCP) and Kernel density estimators (KDE). Both KDE and MCP incorporated higher levels of Type I and Type II errors, which would lead to biases in our understanding of this species space-use and habitat selection. Although these methods identified some general spatial-temporal patterns, dBBMMs were more efficient at detecting movement corridors and accurately representing long-term shelters sites, showing an improvement over methods traditionally favored in reptile studies. The additional flexibility of the dBBMM approach in providing insight into movement patterns can help further improve conservation and management actions. Additionally, our results suggest that dBBMMs may be more widely applicable in studies that rely on VHF telemetry and not limited to studies employing GPS tags.

Arboreal Mating Behaviors of the Big-eyed Green Pit Viper ( Trimeresurus macrops ) in Northeast Thailand (Reptilia: Viperidae)

Abstract: Little is known about mating behaviors in arboreal snakes. We report three observations of mating in wild big-eyed pit vipers (Trimeresurus macrops) in northeast Thailand from 2013 to 2015. Mating occurred at the end of the rainy season, between 20 September and 28 October. One copulation occurred on the ground and two were arboreal (<1.5 m high). Females pulled males up trees during arboreal mating. Observations lasted from 2.2 to 12.9 h, but two of the three observations were initiated after copulation had started and were thus incomplete. Females were larger than males in all copulations. On one occasion a second male attempted to disrupt a mating pair using aggressive body movements and tail wrestling. All mating occurred in human disturbed forests, and two of them were observed in close proximity to human habitations.

Spatial ecology of a small arboreal ambush predator, Trimeresurus macrops Kramer, 1977, in Northeast Thailand

The Big-Eyed Green Pit Viper ( Trimeresurus macrops ; Kramer, 1977) is a venomous snake species endemic to Southeast Asia. Although we have some knowledge of the systematics and toxicology of T. macrops , little is known about the spatial ecology of this species. From May 2013 to February 2014, we used radio-telemetry to determine home-range sizes of 13 adult female T. macrops inhabiting the Sakaerat Biosphere Reserve in Northeast Thailand. We found that individual home ranges for T. macrops averaged 0.175 ha, with activity areas ranging from 0.112-0.303 ha and core areas ranging from 0.023-0.052 ha. There was little overlap between conspecific tracked females, especially for the most used areas of their home ranges. We find that T. macrops ambushes more in higher humidity and expresses very little diurnal activity. They use the groundstory for ambushing, then retreat over small distances to higher refuge during the day. Future studies should focus on prey abundance, habitat selection, and survival rates.

Intra-population Color Dimorphism of Ahaetulla prasina (Serpentes: Colubridae) in Northeastern Thailand

Abstract: Although Ahaetulla prasina is typically a cryptic green color, they have also been observed in brown, grey and orange-yellow morphs. We recorded observations of the A. prasina color morphs found in a population within the Sakaerat Biosphere Reserve (SBR), northeastern Thailand, between 2013 and 2017. We did not detect any green or brown morphs, showing that this population is dimorphic between grey (54%) and orange-yellow (46%) adults. We did not discern any geographic separation of the color morphs within this population, and sex did not determine color. We found four juveniles, all with brownish-grey bodies and yellow on their anterior dorsals. We observed one sub-adult, which was solid grey except for yellow on the top of the head. Our results suggest that this population may be genetically isolated due to the rapid development surrounding the SBR. Furthermore, color does not likely have a strong influence on adult fitness within this population. Our juvenile and sub-adult observations may indicate ontogenetic color shifts in this population of A. prasina. We recommend additional investigations into the relationship between color and A. prasina ecology. We further reason that the SBR A. prasina may be a good model population for snake genetic research in developing areas.

Observations of Arboreality in a Burrowing Frog, the Banded Bullfrog, Kaloula pulchra (Amphibia: Anura: Microhylidae)

Abstract: Despite being known to exhibit arboreal behaviours, Kaloula pulchra, the banded bullfrog, is generally considered terrestrial in its habits and is well known for burrowing into substrate. Here we report seven observations, between October 2015 and March 2017, which document arboreal behaviors in banded bullfrogs in the Sakaerat Biosphere Reserve, Thailand. Our observations comprise the first record of banded bullfrogs predating invertebrates in an arboreal setting. Our observations of K. pulchra climbing large rain jars and subsequently becoming trapped inside also suggest a cause of death for this species. Additional surveys are needed to determine whether this phenomenon prevails throughout rural Thailand.

A Report of a Malayan Krait Snake Bungarus Candidus Mortality as By-Catch in a Local Fish Trap from Nakhon Ratchasima, Thailand:

Thailand is a world biodiversity hotspot with 176 known snake species. However, anthropogenic influences on snakes associated with growing human populations are poorly understood. Aquatic funnel traps (AFTs) are in widespread use in agricultural areas throughout Thailand, and they have the ability to collect large quantities of by-catch, including snakes. During an on-going study on the human-snake conflict we found, using radio-telemetry, one of our radio-tracked Bungarus candidus (Malayan Krait) individuals dead on 13 October 2015. We had tracked the individual for only 14 days before finding it decapitated 10 m from a villagers house. Upon interviewing the owner, we discovered that the snake had been found dead in a fishing trap, in a man-made irrigation canal located 65 m southeast from his house. Our observation is the first documented case of incidental mortality among upland-dwelling snakes as a result of aquatic trapping in Thailand, and may have implications throughout Southeast Asia. This report suggests fishing traps may be another source of mortality for snakes in human-dominated landscapes, and that further studies may reveal significant rates of terrestrial by-catch in agricultural canals.