Comparing camera traps and visual encounter surveys for monitoring small animals

Amphibian and reptile species face numerous threats including disease, habitat loss and degradation, invasive species, and global climate change. However, effective management and conservation of herpetofauna largely depends upon resource-intensive survey methodologies. Recent research has shown promise in the use of camera trapping techniques, but these methods must be tested alongside traditional methods to fully understand their advantages and disadvantages. To meet this research need, we tested two herpetofauna survey methods: a modified version of the Adapted-Hunt Drift Fence Technique, which combines a drift fence with camera traps; and a traditional method of visual encounter surveys (VES) with cover boards. Between June and August 2020, we conducted two VES and installed one drift fence with camera traps at ten sites in Monterey County, CA, USA. The drift fence/camera setup outperformed the VES in terms of number of observations and herpetofauna species detected. Drift fences with cameras produced a mean of 248 images of three to six species per site, while VES and cover objects produced a mean of 0.6 observations of zero to one species per site. Across all sites, we detected seven reptile and one amphibian species with the drift fence/camera setup, while VES resulted in identifications of two reptile and one amphibian species. In addition, drift fence/camera setups recorded a minimum of nine nonherpetofauna species including small mammals, birds, and invertebrates. Our research supports that drift fences combined with camera traps offer an effective alternative to VES for large-scale, multi-species herpetofauna survey efforts. Furthermore, we suggest specific improvements to enhance this method’s performance, cost-effectiveness, and utility in remote environments. These advances in survey methods hold great promise for aiding efforts to manage and conserve global herpetofauna diversity.

Reptile Host Associations of Ixodes scapularis in Florida and Implications for Borrelia spp. Ecology

Host associations of the tick vector for Lyme Borreliosis, Ixodes scapularis, differ across its geographic range. In Florida, the primary competent mammalian host of Lyme disease is not present but instead has other small mammals and herpetofauna that I. scapularis can utilize. We investigated host–tick association for lizards, the abundance of ticks on lizards and the prevalence of Borrelia burgdorferi sensu lato (sl). To determine which lizard species I. scapularis associates with, we examined 11 native lizard species from historical herpetological specimens. We found that (294/5828) of the specimens had attached ticks. The most infested species were Plestiodon skinks (241/1228) and Ophisaurus glass lizards (25/572). These species were then targeted at six field sites across Florida and sampled from June to September 2020, using drift fence arrays, cover boards and fishing. We captured 125 lizards and collected 233 immature I. scapularis. DNA was extracted from ticks and lizard tissue samples, followed by PCR testing for Borrelia spp. Of the captured lizards, 69/125 were infested with immature I. scapularis. We did not detect Borrelia spp. from tick or lizard tissue samples. Overall, we found that lizards are commonly infested with I. scapularis. However, we did not detect Borrelia burgdorferi sl. These findings add to a growing body of evidence that lizards are poor reservoir species.

Evaluation of the AHDriFT Camera Trap System to Survey for Small Mammals and Herpetofauna

Traditional surveys for small mammals and herpetofauna require intensive field effort because these taxa are often difficult to detect. Field surveys are further hampered by dynamic environmental conditions and dense vegetative cover, which are both attributes of biodiverse wet meadow ecosystems. Camera traps may be a solution, but commonly used passive infrared game cameras face difficulties photographing herpetofauna and small mammals. The Adapted-Hunt Drift Fence Technique (AHDriFT) is a camera trap and drift fence system designed to overcome traditional limitations, but has not been extensively evaluated. We deployed 15 Y-shaped AHDriFT arrays (three cameras per array) in northern Ohio wet meadows from March 10 to October 5, 2019. Equipment for each array cost approximately US$1,570. Construction and deployment of each array took about three hours, with field servicing requiring 15 minutes per array. Arrays proved durable under wind, ice, snow, flooding and heat. Processing two-weeks of images of 45 cameras averaged about 13 person-hours. We obtained 9,018 unique-capture events of 41 vertebrate species comprised of 5 amphibians, 13 reptiles (11 snakes), 16 mammals and 7 birds. We imaged differing animal size classes ranging from invertebrates to weasels. We assessed detection efficacy using expected biodiversity baselines. We determined snake communities from three years of traditional surveys and possible small mammal and amphibian biodiversity from prior observations and species ranges and habitat requirements. We cumulatively detected all amphibians and 92% of snakes and small mammals that we expected to be present. We also imaged four mammal and two snake species where they were not previously observed. However, capture consistency was variable by taxa and species, and low-mobility species or species in low densities may not be detected. In its current design, AHDriFT proved to be effective for terrestrial vertebrate biodiversity surveying.

Aspidoscelis costatus costatus (Squamata, Teiidae): high elevation clutch production for a population of whiptail lizards

Clutch size and number of clutches per reproductive cycle are important life history traits that can be influenced by anatomical, physiological, evolutionary, and ecological factors. This report on the clutch size and number of clutches of an endemic Mexican whiptail lizard, Aspidoscelis costatus costatus (Cope, 1878), is based on a study of population at an unusually high elevation for a member of this genus. The study site is located in Ixtapan de la Sal, southeastern Estado de México, Central Mexico, at 2090 m a.s.l. Lizards were sampled in June 2006, and from May to July 2007, where females of Aspidoscelis costatus costatus were collected by hand along a drift fence. Female reproductive condition was evaluated based on abdominal palpation for presence of developing eggs; clutch size was determined by actual counts of either vitellogenic follicles or oviductal eggs. The smallest reproductive female was 77 mm snout-vent length; females produced a minimum of two clutches during the breeding season, the mean clutch size of 6.5 eggs (n = 33) was one of the largest reported for the genus. However, both length and width of its eggs, and the relative clutch mass have not been diminished by development of a large clutch. Additionally, comparisons of clutch size were undertaken within the polytypic A. costatus complex, within the genus Aspidoscelis, and between certain genera of whiptail lizards. This apparently represents the first study of whiptail lizards (genus Aspidoscelis), assessing the aforementioned reproductive characteristics, in a population above 2000 m.

Incidentally gathered natural history information on Bullsnakes (Pituophis catenifer sayi) in southeastern Alberta

We present observations on Bullsnakes (Pituophis catenifer sayi) gathered during a study of Prairie Rattlesnakes (Crotalus viridis) in a multiple-use, mixed grass landscape adjacent to the South Saskatchewan River, ~30 km northeast of Medicine Hat, Alberta, in May–October 1997. Hibernacula shared with rattlesnakes were located close to the river. We captured 31 Bullsnakes, either in a drift fence array around a hibernaculum or by hand; three were recaptured once. Emergence from the hibernaculum ended in mid-May, and return to it began in early September. A gap in capture events occurred between early July and late August, possibly attributable to fossorial activity during the height of the summer. The sex ratio of captured adult snakes was 0.64 in favour of males. Males attained the greatest maximum body sizes, but there was no significant size dimorphism by sex. Bullsnakes were assignable to juvenile, subadult, and adult classes by body size. Most captures were made on slopes in the immediate vicinity of the river, in areas classed as “thin breaks”, but four captures, about 7 km east of the river, provide evidence of long-distance movements from hibernacula. Captures were seldom made in the vicinity of anthropogenic features. Gas field development has increased greatly in the years since these data were collected. Our findings provide a baseline for Bullsnake population responses to such changes.

THE DIVERSITY OF AMPHIBIANS IN CAMPUS AREA OF SRIWIJAYA UNIVERSITY INDRALAYA, OGAN ILIR, SOUTH SUMATERA

The study is diversity of amphibians in campus area of sriwijaya university indralaya, ogan ilir, south sumatra was aimed to determine the diversity of amphibian species present in this area. The research has been done in March until May 2015, in the campus of the Sriwijaya University, Indralaya. The method in this study is use the transect method by placing seventh transect line on line with the direction of cutting contour lines. Data collection techniques using the Visual Encounter Survey (VES) and Pit-Fall Trap method in combination with the Straight Line Method and Fence (Drift Fence). Results from this study recorded 11 species of amphibians from five families of the Anura. Average diversity index at Sriwijaya University Indralaya region is 1.70 which fall into the medium category. Keywords : Sriwijaya university, amphibians, transect,diversity

THE DIVERSITY OF REPTILES ON SEVERAL HABITAT TYPES IN CAMPUS AREA OF SRIWIJAYA UNIVERSITY INDRALAYA, OGAN ILIR

The Diversity of Reptiles on Several Habitat Types in Campus Area of Sriwijaya University Indralaya, Ogan Ilir was aimed to determine the diversity of amphibian species present in this area. The research has been done in March until May 2015, in the campus of the Sriwijaya University, Indralaya. The method in this study is use the transect method by placing seventh transect line on line with the direction of cutting contour lines. Data collection techniques using the Visual Encounter Survey (VES) and Pit-Fall Trap method in combination with the Straight Line Method and Fence (Drift Fence). Results from this study recorded 11 species of amphibians from five families of the Anura Order. Average diversity index at Sriwijaya University Indralaya region is 1.70 which fall into the medium category. Keywords : Sriwijaya university, amphibians, transect,diversity