USGS Science⌕ Search
Home/Archive/USGS

USGS · 70171353

Monitoring Eastern Spadefoot ( Scaphiopus holbrookii ) response to weather with the use of a passive integrated transponder (PIT) system

Kevin J. Ryan·Aram J.K. Calhoun·Brad C. Timm·Joseph D. Zydlewski
View original source ↗Export metadata ↓

Abstract

Eastern Spadefoots ( Scaphiopus holbrookii ) are probably one of the least-understood amphibian species in the United States. In New England, populations are localized and it is likely that some populations go undocumented because of the species' cryptic habits. We used passive integrated transponders (PIT tags) to monitor burrow emergence with the aid of continuously running, stationary (but portable) PIT tag readers. We monitored the activity of individual Eastern Spadefoots by placing circular antennae directly over burrows of PIT tag-implanted individuals. We monitored 18 Eastern Spadefoots from 1 to 84 nights in the spring, summer, and fall of 2009–2011. Our results indicate that, on average, Eastern Spadefoots emerged on 43% of the nights that they were monitored. Nights when Eastern Spadefoots emerged were warmer and more humid than nonemergence nights. Eastern Spadefoots were also much more likely to emerge on a given night if they had emerged the night before. Our results have improved the understanding of Eastern Spadefoot burrow-emergence patterns in the northeast region. Our findings may considerably enhance the prospect of employing nocturnal visual encounter surveys as a method for monitoring known, and detecting previously undocumented, populations of this species.

Explore related subjects

Journal of HerpetologyArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Kevin J. Ryan, Aram J.K. Calhoun, Brad C. Timm, Joseph D. Zydlewski. 2015. Monitoring Eastern Spadefoot ( Scaphiopus holbrookii ) response to weather with the use of a passive integrated transponder (PIT) system. https://doi.org/10.1670/12-230

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Blanchard's cricket frogs (Acris blanchardi) have re-expanded northward since mid-2000s: Landscape predictors of occupancy

Blanchard's Cricket Frogs ( Acris blanchardi ) declined along their northern range edge in the upper Midwest in the mid-to late 1900s. The causes of these declines remain poorly understood, as does the current status of this species and their habitat requirements. In 2024, we revisited more than 300 locations previously sampled between 2003 and 2008 along this range edge in Minnesota, Wisconsin, Iowa, and Illinois. We conducted roadside anuran call surveys at each site and extracted land cover information from the National Land Cover Database and a global stream layer. We developed a multi-species occupancy model, which included imperfect detection, species traits, and species associations, to test for changes in occupancy through time and determine whether environmental characteristics were associated with cricket frog presence. Blanchard's Cricket Frogs occupied more sites and occurred farther north in 2024 relative to the mid-2000s, suggesting a partial recolonization in the zone of previous decline. Forest, croplands, and latitude were negatively associated with cricket frog occupancy, whereas wetlands, river size, and development did not have strongly supported effects. Species associations implied that wetland permanence could have been an important determinant of occupancy, but we did not have this covariate information for many of our sites due to private ownership of surrounding lands. Causes of earlier declines remain largely unknown, and many previously occupied regions apparently remain devoid of cricket frogs. However, some populations have been expanding northward over the past two decades in the upper Midwest.

Iowa, Minnesota, Wisconsin↗
USGS2023

Long-term effects of timber harvest on ephemeral pool and occupancy of Spotted Salamanders (Ambystoma maculatum) and Wood Frogs (Lithobates sylvaticus)

The effects of timber harvest on amphibians can be complex and persist for years postharvest, but overall they are poorly understood. We examined how timber harvest has impacted two pool-breeding species, Spotted Salamander ( Ambystoma maculatum ) and Wood Frog ( Lithobates sylvaticus ), across the Canaan Valley National Wildlife Refuge, West Virginia, USA. We surveyed Spotted Salamanders and Wood Frogs at 49 pools from 2004 to 2016. Pools in recently harvested tracts tended to be smaller and less likely to hold water than pools in unharvested tracts for the duration of the breeding period. For both species, mean egg mass abundance was lower in harvested tracts than in the unharvested tracts, and over time declined substantially for Wood Frogs. Similarly, occupancy rates were lower in harvested sites for the duration of the study for both species. Occupancy rates declined over time for both species across all sites; this decline was steeper for Wood Frogs in harvested sites. Our results show the importance of long-term landscape-level studies when evaluating the effects of habitat disturbance. Understanding how forest loss and degradation impact pool-breeding amphibians will help to develop better management targets and mitigate compounding factors of decline to promote survival of these species.

West Virginia↗
USGS2023

Sexual dimorphism in endangered Jemez Mountains Salamanders (Plethodon neomexicanus)

Sex ratio is a key demographic characteristic indicative of the condition of populations. Despite over 70 yr of study, researchers have not fully evaluated morphological characteristics that differentiate sex in Jemez Mountains Salamanders ( Plethodon neomexicanus ; federally endangered). Populations of this endemic salamander, which are distributed in north-central New Mexico, have undergone declines in the past two decades. We assessed morphological characters of 160 preserved P. neomexicanus specimens, evaluated our ability to infer sex in the field, and tested our ability to determine sex on a subset of preserved specimens. In preserved salamanders with body length (i.e., postcloaca snout–vent length, SVLp) ≥ 55 mm, females exhibited greater total length, trunk length, tail length, and cloaca length, and males exhibited greater precloacal tail width, head length, head width, and head height. We documented weakly female-biased size dimorphism. Females with SVLp ≥ 52 mm had cloacal rugae, whereas males with SVLp ≥ 51 mm had distinct papillose tissue in the cloaca and a cloacal cleft. In an evaluation of 30 preserved specimens, we correctly inferred sex in 97% of salamanders by cloacal characters alone. Of 29 adult salamanders captured in the field, we confidently inferred the sex of 27 individuals (16 females, 11 males) with SVL ≥ 44 mm. Thus, sex of most individuals can be correctly inferred in the field by cloacal characters. This information will aid researchers in better understanding population trajectories of this endangered species.

Journal of Herpetology↗