Endangered Species I

Contributed Oral

Evaluation of Gopher Tortoise Population and Habitat Characteristics on Working Forest Landscapes
Duston Duffie, Scott Rush, Darren Miller, Daniel Greene, Keri Lejeune

Gopher tortoise (Gopherus polyphemus), keystone species in southern pine (Pinus spp.) ecosystems, is federally threatened in the western portion of its range. Approximately 70% of potential habitat is on privately owned lands often managed for timber production. To better understand tortoise response to forest management, we evaluated population demographics (2017-2020) and habitat use at two sites in Washington Parish, Louisiana and Perry County, Mississippi. At our Louisiana site, we captured 40 individuals (16F:23M; 1 immature) and estimated population size to be 47±5 adults. At this site, tortoises were generally clustered along utility rights-of-way and roadways and burrow abundance was positively correlated with increased soil percent sand composition and negatively correlated with increased pine basal area. At our Mississippi site, we captured 54 individuals (15F:24M; 15 immature) and estimated population size to be 69±23 adults. At this site, burrow abundance was positively correlated with both increased basal area and increased vegetative structure. Burrows were clustered within forest stands containing soils with higher sand composition, but we did not consider sand composition due to low variability across this site. The tortoise population at our Mississippi site appears stable with active recruitment and multiple age classes. However, at our Louisiana site, recruitment was low, which has been reported for the last 25 years. Factors affecting this population appear to be poor soil drainage, unusually high-water table, and low-moderate habitat quality. Following prescribed burns in 2019 and 2020, we captured one juvenile along rights-of-way and detected three juvenile burrows within a forest stand interior. Although we observed signs of reproduction prior to burning, including depredated nests and a single inactive juvenile burrow, this juvenile was the first immature tortoise captured in at least 10 years. Prescribed fire, combined with other forest management practices, may have improved conditions for gopher tortoise reproduction on this site.

Decline of Novel Ecosystems Used by Endangered Species: The Case of Piping Plovers, Least Terns and Aggregate Mines
Mark Vrtiska, Joel Jorgensen, Stephen Brenner, Lauren Greenwalt

Sand and gravel mining creates novel ecosystems along the Platte, Loup, and Elkhorn rivers in Nebraska, USA. Piping plovers (plovers) and least terns (terns) are state and/or federally threatened and endangered species, respectively, that nest and raise young at these sites and their derivatives. Despite hosting relatively large numbers of plovers and terns for decades, it is unknown whether the industry will continue to produce habitat consistently in the future. We evaluated how the number, size, and spatial distribution of different site types hosting different numbers of nesting plovers and terns have changed over time and how current trends in the number of different site types will affect future habitat using a multi‐state modeling approach. Overall area and total number of sites declined during the period 1993–2020. More importantly, traditional mines are being replaced by another site type, modern mines, which host lower numbers of nests of both species.  Traditional mines store waste sand in spoil piles or plumes along the edge of a lake, forming relatively large expanses of nesting habitat used by both species. Modern mines store waste sand in limited quantities along the edge of the lake but also in piles away from the lake. Traditional mines also differ from modern mines in that they are routinely converted to housing developments with intermediate transition sites that host the largest number of nests for brief periods. Based on the previous 28 yr of decline, traditional mines and their productive derivatives are projected to continue to decline, thereby further reducing overall nesting habitat. Plovers and terns are expected to continue to nest in our study area, but overall numbers are expected to decline. Local declines in our study area will have local and regional implications for the recovery and management of these two species of conservation concern.

Contemporary and Potential Future Habitat for the Threatened Cheat Mountain Salamander
Lacy Rucker, Donald Brown, Thomas Pauley

Habitat suitability models are a widely used method to estimate species distributions and predict habitat quality changes in relation to climate change and habitat loss and are an important tool for the conservation of declining and imperiled taxa. In the Appalachian region, woodland salamanders (genus Plethodon) are thought to be particularly vulnerable to environmental changes due to their low vagility, and for many species, restriction to high elevations. In West Virginia, there is a strong management focus on the protection and monitoring of federally-threatened Cheat Mountain Salamander (Plethodon nettingi; CMS) populations. To assist with permitting and monitoring actions, and improve our understanding of CMS occurrence-habitat relationships, we created a habitat suitability model for CMS using the full occurrence record database and the Random Forest classification model optimized for the Kappa statistic, and projected contemporary habitat availability and quality across the species’ distribution. We then projected potential impacts of climate change on mid-century and end-of-century habitat availability and quality. The best approximating model (out-of-bag error = 9.78%) contained seven landscape predictors and three climatic predictors. We estimated that 18.59% of the study area contained potential CMS habitat, and 3.66% and 15.29% of the CMS habitat was high and moderate quality, respectively. Preliminary climate change analyses indicate that up to 7.79% of the contemporary habitat could be lost by mid-century. This study will assist management agencies with delineating the spatial extent of known CMS populations and will facilitate the potential discovery of new populations. Consistent with many high elevation-endemic salamanders, the CMS appears to be highly vulnerable to climate change.

Threatened Species Require Similar Protections as Endangered Species Under the ESA
Delaney Costante, Aaron Haines, Matthias Leu

With species increasingly becoming imperiled due to anthropogenic activities, conservation practitioners are tasked with determining conservation priorities with limited resources. One way of setting these priorities is to categorize species based on their risk of extinction. The United States’ Endangered Species Act (ESA) has two listing statuses into which imperiled species are placed to receive protections: Threatened or Endangered. Our objective was to identify differences between Threatened and Endangered species beyond what is outlined in their ESA definitions. For six broad-resolution threats (habitat modification, overutilization, pollution, species-species interactions, environmental stochasticity, and demographic stochasticity), we investigated whether there is a difference in the number and types of threats which impact Threatened and Endangered species at the time of their listing. We found that Threatened (X̄ = 2.9, SD = 1.4) and Endangered (X̄ = 3.0, SD = 1.1) species were faced by a similar number of threats at time of their listing. The only broad-resolution threat that impacted Endangered species more than Threatened species was demographic stochasticity; Endangered species were 1.9 times (95% CI = 1.4 -2.7) more likely to have this threat than Threatened species. We further examined demographic stochasticity by breaking it down into finer-resolution threats to identify additional differences between Threatened and Endangered species. We found four finer-resolution demographic stochasticity threats (few individuals in one population, few individuals in multiple populations, lack of reproduction, and genetic loss) to be strong predictors of Endangered status. However, the overall similarities in the number and types of broad-resolution threats faced by Threatened and Endangered species suggest that changes recently made to the ESA’s implementing regulations may be detrimental to the recovery efforts of newly listed or reclassified Threatened species.

Recruitment and Natal Homing in Northern Recovery Unit Loggerhead Turtles Inferred Through Subpopulation-Scale Genetic Tagging
Brian Shamblin, Mark Dodd, Michelle Pate, Matthew Godfrey, Sarah Dawsey, Breanna Ondich, James Richardson, Rebecca Bell, Michael Arendt, Ruth Boettcher, Campbell Nairn

Recruitment into marine turtle nesting populations is typically inferred from tagging data, but weak nest site fidelity can confound identification of neophyte recruits. Genetic capture-recapture via clutch sampling permits characterization of recruitment patterns at the subpopulation scale through individual female identification and relatedness analysis. We characterized recruitment and compared relative nesting sites within maternal families with three or more assigned daughters to indirectly assess the scale of natal site fidelity in Northern Recovery Unit loggerhead turtles (Caretta caretta). From 2010 through 2019, we assigned approximately 77,000 clutches laid from Georgia through Maryland to 11,500 unique females using 16 to 18 microsatellite loci. Among approximately 6,000 females genetically tagged from 2008-2012, 893 could not be excluded as potential mothers of 1,538 females that nested through 2019. Among 136 candidate mothers with three or more assigned daughters, 57 nested at Cape Romain, South Carolina, highlighting its importance for recruitment at the subpopulation scale. Comparisons of relative nesting locations within maternal families suggest regional natal homing spanning 10s of km. Most daughters nested in close proximity to their mothers (on the same or adjacent barrier islands), but a minority nested as far as 200 km away. Full siblings typically nested in close proximity to one another even if distant from their mother’s recent nesting sites, invoking possible shifts in nesting sites over the mother’s reproductive life. Of 47 females tagged on southern Georgia barrier islands through 1999 and were genetically tagged, 13 were assigned as candidate mothers of 21 nesting females. Among these was a female with a 36-year nesting history, a record for loggerheads globally, with three daughters assigned thus far. The potential for reproductive longevity spanning nearly four decades underscores the need for continued long-term monitoring to better resolve population dynamics in marine turtle populations.  

Aquatic Edna Can Advance Monitoring of a Small-Bodied Terrestrial Salamander and Amphibian Pathogen
Alyssa Kaganer, G. Sean Stapleton, Elizabeth Bunting, Matthew Hare

Successful conservation efforts for threatened species depend on accurate determination of their distribution, habitat use, and characterization of threats. However, surveillance can be extremely challenging for many species due to small size, cryptic coloring, or elusive life history traits. Environmental DNA (eDNA) monitoring may provide a sensitive and non-invasive alternative to traditional surveillance techniques by enabling detection of trace DNA shed by a target species into the environment. We evaluated the efficacy of eDNA monitoring for the four-toed salamander (Hemidactylium scutatum), a terrestrial salamander threatened throughout its range. Additionally, we characterized co-location of H. scutatum and eDNA of ranavirus, a widespread pathogen of ectothermic vertebrates, in amphibian breeding pools. We designed a species-specific qPCR assay for H. scutatum, multiplexed the assay with a previously developed ranavirus qPCR assay, and validated the multiplexed tests in silico, in vitro, and in situ. We collected aquatic eDNA weekly for 8 weeks from vernal pools with historical reports of H. scutatum presence (n = 6) and contemporary reports of H. scutatum adults on associated pool uplands (n = 4). We identified H. scutatum eDNA at low quantities (< 12 copies/reaction) on multiple days in two vernal pools with historic reports of the species presence. Ranavirus eDNA was widespread; nine pools tested positive including the two pools where H. scutatum eDNA was detected. Ranavirus eDNA quantities consecutively increased, peaked, then decreased in several pools but never rose in abundance to a level associated with ranavirosis in other studies. Our results suggest that H. scutatum eDNA is distributed sporadically at low quantities in vernal pools; we recommend that future surveillance efforts prioritize increased quantity and volume of sample collection per site visit and include repeat surveys of candidate sites. Further work to characterize Ranavirus eDNA transport, temporal trends, relationship to infectious virions, and decay is needed before this tool can reach its full potential.

Effects of Stream Geomorphology on New Mexico Meadow Jumping Mouse Occupancy in the Apache-Sitgreaves National Forests, Arizona
Charlotte Rozanski, Carol Chambers, Stuart Tuttle

The New Mexico meadow jumping mouse (Zapus hudsonius luteus) is a federally endangered small mammal that persists in isolated populations in Arizona, New Mexico, and southern Colorado. This riparian associate requires dense, structurally diverse riparian vegetation and perennial flowing water. Alterations to the natural fluvial conditions of a watershed can directly affect the quality of riparian habitat available. Stream geomorphic data is used to describe the condition of fluvial processes, riparian habitat, and floodplain creation and maintenance. The purpose of this study is to determine and quantify the effects of local fluvial geomorphology on jumping mouse occupancy. We conducted geomorphic surveys at 59 stream locations in the Apache-Sitgreaves National Forest, 29 occupied by jumping mice and 30 unoccupied. At each stream location we conducted a stream cross-section, longitudinal and water surface profile, and characterized the bed materials (D50). We present results of our research and recommendations for watershed restoration. A greater understanding of the current fluvial conditions will assist in identifying suitable habitat, selecting potential survey sites, and developing appropriate restoration actions for degraded watersheds throughout the species range.

Contributed Oral
Location: Virtual Date: November 3, 2021 Time: 1:00 pm - 2:00 pm