8 Aug 2022

The Use of US Army Corps of Engineers Reservoirs as Stopover Sites for the Aransas–Wood Buffalo Population of Whooping Crane

Abstract: This technical report summarizes the use of US Army Corps of Engineers (USACE) reservoirs as spring and fall migration stopover sites for the endangered Aransas–Wood Buffalo population of whooping cranes (WHCR), which proved much greater than previously known. We assessed stopover use within the migration flyway with satellite transmitter data on 68 WHCR during 2009–2018 from a study by the US Geological Survey (USGS) and collaborators, resulting in over 165,000 location records, supplemented by incidental observations from the US Fish and Wildlife Service (USFWS) and the USGS Biodiversity Information Serving Our Nation (BISON) databases. Significant stopover use was observed during both spring and fall migration, and one reservoir served as a wintering location in multiple years. Future efforts should include (a) continued monitoring for WHCR at USACE reservoirs within the flyway; (b) reservoir-specific management plans at all projects with significant WHCR stopover; (c) a USACE-specific and range-wide Endangered Species Act Section 7(a)(1) conservation plan that specifies proactive conservation actions; (d) habitat management plans that include potential pool-level modifications during spring and fall to optimize stopover habitat conditions; and (e) continued evaluation of habitat conditions at USACE reservoirs.

18 Nov 2021

Demonstration of Subsurface Passive Acoustic Monitoring (SPAM) to Survey for and Estimate Populations of Imperiled Underwater-calling Frogs

Abstract: The management and recovery of threatened and endangered amphibians on Department of Defense (DoD) lands relies on an understanding of their distribution and abundance. Fortunately, most anuran species can be surveyed acoustically using vocalizations during the breeding season. This work demonstrated the use of subsurface passive acoustic monitoring (SPAM) to survey for rare underwater-calling, at-risk anuran species on DoD installations. We evaluated the performance of SPAM relative to traditional passive acoustic monitoring (PAM) (microphone) and human manual calling survey (MCS) methods. Results showed that SPAM outperformed PAM and MCS in validation experiments where calls were generated underwater; SPAM was less successful than PAM and MCS in the field demonstration. Most leopard frog calls were apparently produced in air despite previous reports of extensive underwater-calling behavior. This project highlights how acoustic information can help address a data gap in the ecology of at-risk species, which can help refine future survey methodology and management efforts. Ultimately, the utility of SPAM for underwater-calling species will depend on the focal species, the landscape where it occurs, and technological considerations available to the surveyor. SPAM is more expensive than traditional methods but, in some situations, may be the only way to effectively detect species.

27 Sep 2021

Summary of Collaborative Wildlife Protection and Recovery Initiative (CWPRI) Conservation Workshop: Least Bell’s Vireo

Abstract: This special report summarizes the regional workshop held 24–26 April 2018 at the US Fish and Wildlife Service (USFWS) Ecological Services Office in Carlsbad, California on the importance of collaboration among federal, state, and nongovernmental agencies to facilitate the recovery of threatened and endangered species (TES). This workshop focused primarily on one species, the least Bell’s vireo (LBVI), and how to achieve full recovery and eventual delisting through agency partnerships. A major theme of the workshop was applying the Endangered Species Act (ESA) Section 7(a)(1) conservation planning process as a building block towards recovery of LBVI—as well as other threatened, endangered, and at-risk riparian species within the Southwest. The main objective of this workshop was to assemble an interagency and interdisciplinary group of wildlife biologists and managers to detail how the Section 7(a)(1) conservation planning approach, in consultation with the USFWS, can assist in the recovery of LBVI primarily on federal lands but also other public and private lands. Goals of this workshop were to (1) review Section 7(a)(1); (2) outline LBVI ecosystem processes, life history, threats, and conservation solutions; and (3) develop and organize agency commitments to collaborative conservation practices.

14 Oct 2020

Estimating the Density of Secretive, At-risk Snake Species on DoD Installations Using an Innovative Approach: IDEASS

Abstract: The Department of Defense (DoD) expends considerable resources managing and conserving threatened, endangered, or at-risk snake species. Management for these species is often hampered by a lack of basic knowledge regarding their population size and trajectory. The low detectability of most snakes makes it difficult to determine their presence, or to employ traditional methods to estimate abundance. This work demonstrated a novel, simulation-based method, Innovative Density Estimation Approach for Secretive Snakes (IDEASS), for estimating snake density based on systematic road surveys, behavioral observations of snake movement, and spatial movement (radio telemetry) data. This method was used to generate meaningful density estimates for two rare and cryptic snakes of conservation concern, the Southern Hognose and Eastern Diamondback Rattlesnake, at Fort Stewart, Georgia. IDEASS was also applied to an existing dataset to retroactively estimate density of a more common species of management concern, the Western Ratsnake, at Fort Hood, Texas. In all three cases, traditional density estimation via visual surveys and capture-mark-recapture (CMR) failed completely due to lack of captures and re-captures, despite extensive field effort. We conclude that IDEASS represents a powerful tool, and in some cases the only viable method, for estimating density of secretive snakes.