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Geology topics

Javan Mathias Bauder

Publications and source records attributed to Javan Mathias Bauder.

At least 19 recordsLinked to original sources
USGS2026

Gambel’s quail (Callipepla gambelii) nest site selection and habitat use in Oracle Junction, Arizona

Gambel’s quail ( Callipepla gambelii ) is the most widespread, abundant, and heavily harvested species of game quail in Arizona. Gambel’s quail population dynamics in Arizona are strongly influenced by seasonal weather conditions. This is particularly relevant for Gambel’s quail management as drought conditions are expected to increase in Arizona, and this may exacerbate inter-annual variation in Gambel’s quail abundance and recruitment. The goal of this study is to provide information on Gambel’s quail population demographics, habitat use, and movement to inform land management decisions for Gambel’s quail in southeast Arizona in a way that mitigates the effect of drought. We used multiple trapping methods to capture Gambel’s quail from February–July 2024 and February–15 May 2025. We found noose mats (n = 57) to be more effective than drop traps (n=14) in capturing Gambel’s quail, with multiple types of walkin traps proving ineffective. We deployed 33 GPS backpack transmitters on female Gambel’s quail to monitor their movements and locate nests. We documented eight mortalities of tracked quail from apparent predation. Quail home range sizes ranged from 3 ha-100 ha (mean = 25 ha) in 2024 and from 7–57 ha (mean = 29 ha) in 2025. We identified four nest sites with 6-15 eggs and all nests were predated. We collected vegetation measurements at nest and brood sites and corresponding random points to examine nest and brood site selection although our small sample sizes limited our ability to make inferences about Gambel’s quail habitat selection.

Arizona↗
USGS2026

Amphibian use of recently created wetlands in the Palouse region of northern Idaho, USA

Human development has resulted in the loss of natural wetlands in many regions and thus has led to amphibian habitat loss. Human-constructed wetlands are increasingly prevalent, particularly in human-modified landscapes, and can be used as breeding habitats by amphibians. It is important to identify factors influencing amphibian use of constructed wetlands to guide future wetland creation efforts. We examined wetland- and landscape-level factors influencing the presence and reproduction of native amphibians in 33 recently created (2–11 yold) wetlands within an urban-agricultural interface in northern Idaho, USA. We recorded wetland age, perimeter vegetation, and percentage of surrounding land cover as covariates and modeled detection and occupancy using Bayesian Multi-scale Occupancy Models for the three species we detected: Sierran Treefrog ( Pseudacris sierra ), Colombia Spotted Frog ( Rana luteiventris ), and Long-Toed Salamander ( Ambystoma macrodactylum ). Our results indicate that these three species can rapidly colonize recently created wetlands in an urban-agricultural interface. The effects of wetland- and landscape-scale features varied across species. Colombia Spotted Frog occupancy was greatest in older wetlands with some evidence for a negative association with more urbanized landscapes. Long Toed Salamanders and Sierran Treefrogs were not associated with wetland age but also showed some evidence of negative associations with urbanization. Long-Toed Salamanders showed evidence of using less vegetated wetlands while Sierran Treefrogs showed evidence of using more vegetated wetlands. Our results are consistent with multiple studies showing that wetlands in human-modified landscapes can provide amphibian breeding habitat, and they suggest that including vegetation plantings within recently created wetlands may promote amphibian colonization. Anecdotal observations also indicate that designing wetlands with sufficient hydroperiod for metamorphoses may be important for ensuring that newly created wetlands benefit amphibian populations.

Idaho↗
USGS2025

Using integrated step-selection analyses to map high-risk electrocution areas for a highly mobile species

Knowledge of animal-movement patterns is a crucial component in identifying areas with high potential for human–wildlife conflict and in prioritizing associated management actions. Electrical energy infrastructure is a major source of mortality for animals worldwide, with millions of birds colliding with or being electrocuted by power lines and power-pole infrastructure each year. Movement, habitat use, and the spatial distribution of electrocution risk can vary with age, but studies of younger age classes are often hampered because these groups are difficult to observe and lack well-defined home ranges. To identify movement patterns and high-use areas of bald eagles in Arizona, USA, we analyzed global positioning system (GPS) telemetry data collected from 13 immature bald eagles ( Haliaeetus leucocephalus ) across Arizona between 2017 and 2023. We built multi-scale, integrated step-selection functions that evaluated eagle responses to a suite of environmental covariates. We then used these models to simulate eagle movement and predict habitat use within and surrounding Maricopa County, which contains both the Phoenix Metropolitan Area and the plurality of bald eagle breeding areas in Arizona. We provide a use case for how these simulated movements could be used by resource managers to identify high-risk areas for electrocution. Eagles avoided urban areas and selected steeper slopes, more pronounced ridges, and areas with greater water and wetland land cover. Predicted habitat use by bald eagles was greatest near waterbodies and along ridges and steep slopes, and indicated where power infrastructure may pose greater electrocution risk. We show how integrated step-selection analyses and movement path simulation may be used for subadult animals lacking stable home ranges to predict high-use areas and identify locations with greater potential for negative human–wildlife interactions.

Arizona↗
USGS2025

Estimated annual abundance of migratory Peale's Peregrine Falcons in coastal Washington, USA

Following the recovery of Peregrine Falcons ( Falco peregrinus ), the US Fish and Wildlife Service began a process to allow “take” (capture) of wild peregrines for falconry in the United States. Recently, that effort involved generating updated estimates of the collective abundance of the three North American peregrine subspecies: F. p. anatum , F. p. tundrius , and F. p. pealei (Peale's Peregrine Falcon). Because of the more limited distribution of F. p. pealei , we conducted an analysis specific to its geographic range. We analyzed data from a long-term banding and resighting program on three beaches on the southern coast of Washington, USA, to estimate the annual abundance of migrating and overwintering F. p. pealei , using the capture histories of 250 Peregrine Falcons, nearly all of which were captured during 1277 vehicle surveys between 1995 and 2024. Because we studied an open population of migratory individuals, we used a zero-inflated Poisson log-normal mark-resight model to estimate annual abundance. For the analyses, we partitioned our survey data into sighting periods, each of which extended from 1 September of one year to 31 May of the next. We anticipated that first-year F. p. pealei would be identified for falconry take, and our annual abundance estimates for first-year birds of this subspecies ranged from a high of 24.8 ± 6.1 (SE) individuals in the 2014–2015 sighting period to a low of 1.9 ± 1.4 individuals in the 2023–2024 sighting period. Peregrine Falcon abundance varied annually and appeared to decline during the last two sighting periods. Our sighting rate of marked peregrines was negatively associated with Bald Eagle ( Haliaeetus leucocephalus ) encounter rate. There was a lesser relationship to human activity, and we suspect the change in sighting rate was a behavioral response by Peregrine Falcons to the threat of kleptoparasitism by Bald Eagles. We currently lack comprehensive information about the natal origin of the individual peregrines in our study area, which prevented us from assessing the degree to which falconry take from the pool of falcons migrating to or through Washington might potentially impact local or regional abundances. Although a better understanding of natal origins is needed, our data add clarity to the migration and overwinter abundance of F. p. pealei on the Washington coast and may inform decisions about the take of this subspecies for falconry.

Washington↗
USGS2025

Maintaining frog monitoring and population on the Las Cienegas National Conservation Area

This report summarizes and analyzes the data collected on the Chiricahua Leopard Frog (CLF) populations on the Las Ciénegas National Conservation Area (LCNCA) in southeast Arizona, U.S.A., during the reporting period covered under this funding agreement from September 2020 through October 2024 and place this analysis in historical context of the previous monitoring efforts. The major findings of this report are: 1. We conducted a total of 465 surveys across 46 sites on the LCNCA and the associated Elgin Buffer Zone during September 2020 through October 2024. We conducted 323 surveys across the 19 core CLF monitoring sites on the LCNCA and 112 surveys across 13 core buffer zone sites. 2. We detected CLF at each of our 19 core LCNCA monitoring sites during at least one year in which we conducted surveys across the year’s entire field season (i.e., 2021-2024). We detected CLF reproduction in each of these four years at four sites and suspected reproduction to have occurred during all four years at a fifth site. We did not detect CLF reproduction at seven of these 19 core monitoring sites during the report period. We assisted with six CLF translocations to sites on the LCNA during the report period. 3. Site occupancy rates across the LCNCA during the report period remain consistent with those reported during previous years and continue to indicate the presence of a stable CLF metapopulation within the LCNCA. 4. Monitoring efforts in the Elgin Buffer Zone continue to be successful at preventing reinvasion by invasive American bullfrogs to the LCNCA. We detected and removed bullfrogs from three sites in the Elgin Buffer Zone and no bullfrogs were detected during 2024. The LCNCA continues to remain bullfrog free since 2014.

Arizona↗
USGS2025

Northward migrations of nonbreeding Bald Eagles from Arizona, USA.

Knowledge of the spatiotemporal patterns of migratory and nonbreeding-season movements by animals is critical for conservation, but can be difficult to obtain if animals move far from known breeding territories and across administrative and country borders. To understand the migratory movements of Bald Eagles ( Haliaeetus leucocephalus ) originating from a demographically closed population in Arizona, USA, we deployed GPS transmitters on 24 juveniles and 2 nonbreeding adult eagles between 2017 and 2023. We identified common migration routes, stopover locations, and migration phenology. Eagles moved north from Arizona during the population's post-breeding period in the boreal spring and summer, and returned south in autumn in advance of the breeding season. Eagles migrated along two primary routes: (1) along the Wasatch Mountains in Utah and extending into the Rocky Mountains of southern Idaho, and (2) through eastern Nevada and along the Rocky Mountains in western and northern Idaho. Stopover locations were frequently near lakes and rivers. Recent fledglings began migration later than older individuals and 15 of 16 of these juveniles that survived until the following breeding season returned to Arizona. The individual that did not return showed evidence of permanent emigration to northern California. Our results contribute to a growing understanding of avian migration routes within the Pacific Flyway and the diverse migration strategies, including northward migration following the breeding season, exhibited across raptor populations. We highlight that explicit studies of juveniles, subadults, and nonbreeding adults are key to understanding avian migration dynamics and identifying opportunities for conservation.

Arizona↗
USGS2024

Evaluating the effects of nest management on a recovering raptor using integrated population modeling

Evaluating population responses to management is a crucial component of successful conservation programs. Models predicting population growth under different management scenarios can provide key insights into the efficacy of specific management actions both in reversing population decline and in maintaining recovered populations. Bald eagle ( Haliaeetus leucocephalus ) conservation in the United States has seen many successes over the last 50 years, yet the extent to which the bald eagle population has recovered in Arizona, an important population within the Southwest region, remains an area of debate. Estimates of the species' population trend and an evaluation of ongoing nest-level management practices are needed to inform management decisions. We developed a Bayesian integrated population model (IPM) and population viability analysis (PVA) using a 36-year dataset to assess Arizona bald eagle population dynamics and their underlying demographic rates under current and possible future management practices. We estimated that the population grew from 77 females in 1993 to 180 females in 2022, an average yearly increase of 3%. Breeding sites that had trained personnel (i.e., nestwatchers) stationed at active nests to mitigate human disturbance had a 28% higher reproductive output than nests without this protection. Uncertainty around population trends was high, but scenarios that continued the nestwatcher program were less likely to predict abundance declines than scenarios without nestwatchers. Here, the IPM-PVA framework provides a useful tool both for estimating the effectiveness of past management actions and for exploring the management needs of a delisted population, highlighting that continued management action may be necessary to maintain population viability even after meeting certain recovery criteria.

Arizona↗
USGS2024

Northern Mexican gartersnake demographics and movement ecology

The northern Mexican gartersnake ( Thamnophis eques ; hereafter NMGS) is a federally threatened species occurring in riparian areas in central and southeast Arizona and west-central New Mexico. While previous studies have examined the ecology of this species in central Arizona, less is known about NMGS ecology in grassland landscapes of southeast Arizona. This project continues a long-term mark-recapture study of NMGS in the upper Santa Cruz River in the San Rafael Valley of southeast Arizona. We analyzed mark-recapture data collected by Arizona Game and Fish Department from 2008–2019 and included data we collected during 2022 and 2023. We also studied NMGS movement ecology using a combination of externally attached GPS transmitters and surgically implanted VHF transmitters. We had 517 NMGS captures over 26 survey sessions across the entire study, 186 of which were captures of previously marked snakes. Most of our captures were females and evidence of a statistically significant female-biased sex ratio was present on three survey sessions. Trapping success was generally highest June-September and catch-per-unit-effort (CPUE) was strongly correlated with the number of individuals captured. We used mark-recapture data from 288 individuals to estimate annual apparent survival and session-specific recapture probabilities. Annual apparent survival was higher for females (0.72, 95% highest posterior density intervals [HPDI] = 0.630.81) than for males (0.58, 95% HPDI = 0.44–0.72). Session-specific recapture probabilities were similar for males and females and were highly correlated with CPUE. During 2023, we monitored the movements of 13 adult females using GPS transmitters, two adult males using VHF transmitters, and one adult female using a GPS transmitter followed by a VHF transmitter. GPS transmitters were deployed from 7-18 days at a time as limited by battery life. After filtering out low-quality GPS locations, we obtained a total of 1,688 hourly GPS locations. Mean and maximum distances moved per hour ranged from 5.54–10.92 m and 15.24–135.71 m, respectively, across GPS transmitter attachment periods. Space use estimates from 100% minimum convex polygons ranged from 0.04–1.16 ha across GPS transmitter attachment periods. All documented NMGS movements during 2023 were relatively close (< 100 m) to the Santa Cruz River. These results continue to build upon our knowledge of NMGS ecology and suggest the continued presence of a relatively robust population within the upper Santa Cruz River.

Arizona↗
USGS2024

Control of introduced American bullfrogs and support of Chiricahua leopard frog conservation in southeast Arizona

1. This report summaries field surveys conducted during July 2023 through April 2024 to control introduced American bullfrogs ( Lithobates [ Rana ] catesbeianus ; hereafter bullfrog) and support Chiricahua leopard frog ( Lithobates [ Rana ] chiricahuensis ) conservation in southeast Arizona. We conducted 394 field surveys across 141 sites in Chiricahua leopard frog Recovery Units 1 and 2 during this survey period. 2. During these surveys, we detected bullfrogs at 36 sites and removed a total of 452 bullfrogs. Bullfrog reproduction was only observed during this survey period at sites on private property where we did not have landowner permission to remove bullfrogs. We found bullfrogs and Chiricahua leopard frogs co-occurring at only a single site (Chulo Tank). Only a single bullfrog was present at this site, and it was removed. 3. Within the Cobre Ridge/Recovery Unit 1 region, we detected Chiricahua leopard frogs at 15 sites, with reproductive activity confirmed at two sites. We performed or assisted with Chiricahua leopard frog translocations at five sites. We detected Chiricahua leopard frog overwinter survival at two sites in this region although moribund and dead frogs were observed at one of these two sites. 4. We did not detect Chiricahua leopard frog within our Canelo Hills Buffer Zone or stock tanks along the foothills of the San Rafael Valley. We detected Chiricahua leopard frogs at four sites on the Appleton-Whittell Research Ranch with reproduction documented at two sites. We also removed two adult bullfrogs from a single site. 5. We detected Chiricahua leopard frogs at 17 sites on the Las Cienegas National Conservation Area (LCNCA). While Chiricahua leopard frog reproduction was not confirmed during July–November of 2023, as of 24 April 2025 we detected Chiricahua leopard frog reproduction at three sites. We did detect a moribund Chiricahua leopard frog at Lower Empire Gulch in March 2024. No bullfrogs were detected on the LCNCA and a single adult bullfrog was removed from one site in the Elgin Buffer Zone. 6. We began bullfrog removal efforts at a new eradication site along the Babocomari River on the Babacomari Ranch. This planned four-year eradication project will remove a significant non-urban bullfrog source population that threatens existing Chiricahua leopard frog metapopulations.

Arizona↗
USGS2023

The effects of estradiol-17β on the sex reversal, survival, and growth of Red Shiner and its use in the development of YY individuals

Objective The Red Shiner Cyprinella lutrensis is one of the most prolific and ecologically destructive invasive fish species in the southwestern United States. The production and release of YY individuals as Trojan sex chromosome carriers can theoretically eradicate invasive fish populations by eventually eliminating phenotypic females. Methods The YY individuals are typically produced through hormonally induced sex reversals and selective breeding of subsequently feminized males. We tested three dosages of estradiol-17β (E2)-treated diets (50, 100, and 150 mg of E2 per kg of diet) administered to sexually immature Red Shiner for various durations to determine their effectiveness at feminizing Red Shiner cohorts. Survival, growth, and gonadal development were assessed for each treatment. Result All E2 treatments had minimal, if any, detrimental effects on the growth and gonadal development of Red Shiner. The 50-mg dosage lasting from 2 to 120 days posthatch achieved a 100% feminization rate while using the lowest amount of E2; therefore, this dosage and treatment interval are recommended when attempting Red Shiner feminization under these rearing conditions. Feminization of males allowed for the spawning of neofemales (F XY ) with wild-type males (M XY ), which resulted in the first putative YY Red Shiner. The YY verification crosses ( n = 20) resulted in predominately male offspring (189 males/191 offspring) except for (1) an intersex individual from an M YY × F XX cross with two previtellogenic oocytes in its testis and (2) a single female that may have resulted from an inbred cross between an XY male and a YY female or from an unknown autosomal or environmental effect on sexual phenotype. Conclusion More progeny tests with inbred and outbred crosses should be conducted to determine the prevalence of female offspring from YY individuals and how this may impact an eradication strategy featuring releases of YY Red Shiner.

North American Journal of Aquaculture↗
USGS2023

Native fish abundance and habitat selection changes in the presence of nonnative piscivores

We compared abundance patterns and developed resource selection models for imperilled native southwestern (USA) fishes in the presence and absence of Black Bass ( Micropterus spp.) to evaluate how fishes alter their selection for habitats when sympatric with a nonnative piscivore. We collected data using snorkel surveys and in-stream habitat sampling in Fossil Creek (AZ), upstream (native fish only) and downstream (native and nonnative fish) of a fish barrier. The abundance of all Roundtail Chub ( Gila robusta ), small (≤127 mm total length [TL]; vulnerable to predation) Sonora Sucker ( Catostomus insignis ) and Speckled Dace ( Rhinichthys osculus ) was significantly reduced, but the abundance of both small and large (>127 mm TL; invulnerable to predation) Desert Sucker ( Catostomus clarkii ) was similar in sampling reaches with and without Black Bass. When sympatric with Black Bass, small Roundtail Chub increased their selection for riffles by 2.57 times and small Desert Sucker reduce their selection for pools by 6.90 times while also selecting for faster flow velocity and finer substrates in lotic mesohabitats. Large native fishes altered selection least, notwithstanding an increased selection for canopy cover in sampling reaches with Black Bass. Observed shifts in resource selection are consistent with predator avoidance strategies. Our study highlights the behavioural consequences of nonnative piscivores on native fish communities and stresses the importance of maintaining lotic mesohabitats as potential refugia for vulnerable native fishes when nonnative piscivores are present.

Arizona↗
USGS2023

Food caching by a solitary large carnivore reveals importance of intermediate-sized prey

Pumas ( Puma concolor ) are solitary large carnivores that exhibit high energetic investments while hunting prey that often take multiple days to consume. Therefore, pumas should behave in a way to maximize their energetic gains, including using caching, which is a behavior used by many mammal species to preserve and store food or to conceal it from conspecifics and scavengers to limit their losses. Yet pumas do not always cache their kills. In order to understand caching behavior, we used variables associated with the kills such as prey mass, search time, climate, and habitat to test 20 ecological models (representing four a priori hypotheses: food perishability, resource pulse, consumption time, and kleptoparasitism deterrence) in an information-theoretic approach of model selection to explore factors related to the caching behavior. Models were run with information from tracked radio-collared pumas in California over a 2.5-year period and identified a total of 352 kills. Overall, we documented pumas caching 61.5% of their kills, including 71.6% of Black-tailed Deer ( Odocoileus hemionus columbianus ), their primary prey in the study area. The model with a quadratic effect of adjusted mass of prey on puma caching probability had all of the empirical support ( w = 1.00). Specifically, pumas were most likely to cache intermediate-sized prey, such as yearling and adult female deer, and also fed from cached kills for longer periods of time. Larger prey may be too large to easily cache, making it less energetically efficient—while small prey can often be consumed quickly enough to not require caching. This suggests that intermediate-sized prey may be the optimal size for caching, allowing a puma to feed for multiple days while not greatly increasing energetic output. The hypotheses we tested were not mutually exclusive and pumas caching their prey may occur for several reasons; nevertheless, our study demonstrated that pumas use caching to extend their foraging time and maximize energetic gains when preying on intermediate-sized prey.

California↗
USGS2023

The effects of estradiol-17β on the sex reversal, survival, and growth of green sunfish Lepomis cyanellus

The feminization of green sunfish Lepomis cyanellus could expand their utility as a game fish or aquacultured species by preventing overcrowding and precocious reproduction in stocked systems. Feminization of green sunfish could also help elucidate information on their sex determination system. We report the feminization of green sunfish cohorts via oral administration of estradiol-17β (E2) during early development. A low-dose (100 E2 mg per kg of diet) and a high-dose (150 E2 mg per kg of diet) experimental E2 treatment were fed to juvenile green sunfish from 30 to 90 days post-hatch. Fish were subsequently evaluated for any treatment effect on gonadal development, survival, and growth. Both E2 treatments resulted in 100% feminization, with no morphological or histological differences detected between E2 treated ovaries and those from a control group. The control group was composed mostly of males (82.61%). Overall, there was no effect of E2 on survival ( P = 0.310) and growth rate data suggested no statistical differences ( P = 0.0805). However, the growth rate of the high-dose group increased slightly higher after the treatment ended than the other treatments ( P = 0.042), suggesting that E2 might suppress growth in green sunfish. In addition, the control group did not exhibit a higher survival rate after the treatment period ended ( P = 0.266), whereas both E2 treated groups did ( P = 0.0003–0.0050). We found that the low dose, 100 E2 mg per kg of diet, was sufficient for fully feminizing green sunfish if administered during development from 30 to 90 days post-hatch and E2 dosages may result in deleterious effects on green sunfish's health and growth.

Aquaculture↗
USGS2023

Evaluating growth rates of captive, wild, and reintroduced populations of the imperiled Eastern Indigo Snake (Drymarchon couperi)

Reintroduction of species at sites where populations have been extirpated has become a common technique in wildlife conservation. To track progress towards reintroduction success, effective postrelease monitoring is needed to document vital rates of individuals and the corresponding impact on population trajectories. We assessed growth and body size in Eastern Indigo Snakes (Drymarchon couperi) using a data set from multiple projects across the species' distribution, including free-ranging wild snakes, snakes reared in captive-breeding programs, and snakes released at two reintroduction sites. We used these data to fit a von Bertalanffy growth model in a Bayesian framework to quantify differences in growth among three broad categories of snakes (wild, captive, and reintroduced), while accounting for measurement error across various projects. We also compared changes in body mass of captive-born individuals from four captive rearing facilities. Asymptotic snout–vent length across all groups was 185 cm (95% credible interval = 177–194 cm) for males and 157 cm (95% credible interval = 153–161 cm) for females. Reintroduced snakes had a higher growth coefficient than either captive or wild snakes (e.g., captive females = 1.20 [1.06–1.35] d –1 ; wild females = 1.22 [0.95–1.49] d –1 ; reintroduced females = 1.62 [1.21–2.05] d –1 ), indicating that current captive-breeding and rearing efforts for indigo snakes produce similar or faster growth trends compared to wild populations. Furthermore, daily changes in juvenile body weight relative to body size were similar in three of the four captive rearing facilities (mean for females at Orianne Center for Indigo Conservation = 0.57 [0.48–0.65]; Zoo Atlanta = 0.55 [0.37–0.72]; Welaka National Fish Hatchery = 0.55, [0.36–0.73]; Auburn University = 0.39 [0.21–0.58]). Long-term project success for indigo snake reintroductions will depend on continuing to implement best practices in an adaptive management framework.

Herpetologica↗
USGS2023

Eastern Indigo snake (Drymarchon couperi) shelter site use In peninsular Florida, USA, and implicatIons for habItat conservatIon

Shelters are critical for many species as protection from predators and extreme temperatures. Successful conservation of reptiles requires understanding both shelter site requirements and availability. The Eastern Indigo Snake (EIS; Drymarchon couperi ) is endemic to the southeastern U.S. and is federally listed. Recovery has focused on maximizing unfragmented landscapes, with less attention on fine-scale features such as shelter sites. In the northern EIS range, Gopher Tortoise ( Gopherus polyphemus ) burrows are used extensively for shelter. Although EIS in peninsular Florida often shelter in tortoise burrows, they also use other shelters where tortoise burrows are scarce or absent. Solely focusing EIS survey and management efforts where Gopher Tortoises are present may overlook occupied habitats and misallocate resources. We investigated the importance of different shelter sites in central Florida using data from radio-tracked EIS. We modeled the use of shelter categories as a function of sex, season, and habitat using Bayesian multinomial Generalized Linear Models. Results showed that EIS in peninsular Florida used Gopher Tortoise burrows across all seasons and habitats. Tortoise burrow use was highest in xeric habitats and lowest in mesic habitats where burrows are most and least abundant, respectively. There was less variability in shelter site use in disturbed habitats and flatwoods. Tortoise burrow use by EIS in the cool season across sexes and habitats in our study was much lower than in southern Georgia. Our results indicate that EIS are less dependent on Gopher Tortoise burrows in peninsular Florida and that suitable habitats with few or no tortoise burrows could still provide conservation value for EIS.

Florida, Georgia↗
USGS2022

The development of genetic sex identification markers and evidence of a male heterogametic sex determination system in Red Shiner

The Red Shiner Cyprinella lutrensis is of increasing management interest as an invasive species that negatively impacts many native fishes throughout North America. Trojan sex chromosome (TSC)-carrying individuals could theoretically control invasive fish populations by skewing the sex ratio to 100% male. The efficacy of TSC-based control programs requires an understanding of a population's sex determination system, yet such information is lacking for Red Shiner. We used single-digest restriction site-associated DNA sequencing to discover sex-linked single-nucleotide polymorphisms (SNPs), and we conducted a series of breeding experiments to uncover the sex determination system. All candidate sex-linked SNPs that fit our selection criteria exhibited a pattern of male heterogamety. We developed two sex-identification (sex-ID) marker assays, XY_248 and XY_170, which showed phenotype–genotype concordance scores of 77.00% and 84.35%, respectively. These sex-ID markers exhibited relatively high phenotype–genotype concordance in females (XY_248 = 96.30%; XY_170 = 98.61%), which allowed for selective breeding of phenotypically feminized genetic males. We observed a 3:1 male : female sex ratio in spawns from feminized males crossed with wild-type males, indicative of a male heterogametic sex determination system (i.e., XY male/XX female). The discovery of a male heterogametic sex determination system, in combination with our two markers, increases the likelihood of developing an effective TSC eradication strategy for invasive Red Shiner populations.

North American Journal of Aquaculture↗