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USGS2016

Mechanistic variables can enhance predictive models of endotherm distributions: The American pika under current, past, and future climates

How climate constrains species’ distributions through time and space is an important question in the context of conservation planning for climate change. Despite increasing awareness of the need to incorporate mechanism into species distribution models (SDMs), mechanistic modeling of endotherm distributions remains limited in this literature. Using the American pika ( Ochotona princeps ) as an example, we present a framework whereby mechanism can be incorporated into endotherm SDMs. Pika distribution has repeatedly been found to be constrained by warm temperatures, so we used Niche Mapper, a mechanistic heat-balance model, to convert macroclimate data to pika-specific surface activity time in summer across the western United States. We then explored the difference between using a macroclimate predictor (summer temperature) and using a mechanistic predictor (predicted surface activity time) in SDMs. Both approaches accurately predicted pika presences in current and past climate regimes. However, the activity models predicted 8–19% less habitat loss in response to annual temperature increases of ~3–5 °C predicted in the region by 2070, suggesting that pikas may be able to buffer some climate change effects through behavioral thermoregulation that can be captured by mechanistic modeling. Incorporating mechanism added value to the modeling by providing increased confidence in areas where different modeling approaches agreed and providing a range of outcomes in areas of disagreement. It also provided a more proximate variable relating animal distribution to climate, allowing investigations into how unique habitat characteristics and intraspecific phenotypic variation may allow pikas to exist in areas outside those predicted by generic SDMs. Only a small number of easily obtainable data are required to parameterize this mechanistic model for any endotherm, and its use can improve SDM predictions by explicitly modeling a widely applicable direct physiological effect: climate-imposed restrictions on activity. This more complete understanding is necessary to inform climate adaptation actions, management strategies, and conservation plans.

Global Change Biology↗

USGS2019

Migration routes, foraging behavior, and site fidelity of loggerhead sea turtles (Caretta caretta) satellite tracked from a globally important rookery

The Archie Carr National Wildlife Refuge, Florida, USA (27.946°N, − 80.494°W) represents one of the largest loggerhead turtle ( Caretta caretta ) nesting sites in the Western Hemisphere. Surprisingly, little work has been conducted to determine females’ post-nesting migratory behavior and characteristics of their foraging areas. Between 2008 and 2017, satellite telemetry was used to trace the locations and movements of 45 post-nesting loggerhead turtles. A switching state-space model was employed to estimate the behavioral state of each location. Internesting, migrating and foraging activity periods were determined for 38 loggerheads based on the SSSM. Seven environmental variables were extracted from remote sensing imagery for each location to compare values among behaviors. Core primary foraging areas ranged in size from 5.89 to 4572.80 km 2 . Four foraging types (primary, secondary, seasonal, and loops) were observed. Most turtles resided at a primary foraging area year round. A few individuals conducted foraging loops away from a primary foraging area. Both seasonal and loop movements were associated with changes in sea surface temperature as turtles moved to avoid temperatures that could cause cold-stunning or mortality. Turtle size and nesting beach offshore currents may play a role in foraging area selection, and date of departure from the nesting beach may be linked to foraging destination. By making the connection among oceanic features, foraging areas, and the influence of environmental variables on these areas, it is possible to identify and characterize critically important feeding areas and migration corridors for loggerheads nesting on the east coast of Florida.

Marine Biology↗

USGS2026

Wildfire smoke reduces the vocal activity of imperiled grassland birds in New York State

Smoke from new fire regimes driven by climate change may affect biodiversity in new regions of the world. Wildfires that occurred in eastern Canada in 2023 burned nearly 7.8 million hectares of forest, sending smoke throughout the northeastern United States. We leveraged passive acoustic monitoring to investigate real-time effects of wildfire smoke on vocalization behavior of globally imperiled grassland birds during the breeding season in open land covers across New York State. We determined an overall negative effect of elevated smoke levels on breeding grassland bird vocal activity. We observed the strongest vocalization responses in Bobolink ( Dolichonyx oryzivorus ) – a colonial breeding, grassland-obligate species; Bobolink vocal activity sharply dropped during intense smoke early in the breeding season, yet increased during a milder smoke event later in the breeding season. Our results indicate that wildfire smoke can present an additive stressor to already imperiled grassland bird species via potential fitness reductions from decreased communication. While some aspects of smoke exposure may be uncontrollable, our results suggest that increased attention to conservation practices that promote grassland birds in the Northeast could be prioritized to offset negative effects of increased smoke associated with global change.

New York↗

USGS2024

Silver Chub spawning confirmed in the Maumee River, a tributary of Lake Erie

Objective Biodiversity is declining due to invasive species and other factors that can affect individual species differently. Silver Chub Macrhybopsis storeriana are declining in their native range, and their conservation status in the Great Lakes ranges from secure to possibly extirpated. Lake Erie once supported a large Silver Chub population until it crashed in the 1950s. Additionally, the spawning behavior and reproductive guild of Silver Chub in Lake Erie is unknown. Our objective was to document Silver Chub spawning in the Maumee River, a Lake Erie tributary. Methods Invasive Grass Carp Ctenopharyngodon idella are known to spawn in the Maumee River during high-flow events from May to July, and the University of Toledo and U.S. Geological Survey regularly sample the lower 24 km for early life stages using paired bongo nets. Contents from paired bongo nets are returned to the laboratory for processing, and a subset of potential Grass Carp eggs are sent for genetic analysis. Result On June 8, 2022, several potential Grass Carp eggs were captured at two sites on the Maumee River during a high-flow event. Fifteen potential Grass Carp eggs were sent for genetic analysis, and DNA sequencing revealed that six of these eggs were Silver Chub. Discussion This was the first known collection of Silver Chub eggs in a Lake Erie tributary, and our findings indicate that Silver Chub likely belong to the pelagophil reproductive guild. Although Grass Carp and Silver Chub spawn under similar conditions, management actions to control Grass Carp in the Maumee River may be unlikely to affect Silver Chub due to electrofishing settings used in the capture of Grass Carp. The verification of Silver Chub spawning in a Western Erie Basin tributary provides insights into their reproductive biology that could be useful in recovery planning in Lake Erie and throughout the Great Lakes.

Ohio↗

USGS2025

Spawning and larval development of the mesophotic octocoral Swiftia exserta in aquaria

The 2010 Deepwater Horizon oil spill injured mesophotic and deep-sea environments over a vast area. In order to restore mesophotic and deep-sea coral species impacted by the spill, information on fundamental ecosystem processes such as reproduction is needed. During expeditions in 2021 and 2022, fragments of the mesophotic octocoral Swiftia exserta were collected from the northern Gulf of Mexico and transported to aquaria at federal facilities in South Carolina, Florida, and Texas. In fall of 2021 and 2022, several of these fragments spawned in captivity, providing an opportunity to learn about their reproduction and inform future restoration activities. Broadcast spawning occurred on 19 and 20 October, 2021, and on 20 days from 29 September to 7 November, 2022. These spawning events permitted detailed observations of spawning behavior and timing, and yielded over 2,400 oocytes. Individual spawns were preceded by a distinctive “spawning posture” in the polyps, lasting between five minutes and two hours, and may have been cued by light. Swiftia exserta larvae settled and developed at comparable rates to other broadcast spawning octocorals, becoming swimming planulae by three days post spawn (dps) and starting to settle by 14 dps. These observations represent the first such records for S. exserta and, more broadly, for any mesophotic coral in the Gulf of Mexico, providing important insights for the restoration of these species. This investigation lays the foundation for future work to explore the influences of seasonal environmental variables, such as light and temperature, on spawning and reproductive seasonality in this species.

Marine Biology↗

USGS1999

Influence of prerelease experience on reintroduced black-footed ferrets (Mustela nigripes)

Captive breeding is increasingly being used to create supplies of endangered animals for release into natural habitats, but rearing strategies vary and debates arise over which methods are most efficient. We assessed postrelease behaviors and survival of three groups of black-footed ferrets, each with different prerelease experience. Eighteen ferret kits ???60 days of age were moved with their dams from cages to 80-m2 outdoor pens with prairie dog burrows. These animals were compared to animals reared in standard cages (n = 72), some of which were given experience killing prairie dogs (n = 32). Ferrets were released onto white-tailed prairie dog (Cynomys leucurus) colonies in Wyoming, USA, in fall, 1992. Radio-tagged cage-reared ferrets made longer nightly moves and dispersed further from release sites than their pen-reared counterparts. The band return rate was 4-fold higher for pen-reared animals than for cage-reared animals during surveys conducted about 1 month after release. We recommend routine use of quasi-natural outdoor pens for prerelease conditioning of black-footed ferrets.

Biological Conservation↗

USGS2019

West Florida shelf pipeline serves as sea turtle benthic habitat based on in-situ towed camera observations

The use of marine offshore benthic habitats by sea turtles is poorly characterized due to the difficulty of obtaining in situ data. Understanding benthic habitat use that is important to the species’ reproduction, foraging, and migrations is critical for guiding management decisions. A towed camera-based assessment survey system (C-BASS) equipped with environmental sensors was used to characterize and assess benthic habitats on the West Florida Shelf (WFS) from 2014 to 2018. During these cruises, sea turtles were opportunistically observed during the surveys, and critical in situ data such as spatiotemporal information, species identification, habitat use, behavior, and environmental data were collected and evaluated. In total, 79 sea turtles were observed during 97 transects of approximately 2700 km of seafloor, which was recorded on 380 h of video. Several sea turtle species were spotted within the WFS, including loggerhead Caretta caretta, Kemp’s ridley Lepidochelys kempii, and green turtles Chelonia mydas. These opportunistic sightings revealed an area of high use on the WFS, an anthropogenic structure known as the Gulfstream natural gas pipeline (GSPL). C-BASS survey results suggest that 2 sea turtle species (C. caretta and L. kempii) utilize this artificial structure primarily as a resting area. We emphasize the importance of combining habitat mapping techniques (towed underwater video and multibeam bathymetry/backscatter) with tracking technology to better understand the fine-scale habitat use of sea turtles.

Florida↗

USGS2017

Why social values cannot be changed for the sake of conservation

The hope for creating widespread change in social values has endured among conservation professionals since early calls by Aldo Leopold for a “land ethic.” However, there has been little serious attention in conservation to the fields of investigation that address values, how they are formed, and how they change. We introduce a social–ecological systems conceptual approach in which values are seen not only as motivational goals people hold but also as ideas that are deeply embedded in society's material culture, collective behaviors, traditions, and institutions. Values define and bind groups, organizations, and societies; serve an adaptive role; and are typically stable across generations. When abrupt value changes occur, they are in response to substantial alterations in the social–ecological context. Such changes build on prior value structures and do not result in complete replacement. Given this understanding of values, we conclude that deliberate efforts to orchestrate value shifts for conservation are unlikely to be effective. Instead, there is an urgent need for research on values with a multilevel and dynamic view that can inform innovative conservation strategies for working within existing value structures. New directions facilitated by a systems approach will enhance understanding of the role values play in shaping conservation challenges and improve management of the human component of conservation.

Conservation Biology↗

USGS2019

Consistent compensatory growth offsets poor condition in trout populations

1. Compensatory growth – when individuals in poor condition grow rapidly to “catch up” to conspecifics – may be a mechanism that allows individuals to tolerate stressful environmental conditions, both abiotic and biotic. This phenomenon has been documented fairly widely in laboratory and field experiments, but evidence for compensatory growth in the wild is scarce. 2. Cutthroat trout (Oncorhynchus clarkii subsp) are cold-water specialists that inhabit streams in montane ecosystems where seasonal conditions can be harsh and growth rates vary greatly among seasons. Understanding if individuals compensate for periods of reduced growth and body condition will improve understanding of the requirements of fish throughout their life-cycle and across freshwater habitats. 3. We quantified compensatory growth of juvenile cutthroat trout using extensive mark-recapture data from 11 stream populations (1,125 individuals) and two subspecies inhabiting a wide range of ecological settings in the northern Rocky Mountains, USA. Our objectives were to determine how growth was linked across seasons and determine if individuals behaviorally compensated for depressed body condition via emigration. 4. Fish in relatively poor condition consistently demonstrated compensatory growth in mass during subsequent seasons. In contrast, fish in relatively better condition responded with positive growth in length during the summer signaling these fish may be better suited to headwater environments; no compensatory growth in length was found during the winter. Furthermore, we found no evidence that individual condition mediated migration tendencies of fish to seek more favorable habitat. 5. Across a wide range of environmental conditions, we found consistent empirical support for compensatory growth in mass in the wild. A critical next step is to quantify how changing abiotic and biotic conditions influence the ability of stream fishes to compensate for locally or seasonally challenging conditions, thereby affecting long-term resiliency, viability, and adaptation in the face of changing environmental conditions.

Montana, Wyoming↗

USGS2022

Phenological variation in spring migration timing of adult alewife (Alosa pseudoharengus) in coastal Massachusetts

The timing of biological events in plants and animals, such as migration and reproduction, is shifting due to climate change. Anadromous fishes are particularly susceptible to these shifts as they are subject to strong seasonal cycles when transitioning between marine and freshwater habitats to spawn. We used linear models to determine the extent of phenological shifts in adult Alewife Alosa pseudoharengus as they migrated from ocean to freshwater environments during spring to spawn at 12 sites along the northeastern USA. We also evaluated broadscale oceanic and atmospheric drivers that trigger their movements from offshore to inland habitats, including sea surface temperature, North Atlantic Oscillation index, and Gulf Stream index. Run timing metrics of initiation, median (an indicator of peak run timing), end, and duration were found to vary among sites. Although most sites showed negligible shifts towards earlier timing, statistically significant changes were detected in three systems. Overall, winter sea surface temperature, spring and fall transition dates, and annual run size were the strongest predictors of run initiation and median dates, while a combination of within-season and seasonal-lag effects influenced run end and duration timing. Disparate results observed across the 12 spawning runs suggest that regional environmental processes were not consistent drivers of phenology and local environmental and ecological conditions may be more important. Additional years of data to extend time series and monitoring of Alewife timing and movements in nearshore habitats may provide important information about staging behaviors just before adults transition between ocean and freshwater habitats.

Massachusetts↗

USGS2020

Assessing nest attentiveness of Common Terns via video cameras and temperature loggers

While nest attentiveness plays a critical role in the reproductive success of avian species, little nest attentiveness data with high temporal resolution is available for many species. However, improvements in both video monitoring and temperature logging devices present an opportunity to improve our understanding of this aspect of avian behavior. To investigate nest attentiveness behaviors and evaluate the ability of these technologies to record the needed data we monitored 13 nests across two Common Tern (Sterna hirundo) breeding colonies with a paired video camera - temperature logger approach, while monitoring 63 additional nests with temperature loggers alone. We examined data respective to four times of day: Morning (civil dawn-11:59), Peak (12:00-16:00), Cooling (16:01-civil dusk), and Night (civil dusk-civil dawn). Our results show that while successful nests had mostly short duration off-bouts and maintained consistent nest attentiveness throughout the day, failed nests had dramatic reductions in nest attentiveness during the Cooling and Night periods (p < 0.05) with one colony experiencing repeated nocturnal abandonment due to predation pressure from a Great Horned Owl (Bubo virginianus). Incubation appeared to ameliorate ambient temperatures during Night, as nests were significantly warmer during Night when birds were on versus off the nest (p < 0.05). Meanwhile, off bouts during the Peak period occurred during higher ambient temperatures, perhaps due to adults leaving the nest during the hottest periods to perform belly soaking. Unfortunately, temperature logger data alone had limited ability to predict nest attentiveness status, with results highly dependent on time of day and bout duration. While our methods did not affect hatching success (p > 0.05) video-monitored nests did have significantly lower clutch sizes (p < 0.05). Despite the high-quality data recorded in this study, the logistical and potential biological complications reported suggest that careful planning is needed before these devices can be utilized.

Avian Research↗

USGS1989

Behavior of fish predators and their prey: Habitat choice between open water and dense vegetation

Behavior of largemouth bass, Micropterus salmoides , and northern pike, Esox lucius , foraging on fathead minnows, Pimephales promelas , or bluegills, Lepomis macrochirus , was quantified in pools with 50% cover (half the pool had artificial stems at a density of 1000 stems m −2 ). Both predators spent most of their time in the vegetation. Largemouth bass searched for bluegills and ambushed minnows, whereas the relatively immobile northern pike ambushed all prey. Minnows were closer to predators and were captured more frequently than bluegills. Even when minnows dispersed, they moved continually and eventually wandered within striking distance of a predator. Bluegills dispersed in the cover with predators. Bass captured the few bluegills that strayed into the open and pike captured those that approached too closely in the cover. The ability of predators to capture prey while residing in habitats containing patches of dense cover may explain their residence in areas often considered to be poor ones for foraging.

Environmental Biology of Fishes↗

USGS2013

Factors influencing the movement biology of migrant songbirds confronted with an ecological barrier

Whether or not a migratory songbird embarks on a long-distance flight across an ecological barrier is likely a response to a number of endogenous and exogenous factors. During autumn 2008 and 2009, we used automated radio tracking to investigate how energetic condition, age, and weather influenced the departure timing and direction of Swainson’s thrushes ( Catharus ustulatus ) during migratory stopover along the northern coast of the Gulf of Mexico. Most birds left within 1 h after sunset on the evening following capture. Those birds that departed later on the first night or remained longer than 1 day were lean. Birds that carried fat loads sufficient to cross the Gulf of Mexico generally departed in a seasonally appropriate southerly direction, whereas lean birds nearly always flew inland in a northerly direction. We did not detect an effect of age or weather on departures. The decision by lean birds to reorient movement inland may reflect the suitability of the coastal stopover site for deposition of fuel stores and the motivation to seek food among more extensive forested habitat away from the barrier.

Behavioral Ecology and Sociobiology↗

USGS2001

Design and performance of a rugged standard operative temperature thermometer for avian studies

The lack of a truly satisfactory sensor which can characterize the thermal environment at the spatial scale experienced by small endotherms has hindered study of their thermoregulatory behavior. We describe a general design for a rugged, easily constructed sensor to measure standard operative temperature, Tes. We present specific designs for adult dark-eyed juncos (Junco hyemalis) and hatchling mallards (Anas platyrhynchos). Sensor response was stable and repeatable (??1.4%) over the course of several months. Over the range of conditions for which validation data were available (variable air temperature and wind with negligible net radiation), sensors predicted the mean net heat production of live animals to within ??0.023W (equivalent to ??1??C at Tes= 15??C). The main limit on accuracy was scatter in the data on metabolism and evaporative water loss in live animals. These sensors are far more rugged and easily constructed than the heated taxidermic mounts previously used to measure Tes. These characteristics facilitate the use of significant numbers of sensors in thermal mapping studies of endotherms. ?? 2001 Elsevier Science Ltd. All rights reserved.

Journal of Thermal Biology↗

USGS2014

Spatiotemporal variations in estrogenicity, hormones, and endocrine-disrupting compounds in influents and effluents of selected wastewater-treatment plants and receiving streams in New York, 2008-09

Endocrine-disrupting compounds (EDCs) in wastewater effluents have been linked to changes in sex ratios, intersex (in males), behavioral modifications, and developmental abnormalities in aquatic organisms. Yet efforts to identify and regulate specific EDCs in complex mixtures are problematic because little is known about the estrogen activity (estrogenicity) levels of many common and emerging contaminants. The potential effects of EDCs on the water quality and health of biota in streams of the New York City water supply is especially worrisome because more than 150 wastewater-treatment plants (WWTPs) are permitted to discharge effluents into surface waters and groundwaters of watersheds that provide potable water to more than 9 million people. In 2008, the U.S. Geological Survey (USGS), the New York State Department of Environmental Conservation (NYSDEC), New York State Department of Health (NYSDOH), and New York City Department of Environmental Protection (NYCDEP) began a pilot study to increase the understanding of estrogenicity and EDCs in effluents and receiving streams mainly in southeastern New York. The primary goals of this study were to document and assess the spatial and temporal variability of estrogenicity levels; the effectiveness of various treatment-plant types to remove estrogenicity; the concentrations of hormones, EDCs, and pharmaceuticals, personal care products (PPCPs); and the relations between estrogenicity and concentrations of hormones, EDCs, and PPCPs. The levels of estrogenicity and selected hormones, non-hormone EDCs, and PPCPs were characterized in samples collected seasonally in effluents from 7 WWTPs, once or twice in effluents from 34 WWTPs, and once in influents to 6 WWTPs. Estrogenicity was quantified, as estradiol equivalents, using both the biological e-screen assay and a chemical model. Results generally show that (1) estrogenicity levels in effluents varied spatially and seasonally, (2) a wide range of known and unknown EDCs were present in both WWTP effluents and receiving streams, (3) some effluents may be important sources of estrogenicity in weakly diluted streams, (4) measured levels of biological estrogenicity were often higher than estimated levels of chemical estrogenicity, and (5) the type of treatment had a large effect on the removal efficacy, and consequently, the estrogenicity levels observed in treated effluents.

New York↗

USGS2015

Acoustical deterrence of Silver Carp ( Hypophthalmichthys molitrix )

The invasive Silver Carp ( Hypophthalmichthys molitrix ) dominate large regions of the Mississippi River drainage and continue to expand their range northward threatening the Laurentian Great Lakes. This study found that complex broadband sound (0–10 kHz) is effective in altering the behavior of Silver Carp with implications for deterrent barriers or potential control measures (e.g., herding fish into nets). The phonotaxic response of Silver Carp was investigated using controlled experiments in outdoor concrete ponds (10 × 4.9 × 1.2 m). Pure tones (500–2000 Hz) and complex sound (underwater field recordings of outboard motors) were broadcast using underwater speakers. Silver Carp always reacted to the complex sounds by exhibiting negative phonotaxis to the sound source and by alternating speaker location, Silver Carp could be directed consistently, up to 37 consecutive times, to opposite ends of the large outdoor pond. However, fish habituated quickly to pure tones, reacting to only approximately 5 % of these presentations and never showed more than two consecutive responses. Previous studies have demonstrated the success of sound barriers in preventing Silver Carp movement using pure tones and this research suggests that a complex sound stimulus would be an even more effective deterrent.

Biological Invasions↗

USGS2023

Potential economic consequences along migratory flyways from reductions in breeding habitat of migratory waterbirds

The migration of species, often across continents, makes it difficult to quantify the cumulative effects of local- and regional-scale conservation actions. Further, variation in stakeholder interests, differing jurisdictional governance processes, priorities, and monitoring abilities across the migratory range shapes place-specific differences in management actions. These differences may lead management of migratory species to benefit both species and stakeholders in some places more than others. In the case of North American waterfowl, possible reduction of wetland protection in breeding areas may lead to substantive shifts in benefits among stakeholders across their range by adversely affecting recreational viewing and hunting opportunities for these species. To understand possible consequences of wetland loss in the U.S. Prairie Pothole Region, the breeding region for 12 focal species of waterfowl, on the recreation economics for these species, we modeled a causal pathway linking wetland loss in the breeding grounds to changes in duck abundance and then assessed the consequences of that change in abundance on recreational hunting and viewing within migratory flyways. Under a scenario where wetland protections cease, we find annual economic activity associated with recreation may decrease as much as \$489 million at the highest levels of predicted wetland loss, the majority of it coming from impacts to viewing behavior in the Mississippi Flyway. The number of hunters may decline by as much as 18,000, leading to \$32 million less in annual economic activity. At highest levels of wetland loss, viewing value is expected to decline by more than one-quarter. Lost economic value associated with reductions in recreation in the Mississippi and Central Flyway states is not likely to be overcome by increases in agricultural economic output in drained wetlands of the Prairie Pothole Region. Our analyses indicate local effects of national water policies likely have far-reaching consequences because of the multi-dimensional connections arising from place-specific differences in management action, global and national agricultural economic drivers of crop expansion, and the biotic phenomena of transcontinental avian migration. Reductions in habitat in one location could ramify to economic consequences throughout the continent through connections fostered by migrating waterfowl.

Biological Conservation↗

USGS2019

Coast to coast: High genomic connectivity in North American scoters

Dispersal shapes demographic processes and therefore is fundamental to understanding biological, ecological, and evolutionary processes acting within populations. However, assessing population connectivity in scoters ( Melanitta sp.) is challenging as these species have large spatial distributions that span remote landscapes, have varying nesting distributions (disjunct vs. continuous), exhibit unknown levels of dispersal, and vary in the timing of the formation of pair bonds (winter vs. fall/spring migration) that may influence the distribution of genetic diversity. Here, we used double‐digest restriction‐associated DNA sequence (ddRAD) and microsatellite genotype data to assess population structure within the three North American species of scoter (black scoter, M. americana ; white‐winged scoter, M. deglandi ; surf scoter, M. perspicillata ), and between their European congeners (common scoter, M. nigra ; velvet scoter, M. fusca ). We uncovered no or weak genomic structure (ddRAD Φ ST < 0.019; microsatellite F ST < 0.004) within North America but high levels of structure among European congeners (ddRAD Φ ST > 0.155, microsatellite F ST > 0.086). The pattern of limited genomic structure within North America is shared with other sea duck species and is often attributed to male‐biased dispersal. Further, migratory tendencies (east vs. west) of female surf and white‐winged scoters in central Canada are known to vary across years, providing additional opportunities for intracontinental dispersal and a mechanism for the maintenance of genomic connectivity across North America. In contrast, the black scoter had relatively elevated levels of divergence between Alaska and Atlantic sites and a second genetic cluster found in Alaska at ddRAD loci was concordant with its disjunct breeding distribution suggestive of a dispersal barrier (behavioral or physical). Although scoter populations appear to be connected through a dispersal network, a small percentage (<4%) of ddRAD loci had elevated divergence which may be useful in linking areas (nesting, molting, staging, and wintering) throughout the annual cycle.

North America↗