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At least 775 records · Page 43Linked to original sources
USGS2020

Differences in rhizosphere microbial communities between native and non‐native Phragmites australis may depend on stand density

Microorganisms surrounding plant roots may benefit invasive species through enhanced mutualism or decreased antagonism, when compared to surrounding native species. We surveyed the rhizosphere soil microbiome of a prominent invasive plant, Phragmites australis , and its co‐occurring native subspecies for evidence of microbial drivers of invasiveness. If the rhizosphere microbial community is important in driving plant invasions, we hypothesized that non‐native Phragmites would cultivate a different microbiome from native Phragmites , containing fewer pathogens, more mutualists, or both. We surveyed populations of native and non‐native Phragmites across Michigan and Ohio USA, and we described rhizosphere microbial communities using culture‐independent next‐generation sequencing. We found little evidence that native and non‐native Phragmites cultivate distinct bacterial, fungal, or oomycete rhizosphere communities. Microbial community differences in our Michigan survey were not associated with plant lineage but were mainly driven by environmental factors, such as soil saturation and nutrient concentrations. Intensive sampling along transects consisting of dense monocultures of each lineage and mixed zones revealed bacterial community differences between lineages in dense monoculture, but not in mixture. We found no evidence of functional differences in the microbial communities surrounding each lineage. We extrapolate that the invasiveness of non‐native Phragmites , when compared to its native congener, does not result from the differential cultivation of beneficial or antagonistic rhizosphere microorganisms.

Michigan, Ohio↗
USGS2025

Pan-amphibia distribution of the fungal parasite Batrachochytrium dendrobatidis varies with species and temperature

Batrachochytrium dendrobatidis (Bd) is a globally distributed fungal pathogen of amphibians that has contributed to one of the largest disease-related biodiversity losses in wildlife. Bd is regularly viewed through the lens of a global wildlife epizootic because the spread of highly virulent genetic lineages has resulted in well-documented declines and extinctions of multiple amphibian species. However, the current state of Bd occurrence, host range, host impacts, and ecological drivers remains poorly understood outside of the most negatively affected amphibian species and regions. Our objective was to describe the macroecology of Bd occurrence and infection intensity on caudates (salamanders) across the United States and to compare these patterns with better-studied anurans (frogs and toads). We collected swabs from 11,183 amphibians at 609 sites from 54 species across the United States from 2015 to 2017. We analyzed the prevalence and intensity of Bd infection jointly using a Bayesian hurdle model with covariates of site-level temperature and precipitation, as well as individual characteristics and species identification. Bd was distributed widely across sites and species sampled across the spatial extent of the conterminous United States. We found that Bd prevalence and intensity were most strongly influenced by temperature in the month preceding sampling and by differences among taxon groups. We estimated that temperature had a strong and nonlinear influence on both Bd prevalence and intensity with peak infection at intermediate temperatures and lower infection at low and high temperatures. We found Caudate hosts tended to have higher prevalence than Anuran hosts and Anuran hosts tended to have higher intensity at optimal temperatures for Bd infection. Our findings suggest that Bd has an amphibian-wide host range, temperature gradients exert a strong influence on Bd, and enzootic transmission likely encompasses a much larger spatial and species distribution than previously recognized across North America.

conterminous United States↗
USGS2016

Tick-, mosquito-, and rodent-borne parasite sampling designs for the National Ecological Observatory Network

Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term time series data on infection rates among vectors and reservoirs, the National Ecological Observatory Network (NEON) will collect measurements and samples of a suite of tick-, mosquito-, and rodent-borne parasites through a continental-scale surveillance program. Here, we describe the sampling designs for these efforts, highlighting sampling priorities, field and analytical methods, and the data as well as archived samples to be made available to the research community. Insights generated by this sampling will advance current understanding of and ability to predict changes in infection and disease dynamics in novel, interdisciplinary, and collaborative ways.

Ecosphere↗
USGS2016

Factors that affect parasitism of black-tailed prairie dogs by fleas

Fleas (Insecta: Siphonaptera) are hematophagous ectoparasites that feed on vertebrate hosts. Fleas can reduce the fitness of hosts by interfering with immune responses, disrupting adaptive behaviors, and transmitting pathogens. The negative effects of fleas on hosts are usually most pronounced when fleas attain high densities. In lab studies, fleas desiccate and die under dry conditions, suggesting that populations of fleas will tend to decline when precipitation is scarce under natural conditions. To test this hypothesis, we compared precipitation vs. parasitism of black-tailed prairie dogs ( Cynomys ludovicianus ) by fleas at a single colony during May and June of 13 consecutive years (1976–1988) at Wind Cave National Park, South Dakota, USA. The number of fleas on prairie dogs decreased with increasing precipitation during both the prior growing season (April through August of the prior year) and the just-completed winter–spring (January through April of current year). Due to the reduction in available moisture and palatable forage in dry years, herbivorous prairie dogs might have been food-limited, with weakened behavioral and immunological defenses against fleas. In support of this hypothesis, adult prairie dogs of low mass harbored more fleas than heavier adults. Our results have implications for the spread of plague, an introduced bacterial disease, transmitted by fleas, that devastates prairie dog colonies and, in doing so, can transform grassland ecosystems.

Ecosphere↗
USGS2016

Whitebark pine mortality related to white pine blister rust, mountain pine beetle outbreak, and water availability

Whitebark pine ( Pinus albicaulis ) forests in the western United States have been adversely affected by an exotic pathogen ( Cronartium ribicola , causal agent of white pine blister rust), insect outbreaks ( Dendroctonus ponderosae , mountain pine beetle), and drought. We monitored individual trees from 2004 to 2013 and characterized stand-level biophysical conditions through a mountain pine beetle epidemic in the Greater Yellowstone Ecosystem. Specifically, we investigated associations between tree-level variables (duration and location of white pine blister rust infection, presence of mountain pine beetle, tree size, and potential interactions) with observations of individual whitebark pine tree mortality. Climate summaries indicated that cumulative growing degree days in years 2006–2008 likely contributed to a regionwide outbreak of mountain pine beetle prior to the observed peak in whitebark mortality in 2009. We show that larger whitebark pine trees were preferentially attacked and killed by mountain pine beetle and resulted in a regionwide shift to smaller size class trees. In addition, we found evidence that smaller size class trees with white pine blister rust infection experienced higher mortality than larger trees. This latter finding suggests that in the coming decades white pine blister rust may become the most probable cause of whitebark pine mortality. Our findings offered no evidence of an interactive effect of mountain pine beetle and white pine blister rust infection on whitebark pine mortality in the Greater Yellowstone Ecosystem. Interestingly, the probability of mortality was lower for larger trees attacked by mountain pine beetle in stands with higher evapotranspiration. Because evapotranspiration varies with climate and topoedaphic conditions across the region, we discuss the potential to use this improved understanding of biophysical influences on mortality to identify microrefugia that might contribute to successful whitebark pine conservation efforts. Using tree-level observations, the National Park Service-led Greater Yellowstone Interagency Whitebark Pine Long-term Monitoring Program provided important ecological insight on the size-dependent effects of white pine blister rust, mountain pine beetle, and water availability on whitebark pine mortality. This ongoing monitoring campaign will continue to offer observations that advance conservation in the Greater Yellowstone Ecosystem.

Ecosphere↗
USGS2018

Estimating the probability of movement and partitioning seasonal survival in an amphibian metapopulation

Movement of individuals has been described as one of the best studied, but least understood concepts in ecology. The magnitude of movements, routes, and probability of movement have significant application to conservation. Information about movement can inform efforts to model species persistence and is particularly applicable in situations where specific threats (e.g., disease) may depend on the movement of hosts and potential vectors. We estimated the probability of movement (breeding dispersal and permanent emigration) in a metapopulation of 16 breeding sites for boreal toads ( Anaxyrus boreasboreas ). We used a multi‐state mark–recapture approach unique in its complexity (16 sites over 18 yr) to address questions related to these movements and variation in resident survival. We found that individuals had a 1–2% probability of dispersing in a particular year and that approximately 10–20% of marked individuals were transient and observed in the metapopulation only once. Resident survival probabilities differed by season, with 71–90% survival from emergence from hibernation through early post‐breeding and >97% survival from mid‐/late active season through hibernation. Movement‐related probabilities are needed to predict species range expansions and contractions, estimate population and metapopulation dynamics, understand host–pathogen and native–invasive species interactions, and to evaluate the relative effects of proposed management actions.

Colorado↗
USGS2020

Flea sharing among sympatric rodent hosts: implications for potential plague effects on a threatened sciurid

For vector-borne diseases, the abundance and competency of different vector species and their host preferences will impact the transfer of pathogens among hosts. Sylvatic plague is a lethal disease caused by the primarily flea-borne bacterium Yersinia pestis . Sylvatic plague was introduced into the western United States in the early 1900s and impacts many species of rodents. Plague may be suppressing populations of the threatened northern Idaho ground squirrel ( Urocitellus brunneus ) if a competent flea community is allowing plague to be maintained within the few extant sites that support this rare ground squirrel. We collected fleas from four species of sympatric rodents in central Idaho: northern Idaho ground squirrels, Columbian ground squirrels ( Urocitellus columbianus ), yellow-pine chipmunks ( Tamias amoenus ), and deer mice ( Peromyscus maniculatus ). We evaluated which flea species were present and whether fleas were shared among the rodent community. We documented seven species of fleas among 3356 fleas collected from the four host species of rodents, and all seven species of fleas are known vectors of plague. Three of the seven flea species were detected on all four rodent species, demonstrating potential for spillover of plague (bridge vectors) in the rodent community. We used generalized linear mixed models to evaluate which abiotic and biotic factors influence flea abundance (total number of fleas, regardless of flea species, on each individual host of the four rodent host species). Factors that impacted flea abundance varied among the four host species, but flea abundance: (1) changed over summer depending on host species, (2) was greater on males, and (3) was impacted by summer and winter precipitation depending on host species. Our results suggest this diverse flea community has the capacity to transfer Y. pestis among populations of the four rodents if Y. pestis is present. Furthermore, the disease may be more likely to persist in some locations than others, those that have higher flea abundances, more sympatric hosts, or optimal conditions for fleas, and such high-risk sites can be identified based on their abiotic and biotic factors.

Idaho↗
USGS2021

Hippopotamus movements structure the spatiotemporal dynamics of an active anthrax outbreak

Globally, anthrax outbreaks pose a serious threat to people, livestock, and wildlife. Furthermore, environmental change can exacerbate these outbreak dynamics by altering the host–pathogen relationship. However, little is known about how the quantitative spatial dynamics of host movement and environmental change may affect the spread of Bacillus anthracis , the causative agent of anthrax. Here, we use real-time observations and high-resolution tracking data from a population of common hippopotamus ( Hippopotamus amphibius ) in Tanzania to explore the relationship between river hydrology, H. amphibius movement, and the spatiotemporal dynamics of an active anthrax outbreak. We found that extreme river drying, a consequence of anthropogenic disturbances to our study river, indirectly facilitated the spread of B. anthracis by modulating H. amphibius movements. Our findings reveal that anthrax spread upstream in the Great Ruaha River (~3.5 km over a 9-day period), which followed the movement patterns of infected H. amphibius , who moved upstream as the river dried in search of remaining aquatic refugia. These upstream movements can result in large aggregations of H. amphibius . However, despite these aggregations, the density of H. amphibius in river pools did not influence the number of B. anthracis -induced mortalities. Moreover, infection by B. anthracis did not appear to influence H. amphibius movement behaviors, which suggests that infected individuals can vector B. anthracis over large distances right up until their death. Finally, we show that contact rates between H. amphibius- and B. anthracis- infected river pools are highly variable and the frequency and duration of contacts could potentially increase the probability of mortality. While difficult to obtain, the quantitative insights that we gathered during a real-time anthrax outbreak are critical to better understand, predict, and manage future outbreaks.

Ruaha National Park↗
USGS2024

Effects of Mycoplasma ovipneumoniae, abundance, and environmental conditions on bighorn sheep lamb:ewe ratios and adult survival in New Mexico

Mycoplasma ovipneumoniae is a primary causative agent responsible for initiating polymicrobial pneumonia in bighorn sheep ( Ovis canadensis ). Infections of bighorn sheep populations are typically characterized by initial all-age epizootics followed by long-term periods of repressed juvenile (lamb) survival. Populations of bighorn sheep in New Mexico, USA, were thought to be free of this pathogen prior to 2017 but recent infection of multiple herds raised concerns regarding impacts on population size and juvenile:female ratios. Using aerial survey, survival, and disease sampling data in an exploratory framework, we (1) characterize age-related differences in M. ovipneumoniae prevalence and seroprevalence, (2) quantify differences in lamb:ewe ratios pre- and post- M. ovipneumoniae detection, and (3) investigate differences in survival between previously exposed and naïve individuals. From 2007 to 2022, we sampled 466 bighorn sheep across 19 populations in New Mexico for M. ovipneumoniae exposure. While the timing of initial herd infections varied across populations, one population sustained active infections for over 15 years. We found reduced juvenile:female ratios post M. ovipneumoniae exposure for both desert ( O. c. mexicana ) and Rocky Mountain ( O. c. canadensis ) bighorn sheep populations. Post-exposure ratio declines ranged from 20% to 69%. Evaluation of population size and environmental condition effects on juvenile:female ratios indicated varying impacts for each subspecies. Notably, population size was negatively related to Rocky Mountain juvenile:female ratios only after populations were exposed to M. ovipneumoniae . Additionally, climatic conditions in the previous lambing season and pre-parturition time frame were associated with juvenile:female ratios for Rocky Mountain populations, while juvenile:female ratios of desert bighorn appeared to only be affected by pre-parturition climatic conditions. Kaplan–Meier survival estimation of previously exposed, but putatively recovered, individuals ( n = 31) and naïve individuals ( n = 70) revealed lower (75%; 95% CI: 62%–93%) but not statistically significant ( p = 0.2) 1-year survival rates for individuals that were seropositive but not actively infected, when compared to seronegative individuals (88%; 95% CI: 81%–97%). These results collectively suggest that following M. ovipneumoniae introduction, bighorn sheep populations in New Mexico could be limited by lamb survival.

New Mexico↗
USGS2025

Unintended indirect effects limit elk productivity from supplemental feeding in the Greater Yellowstone Ecosystem

The widespread practice of supplemental feeding, a bottom-up forcing of resource availability, is intended to improve wildlife population health and survival. However, supplemental feeding could trigger indirect effects by altering predation rates and disease dynamics. We investigated the effects of feeding on three key elk ( Cervus canadensis ) population productivity metrics (calf:cow ratios, annual change in elk density, and harvestable surplus) across 13 regions in the Greater Yellowstone Ecosystem (GYE) over 26 years. Incorporating previous population size, climate, predator, and harvest data in a Bayesian regression framework revealed new insights about elk productivity metrics in the GYE. Supplemental feeding was associated with increased calf:cow ratios (4.9%) but was not substantially related to changes in elk density and harvestable surplus, which are both management targets. Notably, the feeding effect on calf:cow ratios appeared to be offset by increased wolf ( Canis lupus ) and grizzly bear ( Ursus arctos horribilis ) predation. We hypothesize that increased elk productivity resulting from supplemental feeding is primarily transferred to predator and pathogen trophic levels in this system with limited observed effects on elk abundance and harvestable surplus. Anthropogenic food resources may have unintended indirect consequences on other trophic levels that potentially limit the direct impacts of feeding.

Idaho, Montana, Wyoming↗
USGS2017

Using decision analysis to support proactive management of emerging infectious wildlife diseases

Despite calls for improved responses to emerging infectious diseases in wildlife, management is seldom considered until a disease has been detected in affected populations. Reactive approaches may limit the potential for control and increase total response costs. An alternative, proactive management framework can identify immediate actions that reduce future impacts even before a disease is detected, and plan subsequent actions that are conditional on disease emergence. We identify four main obstacles to developing proactive management strategies for the newly discovered salamander pathogen Batrachochytrium salamandrivorans ( Bsal ). Given that uncertainty is a hallmark of wildlife disease management and that associated decisions are often complicated by multiple competing objectives, we advocate using decision analysis to create and evaluate trade-offs between proactive (pre-emergence) and reactive (post-emergence) management options. Policy makers and natural resource agency personnel can apply principles from decision analysis to improve strategies for countering emerging infectious diseases.

Frontiers in Ecology and the Environment↗
USGS2019

Successful molecular detection studies require clear communication among diverse research partners

Molecular detection techniques are powerful tools used in ecological applications ranging from diet analyses to pathogen surveillance. Research partnerships that use these tools often involve collaboration among professionals with expertise in field biology, laboratory techniques, quantitative modeling, wildlife disease, and natural resource management. However, in many cases, each of these collaborators lacks specific knowledge about the approaches, decisions, methods, and terminology used by their research partners, which can impede effective communication and act as a barrier to the efficient use of molecular data for ecological inferences and subsequent conservation decision making. We outline a collaborative framework to assist colleagues with diverse types of expertise to effectively translate their scientific and management needs to research partners from other specialties. The molecular techniques used to detect organisms will continue to advance both in sophistication and in the breadth of ecological applications. Our objective is to enable ecologists to harness the full utility of these methods by developing effective collaborative partnerships.

Frontiers in Ecology and the Environment↗
USGS2025

Integrating climate change, biological invasions, and infectious wildlife diseases

Climate change is likely to affect infectious diseases that are facilitated by biological invasions, with repercussions for wildlife conservation and zoonotic risks. Current invasion management and policy are underprepared for the future risks associated with such invasion-related wildlife diseases. By considering evidence from bioclimatology, invasion biology, and disease research, we illustrate how climate change is anticipated to affect disease agents (parasites and pathogens), hosts, and vectors across the different stages of invasions. We highlight the opportunity to integrate these disciplines to identify the effects of climate change on invasion related wildlife diseases. In addition, shifting to a proactive stance in implementing management and policy, such as by incorporating climate-change effects either into preventative and mitigation measures for biosecurity or with rapid response protocols to limit disease spread and impacts, could help to combat future ecological, economic, and human health risks stemming from invasion-related wildlife diseases.

Frontiers in Ecology and the Environment↗
USGS2023

Environmental DNA as a tool for better understanding the distribution, abundance, and health of Atlantic and Pacific salmon

The development and application of approaches to detect and quantify environmental DNA (eDNA) have potential to improve our understanding of the distribution, abundance, and health of Atlantic Salmon Salmo salar and Pacific salmon Oncorhynchus spp. Here, we review 61 articles focusing on eDNA applications pertaining to salmon occupying natural habitat and aquaculture facilities in the context of advances, opportunities, and challenges. Given recent advances, eDNA now serves as a useful tool for detecting Atlantic Salmon and Pacific salmon and understanding threats to the health of fish and their habitats. Opportunities exist to apply sensitive and minimally invasive eDNA approaches to detect fish and assess fish habitat, assess range expansions of salmon and salmon pathogens, and detect invasive species that may threaten salmon health and abundance. Near real-time eDNA detection and quantification approaches to inform fisheries management may be on the horizon. Challenges limiting the widespread application of eDNA approaches for informing salmon management include accounting for the many factors affecting detection and quantification of eDNA, limits of data for deriving inference, and expense. Through continued development and refinement, eDNA approaches are anticipated to become increasingly available to, and utilized by, managers of Atlantic Salmon and Pacific salmon fisheries.

Fisheries Magazine↗
USGS2016

Behavioral connectivity among bighorn sheep suggests potential for disease spread

Connectivity is important for population persistence and can reduce the potential for inbreeding depression. Connectivity between populations can also facilitate disease transmission; respiratory diseases are one of the most important factors affecting populations of bighorn sheep ( Ovis canadensis ). The mechanisms of connectivity in populations of bighorn sheep likely have implications for spread of disease, but the behaviors leading to connectivity between bighorn sheep groups are not well understood. From 2007–2012, we radio-collared and monitored 56 bighorn sheep in the Salmon River canyon in central Idaho. We used cluster analysis to define social groups of bighorn sheep and then estimated connectivity between these groups using a multi-state mark-recapture model. Social groups of bighorn sheep were spatially segregated and linearly distributed along the Salmon River canyon. Monthly probabilities of movement between adjacent male and female groups ranged from 0.08 (±0.004 SE) to 0.76 (±0.068) for males and 0.05 (±0.132) to 0.24 (±0.034) for females. Movements of males were extensive and probabilities of movement were considerably higher during the rut. Probabilities of movement for females were typically smaller than those of males and did not change seasonally. Whereas adjacent groups of bighorn sheep along the Salmon River canyon were well connected, connectivity between groups north and south of the Salmon River was limited. The novel application of a multi-state model to a population of bighorn sheep allowed us to estimate the probability of movement between adjacent social groups and approximate the level of connectivity across the population. Our results suggest high movement rates of males during the rut are the most likely to result in transmission of pathogens among both male and female groups. Potential for disease spread among female groups was smaller but non-trivial. Land managers can plan grazing of domestic sheep for spring and summer months when males are relatively inactive. Removal or quarantine of social groups may reduce probability of disease transmission in populations of bighorn sheep consisting of linearly distributed social groups.

Journal of Wildlife Management↗
USGS2021

Waif gopher tortoise survival and site fidelity following translocation

Gopher tortoises ( Gopherus polyphemus ) are among the most commonly translocated reptiles. Waif tortoises are animals frequently of unknown origin that have been displaced from the wild and often held in human possession for various reasons and durations. Although there are risks associated with any translocation, waif tortoises are generally excluded from translocation projects because of heightened concerns of introducing pathogens and uncertainty about the post-release survival of these individuals. If these risks could be managed, waif tortoises could have conservation value because they can provide the needed numbers to stabilize populations. In the early 1990s, the discovery of an isolated population of gopher tortoises (≤15 individuals) near Aiken, South Carolina, USA, prioritized establishment of the Aiken Gopher Tortoise Heritage Preserve (AGTHP). Because of the population's need for augmentation and the site's isolation from other tortoise populations, the AGTHP provided the opportunity to evaluate the post-release survival of translocated waif tortoises without compromising a viable population. Since 2006, >260 waif tortoises have been introduced to the preserve. Using a Cormack-Jolly-Seber modeling framework to analyze release records and capture histories from trapping efforts in 2017 and 2018, we estimated the long-term apparent survival and site fidelity of this population composed largely of waif tortoises. We estimated annual apparent survival probabilities to be high (≥0.90) for subadult, adult male, and adult female tortoises, and these rates were similar to those reported for wild-to-wild translocated gopher tortoises and those from unmanipulated populations. Of the tortoises recaptured within the boundaries of the preserve, 75% were located within 400 m of their release location. These results suggest that waif tortoises could be an important resource in reducing the extirpation risk of isolated populations. © 2021 The Wildlife Society.

South Carolina↗
USGS2022

Disease and secondary sexual traits: Effects of pneumonia on horn size of bighorn sheep

Secondary sexual traits (e.g., horns and antlers) have ecological and evolutionary importance and are of management interest for game species. Yet, how these traits respond to emerging threats like infectious disease remains underexplored. Infectious pneumonia threatens bighorn sheep ( Ovis canadensis ) populations across North America and we hypothesized it may also reduce horn growth in male sheep. We assess the effect of pneumonia on horn size in male bighorn sheep using 12 herd datasets from across the western United States that had horn growth and disease data. Disease resulted in 12–35% reduction in increment (yearly) length and 3–13% reduction in total horn length in exposed individuals. The disease effect was prolonged when pathogens continued to circulate in sheep populations. Further, disease likely delays the age at which horns reach ¾-curl and prevents achievement of full-curl. This is further evidenced with 6 of the 12 herds experiencing an increase in average age at harvest following die-off events.

Colorado, Idaho, Montana, Utah, Washington, Wyomin↗
USGS2024

Sampling for disease surveillance: Assessing effects on blue-winged teal survival and recovery

Outbreaks of highly pathogenic avian influenza virus in wild animals highlight the need for disease surveillance in wild birds to improve our understanding of their role as reservoirs and dispersers, and potential threats to domestic poultry and wild bird populations. Surveillance for avian influenza varies in its approach, objectives, and coordination with other monitoring efforts. For waterfowl, a common host to avian influenza viruses, banding represents a concerted effort of capturing and marking thousands of individuals annually to estimate survival and harvest rates, but users of these data have generally taken a conservative approach to remove any banded birds from analyses that had a sample taken for disease surveillance during capture. We tested for differences in survival and encounter probabilities of blue-winged teal ( Spatula discors ) marked ( n = 21,702 teal) and sampled for disease surveillance ( n = 4,216) during the nonbreeding season in Louisiana, USA, from 2016 to 2023. Although we found no consistent effect of collecting biological samples on survival probability, including an additional test showing no detectable effects of sampling for disease surveillance with oropharyngeal and cloacal swabs versus sampling with swabs and a syringe-drawn blood sample, wide 95% credible intervals on the posterior survival estimates (mean 0.36 difference between upper and lower values across all year-sex-sampling groups; 0.44 for sampling type groups) indicated low statistical power to detect an effect. Seber recovery probability during the first interval following sampling was lower among birds sampled using swabs only, but we assume this stems from low sample sizes rather than an effect of collecting biological samples. Because recovery probabilities can vary as a function of individual covariates, we also examined direct recovery probabilities and observed no meaningful effect of disease surveillance sampling type but strong effects of capture date, suggesting the effect on Seber recovery probability may have been due to heterogeneity in exposure to natural and harvest mortality risks. Although we suggest that aligning disease surveillance sample collection efforts with landscape-scale waterfowl banding efforts may have little effect on observed demographic rates, additional studies with larger sample sizes are likely needed to provide the statistical power necessary to formally conclude no effect of biological sampling on survival probabilities.

Louisiana↗