Reproductive success and contaminant associations in tree swallows (Tachycineta bicolor) used to assess a Beneficial Use Impairment in U.S. and Binational Great Lakes' Areas of Concern

Per- and Polyfluoroalkyl Substances in the Duluth, Minnesota Area: Exposure to and Biomarker Responses in Tree Swallows Relative to Known Fire-Fighting Foam Sources

Tree swallow nest boxes were deployed at sites proximal to two putative aqueous film forming foam (AFFF) sources in the Duluth, MN area, as well as along the St. Louis River and a reference lake for comparative purposes in 2019, 2020 and 2021. The two AFFF sites were the current Duluth Air National Guard Base (ANG) and the Lake Superior College Emergency Response Training Center. Between 13 and 40 per- and polyfluoroalkyl substances (PFAS), depending on year, were detected and quantified in tree swallow egg, nestling carcasses, and stomach contents. Assessments were made of oxidative stress and ethoxyresorufin-O-dealkylase activity in liver tissue, thyroid hormone levels in plasma and thyroid glands, DNA damage in red blood cells, and two measures of immune response (haptoglobin-like activity and immunoglobulin) in plasma of the nestlings. Additionally, other contaminants, such as polychlorinated biphenyls, legacy organochlorine pesticides, and trace elements, were assessed at sites with no previous data. Total egg PFAS concentrations at the ANG site and north of that site were 30-40 times higher than at the reference lake, while nestling PFAS concentrations were 10-15 times higher. In contrast, the St. Louis River sites had slightly, but non-statistically significant, elevated egg and nestling PFAS concentrations relative to the reference lake (2-5 times higher). One PFAS, perfluorohexane sulfonate (PFHxS), was higher, as a proportion of total PFAS, at sites with a known AFFF source compared to the reference lake, as well as compared to sites along the St. Louis River with mainly urban and industrial sources of PFAS. The ratio of total carboxylates to total sulfonates also distinguished between PFAS sources. There were few to no differences in biomarker responses among sites, and no association with PFAS exposure.

Sublethal effects of early-life exposure to common and emerging contaminants in birds

The plight of wild birds is becoming critical due to exposure to environmental contaminants. Although laboratory studies have provided insights into the developmental effects of chemical exposures, less is known about the adverse effects of environmental chemicals in developing wild birds. Early life stages are critical windows during which long-term organization of physiological, behavioral, and neurological systems can occur. Thus, contaminant exposure at early life stages can directly influence survival and reproductive success, with consequences for population stability and resilience in wild species. This review synthesizes existing knowledge regarding both short- and long-term effects of early-life exposure to widespread contaminants in birds. We focus especially on wild birds and on contaminants of concern within the Gulf of Mexico as an example of a habitat under anthropogenic stress from exposure to a complex mixture of chemicals and changing land uses that exacerbate existing vulnerabilities of wildlife in this region. Chemical contaminants for discussion in this review are based on avian mortality records from the Wildlife Health Information Sharing Partnership (WHISPers) database and on additional review of the literature regarding avian contaminants of concern for the northern Gulf of Mexico, and include oil and associated polycyclic aromatic hydrocarbons, dioxin and dioxin-like compounds, flame retardants, pesticides, heavy metals, and plastics. We provide an overview of effects in bird species at both the pre-hatching and post-hatching early life stages, discuss differences in sensitivities by route of exposure, life stage, and life history, and provide recommendations for future research. We find that additional research is needed on altricial species, post-hatching early-life exposure, long-term effects, and on ecologically relevant contaminant concentrations and routes of exposure. Given the increasing frequency and intensity of anthropogenic stressors encountered by wild animals, understanding both lethal and sublethal impacts of contaminants on the health of individuals and populations will be critical to inform restoration, management, and mitigation efforts.

Wildlife ecological risk assessment in the 21st century: Promising technologies to assess toxicological effects

Despite advances in toxicity testing and the development of new approach methodologies (NAMs) for hazard assessment, the ecological risk assessment (ERA) framework for terrestrial wildlife (i.e., air-breathing amphibians, reptiles, birds, and mammals) has remained unchanged for decades. While survival, growth, and reproductive endpoints derived from whole-animal toxicity tests are central to hazard assessment, nonstandard measures of biological effects at multiple levels of biological organization (e.g., molecular, cellular, tissue, organ, organism, population, community, ecosystem) have the potential to enhance the relevance of prospective and retrospective wildlife ERAs. Other factors (e.g., indirect effects of contaminants on food supplies and infectious disease processes) are influenced by toxicants at individual, population, and community levels, and need to be factored into chemically based risk assessments to enhance the "eco" component of ERAs. Regulatory and logistical challenges often relegate such nonstandard endpoints and indirect effects to postregistration evaluations of pesticides and industrial chemicals and contaminated site evaluations. While NAMs are being developed, to date, their applications in ERAs focused on wildlife have been limited. No single magic tool or model will address all uncertainties in hazard assessment. Modernizing wildlife ERAs will likely entail combinations of laboratory- and field-derived data at multiple levels of biological organization, knowledge collection solutions (e.g., systematic review, adverse outcome pathway frameworks), and inferential methods that facilitate integrations and risk estimations focused on species, populations, interspecific extrapolations, and ecosystem services modeling, with less dependence on whole-animal data and simple hazard ratios. Integr Environ Assess Manag 2024;20:725-748. © 2023 His Majesty the King in Right of Canada and The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Reproduced with the permission of the Minister of Environment and Climate Change Canada. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Exposure to and Biomarker Responses From Legacy and Emerging Contaminants Along Three Drainages in the Milwaukee Estuary, Wisconsin, USA

Legacy contaminants and contaminants of emerging concern (CECs) were assessed in tree swallow (Tachycineta bicolor) tissue and diet samples from three drainages in the Milwaukee estuary, Wisconsin, USA, to understand exposures and possible biomarker responses. Two remote Wisconsin lakes were assessed for comparative purposes. Bioaccumulative classes of contaminants, such as polybrominated diphenyl ethers and per- and polyfluoroalkyl substances, while at higher concentrations than the reference lakes, did not vary significantly among sites or among the three drainages. Polycyclic aromatic hydrocarbons were assessed in diet and sediment and were from primarily pyrogenic sources. Ten biomarkers were assessed relative to contaminant exposure. Polychlorinated biphenyls (PCBs) were elevated above reference conditions at all Milwaukee sites but did not correlate with any measured biomarker responses. Only one site, Cedarburg, just downstream from a Superfund site, had elevated PCBs compared to other sites in the Milwaukee estuary. Few non-organochlorine insecticides or herbicides were detected in tree swallow liver tissue, except for the atrazine metabolite desethylatrazine. Few pharmaceuticals and personal care products were detected in liver tissue except for N,N-diethyl-meta-toluamide, iopamidol, and two antibiotics. The present study is one of the most comprehensive assessments to date, along with the previously published Maumee River data, on the exposure and effects of a wide variety of CECs in birds. Environ Toxicol Chem 2024;00:1-22. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Systematic review of avian hatching failure and implications for conservation

Avian hatching failure is a widespread phenomenon, affecting around 10% of all eggs that are laid and not lost to predation, damage, or desertion. Our understanding of hatching failure is limited in terms of both its underpinning mechanisms and its occurrence across different populations. It is widely acknowledged that rates of hatching failure are higher in threatened species and in populations maintained in captivity compared to wild, non-threatened species, but these differences have rarely been quantified and any broader patterns remain unexplored. To examine the associations between threat status, management interventions, and hatching failure across populations we conducted a phylogenetically controlled multilevel meta-analysis across 231 studies and 241 species of birds. Our data set included both threatened (Critically Endangered, Endangered, and Vulnerable) and non-threatened (Near Threatened and Least Concern) species across wild and captive populations, as well as 'wild managed' ('free-living') populations. We found the mean overall rate of hatching failure across all populations to be 16.79%, with the hatching failure rate of wild, non-threatened species being 12.40%. We found that populations of threatened species experienced significantly higher mean hatching failure than populations of non-threatened species. Different levels of management were also associated with different rates of hatching failure, with wild populations experiencing the lowest rate of hatching failure, followed by wild managed populations, and populations in captivity experiencing the highest rate. Similarly, populations that were subject to the specific management interventions of artificial incubation, supplementary feeding, and artificial nest provision displayed significantly higher rates of hatching failure than populations without these interventions. The driver of this correlation between hatching failure and management remains unclear, but could be an indirect result of threatened species being more likely to have lower hatching success and also being more likely to be subject to management, indicating that conservation efforts are fittingly being focused towards the species potentially most at risk from extinction. This is the most comprehensive comparative analysis of avian hatching failure that has been conducted to date, and the first to quantify explicitly how threat status and management are associated with the rate of hatching failure in a population. We discuss the implications of our results, focusing on their potential applications to conservation. Although we identified several factors clearly associated with variation in hatching failure, a significant amount of heterogeneity was not explained by our meta-analytical model, indicating that other factors influencing hatching failure were not included here. We discuss what these factors might be and suggest avenues for further research. Finally, we discuss the inconsistency in how hatching failure is defined and reported within the literature, and propose a standardised definition to be used in future studies which will enable better comparison across populations and ensure that the most accurate information is used to support management decisions.

Mercury exposure of tidal marsh songbirds in the northeastern United States and its association with nest survival

The biogeochemistry of tidal marsh sediments facilitates the transformation of mercury (Hg) into the biologically available form methylmercury (MeHg), resulting in elevated Hg exposures to tidal marsh wildlife. Saltmarsh and Acadian Nelson's sparrows (Ammospiza caudacutua and A. nelsoni subvirgatus, respectively) exclusively inhabit tidal marshes, potentially experiencing elevated risk to Hg exposure, and have experienced range-wide population declines. To characterize spatial and temporal variation of Hg exposure in these species, we sampled total mercury (THg) in blood collected from 9 populations spanning 560 km of coastline, including individuals resampled within and among years. Using concurrent nesting studies, we tested whether THg was correlated with nest survival probabilities, an index of fecundity. Blood THg ranged from 0.074-3.373 µg/g ww across 170 samples from 127 individuals. We detected high spatial variability in Hg exposure, observing differences of more than 45-fold across all individuals and 8-fold in mean blood THg among all study plots, including 4-fold between study plots within 4 km. Intraindividual changes in blood Hg exposure did not vary systematically in time but were considerable, varying by up to 2-fold within and among years. Controlling for both species differences and maximum water level, the dominant driver of fecundity in this system, nest survival probability decreased by 10% across the full range of female blood THg concentrations observed. We conclude that Hg has the potential to impair songbird reproduction, potentially exacerbating known climate-change driven population declines from sea-level rise in saltmarsh and Acadian Nelson's sparrows.

Linking field and laboratory studies: Reproductive effects of perfluorinated substances on avian populations

Although both laboratory and field studies are needed to effectively assess effects and risk of contaminants to free-living organisms, the limitations of each must be understood. The objectives of this paper are to examine information on field studies of reproductive effects of perfluorinated substances (PFASs) on bird populations, discuss the differences among field studies, and then place those results in context with laboratory studies. Hypotheses to explain the divergences between field studies and between laboratory and field studies will be discussed. Those differences include mixture issues, misattribution of the mechanism or the specific PFAS causing impairments, as well as other possible reasons. Finally, suggestions to better link laboratory and field studies will be presented. Integr Environ Assess Manag 2021;17:690-696. Published 2021. This article is a US Government work and is in the public domain in the USA.

Foraging Ecology Differentiates Life Stages and Mercury Exposure in Common Terns (Sterna hirundo)

Some populations of common terns (Sterna hirundo) breeding at inland lakes in North America are declining, including the Laurentian Great Lakes. Terns nesting at inland colonies forage in freshwater during the breeding season and primarily in coastal marine environments during the nonbreeding season. As piscivores, they are susceptible to dietary Hg exposure. To characterize patterns of Hg exposure in this population, we 1) quantified within and among season differences in total mercury (THg) concentrations (μg/g) in blood and feathers at 2 Lake Superior breeding colonies, and 2) documented spatial and temporal variation in exposure by studying adult foraging ecology using geospatial tracking devices and stable isotopes. We used general linear models to assess the relationship between isotopic composition and THg concentrations in bird tissues relative to sex, age, colony location, and season. The THg concentrations were lowest in winter-grown feathers (geometric mean [95% confidence limits]): 1.32 (1.09-1.59) μg/g dw (n = 60), higher at the more industrially influenced colony (chick feathers: 4.95 [4.62-5.37] μg/g dw [n = 20]), and increased with a riverine-based diet. During the breeding season, Hg exposure varied along a gradient from lake to river, with adult females having lower blood THg concentrations than males (females: 0.83 [0.67-1.03]) μg/g ww (n = 7); males: 1.15 (0.92-1.45) μg/g ww (n = 5). Stable isotope values suggested adults obtained 42 ± 12% (n = 12) of their diet from the river during incubation, which was validated with tracking data. During chick-rearing, chicks obtained 68 ± 19% (n = 44) of their diet from the river. Our results indicate colony location, foraging behavior, and season influenced Hg exposure for these Lake Superior colonies and underscores the importance of local contamination with respect to exposure. Integr Environ Assess Manag 2021;17:398-410. © 2020 SETAC.

Legacy and Contaminants of Emerging Concern in Tree Swallows Along an Agricultural to Industrial Gradient: Maumee River, Ohio

Exposure to multiple classes of contaminants, both legacy and contaminants of emerging concern (CECs), were assessed in tree swallow (Tachycineta bicolor) tissue and diet samples from 6 sites along the Maumee River, Ohio, USA, to understand both exposure and possible effects of exposure to those CECs for which there are little avian data. The 6 sites represented a gradient from intensive agriculture upstream to highly urbanized and industrial landscapes downstream; 1 or 2 remote Wisconsin lakes were assessed for comparative purposes. Cytochrome P450 induction, DNA damage, and thyroid function were also assessed relative to contaminant exposure. Bioaccumulative CECs, such as polybrominated diphenyl ethers (PBDEs) and perfluorinated substances, did not follow any upstream to downstream gradient; but both had significantly greater concentrations along the Maumee River than at the remote lake sites. Greater exposure to PBDEs was apparent in swallows at or near wastewater-treatment facilities than at other sites. Total polychlorinated biphenyl and total polycyclic aromatic hydrocarbon concentrations were greater in swallows at downstream locations compared to upstream sites and were associated with higher ethoxyresorufin-O-dealkylase activity. Few herbicides or nonorganochlorine insecticides were detected in swallow tissues or their food, except for atrazine and its metabolite desethylatrazine. Few pharmaceuticals and personal care products were detected except for DEET and iopamidol. Both were detected in most liver samples but not in eggs, as well as detected at the remote lake sites. This is one of the most comprehensive assessments to date of exposure and effects of a wide variety of CECs in birds. Environ Toxicol Chem 2020;39:1936-1952. © 2020 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Perfluoroalkyl Contaminant Exposure and Effects in Tree Swallows Nesting at Clarks Marsh, Oscoda, Michigan, USA

A site in northeastern Michigan, Oscoda Township, has some of the highest recorded exposure in birds to perfluorinated substances (PFASs) in the United States. Some egg and plasma concentrations at that location exceeded the lowest reproductive effect threshold established for two avian laboratory species. The objectives of this study were to determine whether there were reproductive effects or physiological responses in a model bird species, the tree swallow (Tachycineta bicolor), associated with this extremely high exposure to PFASs. The lack of exposure above background to other contaminants at this site allowed for an assessment of PFAS effects without the complication that responses may be caused by other contaminants. A secondary objective was to determine the distribution of PFASs in multiple tissue types to better understand and interpret residues in different tissues. This can best be done at highly exposed locations where tissue concentrations would be expected to be above detectable levels if they are present in that tissue. There were no demonstrable effects of PFAS exposure on reproduction nor on most physiological responses.

Element Concentrations in Tree Swallows (Tachycineta bicolor) from the U.S. and Binational Great Lakes Areas of Concern

Selected elements were targeted in state Remedial Action Plans as one group of chemicals affecting the Beneficial Use Impairments of Great Lakes Areas of Concern (AOCs). Livers of nestling tree swallows, Tachycineta bicolor, were harvested from 76 sites in the Great Lakes, which included multiple sites at 27 AOCs and 12 reference sites from 2010 to 2015, and were analyzed for 21 elements. Mercury concentrations were at background levels at all sites. Elevated cadmium (Cd) concentrations were associated with industry. The highest Cd values were from the Black River, OH AOC and were associated with historic coke production but were not at toxic levels. Lead (Pb) concentrations were highest on the Rouge River, MI AOC-the oldest and most heavily populated and industrialized area in southeast Michigan. Individual Pb concentrations were elevated to a level associated with delta-aminolaevulinic acid dehydratase inhibition but not to a level considered toxic. In contrast, livers harvested from sites on the southwest shore of Lake Michigan had selenium (Se) concentrations elevated to levels associated with reduced avian reproduction. One likely source of the high Se concentrations was pollution from a local coal-fired power plant. Concentrations of the remaining elements were at background levels.

Contaminants in bald eagles of the upper Midwestern U.S.: A framework for prioritizing future research based on in-vitro bioassays

Several organic contaminants (OCs) have been detected in bald eagle (Haliaeetus leucocephalus) nestling (eaglet) plasma in the upper Midwestern United States. Despite frequent and relatively high concentrations of OCs in eaglets, little is understood about potential biological effects associated with exposure. We screened an existing database of OC concentrations in eaglet plasma collected from the Midwestern United States against bioactivity information from the ToxCast database. ToxCast bioactivity information consists of concentrations expected to elicit responses across a range of biological space (e.g. cellular, developmental, etc.) obtained from a series of high throughput assays. We calculated exposure-activity ratios (EAR) by calculating the ratio of plasma concentrations to concentrations available in ToxCast. Bioactivity data were not available for all detected OCs. Therefore, our analysis provides estimates of potential bioactivity for 19 of the detected OCs in eaglet plasma. Perfluorooctanesulfonic acid (PFOS) EAR values were consistently the highest among all study areas. Maximum EAR values were ≥1 for PFOS, perfluorononanoic acid, and bisphenol A in 99.7, 0.53 and 0.26% of samples, indicating that some plasma concentrations were greater than what may be expected to elicit biological responses. About 125 gene targets, indicative of specific biological pathways, were identified as potentially being affected. Inhibition of several CYP genes, involved in xenobiotic metabolism, were most consistently identified. Other identified biological responses have potential implications for motor coordination, cardiac functions, behavior, and blood circulation. However, it is unclear what these results mean for bald eagles, given that ToxCast data are generated using mammalian-based endpoints. Despite uncertainties and limitations, this method of screening environmental data can be useful for informing future monitoring or research focused on understanding the occurrence and effects of OCs in bald eagles and other similarly-positioned trophic species.