The release of waterborne chemical cues is a well-documented anti-predator strategy in teleost fish, allowing individuals to detect, and respond to, predation threats. However, little is known about whether an ancient group of fishes, elasmobranchs, employ similar mechanisms to communicate predation risk. Here, we experimentally investigate the behavioral and physiological responses of Bat rays (Myliobatis californica) following the manipulation of an upstream conspecific. Specifically, we examined whether Bat rays receiving water from an upstream conspecific that had been physically chased with a stick for 30 s, simulating a non-injurious predation disturbance, exhibited changes in activity levels and physiological stress markers. Receiving Bat rays increased their velocity by approximately 3 cm/s (~21%) compared to their pre-exposure state, whereas Control rays showed no significant change. Receivers also exhibited a significant shift toward active swimming behaviors, while Controls spent more time in passive behaviors. This shift was positively correlated with velocity, reinforcing that exposure to waterborne disturbance cues from a distressed conspecific triggered increased activity. Physiological measurements showed no significant differences between groups in glucose, β-HB, lactate, or pH levels. We suggest the activity increase corresponds with a flight-type response to predation risk. These findings reveal a previously undocumented communication mechanism in marine predators, contributing to a broader understanding elasmobranch behavior and physiology.

Synopsis Environmental changes driven by human activities are exposing organisms to novel and increasingly variable selective pressures. Among many possible responses, behavior stands out as rapid and often reversible mechanisms by which individuals adjust to altered conditions. By shaping how organisms interact with their environments, behaviors can influence exposure to challenges, mediate interactions with other components of the phenotype, such as physiology, morphology, or life history, and ultimately affect ecological and evolutionary outcomes. Despite their potential importance, behavioral responses to anthropogenic changes are not as well integrated across systems and disciplines. Here, we synthesize current research drawn from discussions at a symposium focused on the role behavior plays in confronting a rapidly changing world. We integrate insights across taxa and across major forms of human-driven environmental change, including sensory pollution, urbanization, wildfire, habitat modification, and climate change. Across contexts, we examine how behaviors interact with physiology, life history, ecology, and evolution, emphasizing the need to understand behavior as part of a dynamic and interconnected system in which plastic responses can buffer, redirect, or amplify the effects of environmental change. We identify common themes in how behaviors respond to different anthropogenic challenges, as well as key differences related to ecological context or biological constraint. We also highlight persistent gaps in knowledge, particularly regarding when behavioral flexibility is sufficient to mitigate environmental challenges, how behaviors interact with other traits over different timescales, and when behavioral flexibility may constrain or facilitate evolutionary responses. By synthesizing current knowledge and identifying priorities for future research, we advance an integrative approach to understanding the role of behavior in anthropogenic change. In doing so, we aim to promote cross-system comparisons and collaboration while also clarifying the conditions under which behavioral plasticity plays a critical role in shaping organismal resilience in an increasingly human-altered world.

Long-term cold exposure induces many endotherms to invest in metabolic heat production, but how precipitation impacts thermogenic capacity in the context of different thermal conditions is largely undescribed in animals. In this study, songbirds (red crossbills; Loxia curvirostra) were held in warm (21°C) or cold (6°C) temperatures and either dry or rain precipitation treatments while experiencing a more northern or southern latitude photoperiod. We hypothesized that individuals experiencing winter rain would increase investment in thermogenic capacity, metabolic machinery and catabolic enzymes to cope with increased thermogenic demands. Food intake and activity were monitored weekly, summit (Msum) and basal metabolic rates were measured in November, January and February, and tissues were collected at the end of the study. Individuals held in cold rain treatments achieved the highest Msum and had higher food intake, subcutaneous fat, heart mass and metabolic enzyme activities. Furthermore, birds in dry conditions showed slight disinvestment of Msum in late winter, while birds in rain treatments maintained thermogenic investment. Our results suggest that cold rain induces increased investment in thermogenic capacity across the winter season. Thus, rain may offset the potential thermal benefits that warming winters would otherwise provide to small-bodied endotherms.

Glucocorticoids facilitate the integration of environmental information and coordination of organismal responses to perturbations. Circulating glucocorticoids are hypothesized to depend on an individual’s environment and condition (i.e., state) to facilitate surviving challenges while minimizing fitness costs. Studies specifically focused on sources of individual variation in circulating glucocorticoids are critical to understanding state-dependent modulation of glucocorticoids and integrated phenotypes more broadly. Such studies can also provide insight into the evolution and adaptive significance of circulating glucocorticoids. Here, we repeatedly sample individuals before and during food restriction to identify how and when food availability and intrinsic differences (i.e., body condition and telomere length), including those of social partners, covary with glucocorticoids in captive Red Crossbills (Loxia curvirostra), a nomadic songbird that specializes on foraging for conifer seeds. Conifer seeds are ephemeral resources produced during unpredictable, but locally synchronous, masting events. Fluctuating food availability and social cues, change the behavior and glucocorticoid physiology of Red Crossbills. Pairs consisting of an adult and juvenile were food restricted using an environmental manipulation known to induce socially mediated changes in glucocorticoid signaling. Baseline and stress-induced glucocorticoids were measured before and during food restriction. Amongst adults, stress-induced glucocorticoids declined following food restriction and positively covaried with telomere length, independent of food availability. These results support the hypothesis that the acute glucocorticoid response is adaptively modulated based on environmental conditions and individual differences in state as measured by telomere length. Under food restriction, juvenile baseline glucocorticoids negatively covaried with body condition and the telomere lengths of adult social partners. The covariation between adult telomere lengths and juvenile baseline glucocorticoids suggests that telomere lengths of adults may relate to adult phenotypes, a hypothesis supported by the covariation between adult telomeres and stress-induced glucocorticoids. Further, as patterns were absent before food restriction, our results demonstrate how environmental challenges can reveal the importance of intrinsic differences to organismal responses and social cues. This study leverages a non-model organism experiencing an ecologically relevant environmental challenge to exemplify how intrinsic differences, including those of social partners, can modulate an endocrine mediator of organismal responses to environmental perturbations.

The neuroendocrine system plays a critical role in the synchronization of life cycle stages with variation in the environment, and in the coordination of life cycle stages with one another. When humans modify environments, these neuroendocrine mechanisms may impact how different individuals, populations, species, and even communities are affected. Here we conceptualize how endocrine mechanisms may influence the likelihood of: (1) timing mismatches between life cycle stages and environmental conditions, and (2) carryover effects within annual cycles. Timing mismatches can occur when an individual fails to synchronize a particular life cycle stage to the appropriate environmental conditions. Carryover effects occur when activities of one stage (including its timing) affect the performance in one or more subsequent stages. We suggest that there is a trade-off between timing adjustments within and across stages such that neuroendocrine mechanisms that reduce timing mismatches in temporally changing environments (e.g., strong neuroendocrine responsiveness to short-term cues, with resultant increased temporal flexibility to fine-tune the current stage to local conditions) may inherently increase the likelihood of carryover effects (e.g., through delay of a transition between stages), and vice versa. We use two examples-flexibility of the onset of photorefractoriness mediated by responsiveness to short-term cues, and sensitivity of molt to sex steroids-to illustrate these ideas, and suggest that future work should investigate the impacts of variation in these and potentially other seasonal timing mechanisms on carryover effects. The conceptual framework presented here suggests that there may be no single best set of tactics for coping with the effects of climate change; species with neuroendocrine mechanisms facilitating temporal flexibility may avoid some timing mismatches but set themselves up for deleterious carryover effects as they make temporal adjustments to environmental conditions modified by climate change.

Energy expenditure strongly influences an animal’s foraging decisions and activity budgets. Diving animals especially need to be energetically efficient because they exercise while oxygen is limited. By estimating the energetics of behavior, we can better understand the cascading effects of individual responses to disturbance and environmental change. Pacific Coast Feeding Group (PCFG) gray whales use a variety of foraging tactics in shallow habitats (<20 m), which present challenges associated with maneuverability and buoyancy. We use a seven-year dataset of concurrent individual behavior, morphology, and breath-by-breath respiration data collected via drone paired with two years of tri-axial accelerometry tag data to study patterns and correlates of respiration. We assess how several respiration metrics (acting as proxies for oxygen consumption) are associated with individual length, body condition and behavior (forage and travel), and test whether respiration reflects recovery from, or anticipation of, a foraging dive using Bayesian linear mixed effects models. Given model results, we simulated daily field metabolic rate (FMR) to explore how diving costs may affect energetics at a daily scale. We find that respiration reflects recovery from the preceding dive and that dives are more energetically expensive for longer, more buoyant whales. Longer dives and the most common foraging tactics also incur higher energetic costs. FMR simulations show that individual size and dive duration have the largest effects on energy expenditure. Thus, PCFG gray whale foraging success may be limited by the energetic costs associated with size and buoyancy, highlighting the costs of a shallow habitat foraging niche.

Migration is an important event in the annual cycle of many animals that facilitates the use of resources that vary across space and time. It can occur with regular and predictable timing, as in obligate migration, or with much greater flexibility, as in facultative migration. Most research aimed at understanding the endocrine mechanisms regulating the transition to a migratory stage has focused on obligate migration, whereas less is known about facultative forms of migration. One challenge for research into the endocrine regulation of facultative migration is that facultative migrations encompass a diverse array of migratory movements. Here, we present a framework to describe and conceptualize variation in facultative migrations that focuses on conditions at departure. Within the context of this framework, we review potential endocrine mechanisms involved in the initiation of facultative migrations in vertebrates. We first focus on glucocorticoids, which have been the subject of most research on the topic. We then examine other potential hormones and neurohormones that have received less attention, but are exciting candidates to consider. We conclude by highlighting areas where future research is particularly needed.

High levels of pollutants can occur in urban environments and pose a threat to human residents as well as local wildlife. Many urban centers suffer from lead-contaminated drinking water due to the corrosion of pipe infrastructure. Irrigation with this water may contribute to soil lead levels. The American robin (Turdus migratorius) is a widespread songbird in North America, well-known for hunting earthworms in urban lawns. This earthworm specialization results in the ingestion of large amounts of soil. This study investigates the impact of the Flint, Michigan (MI) water crisis, during which the city water supply was contaminated with lead, on American robins during their breeding season in southeast MI. We compared soil lead levels (SLL) and blood lead levels (BLL) of birds captured at irrigated sites of Flint to those captured at non-irrigated sites of Flint during April - August from 2018 to 2020. Control sites included irrigated sites in a nearby city without a known history of lead pollution (Ypsilanti, MI: irrigated urban control) and non-irrigated rural sites. BLL were elevated in irrigated sites of Flint relative to the irrigated urban control and non-irrigated rural sites. Further, robin BLL were positively and strongly correlated with lawn SLL across our seven study sites suggesting that high BLL in American robins may predict elevated soil lead levels. Further research should address how lead might be impacting urban wildlife and if robins can serve as a bioindicator of lead exposure for other neighborhood inhabitants, including human children whose main route of lead exposure is through soil contact.

Science frequently requires the collection of data in a field setting that is markedly different from the stereotypical laboratory often associated with scientists.For example, archeologists may collect data from field excavations to address questions about the foundations and development of civilization, and epidemiologists often conduct research under field conditions to learn about disease pathology in response to outbreaks.Successful field data collection requires considerable planning and organization to navigate challenges that stem from conducting research in such uncontrolled settings.Inadequate preparation can limit data quantity and quality, and may even create safety risks.Thus, a concerted effort that starts well before data collection begins and extends throughout the field season is critical to project success.The skills required to implement successful field work often develop with time and experience.However, we note the need for a guiding framework to accelerate and facilitate this process among new researchers, including graduate students who may be inexperienced or are constrained by time.Here, we draw upon our collective experience conducting field research in the natural sciences-covering >200 cumulative field seasons undertaken in 12 countries and 29 US states-to develop rules that we have found to be essential for implementing a successful field season.Our goal is to provide researchers in the natural sciences who have limited field experience with a suite of considerations that we have found to be useful when planning a field season.Of note, many of our rules are germane to field data collection efforts in other disciplines, especially those conducted by a team in the field.Indeed, those of us who supervise graduate students often share these rules with students who are planning their first field season.In assembling these rules, we have made several assumptions about our intended audience, whom we refer to as "lead researchers": (1) they can draw upon their prior field experience from a previous position(s) (e.g., as a field technician); (2) they have already identified research questions and selected locations for undertaking fieldwork; (3) their study design and data collection methods are feasible and scientifically sound; and (4) their research is being undertaken

Temperate winters can impose severe conditions on songbirds that threaten survival, including shorter days and often lower temperatures and food availability. One well-studied mechanism by which songbirds cope with such conditions is seasonal acclimatization of thermal metabolic traits, with strong evidence for both preparative and responsive changes in thermogenic capacity (i.e., the ability to generate heat) to low winter temperatures. However, a bird's ability to cope with seasonal extremes or unpredictable events is likely dependent on a combination of behavioral and physiological traits that function to maintain allostatic balance. The ability to cope with reduced food availability may be an important component of organismal response to temperate winters in songbirds. Here, we compare responses to experimentally reduced food availability at different times of year in captive red crossbills (Loxia curvirostra) and pine siskins (Spinus pinus)-two species that cope with variable food resources and live in cold places-to investigate seasonal changes in the organismal response to food availability. Further, red crossbills are known to use social information to improve responses to reduced food availability, so we also examine whether the use of social information in this context varies seasonally in this species. We find that pine siskins and red crossbills lose less body mass during time-restricted feedings in late winter compared to summer, and that red crossbills further benefit from social information gathered from observing other food-restricted red crossbills in both seasons. Observed changes in body mass were only partially explained by seasonal differences in food intake. Our results demonstrate seasonal acclimation to food stress and social information use across seasons in a controlled captive environment and highlight the importance of considering diverse physiological systems (e.g., thermogenic, metabolic, digestive, etc.) to understand organismal responses to environmental challenges.

Many animals rely on photoperiodic and non-photoperiodic environmental cues to gather information and appropriately time life-history stages across the annual cycle, such as reproduction, molt, and migration. Here, we experimentally demonstrate that the reproductive physiology, but not migratory behavior, of captive Pine Siskins (Spinus pinus) responds to both food and social cues during the spring migratory-breeding period. Pine Siskins are a nomadic finch with a highly flexible breeding schedule and, in the spring, free-living Pine Siskins can wander large geographic areas and opportunistically breed. To understand the importance of non-photoperiodic cues to the migratory-breeding transition, we maintained individually housed birds on either a standard or enriched diet in the presence of group-housed heterospecifics or conspecifics experiencing either the standard or enriched diet type. We measured body condition and reproductive development of all Pine Siskins and, among individually housed Pine Siskins, quantified nocturnal migratory restlessness. In group-housed birds, the enriched diet caused increases in body condition and, among females, promoted reproductive development. Among individually housed birds, female reproductive development differed between treatment groups, whereas male reproductive development did not. Specifically, individually housed females showed greater reproductive development when presented with conspecifics compared to heterospecifics. The highest rate of female reproductive development, however, was observed among individually housed females provided the enriched diet and maintained with group-housed conspecifics on an enriched diet. Changes in nocturnal migratory restlessness did not vary by treatment group or sex. By manipulating both the physical and social environment, this study demonstrates how multiple environmental cues can affect the timing of transitions between life-history stages with differential responses between sexes and between migratory and reproductive systems. center dot Many animals inform decisions associated with survival and reproduction using a multitude of environmental cues, including photoperiodic and non-photoperiodic cues.center dot How multiple environmental cues combine to influence animal decision-making is not well understood.center dot We experimentally tested how different combinations of non-photoperiodic cues, including social cues, influenced the spring migratory behavior and reproductive physiology of Pine Siskins.center dot Pine Siskins are a nomadic finch with highly flexible breeding and migratory behavior that are known to be modulated by non-photoperiodic cues.center dot Results demonstrate that the presence of conspecifics-but not heterospecifics that are ecologically relevant-and direct access to preferred diet items promote female reproductive development.center dot Male reproductive development and nocturnal migratory restlessness did not differ across experimental treatments.center dot Our results highlight sex-specific differences in environmental cue use and demonstrate how animals can use multiple types of environmental cues to differentially inform decisions associated with the timing of annual cycle events. Muchos animales dependen de senales ambientales fotoperiodicas y no fotoperiodicas para recopilar informacion y sincronizar adecuadamente las etapas del ciclo anual de su historia de vida, como la reproduccion, la muda y la migracion. Aqui, demostramos experimentalmente que la fisiologia reproductiva, pero no el comportamiento migratorio, de individuos de Spinus pinus en cautiverio responden tanto a senales alimenticias como sociales durante el periodo migratorio-reproductivo de primavera. S. pinus es un ave nomada con un esquema reproductivo altamente flexible y, en primavera, los individuos que viven en libertad pueden deambular por grandes areas geograficas y reproducirse de modo oportunista. Para entender la importancia de las senales no fotoperiodicas en la transicion migratoria-reproductiva, mantuvimos aves alojadas individualmente ya sea con una dieta estandar o una enriquecida, en presencia de individuos heteroespecificos o conspecificos alojados en grupo, que recibieron ya sea el tipo de dieta estandar o la enriquecida. Medimos la condicion corporal y el desarrollo reproductivo de todos los individuos de S. pinus y, entre los individuos alojados individualmente, cuantificamos la inquietud migratoria nocturna. En las aves alojadas en grupo, la dieta enriquecida causo aumentos en la condicion corporal y, entre las hembras, promovio el desarrollo reproductivo. Entre las aves alojadas individualmente, el desarrollo reproductivo de las hembras difirio entre los grupos de tratamiento, mientras que el desarrollo reproductivo de los machos no lo hizo. En particular, las hembras alojadas individualmente mostraron un mayor desarrollo reproductivo cuando se presentaban con conspecificos en comparacion con heteroespecificos. La tasa mas alta de desarrollo reproductivo en las hembras, sin embargo, se observo entre las hembras alojadas individualmente que recibieron la dieta enriquecida y que se mantuvieron con conspecificos alojados en grupo con la dieta enriquecida. Los cambios en la inquietud migratoria nocturna no variaron segun el grupo de tratamiento o el sexo. Al manipular tanto el entorno fisico como social, este estudio demuestra como multiples senales ambientales pueden afectar el momento de las transiciones entre las etapas de la historia de vida, con respuestas diferenciales entre los sexos y entre los sistemas migratorios y reproductivos.

Corticosterone (CORT), the main glucocorticoid in birds, regulates physiological and behavioral traits linked to predictable and unpredictable environmental fluctuations (i.e., stressors). Baseline and stress-induced CORT concentrations are known to fluctuate seasonally, linked to life history stages (LHS) such as breeding, molt, and wintering stage. These variations have been relatively well described in North American birds, but poorly addressed in neotropical species. To fill this gap, we explored how baseline and stress-induced CORT variation by LHS was affected by seasonality and environmental heterogeneity (i.e., frequency of unpredictable events such as droughts, flashfloods, etc) within the Neotropics using two approaches. First, we reviewed all currently available data about CORT concentrations for neotropical bird species. Second, we performed an in-depth analysis comparing the CORT responses of the two most common species of the Zonotrichia genus from North and South America (Z. leucophrys and Z. capensis, respectively) and their subspecies to seasonality and environmental heterogeneity. These species have been analyzed with the same methodology, allowing for an in-depth comparison of CORT variations. Despite scant data on neotropical bird species, we observed overlap between molt and breeding, and lower fluctuations of CORT among LHS. These patterns would be considered atypical compared to those described for North temperate species. Further, we found no significant associations between environmental heterogeneity and the stress-responses. In Zonotrichia we observed a positive association between baseline and stress-induced concentrations of CORT and latitude. We also observed differences by LHS. Both baseline and stress-induced CORT concentrations were higher during breeding and lower during molt. In addition, for both species, the overall pattern of seasonal modulation of stress response was heavily influenced by the migration strategy, with long-distance migrants showing significantly higher stress-induced CORT levels. Our results highlight the need for more data collection in the Neotropics. Comparative data would shed further light on the sensitivity of the adrenocortical response to stress under different scenarios of environmental seasonality and unpredictability.

Social information is widely used by animals to inform decisions made in a variety of contexts. Less well understood is how the state of the information source influences social information use and if social information informs migratory decisions. Furthermore, most studies on social information use in the context of migration focus on obligate migrants, yet social information is predicted to be particularly important for species that exhibit more flexible migratory behavior. We experimentally tested for social cue use during the vernal migratory period in a captive population of pine siskins (Spinus pinus). Pine siskins are nomadic migrants that exhibit a highly flexible spring migratory period that is associated with elevated energy reserves and, in captivity, nocturnal migratory restlessness. Beginning in May, male and female subjects were presented same-sex neighbors that were previously maintained on either a standard photoperiod (control neighbors) or a longer, summer photoperiod (photo-advanced neighbors, who exhibited more advanced reproductive development). We assessed the effect of these differing social cues on subjects over 28 days by monitoring nocturnal migratory behavior, body condition, and reproductive development. Subjects presented with photo-advanced neighbors ceased nocturnal migratory behavior more rapidly than subjects paired with control neighbors. We also observed a relatively stronger response to social cues among female subjects. Rates of change in the body condition and reproductive development of subjects did not differ between treatment groups. This study provides novel insight into how social cues can influence migratory decision-making and provides evidence of sex-specific differences in cue use. Significance statement Animals often use social information when making decisions. Less well understood is how the state of the information source influences social information use, particularly during migratory decision-making. Using a species of nomadic songbird, we experimentally demonstrate that the decision to terminate migratory behavior depends upon the state of nearby conspecifics. This study informs our understanding of how animals use social information to inform migratory decisions.

Sublethal exposure to methylmercury (MeHg) can have consequences for the reproductive, neurological, and physiological health of birds. Songbirds, regardless of trophic position, are often exposed to mercury (Hg) and may be at risk for health effects – especially if they inhabit a place that is subject to high Hg atmospheric deposition and/or have local conditions that are prone to methylation. This study investigates Hg concentrations in terrestrial songbirds of Southeast Michigan, where historical and present-day anthropogenic emissions of heavy metals are elevated. We collected tail feather samples from 223 songbirds across four different species during summer and fall of 2018 and 2019. The mean (±SE) Hg concentration across all samples was 103 ± 3.43 ng/g of dry feather weight. Mercury concentration varied significantly among species, and by age and site in some species, but not by sex. Mean concentrations were nearly seven times higher in two omnivore species, American robin (Turdus migratorius) and European starling (Sturnus vulgaris), than in the two granivore species, American goldfinch (Spinus tristus) and house sparrow (Passer domesticus). Juveniles had higher feather Hg concentrations than adults in all species except American goldfinches - which feed their young primarily seeds, further supporting a role of diet in exposure. We also found a negative correlation between Hg concentration and body condition in American robins, but further research is needed to verify this relationship. While our sample concentrations do not exceed the threshold for sublethal effects, our findings provide insight into the patterns of Hg concentrations in terrestrial songbirds, which may help in understanding Hg exposure pathways, bioaccumulation and risks in terrestrial species.

Animals prepare for fluctuations in resources through advance storage of energy, planned reduction in energy costs or by moving elsewhere. Unpredictable fluctuations in food, however, may be particularly challenging if animals cannot avoid negative impacts on body condition. Social information may help animals to cope with unpredictable resources if cues from individuals with low foraging success give advance warning about deteriorating conditions. This study investigates the impact of social information on behaviour and physiology of food-restricted captive red crossbills (Loxia curvirostra). Birds were restricted to two short feeding periods per day to simulate a decline in resources and were given social information from food-restricted neighbours either before (i.e. predictive) or during (i.e. parallel) the food-restriction period. Focal birds better conserved body mass during food restriction if social information was predictive of the decline in resources. Crossbills with predictive information ate more food, had larger intestinal mass and better conserved pectoral muscle size at the end of the restriction period compared to those with parallel social information. These data suggest that birds can use social information to alter behavioural and physiological responses during food shortage in ways that may confer an adaptive advantage for survival.

High levels of pollutants often occur in urban environments and can pose a threat to human residents as well as local wildlife. The Flint, Michigan water crisis was caused by the corrosion of pipe infrastructure, resulting in high levels of lead (Pb) leaching into the drinking water. Irrigation with contaminated water may have introduced lead into the soil causing another source of exposure to humans as well as wildlife. A widespread songbird species, the American robin ( Turdus migratorius), feeds heavily on earthworms and ingests large amounts of soil during foraging. This study investigated the impact of the Flint water crisis on American robin blood lead levels (BLL) during the breeding season in southeast MI by comparing BLL of birds captured at irrigated sites of Flint to those captured at unirrigated sites in Flint, irrigated sites in a nearby city (Ypsilanti) and rural sites. Robins captured at irrigated Flint sites had nearly double BLL compared to unirrigated Flint sites and all other control sites. Body condition declined with increasing BLL at these irrigated sites of Flint, suggesting a measurable fitness impact of lead at these levels. Because BLL in American robins is known to reflect soil lead levels and soil lead is a known driver of BLL in children, robins may act as a bioindicator for urban communities. Further research should determine the efficacy of using robin BLL as a bioindicator of soil lead and how lead might be impacting body condition and other long-term fitness metrics in urban wildlife.