Predicting density dependence of welfare of wild animal populations based on resource access linked to habitat availability and usage

Grantee: Ross MacLeod

Institutions: Liverpool John Moores University, United Kingdom

Grant amount: $159,744

Grant type: Challenge grants

Focal species: House sparrow (Passer domesticus)

Conservation status: Least concern

Disciplines: Ecological modeling, population ecology, animal welfare science

Research location: United Kingdom

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Project summary

This project seeks to adapt a habitat and population model to incorporate welfare and apply it to the study of an abundant and widespread avian species, the house sparrow (Passer domesticus). The researchers propose to utilize a variety of welfare metrics to validate model assumptions, which will then allow them to test assumptions related to the welfare implications of density-dependent population dynamics.

Why we funded this project

We funded this project because it addresses our proposal request very closely and proposes to investigate a key wild animal welfare question using a modeling framework. They are also planning to address their question using an abundant avian species. The project has high potential to inform future work focused on modeling total welfare in a population (i.e., combining both individual welfare and population size), and to create a model that can be replicated in other systems.

Find Ross’ other project, studying wild birds, here.

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Empirical assessment of welfare in wild American mink and Eurasian otters: the effects of intra- and inter-specific population density

Grantees: Lauren A. Harrington, Maria Diez Leon

Institutions: Oxford University, United Kingdom

Grant amount: $162,257

Grant type: Challenge grants

Focal species: American mink (Neovison vison), Eurasian otter (Lutra lutra)

Conservation status: Near threatened

Disciplines: Animal welfare science, community ecology, wildlife management

Research location: United Kingdom

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Project summary

This project seeks to determine whether the welfare of American mink (Neovison vison) is negatively impacted in the presence of high densities of Eurasian otters (Lutra lutra), whether both species’ welfare is compromised at relatively higher densities of conspecifics, and whether there is a seasonality to welfare impacts. The project will also assess whether behavioral time budget shifts in mink are associated with higher chronic stress levels, as a proxy for negative impact on mink welfare. These questions will be addressed by measuring welfare through several different domains, including behavioral (exploratory behavior, vocalizations), physical (body condition, ectoparasite load), and physiological (telomere length, fecal glucocorticoid metabolites and hair cortisol) metrics. 

Why we funded this project

This project has the potential to contribute significant information to the understanding of intra-specific density-dependent welfare and to the understanding of network effects among predator-prey and competitor interactions of wild animals. Its unusually diverse set of welfare metrics will allow for cross-validation, strengthening both this project and other projects applying the same metrics. The investigators each have a strong background in animal welfare and have made efforts to better align their work with  Wild Animal Initiative’s priorities for wild animal welfare, which makes them good candidates to carry forward the validation of these welfare indicators (particularly telomere attrition, which is still relatively immature in its use as a welfare indicator).

Find Maria’s other project, studying European minks, here.

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Social connections and their welfare implications in the wild

Grantee: Alex Thornton

Institutions: University of Exeter, University of Bristol, United Kingdom

Grant amount: $157,962

Grant type: Challenge grants

Focal species: Jackdaws (Coloeus sp.)

Conservation status: Least concern

Disciplines: Animal behavior, ornithology, animal welfare science

Research location: United Kingdom

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Project summary

This project seeks to understand the relationship between welfare and social interactions in wild bird populations. Using historical data, the researchers will also seek insight into how welfare varies among individuals in relation to the social system, early-life experiences, and interactions among individuals. They will also investigate whether social systems might play a role in helping to mitigate some of the negative anthropogenic impacts on welfare.

Why we funded this project

The study findings will help in understanding how wild animals cope with increasing temperatures and the impact of thermal stress on their welfare and health. Notably, previous work has suggested that T3 measurements in ungulates are especially sensitive to thermal stress, and so comparing T3 with other indicators based on different physiological pathways, such as glucocorticoids, could help researchers to diagnose the relative significance of different environmental stressors an animal is facing. The project’s behavioral metrics are also crucial for realizing that potential. A secondary reason for our interest in this project is that it has near-term policy implications, potentially highlighting the value of preserving or promoting specific landscape features for the ecosystem service they offer, in the form of shade, to wild ungulates.

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Development of novel measures of welfare in juvenile European starlings exposed to nutritional stress

Grantee: Melissa Bateson

Institution: Newcastle University, United Kingdom

Grant amount: $60,000

Grant type: Challenge grants

Focal species: Starlings (Sturnidae sp.)

Conservation status: Least concern

Disciplines: Physiology, ornithology

Research location: United Kingdom

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Project summary

Juveniles of passerine species such as the European starling (Sturnus vulgaris) experience massive mortality, much of which is caused by direct or indirect effects of nutritional stress. Of birds that survive, many will bear the “scars” of early-life stress that have consequences for their welfare. The aim of this project is to identify the metabolic “fingerprint” of nutritional stress in starling nestlings and to validate sensitive and non-invasive molecular biomarkers that can be used to assess the welfare of wild starlings.

This group has been developing the hypothesis that biomarkers of biological age not only predict future morbidity and mortality, but also reflect the quality of an animal’s cumulative lifetime experience. Existing metrics of biological age, particularly telomere length, require invasive blood samples, and measurements are imprecise, meaning that large sample sizes are currently required to obtain significant effects in epidemiological studies. Estimating biological age based on measuring multiple age-related biomarkers (as is typical in the human aging literature) is likely to be more reliable than using telomere length alone. 

This project will use untargeted metabolomics to identify multiple novel biomarkers of exposure to nutritional stress in nestling starlings. This “fingerprint” will be validated by testing whether it predicts gold-standard behavioral measures of adult affective experience in a cohort of laboratory-raised birds. Metabolomics measures thousands of small molecules in one biological sample and can be performed on a range of tissues including blood, hair, and urine. The aim will be to identify an applicable panel of metabolites that can be measured cheaply and easily from feathers and the uric acid component of guano.

Why we funded this project

This project should introduce a novel indicator of long-term welfare that is less invasive, requires fewer resources, and is potentially more reliable than similar existing methods. The PI is a world leader in the field of animal behavior and is the main originator of using biological aging to understand long-term animal welfare, especially in non-model species. For that reason, we are especially confident in this work being high-quality and having great academic reach and influence.

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Integrating individual-level juvenile welfare in dynamic habitats across time and space

Grantee: Tom Luhring

Institutions: Wichita State University, Texas State University, and Stephen F. Austin University, United States

Grant amount: $162,604

Grant type: Challenge grants

Focal species: Sirens (Siren intermedia)

Conservation status: Least concern

Disciplines: Herpetology, physiology, climate science

Research location: United States

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Project summary

The project will track individual juvenile lesser sirens (Siren intermedia) within and across years for four populations in Eastern Texas. The lack of a terrestrial life-stage and severely limited overland dispersal ability means that hydrologically isolated pools function as closed populations, facilitating recaptures and simplifying demographic estimates. Siren health is directly impacted by the effects of the environment (e.g., drought conditions) through the impacts of resource availability on body condition and growth rates. Furthermore, sirens show strong size-dependent and seasonal shifts in antagonistic behaviors such as biting which lead to acute injuries. 

Aquatic amphibians are especially well-suited for the collection of water-borne stress hormones (corticosterone), which offer the least invasive method of evaluating an integrated measure of corticosterone levels that are passively being released through the skin, gills, feces, and urine. This project will use water-borne corticosterone release rates to investigate changes in stress physiology as a function of changes in the environment experienced by the individual (population density, drought severity index, water temperature, pH, conductivity) across time and space to understand coping capacity. These data will also be used to investigate the welfare impact of an established marking technique compared to a novel approach based on pattern recognition by a machine-learning algorithm. 

Why we funded this project

Juvenile mortality is especially high in amphibians, and amphibian welfare in general is a neglected subject. This project should provide proof of concept for a cost-effective approach for assessing welfare at both an individual and population level. The waterborne measurements have the potential to integrate corticosterone over a longer period of time, increasing its reliability as a welfare indicator. Finally, this project will test a novel, non-invasive approach to mark-recapture studies, which could facilitate much better individual-level welfare research for amphibians and other (especially aquatic) animals in the future.

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Development of octopus mind in the wild: a behavioral, ecological and evolutionary investigation into sentience and emotional states in Octopus insularis juveniles

Grantee: Michaella Andrade

Institution: Federal University of ABC, Brazil

Grant amount: $37,959

Grant type: Challenge grants

Focal species: Octopuses (Octopoda sp.)

Conservation status: Data deficient

Disciplines: Sentience, animal behavior

Research location: Brazil

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Publications

Andrade M.P., et al. (2023). Assessing Negative Welfare Measures for Wild Invertebrates: The Case for Octopuses. Animals, 13(19), 3021. https://doi.org/10.3390/ani13193021

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Project summary

Welfare refers to the quality of life of animals that possess sentient capacity and emotional states. Although the precursors of sentience were possibly present on the planet as early as 890 million years ago, the evolution of sentience is still poorly understood. However, cephalopods are increasingly being recognized as sentient, yet we do not know about this phenomenon in juvenile wild animals. In this sense, studies with wild animals can be beneficial for finding a wider range of ecological triggers and their relationship with behaviors.

There’s evidence that evolutionary pressures can cause behaviors with opposite meanings to eventually develop opposite forms, the way a frown is the opposite of a smile. One way to understand the expression of emotion in animals therefore may be to find pairs of behaviors that are opposites. In octopus, colors can be a signal of emotional valence during conflict and other contexts. Although researchers began to see this dimension in octopuses, no study has tested whether opposite pairs of color signals are present in octopuses. This project will produce descriptions of evolutionary and behavioral patterns that reflect the emotional states and sentience for juvenile octopuses, which may contribute to the welfare of octopuses and other invertebrates.

Why we funded this project

Although octopuses are widely assumed to be sentient at the adult stage, no studies that we are aware of have examined sentience at earlier life stages. As the vast majority of octopuses alive at any one time are juveniles, and octopuses have enormously high juvenile mortality, the question of when in their development sentience arises is particularly important. This project is also interesting because it will teach us about what the lives of juvenile octopuses are like and the extent to which welfare effects are mediated by personality traits.

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Evaluating short- and long-term impacts of injury and illness on wild bird welfare

Grantee: Katie LaBarbera

Institution: San Francisco Bay Bird Observatory, United States

Grant amount: $20,000

Grant type: Challenge grants

Focal species: Wild birds

Conservation status: Least concern

Disciplines: Wildlife rehabilitation, ornithology

Research location: United States

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Project summary

There is surprisingly little known about how illness and injury impact the experience of wild animals. Studying such patterns can be limited by the challenges of detecting and assessing injuries and then following up to determine individual fate in wild animals. The San Francisco Bay Bird Observatory’s (SFBBO) long-term bird-banding dataset (>30 years and >100,000 captures) is well-suited to address these questions in wild birds.

Bird banding involves close examination of wild individuals, and individuals are frequently recaptured over time. The SFBBO has a high rate of recapture, which allows them to track individuals over years and to estimate survival, tracking the state of injuries and bird health over multiple years. Understanding how injury impacts individual welfare and survival is of both intellectual and practical value. Bird banding stations vary considerably in their criteria for deciding whether an injured bird should be released or taken to a wildlife rescue. Wildlife rescues must in turn decide whether birds can be ethically released with long-term impairments; for example, many rescues will euthanize rather than release one-legged songbirds. Banding stations and wildlife rescues need real data on wild birds' experiences and prognoses to inform such policies; otherwise, they risk enacting harm.

Why we funded this project

With thousands of wild animal rehabilitation centers in the US alone, this study could provide information that would allow wild animal rehab staff to make data-driven decisions about their bird patients. We think there may be potential to greatly grow interest in the wild animal welfare community via connections with wild animal rehabilitation groups, and this project could provide connections to that community. The project also advances one of our core goals — understanding what wild animals’ lives are like — using an existing and humanely acquired dataset, by providing data on injury rates, severity, and recovery processes. The data could be used to define a metric of “time spent suffering” for injured songbirds.

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Determining the practical and statistical methods necessary for employing field-based metrics of welfare on wild, juvenile, birds

Grantee: Daniel Hanley

Institution: George Mason University, United States

Grant amount: $60,000

Grant type: Challenge grants

Focal species: Prothonotary warbler (Protonotaria citrea)

Conservation status: Least concern

Disciplines: Ornithology, animal behavior, population ecology

Research location: United States

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Project summary

The juvenile stage is where welfare conditions are likely the most variable and impactful on an individual’s growth and behavior. Unfortunately, methods for measuring, assessing, and comparing welfare have been a barrier to our understanding of juvenile welfare. Like other aspects of animal life history, welfare will vary between individuals and also over the lives of animals in an age-specific fashion. Thus, metrics such as welfare expectancy can inform us of the welfare that an organism is likely to experience, similar to how life expectancy can provide an estimate on how much longer an organism may live. 

This study examines welfare in free-living juvenile songbirds to establish standardized field and analytical procedures necessary to obtain age-specific animal welfare estimates. Prothonotary warblers are an ideal model system for studying age-specific welfare because they have well-defined life stages (i.e., egg, nestling, fledgling, subadult, adult), face unique environmental risks (e.g., drought and flooding), and have variable survival. Furthermore, members of this species nest within cavities, which affords a degree of standardization and control necessary for an initial investigation of welfare metrics. Such initial investigations are crucial to estimate age-specific welfare on wild juvenile animals, to determine how they deviate from population-level welfare estimates, and to extend these methods and metrics to other systems.

Why we funded this project

We funded this project because it sought to explicitly quantify welfare across life stages, using multiple physiological, behavioral, and environmental/demographic indicators. Knowing how (and ideally why) average welfare differs over the course of life in a population could have important implications for interventions to improve their welfare (e.g., fertility control). We were also impressed with this PI because he engages numerous students in their lab and is relatively early in his own career, potentially allowing for pivot to focus more on wild animal welfare. He also demonstrated a good understanding of Wild Animal Initiative’s research on the welfare expectancy framework and sought to put the concepts into practice. That sort of theory-to-practice pipeline would represent a significant step for welfare biology as a research field.

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Thermal imaging to investigate physiological state in altricial nestlings

Grantee: Paul Jerem

Institution: Tufts University, United States

Grant amount: $37,780

Grant type: Challenge grants

Focal species: House sparrow (Passer domesticus)

Conservation status: Least concern

Disciplines: Physiology, ornithology

Research location: United States

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Project summary

Animal stress responses evolved to increase survival, in part by stimulating behaviors that reduce exposure to challenging situations. However, young birds who are entirely reliant on their parents (“altricial”) are incapable of acting to change their circumstances, potentially exposing them to the damaging effects of chronic stress. Such species are known to suppress aspects of their stress physiology during development. However, it remains unclear if other parts of the system remain active and could serve as useful indicators for efforts to improve early life welfare. This project seeks to investigate this possibility in juvenile house sparrows (Passer domesticus) using a novel, non-invasive method for inferring internal state — thermal imaging of body surface temperatures.

Why we funded this project

We especially want to understand juvenile welfare, because in most species that is the most experienced life stage, and often the most vulnerable. However, developmental changes can make it difficult to compare welfare between juveniles and adults. This project will calibrate a non-invasive proxy of welfare that can be applied to both adult and altricial juvenile birds, enabling not only better welfare assessments, but more effective lifetime comparisons. A better understanding of the “shape” of lifetime welfare would in turn inform interventions that might disproportionately affect individuals of certain ages.

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It takes guts to grow in the city: the role of the gut microbiome in the welfare of juvenile urban birds

Grantee: Pablo Capilla-Lasheras

Institution: University of Glasgow, United Kingdom

Grant amount: $59,052

Grant type: Challenge grants

Focal species: Blue tits (Cyanistes caeruleus)

Conservation status: Least concern

Disciplines: Physiology, population ecology, animal welfare science, ornithology, animal behavior

Research location: United Kingdom

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Publications

Reid, R., et al. (2024). The impact of urbanization on health depends on the health metric, life stage and level of urbanization: a global meta-analysis on avian species. Proceedings of the Royal Society B, 291(2027). https://doi.org/10.1098/rspb.2024.0617

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Project summary

Amongst the novel stressors that wildlife face in cities, shifts in diet are prevalent and have negative consequences for welfare, particularly in juveniles. Research clearly shows that juvenile birds in urban habitats have low-quality diets, causing stunted growth and increased early-life mortality. For example, in the UK alone, approximately 30 million blue tits hatch every year in cities, but around 63% of them die as juveniles. This project will study juvenile blue tits and investigate how to improve their welfare in urban areas using an integrative approach that will combine metrics of animal welfare with the study of gut microbiomes. Human and captive animal studies suggest that the gut microbiome composition may contain indicators of an animal’s welfare, but this has received little attention in a wild animal context. This study will combine a physiological welfare indicator (telomere attrition), a behavioral welfare indicator (begging behavior), and other health metrics with a study of juvenile birds’ gut microbiomes to link poor-quality urban diets, gut microbiome composition, and welfare. The project will also test a potential near-term dietary intervention (gut microbiome enrichment) to improve the life experience of juvenile birds growing in urban habitats.

Why we funded this project

Welfare is shaped by, and in turn influences, numerous aspects of an animal’s phenotype. Individual welfare indicators offer only limited insights, but combining indicators across multiple domains is thought to be extremely important for triangulating affective state, or “true” welfare. Because the gut microbiome represents a partially distinct domain, understanding how it relates to welfare could therefore strengthen all of our other indicators when they are used in combination. We were especially interested in this project due to the inclusion of an intervention experiment that could be implemented in the near future. Finally, this project will support an early-career researcher with an interest in wild animal welfare.

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