Biotelemetry provides insight into a wild eagle’s death

Written by: Jane Capozzelli

Published: December 17, 2020

DOI: https://doi.org/10.71441/zs02-dvqk

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Key takeaways

• Biotelemetry can provide a high level of detail about wild animals’ activities.
• Real-time behavioral and physiological data can indicate how an animal might be feeling.
• Location data can link welfare indicators to the animal’s environmental context.
• Although biotelemetry could advance efforts to improve wild animal welfare, its methods can be harmful or lethal to the animals being studied.
• Wild Animal Initiative will continue to evaluate the costs and benefits of biotelemetry. We hope to identify opportunities to collect highly detailed individual-level data without burdening the animals involved.

Introduction

Biotelemetry devices (“biologgers”) can monitor behavioral and physiological indicators of welfare status in real time, and couple these data with precise information about environmental context (Brown et al. 2013). Biologgers consist of a suite of sensors attached to an animal. The different sensors typically record location, motion, or other biological and environmental features multiple times a day (Cooke et al. 2004). The data collection is remote, meaning that the human observer does not operate in the field except to capture the animals and attach the devices. 

In one such study, ornithologists outfitted a female white-tailed sea eagle (Haliaeetus albicilla) with a biologger that recorded her movement, circadian rhythm, behavioral profile, and body temperature (Krone et al. 2009). In this article, I use this case study to illustrate biotelemetry’s potential to offer insights on wild animals’ welfare. 

The biologger in this case comprised two radio transmitters, a battery pack, and sensors monitoring location, temperature, vertical motion, and horizontal motion. (Figure 1). At 170 g, the device weighed 3.5% as much as the eagle. The study ended after only five months when the eagle unexpectedly died.

A.
B.

Figure 1

A) The biologger attached to the white-tailed sea eagle (Haliaeetus albicilla). Adapted from Krone et al. (2009). B) An eagle outfitted with a biologger comparable to the “backpack” style used in the sea eagle case study. Photo credit: Alan Schumacher/USDA Wildlife Services.

As with many biotelemetry studies, this one focused on a rare species (the white-tailed sea eagle) and collected data to inform its conservation.  Although welfare was not the focus of the project, it nonetheless proved data highly relevant to individual welfare because it documented the eagle’s dying process in unprecedented detail. This illustrates how biologgers could be used to understand the welfare burdens of different causes of death.

Welfare-relevant conclusions from biotelemetry

Cause of death

GPS data enabled the researchers to identify both the immediate cause of death and the broader environmental context for it.

Because the biologger transmitted location data every 5 minutes, the researchers were able to determine the precise time and location of the eagle’s death and to recover her corpse as soon as possible — overcoming major challenges in cause-of-death research. Through necropsy, they determined she died of lead poisoning (Krone et al. 2009).

Because the data stream was continuous for 5 months, there was strong evidence that  the eagle had ingested lead while foraging within her territory. Even though the eagle had a high-quality habitat that was protected in a conservation reserve, she was still at risk of lead exposure because of legal hunting in her environment (Krone et al. 2009).

Welfare while dying

The biologger fitted to this eagle also included accelerometers, which provided a high-resolution behavioral profile. Activity readings were taken 8 times per second for the entire duration of the study. This frequency enabled researchers to characterize the eagle’s usual circadian rhythm, as well as the start of her sickness period and her dying period. The sickness and dying periods each lasted 11 days (Krone et al. 2009).

With an understanding of the animal’s typical daily rhythms, it was clear when she started showing abnormal behaviors that indicated disease: changes to the timing of flight and rest and increases in the frequency of rest periods (Veissier et al. 1989, Scheibe et al. 1999). The eagle eventually ceased all activity. This extreme lethargy signalled the beginning of her dying process (Krone et al. 2009). Her body temperature also dropped a total of 15℃, coinciding with the decreases in activity (Krone et al. 2009). This physiological and behavioral profile provides a basis for inferring welfare status during the dying process (Figure 2).

Figure 2

Using biotelemetry data to estimate welfare. The activity and body temperature timelines approximate the actual data Krone et al. (2009) collected from a biologger attached to a white-tailed sea eagle (Haliaeetus albicilla) in the weeks preceding her death. The inferred feelings timeline estimates the subjective mental states the eagle may have been experiencing at the same time.

I compared the eagle’s behavioural and physiological profiles over time to her baseline readings in order to estimate her mental state (Beausoleil et al. 2018). Although it may be hard to ever know with certainty how physiological conditions relate to subjective feelings in other species, we can make reasonable guesses given similarities between our own and other animals’ needs. 

The eagle’s lethargy could be associated with negative feelings of malaise. The sickness and dying phases spanned 22 days, so the eagle would have also had increasing feelings of hunger, as she was not eating during this time (Mellor and Beausoliel 2015). The necropsy showed total depletion of fat reserves (Krone et al. 2009). Since eagles eagles ideally eat about 5% of their body weight daily to maintain peak body condition, (Fevold and Craighead 1958), it is reasonable to assume that this loss of reserves and lack of hunting activity would lead to feelings of severe hunger and discomfort. Lastly, the 15º C drop in body temperature would likely lead to extreme discomfort associated with coldness (Mellor and Beausoliel 2015).

Advantages of biologgers for wild animal welfare studies

Recovering corpses

For studying death in the wild, the traditional methods such as short-duration video or corpse-recovery surveys have well-known limitations. Corpses are encountered by chance (Dell et al. 2014). Most are not recovered because they are decomposed or scavenged, making it incredibly difficult to estimate the relative frequencies of different causes of death in a population (Tavecchia et al. 2011). 

Biotelemetry has major advantages for cause-of-death research because it provides detailed information on when and where animals die (Klaassen et al. 2014). As a result, most of the deaths can be attributed to a specific cause (Figure 3). The positional data can also help researchers rapidly and systematically recover corpses (Calvete et al. 2002).

Figure 3

Causes of death in eagles who died during biotelemetry studies. Data from a cause-specific mortality database (Hill et al. 2019a).

Knowing the prevalence and severity of different causes of death is important, because the amount of suffering that an animal experiences while dying is largely determined by the cause and manner of death (Beausoleil et al. 2016). Vehicle collisions, hunting with firearms, or electrocution may cause near-instantaneous death, whereas disease, starvation, or intoxication may weaken the animal over an extended period (22 days in our eagle case study). 

Beyond simply identifying the cause of death, comparative studies could allow us to infer the experiences of animals that die from different causes, and how the prevalence of these causes varies by life stage or environment. Such knowledge would allow wild animal welfare advocates to prioritize preventing the most painful manners of death.

Observing behavior

Currently, most welfare assessments are done by in-person human observation (Bailey et al. 2018). But biotelemetry allows continuous data collection from almost any location an animal may occupy — even where people cannot follow (Ropert-Coudert and Wilson 2005).

The ability to record quantitative behavioral profiles anywhere the animal goes allows for much more informed welfare estimates. For example, behavioral profiles can show sickness behaviors or other abnormal trends in function and condition (Brown et al. 2013, Adelman et al. 2014). This multidimensional information allows us to understand an animal’s welfare status in the context of events and environmental variables that matter at the scale of an individual’s preferences and perceptions (Bisson et al. 2009, Martins et al. 2014, McClune et al. 2015, Clemente al. 2016).

Observing community interactions

Because biologgers minimally distort behavior and can transmit data from any location, they are particularly well-suited to observing individuals’ interactions with their communities. For example, animals in different environments could be monitored as they cope with the various habitats that they encounter. This analysis would provide an animal’s-eye view on habitat quality and show to what extent an animal’s welfare might be improved or diminished by altering the environment (Lima and Zollner 1996, Nicol et al. 2020).  

By pairing biotelemetry with an understanding of community interactions, it may be possible to show how community structure degrades or enhances the average welfare of each animal community-member. For example, in a community with two species that cooperate beneficially, biotelemetry could monitor the degree to which stress is reduced when animals have the opportunity to interact (Hammers et al. 2019).  

Concerns about biotelemetry research

Technological limitations

Cost is the largest barrier to scaling wildlife biotelemetry research. Devices typically range from hundreds to thousands of dollars per unit (Cooke et al. 2004). Because of the high cost, sample sizes of biotelemetry studies are typically insufficient to predict a welfare outcome before it occurs, even though the data itself is reflective of welfare status (Lindberg and Walker 2007, Costantini and Møller 2013, Naef-Daenzer and Grüebler 2014).

Additionally, while biologgers have been shrinking in size due to advances in battery technology, they are still most commonly only usable on larger animals (Cooke et al. 2004). Unless the weight barriers can be overcome, the vast majority of animals — small invertebrates — are impossible to study with biotelemetry. 

Among marine invertebrates, biotelemetry is generally only feasible for individuals weighing more than 400 g. If this threshold were decreased to 40 g, then ten times more species could be studied, as could larvae and juveniles (O’Dor 2002). In terrestrial insects, biotelemetry studies have been limited to a few large arthropods, such as locusts or hawkmoths. Insect biologgers usually weigh less than 1 g, but their battery life is 3 hours or less (Sato and Maharbiz 2010). This temporal limitation nearly eliminates the ability to research invertebrate welfare through biologgers.

Welfare harms

Biologgers harm the animals wearing them (Hawkins 2004). Death during the tagging process can occur either at capture, directly after release, or from physical attrition over the course of the study (Casas et al. 2015, Weiser et al. 2016, Lameris et al. 2018). For example, the eagle in our case study was caught with a noose, a particularly stressful and risky method for capturing birds (Kautz and Seamans et al. 1980). 

Even in cases with no tag-related mortality (for example, Goldsmith et al. 2017), the devices can have sublethal impacts such as exhaustion, injury, reduced body condition, and the disruption of social activities and pair bonding (Weiser et al. 2016, Brlík et al. 2020, Hamelin and James 2018, Lameris et al. 2018; but see Niles et al. 2010 which found no sublethal impacts). 

The eagle in our case study appeared to have no negative symptoms from the biologger (Krone et al. 2009). However, the authors noted several instances where the bird was at rest during abnormal periods of the day. The authors theorized that stresses such as hunters, tourists, inclement weather, or even sub-lethal lead exposures, may have disrupted the eagle (Krone et al. 2009). But back-mounted biologgers such as the one worn by this eagle (Figure 4) have been documented to cause significant drag that impairs flight (Irvine et al. 2007, Meyer et al. 2015). Therefore, the device itself could have periodically exhausted the bird and necessitated abnormal rest periods.  

Conclusions

Biotelemetry’s scientific applications are promising for wild animal welfare research. For example, biologgers can be used to understand the prevalence of different causes of death. Biologgers provide behavioral and physiological profiles at such an extraordinary level of detail that they can potentially be used to infer animals’ mental states. As this study illustrates, these details can be discovered not only throughout an animal’s life, but uniquely, during their sickness and dying process, potentially revealing important information about the harms associated with different causes of death. Finally, by linking physiological and behavioral data with precise location data, biotelemetry gives unprecedented insight into the links between animals and their environment in real time.

The shift from direct human observation to remote monitoring is not without costs to the animals themselves. Biologgers’ weight and drag is substantial, and there are many documented instances of welfare harms and tag-related deaths. Therefore, it remains unclear whether biologgers in their current forms are justifiable or necessary for conducting wild animal welfare research. We plan to conduct further work to identify the costs and benefits associated with biologgers, best practices for determining when such work is necessary (if ever), and what can be done (if anything) to eliminate welfare harms during remote monitoring studies.

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Reducing the burden of disease: the One Health approach

Written by: Jane Capozzelli

Published on: October 5, 2020

DOI: https://doi.org/10.71441/08qc-343t

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Abstract

1. I review the One Health approach to public health and veterinary medicine and present three contemporary research projects.

2. One Health is motivated by the maxim that the health and well-being of domestic animals, people, and wildlife are inextricably linked. Many projects focus on mitigating wildlife diseases in ways that help humans or livestock.

3. These projects can benefit the welfare of wild animals by improving the target animals’ health. To maximize wild animal welfare benefits, One Health projects should prioritize targeting common species and particularly prolonged or painful health issues.

Key takeaways

• Although One Health does not optimize for wild animal welfare, it represents a tractable opportunity to expand existing efforts in a beneficial direction.

• One Health researchers seem to care about wildlife health for the sake of wild animals’ welfare, not just because of the ways wildlife health issues affect people.

• Demonstrating that improving wild animal welfare can also benefit public health or livestock health might appeal to people who do not typically prioritize animal welfare.

• Established approaches for wildlife health research are relatively easy to extend to high-priority issues in wild animal welfare.

Introduction to One Health

Health, though not the only determinant of good welfare, is a key component (Mellor and Beausoleil 2015). By replacing feeling sick with feeling healthy, good health improves welfare. For the purposes of this article, when I refer to improvements to wild animal welfare, I mainly refer to improving the health of target animals.

Wildlife health projects are promising avenues for improving wild animal welfare. Many of these projects are designed using the “One Health” approach. The framework views both the human and non-human worlds as morally important and interconnected (Schwabe 1984, Zinsstag et al. 2001). For example, veterinarians swear an oath to use their knowledge for both “the promotion of public health” and “the prevention and relief of animal suffering” (Mackenzie et al. 2013). More specifically, One Health follows the maxim that the health and welfare of animals and people are inextricably linked to each other and to the quality of the environment (Osborn et al. 2009).

One Health has been highly successful relative to other health paradigms (Osofsky and Pongsiri 2018). Historically, wildlife health, livestock health, and human health were treated as separate problems. But solving today’s most complex health problems needs expertise in all three areas (Whitmee et al. 2015). Addressing wildlife health, livestock health, and human health collectively — as part of “One Health” — ultimately yields benefits that can’t be found by addressing each problem individually.

Some leading institutions in the One Health movement include One Health Commission and the One Health Initiative. The CDC also includes “One Health” as an important public health approach. Several large projects also originate from the AVMA-accredited colleges of veterinary medicine.

Existing One Health projects

Removing exclusion fencing

Veterinary cordon fences exclude wild herbivores from rangelands throughout southern Africa to reduce the transmission of foot-and-mouth disease between wild herbivores and livestock (Gadd et al. 2012). Foot-and-mouth disease is nonlethal to livestock, but has painful symptoms. Wild animals typically carry the disease asymptomatically (Young et al. 1972, Vosloo et al. 2007).

Exclusion fencing may degrade wild animals’ quality of life more than foot-and-mouth disease itself. Exclusion fencing fragments home ranges and disrupts migration routes. When their movement is constrained, animals cannot escape from potential harms as easily. As a result, cordoned animals more frequently die from starvation, dehydration, electrocution, and entanglement (Gadd et al. 2012, Lindsey et al. 2012).

The costs of exclusion fencing also permeate the socio-economic climate in Africa (ibid, ibid). Outbreaks of foot-and-mouth disease still occur due to fencing failures or mistakes in the food regulatory chain (Thomson et al. 2018). Meat from exposed livestock cannot be sold (ibid), a burden that is largest for low-income producers (Whitmee et al. 2015).

Exclusion fencing does not eradicate poverty from foot-and-mouth disease, and it creates a number of welfare problems for vast numbers of wild animals. The One Health solutions are two-fold: change the regulations for beef so that the process is more humane for people and livestock (MacKenzie et al. 2013), and dismantle fencing. Deaths by entanglement, electrocution, and exclusion-related starvation and dehydration are reduced, and restoring migratory routes improves animals' abilities to act on their behavioral preferences (Gadd et al. 2012, Mellor and Beausoleil 2015, Allen et al. 2018).

Eradicating tuberculosis

Tuberculosis, a severe bacterial infection of the lungs, circulates among human, livestock, and wildlife hosts. Many low-income countries have not controlled tuberculosis. In Tanzania, for example, as many as 16% of all people have had the disease (Travis et al. 2019), as have 1%-13% of cattle, depending on the region (Katale et al. 2013).

An active One Health project has identified buffalo (Syncerus caffer) as a major disease reservoir (Travis et al. 2019, Roug et al. 2020a) and revealed that habitat loss and intensive cattle grazing in and around natural areas have exacerbated transmission by bringing wild buffalo in more frequent contact with people and domestic animals (Kirksey 2012, Roug et al. 2020b).

Rangeland degradation appears to be an overarching problem contributing to poor health from tuberculosis. Following the One Health approach, reducing habitat loss may be a single-source solution that benefits the quality of life of many people and animals.

Surveilling emerging infectious diseases

“Emerging infectious diseases” is an umbrella term for pathogens that are newly discovered, recently evolved, or occupying new ranges or hosts (Rachowicz et al. 2005, Dazak et al. 2000, Bird and Mazet 2018). Emerging infectious diseases tolerated in one host can become epidemics in others — resulting in extinctions, suffering, or economic damage (Rachowicz et al. 2005, Barrett 2014, Zukai 2014). One Health projects to address this include the establishment of a global disease surveillance system with the capacity to respond to these health threats in real time (Bird and Mazet 2018).

This surveillance network is applied to diseases that primarily affect wild animals. Wild rhinoceroses and giraffes have recently displayed novel ulcerative skin infections. The cause in rhinos is thought to be a roundworm, but for giraffes it remains a mystery (Mutinda et al. 2012, Muneza et al. 2016). Disease monitoring efforts like these are a promising tool for learning more about diseases that primarily affect wild animals.

Uncounted numbers of diseases circulate among different wildlife species, but because of the lack of information on diseases that do not (yet) affect people, we have almost no information on the costs these unmonitored pathogens have for wild animals (Dazak et al. 2000). Understanding disease dynamics helps people stop the spread of wildlife diseases to new populations and intervene to restore good health to wild animals currently burdened by disease.

Future research to improve wild animal welfare

Target the worst diseases

One Health has been used many times to address diseases in wild animals. But in some of these instances, wild animals are merely asymptomatic carriers of these diseases. Pathogens that cause painful and prolonged symptoms in wild animals more significantly decrease their welfare (Beausoleil et al. 2012, Allen et al. 2018).

These diseases should be prioritized. Research that compares the relative severity of emerging infectious diseases — regardless of whether the diseases are transmissible to livestock or people — could be a promising way to apply One Health’s disease surveillance network to address wild animal welfare.

It is also important to increase our capacity to address wildlife health issues so that we can treat the prolonged and painful diseases once we discover them. Wildlife health facilities are also a valuable repository of information about wildlife health issues on the ground (Loyd et al. 2017).  Expanding these facilities helps us understand which diseases are most common or cause the most suffering.

Target common animals

Common species such as urban animals, livestock competitors, and agricultural pests tend to be of minimal conservation concern because of their abundance. But welfare efforts targeting common animals are likely to be most cost effective per capita because interventions can be distributed to vast numbers of individuals.

Pigeons heavily populate human-animal interfaces — areas in the landscape where human and non-human animals cohabitate (Kirksey 2012, Pacini-Ketchabaw and Nxumalo 2015). Because pigeons live in cities, they are vulnerable to avoidable and devastating anthropogenic health problems (Murray et al. 2019).

Targeting common animals like pigeons has strong potential to ameliorate welfare issues due to poor health on a large scale. Citizen science data from New York City pigeons indicate that on average, 165 pigeons annually are poisoned by lead (Cai and Calisi 2016). There is no reason to expect this rate to dissipate with time. It is also a minimum estimate because the data is sourced from one wildlife rehabilitation center. If this rate is reflected in all 33 megacities, then at least 5445 pigeons are poisoned each year globally.

Conclusion

Human, animal, and environmental health are linked. It is essential to address healthcare in wild animals to ensure they have good welfare. Veterinarians and wildlife health scientists who follow the One Health approach care about wildlife health for the sake of wild animals’ welfare, not just because wildlife health issues spill over to people. 

One Health continues to make strides toward building a global healthcare system for people, domestic animals, and wild animals. Though One Health projects tend to focus on implications for livestock and human health, there is potential for expansion into a range of wild animal welfare issues. A maximally beneficial welfare intervention would target common animals and their most prolonged and painful health issues.

One Health represents an unusual example of institutions and funding dedicated to improving wildlife health and engages a wide range of scientists and veterinarians. A wild animal welfare project that demonstrates co-benefits to livestock and people could similarly engage these practitioners by demonstrating that improving the welfare of wild animals is an important, multi-dimensional societal issue.

What is the value of wild animal welfare for restoration ecology?

Authored by former Wild Animal Initiative Staff Researcher Jane Capozzelli, Wild Animal Initiative Science Director Luke Hecht, and Samniqueka Halsey, Assistant Professor in the College of Agriculture, Food and Natural Resources at the University of Missouri, this paper was published in March 2020 in Restoration Ecology.

Abstract

The restoration community continues to discuss what constitutes good environmental stewardship. One area of tension is the extent to which the well-being of wild animals should inform restoration efforts. We discuss three ways that the perspective of wild animal welfare can augment restoration ecology: strengthening people's relationship with nature, reinforcing biotic integrity, and reducing mechanistic uncertainty. The animal welfare movement elevates sentient animals as stakeholders and explores how environmental context directly impacts the well-being of individuals. Viewing wild animals through this lens may encourage people to think and act with empathy and altruism. Second, we incorporate animal welfare into the concept of biotic integrity for ecological and ethical reasons. Restoring ecosystem processes may enhance animal welfare, and vice versa. Alternatively, there may be a trade-off between these factors, requiring local decision-makers to prioritize between restoring ecosystem function and promoting individuals' well-being. We conclude by discussing how welfare can impact population recovery, thereby adding insights about mechanisms underpinning restoration objectives. Ultimately, restoration ecologists and proponents of wild animal welfare could enjoy a productive union.

Summary of “What is the value of wild animal welfare for restoration ecology?”

Written by: Jane Capozzelli, Luke Hecht, Samniqueka Halsey

Published: March 2, 2020

DOI: https://doi.org/10.71441/fcr9-4ecj

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This piece was published in the March 2020 issue of Restoration Ecology.

Why discuss wild animal welfare in restoration ecology? 

Research and outreach disrupts status quo narratives, such as the perception that wild animal welfare and environmental management must operate under mutually-exclusive values, metrics, or models. Writing peer-reviewed articles in environmental science journals builds a common academic language to address environmental problems. It also catalyzes interdisciplinary thinking by considering pluralistic, alternative ethics of environmental stewardship. These two steps both bring us closer to generating solutions for improving the lives of wild animals. 

Our overall thinking is that proponents of wild animal welfare and restoration ecology share, to some extent, a non-anthropocentric worldview and a desire to collaborate to help wild animals. Yet the virtues and consequences of “respect and responsibility for wild animals” are viewed through a different lens by ecologists and proponents of wild animal welfare. 

The research in a nutshell

To build common ground toward solutions for improving the lives of wild animals, we provided a window into the animal welfare community for restoration ecologists, particularly wild animal welfare’s ethical positions and research priorities. We also acknowledged that people may differentially prioritize welfare- and conservation-oriented objectives. Yet, wild animal welfare is relevant, regardless, because of the instrumental value of providing for the needs of individual animals. 

To further frame our argument around animal ethics and morality, we blended our instrumental arguments around the moral foundations of conservation ethics, established in Aldo Leopold’s land ethic. We highlighted that the land ethic includes moral concern for individual, “fellow-members” of the landscape. Despite the value the land ethic places on animals, the management community has not resolved how to support individual animals while maintaining their ecosystem. It also does not sufficiently account for diverse ethical perspectives regarding what constitutes good environmental stewardship, nor take advantage of the information-value of animal welfare, as animal well-being depends on a host of behavioral, physiological, and environmental factors. 

Key takeaways

Our manuscript illustrates three ways that the perspective of wild animal welfare augments restoration ecology. 

1. Strengthening relationships between people and nonhuman animals. Restoration ecology could engage with wild animal welfare to advance a human-nature relationship infused with empathy and altruism.

2. Supporting multidimensional ecosystem health. It is possible to simultaneously improve ecosystem function and animals’ well-being. Synergistic interventions would concurrently support individuals and ecosystems, with the added benefit of encompassing multiple ethical and moral stances regarding what is good environmental stewardship.

3. Reducing uncertainty about interventions. Several aspects of animal welfare, such as health, physiology, behavior, and cognition, can modify species, communities, and ecosystems. A greater understanding of these relationships can reduce uncertainty regarding the outcomes of interventions for wildlife collectives or individuals. 

Next steps

An essential challenge ties together proponents of environmental management and wild animal welfare: resolving ethical and ecological conflicts on an increasingly complex and interconnected planet. The challenge for the wild animal welfare movement is to illustrate the ways that wild animal welfare is important and viable. Future work on these topics continues at Wild Animal Initiative to reorient animal advocacy and environmental science with a view of wild animals as morally-relevant subjects, who are entitled to a good life, and to catalyze evidence-based solutions for modern environmental problems on behalf of wild animals.