The major question that has stimulated most of my research is centered on the role of environmental stressors in moderating ecological and evolutionary change—a question of growing importance as anthropogenic stressors on natural populations continue to increase. I started this exploration by exploring the role of environmental developmental stressors on visual communication, mating, competitive, and anti-predatory behaviors in birds and insects. Subsequently, I expanded my research program to include an explicit conservation angle to study how anthropogenic environmental disturbance (e.g. noise pollution) affects breeding performance and behavioral strategies in song birds. I have also forged links between ecological and biodiversity principles with public health. The most recent and active projects (Sonic Nets, Acoust Lighthouse) are trying to design and implement actual solutions to the conflict between humans and wildlife, using the approaches of behavioral and sensory ecology.

 

Noise pollution and solving problems of human-wildlife conflict
Introduction of anthropogenic noise can cause substantial behavioral problems for wildlife (e.g. blocking vocal communication channels for birds). To date, our work has shown that adult birds’ and nestlings’ vocal communication is disrupted by human noise pollution and that this can result in decreased strength of pair bonds and lower reproductive success. Although there is a fair amount known about how loud noises affect the physiology and development of humans, relatively little is known about how this prevalent form of pollution affects similar processes in wildlife. Here's a short video produced by Jamie Hall ('13) and Conor MacDonnell ('14) (as part of a science film-making class taught by Jes Therkelsen) about noise pollution:

Sonic Nets. Building from our understanding of how birds respond to noise, we are now turning the tables on our knowledge to design acoustic stimuli and technology that will deliberately deter birds from socioeconomically important areas. Specifically, if we broadcast a net of sound into an area that stops birds from hearing each other, their state of fear increases and they leave to go elsewhere. They don't habituate as their real sense of danger increases. These "Sonic Nets" are delivered through seaker systems at places such as farms and airports where some birds can do tremendous damage. They move the birds on to quieter sites. The Sonic Nets can also be deployed at places where birds are harmed, e.g., polluted sites. We've shown that this idea works in both captive and field conditions, and the Sonic Net technology has been commercialized and is currently being sold by a local Virginian company, Midstream Technology.

Acoustic Lighthouse. Millions, perhaps billions, of birds die each year when they collide with large human-built structures, such as buildings, wind turbines, and communication towers. We've developed a new way of thinking about how to limit those collisions. As birds fly during migration they are often looking at the ground and their eyes are positioned toward the side of their skulls. Hence, they are not looking where they are going. By projecting a conspicuous sound field in front of a collision-risk object, we grab the visual attention of the bird and reduce the risk of collision. We've demonstrated the effectiveness of the "Acoustic Lighthouse" in captivity and are now moving on to field studies at various scales.

Video links for these projects:

• PBS SciTech segment on these acoustic projects
• W&M summary of Sonic Nets and Acoustic Lighthouse

 

Ecology, biodiversity, and public health
We have investigated the consequences of avian ecology and diversity for human health. We have collected robust information to indicate that humans are often better protected against avian-borne diseases (e.g. West Nile virus) when avian biodiversity increases in local populations. This is because most avian species are poor host reservoirs for their respective disease organisms, and so adding a bird species to an area most likely adds a low competence host and “dilutes” the disease locally, lowering infection risks for humans. We are currently expanding this project by looking at further ways in which wildlife community structure and life history traits influence infectious disease risks to humans.

Another of our current projects relates ecology with public health. We are investigating how low levels of mercury exposure influence many aspects of individual physiology (cellular immune responses, adreno-coriticol responses) development (neural formation, brain language center development) and behavior (mate preferences, male song, flight mechanics, foraging strategy, antipredatory tactics) in two model songbird species (zebra finches, European starlings). Mercury is a global, persistent contaminant that is released in large amounts from certain chemical processes and coal-fired power plants, and biomagnifies and accumulates in aquatic and terrestrial food webs. Little is known about how low-level exposure to mercury affects key systems in the body and the published “safe levels” are largely driven by litigation rather than strong science. We are performing the first long-term study of how mercury disrupts cellular and organismal processes in terrestrial birds. We have already noticed that there are substantial and consistent among-individual differences in susceptibility to mercury which we would like to investigate by genetic and genomic studies; merging evolutionary biology with ecotoxicology. We are particularly excited about our new project, investigating the effects of mercury on male fertility and could help to explain falling sperm counts around the globe.

Video links for these projects:

• Tack Faculty Lecture Series on the links between West Nile virus and biodiversity
• Homemade video we made for a crowdfunding site for our mercury-fertility project

 

Links to other research sites for John's work: