Welcome to my Research Agenda
Here I present the most relevant sources to my research, describing each in brief detail.
Source 1
Research Article
Clark, Christopher J. et al., “Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage.” Proc. R. Soc. B.28920221164 23 November 2011, https://royalsocietypublishing.org/doi/full/10.1098/rspb.2022.1164#d1e502
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Main Researcher: Christopher J Clark is an assistant professor of biology at the University of California, Riverside. His research interests include courtship displays, how feathers and wings produce sound, and bird flight biomechanics, using hummingbirds as a model system. Clark enjoys researching/experimenting with parts of ornithology that he doesn't fully understand.
Methods:
Researchers placed a speaker in fresh Great Gray Owl plunge holes (created from hunting) and played recorded sounds of a vole tunneling through the snow. They measured at which angles the owl could best hear the vole sounds.
Results:
Snow muffles vole sounds & creates an acoustic mirage (ears perceive different location of vole than actual location); Great Gray Owls counter this by hovering directly above vole, using their hearing to pinpoint exact prey position.
Main Idea:
Great Gray Owls locate voles under snow by ear. The owls' hunting strategy is highly dependent on their hearing. First, they have to make numerous quick adjustments along their flight path towards a prey animal. Each of these adjustments is informed by their asymmetrical ears. Finally, in order to accurately catch a prey animal, the owl has to silently hover directly above their prey to minimize sound refraction
(sounds from snow are misleading unless the owl is directly above prey) & attenuation (sounds below snow are absorbed by the snow, rendering them notably quieter). Using their large facial discs & silent feathers, which muffle the sounds of owl flight so that the owl can both hear better and be unheard by prey, Great Gray owls can effectively catch prey using mostly their ears.
Connections to other articles:
Owls use their hearing to map 3D spaces and determine prey location when their eyes cannot, made possible by owl's unique auditory system adaptations. Internal adaptations (long cochlea) & external adaptations (asymmetrical ears) allow them to easily localize vertical sounds, or sounds above and below them. In contrast, human ears are well adjusted to localizing sounds to our left and right, but not above and below us. (refer to "Designed for Darkness"). Think of the owl as able to fly with only instruments at night, like how a pilot can fly a plane with instruments alone if they know how. The owl has different instruments it can use other than vision alone.
Source 2
Literature about Owls
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Main Researcher: Alan Sieradzaki is a senior researcher at the Global Owl Project and a Principal Investigator at World Owl Bibliography (WOB).
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Main Idea:
Owls have evolved to be effective nocturnal hunters enabled by large eyes containing many light sensitive cells and a complex auditory system. This chapter examines the individual adaptations & shared behaviors that make them effective.
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Ears: Internal adaptations (long cochlea & specially wired brain anatomy) & external adaptations (asymmetrical ears) allow them to easily localize vertical sounds, or sounds above and below them. In contrast, human ears are well adjusted to localizing sounds to our left and right, but not above and below us
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Eyes: Internal adaptations (more rod cells than cone cells in the eye) allow the owl to detect motion and discern between black, white, and grey with greater speed and accuracy than diurnal (daytime) hunters.
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Feathers: External adaptations (comb-like feather shape) disrupts air as it flows over an owl's wings, reducing the sound it makes.
Connections to other articles:
Owls' complex auditory system allows them to overcome acoustic mirage to determine prey location. An owl's feathers and hearing organs are designed to collect accurate sensory information when light is unavailable.
Source 3
General Owl Overview
"Owls - Owl Research Institute." Owl Research Institute, www.owlresearchinstitute.org/owls-1.
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Author: The Owl Research Institute is a nonprofit organization dedicated to owl and wildlife research, conservation, and education. They conduct long-term research into owls, their prey species, and their relationship to the habitat in which they live. They also collaborate on strategic projects, including educating the public about owls and providing research data to land management agencies and conservation partners (Owl Research Institute).
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Main Idea:
Owls are raptors with unique adaptations such as large heads, forward-facing eyes, and soft feathers, allowing them to hunt effectively at night. There are about 250 different owl species divided into two families: Tytonidae (Barn Owls) and Strigidae (all other owls). They use various hunting techniques and hunt by night, by day, or by twilight. Owls may cache food and roost alone or communally. Mating involves vocalizations and courtship displays. Owls often reuse nests from other animals. Their reproductive success depends on nearby food sources. Conservation efforts are crucial for maintaining owl habitats and populations.​
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Connections to other articles:
Human-made owl boxes are effective nests for owls because they often reuse nests from other animals. Since their reproductive success depends on nearby food sources, if nearby food sources are poisoned, the owls in question are likely to suffer and reproduce less, if at all.
Source 4
Interview with an Expert
Ackerman, Jennifer. "What an Owl Knows." Science Friday, 23 Sept. 2011, www.sciencefriday.com/segments/what-an-owl-knows-ackerman/.
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Interview Subject: Jennifer Ackerman is an author whose writing centers around topics related to nature, science, and health.
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Main Idea:
Ackerman explains how owls' specialized features, such as their large, light-sensitive eyes and sophisticated auditory system, allow them to hunt efficiently at night. Recent advancements in technology and research that have provided deeper insights into owl physiology, behavior, and their ecological roles are highlighted. Owls have comparatively the longest cochlea of all birds.
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Connections to other articles:
Similar takeaways to Sieradzaki's "Designed for Darkness" and the Great Gray Owl experiment. Basically glue for the 2 sources above this one.
Secondary Anticoagulant Rodenticide Poisoning:
A major problem for owls across the world
Problem Article 1
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Raylene Cooke, Pam Whiteley, Clare Death, Michael A. Weston, Nicholas Carter, Kieran Scammell, Kaori Yokochi, Hao Nguyen, John G. White,
Silent killers? The widespread exposure of predatory nocturnal birds to anticoagulant rodenticides,
Science of The Total Environment, Volume 904, 2023, 166293,ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2023.166293.
(https://www.sciencedirect.com/science/article/pii/S0048969723049185)
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Main Researcher: Raylene Cooke
Researcher at Deakin University; research focuses on urban-wildlife interaction/effects.
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Methods:
Dead tissue samples from owls were collected in Victoria, Australia. 41 samples collected between 2020 and 2022; 19 samples collected between 2003 and 2019. Samples toxicologically screened.
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Results:
Harmful anticoagulant rodenticides were detected in 92% of nocturnal avian predators. Worse, predators with largely non-rodent diets were also heavily exposed to rodenticides.
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Main Idea:
Regulation of rodenticides is critical for the conservation of native predators, as rodenticides reduce a predator’s overall fitness. Less predators means less natural rodent pest control, therefore humans will respond by increasing rodenticide use, which will kill predators quicker and quicker until none remain.
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Connections to other articles:
Rodenticide exposure to unintended targets (nocturnal avian predators) is widespread, although this study was conducted in Australia, therefore I wonder what similar studies in the USA, Europe, Asia, Africa, & South America would yield. If nocturnal avian predators in similar urban environments have similar concentrations of anticoagulant rodenticides in their system, that would mean that cases like Flaco’s will become more common.
Problem Article 2
Conservation Letter: Raptors and Anticoagulant Rodenticides (click to view article)
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Eres A. Gomez; Sofi Hindmarch; Jennifer A. Smith
Journal of Raptor Research (2022) 56 (1): 147–153.
https://doi.org/10.3356/JRR-20-122
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Main Researcher: Eres A. Gomez is a researcher at University of Texas at San Antonio & the Research Program Coordinator for the Urban Bird Project. Her research focuses on raptor rehabilitation and anthropogenic threats to raptors, specifically anticoagulant rodenticide (rodent poison) exposure in Texas.
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Main Idea:
Secondary rodenticide exposure often doesn’t immediately kill predators. Instead, it induces sublethal effects, such as: delayed blood clotting, anemia, and impaired mobility. These reduce a predator’s fitness, which causes it undue suffering and predisposes it to an early grave. Secondary rodenticide exposure can develop into a lethal case when it begins causing severe blood loss and internal hemorrhaging, both of which are associated with organ failure, shock, and death.
Rodenticides are often used in conjunction; owls often have more than 1 in their system prior to death, exacerbating anti-clotting effects.
Connections to other articles:
Flaco suffered sublethal secondary effects of rodenticide, likely weakening/disorienting him and contributing to his death. Flaco also had 4 different rodenticides in his system.
Problem Article 3
What Flaco the Owl’s Death Teaches Us About Making Cities Safer for Birds (click to view article)
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Magazine, Smithsonian. “What Flaco the Owl’s Death Teaches Us about Making Cities Safer for Birds.” Smithsonian.Com, Smithsonian Institution, 17 Apr. 2024, www.smithsonianmag.com/science-nature/what-flaco-the-owls-death-teaches-us-about-making-cities-safer-for-birds-180984117/
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Author: Lauren Oster is a New York City writer for the Smithsonian Magazine. Her articles are mostly about nature.
Main Idea: Humans, specifically anthropogenic materials, are the biggest threat to birds. Specifically, anti-rodent chemical warfare threatens urban animals. Second Generation Anticoagulant Rodenticides are designed to kill rats slowly; affected rats can survive for up to 10 days, and toxins remain in their bodies for up to 100 days. Predators who consume the rat then experience the effects of rodenticide on their own system.
Secondary rodenticide exposure compromises predators, making them more susceptible to an opportunistic disease, whether bacterial, viral or parasitic. In the case of Flaco, a beloved Eurasian Eagle-Owl who lived free in New York for a year after escaping the zoo, 4 different rodenticides in his system compromised his immune system and weakened him enough to cause a fatal flight error.
Ornithologists and conservationists say urban environments can be made bird-friendly.
Connections to other articles:
Although Flaco lived in an urban environment, wild owls aren’t safe from secondary rodenticide exposure.
Solution Article 1
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Das, Kasturi. "Artificial Nests for Barn Owls Help Farmers Befriend These Natural Rodent Killers." Mongabay-India, 5 Jan. 2022, https://india.mongabay.com/2022/01/artificial-nests-for-barn-owls-help-farmers-befriend-these-natural-rodent-killers/.
Author: Kasturi Das is a journalist for Mongabay who writes about ecological issues in India.
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Main Idea: Rodenticide often kills helpful organisms, flora, & fauna. They’re also expensive & toxic, therefore uneconomical. This article proposes an integrated management system combining natural rodent predation (barn owls) with chemical repellants & plants that rodents are adverse to.
Solution Article 2
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Elliott, J. E. et al., (2016). "Paying the Pipers: Mitigating the Impact of Anticoagulant Rodenticides on Predators and Scavengers" BioScience, vol. 66, no. 5, 2016, pp. 401-407. Oxford University Press, https://doi.org/10.1093/biosci/biw028
Author: John E. Elliot is a scientist whose research focuses on the environment & climate change, especially anthropogenic impacts on birds.
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Main Idea: New risk-mitigation measures for rodenticides are now in effect in some countries (Canada, USA, and to some extent the EU). California has taken the lead in further regulating & restricting anticoagulant rodenticide (AR) usage, requiring licensure and outlining where ARs can and can’t be used. Regardless, further top-down efforts are necessary to further decrease rodenticide-caused environmental harm.
“Under the EPA's Pesticide Environmental Stewardship Program (PESP), some major food and “big-box” retailers have moved to greatly reduce rodenticide usage in their food-supply chains, essentially employing the long-established principles of integrated pest management (IPM) to monitor pest presence and apply pesticides only as needed. It also takes the concept further to develop, for example, “Go Green” programs which have used data on the ecology and behavior of rodents to develop more effective control programs.”
Furthermore, this article calls for the development and implementation of outreach and educational stewardship programs.
Connect to other articles: one example of an outreach/educational stewardship program is the Owl Wise Leader program (https://raptorsarethesolution.org/owl-wise-leader/). This program encourages businesses and other entities to protect owls, hawks, other raptors, and all wildlife—as well as domestic pets—by eliminating rat poison products.
Solution Article 3
"EPA Proposes New Mitigation Measures for Rodenticides, Including Pilot for Protecting Endangered Species." U.S. Environmental Protection Agency, 3 Nov. 2022, www.epa.gov/pesticides/epa-proposes-new-mitigation-measures-rodenticides-including-pilot-protecting-endangered. Accessed 30 May 2024.
Main Idea: The US Environmental Protection Agency has outlined rodenticide harm-reduction strategies for species it deems jeopardized by rodenticide exposure. These strategies include using tamper-resistant bait stations and collecting rodent carcasses to prevent secondary poisoning of non-target wildlife.
Connect to other articles: Although this is a strong step in the right direction, the EPA can follow California’s lead (as mentioned in "Paying the Pipers") and implement stricter regulations to reduce rodenticide impact. Furthermore, this measure doesn't directly address owl populations.
Solution Article 4
OWL BOXES (individual)
"Owl Box." Ontario Wildlife Removal Inc., www.ontariowildliferemoval.ca/owl-box/. Accessed 29 May 2024.
There are benefits that extend to home owners and to the environment too. When an owl has the opportunity to live in your backyard, these benefits include:
Providing a safe haven for a family of owls.
Owls help control rodent and wildlife infestations around the home.
Owls are safer than then using rodenticides.
Owls can help control insect populations.
Owl boxes encourage mating and owl population growth.
They provide entertainment for the whole family.
They’re perfect for the avid bird-watcher in your family.
Promoting wildlife conservation in your own backyard.
If you’re an avid gardener and enjoy planting fruits and vegetables every year, your biggest pet peeve will be crop damage. The same goes with farmers. Owls will without a doubt help control some of the pests that damage your garden.