Risks to Raptors from Rodenticides: Protecting Birds of Prey

By Rene Bartos

A Bald Eagle on a nest…a Red-tailed Hawk overhead…a Peregrine Falcon diving to the earth…an Osprey rising from the shoreline with a fresh catch…a Barred Owl perched on a branch whooo whooing in the moonlight. Majestic, magnificent birds.

Birds of prey have found their way into my heart. I seem to spot them during birding events. While helping with riparian restoration once in Austin, a Red-shouldered Hawk was perched on a branch not more than 20 feet from me. I like to imagine that he was thanking me for the “re-wilding” efforts.

My love for raptors began in Rhode Island a few years back. I was completing a pediatric specialty fellowship. The Covid pandemic hit. Nature became my solace, a source of healing. Volunteering at the Audubon Society of RI was one escape. Perhaps this was in part a way to return to my roots, having grown up on a Midwest farm surrounded by woods and streams. When my older son’s PhD program was interrupted, he travelled to RI and we explored every “wild space” we could, digging into nature in ways we had not since he was a child. When my stress level went up I watched birds, as did many people who suddenly became intrigued by the birds outside their windows. Increased appreciation for the health benefits of nature is a silver lining that emerged from the pandemic storm. Each spring, I watched the Peregrine Falcon cam on top of the “Superman building” in downtown Providence. I watched Osprey cams in Connecticut and took road trips to check out their nests. Somehow watching these birds was calming to me. We humans make life so complicated. Watching parents tend their eggs and young made everything seem clearer. Some of my colleagues thought this a bit odd. Perhaps only birders could understand…

 

And then something happened that turned me into a raptor advocate. It’s funny how a seemingly minor event can change your life. Such was the case for me one day while watching an Osprey nest cam. A chick was struggling to breathe and was not eating. I wasn’t certain what to do. Generally what happens at the nest happens…a harsh reality. But I wondered if the chick had something caught in its throat, and if there was anything that could be done. I left a message with the local Audubon center. I located a raptor rehabilitation center and inquired about whether or not they would intervene. The end of the story is not happy. The chick was very ill and died. But through my outreach, I realized how little I knew about threats to raptors, and after reading information on the rehab center’s website and talking to the owner, I vowed to take action. The rehab center offered adoption for rescued birds of prey. I adopted one, then others on behalf of family members, announcing that their adopted birds were early birthday presents from me. I read more about threats to raptors, including loss of natural habitat, pollution, lead in fishing tackle and ammunition, mercury, collisions with structures, power pole electrocution, entanglement in fishing nets and twine, and something new to me: second generation anti-rodenticides (SGARs). Intended to keep rodents under control, they can also kill raptors that ingest the poisoned rodents. SGARs work by keeping blood from clotting so they can cause the raptor to essentially bleed to death. What? In our attempt to kill rats we are killing these marvelous birds! The irony…harming the natural predators. I wondered about the risk to other wildlife, domestic animals, people?

My thoughts turned to Rachel Carson’s Silent Spring. If not for the efforts of passionate advocates, how much longer would we have used DDT, which poisoned wildlife and caused harm to generations of people?  As years of experience have shown, what we do to nature eventually comes back to all of us. I wondered how many people knew about SGARs. I read startling statistics about the extent to which raptors brought to rehab facilities in northeastern states had SGAR exposure, about the potential effects of SGARs getting into our water and soil, and potential effects on people.  I shared the information and ideas with Audubon of RI staff and contacted the CT Audubon center with the Osprey cam. I asked if they had considered collaboration for educational or legislative efforts. I created Jeopardy style questions about threats to raptors and ways to protect them for the Audubon of RI annual raptor event. I figured if I hadn’t heard of SGARs, possibly people attending the event hadn’t either. This was in 2021 and 2022. Fast forward to today…while I have since moved to Austin, I have continued to follow the work being done, and am thrilled to see the progress in RI and other states to protect raptors.

 

Now, as a Travis Audubon member, I  wonder…are efforts needed in Austin? In Texas? I believe the key is education about the problem, and about alternative solutions. Rodent overpopulation is indeed a problem in some areas. People want to protect birds but unless we promote feasible alternatives, change is challenging. Approaches to consider:

  • Education about integrated pest management and safer options. For example:
    • Sealing building entry points
    • Removing food and water around buildings that attracts rodents
    • Removing debris, securing trash containers
    • Use of natural deterrents and repellents
  • Highlighting pest management practitioners using best practices, to encourage others to adopt safer and more humane options
  • Supporting the concept of raptors as the solution (natural predators of rodents)
  • More research and attention to alternative approaches to rodent overpopulation.
  • Exploring potential legislation

I don’t have all the answers. I am a pediatrician, not an ornithologist or a pest control expert. But I do know that what affects birds likely also affects kids, and as an advocate for both and a pediatrician who believes in the importance of time in nature for kids, when I see a problem I need to speak up. Based on my experience, collaboration with a multi-sector approach, and “storytelling” to reach a larger audience are the keys to success. Collectively, we can find a better path. So let’s get to it!

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Sources

A Place Called Hope. “Alternatives to Rodenticides,” n.d.
Audubon. “The Internet Has a Rat Poison Problem,” December 8, 2021.
Audubon Connecticut. “Rodenticides May Not Target Birds, but They Do Kill Them,” March 19, 2024.
Audubon Vermont. “Are We Burning down Our House to Kill a Rat? Why the Use of Second Generation Anti-Coagulant Rodenticides Is a Bad Idea, for Birds and People,” May 15, 2023.
Gomez, Eres A, Heather L Prestridge, and Jennifer A Smith. “Anthropogenic Threats to Owls: Insights from Rehabilitation Admittance Data and Rodenticide Screening in Texas.PLOS ONE 18, no. 8 (August 4, 2023): e0289228–28.
Hopf-Dennis, Cynthia, Sarrah Kaye, Nicholas Hollingshead, Marjory B Brooks, Elizabeth M Bunting, and Noha Abou?Madi. “Prevalence of Anticoagulant Rodenticide Exposure in Red-Tailed Hawks (Buteo Jamaicensis) and Utility of Clotting Time Assays to Detect Coagulopathy.” Ecotoxicology 31, no. 6 (May 27, 2022): 919–32.
Mass Audubon. “A Campaign to Rescue Raptors,” n.d.
Mass Audubon. “Poison-Free Pest Control.” Accessed June 23, 2024.
Murray, Maureen. “Continued Anticoagulant Rodenticide Exposure of Red-Tailed Hawks (Buteo Jamaicensis) in the Northeastern United States with an Evaluation of Serum for Biomonitoring.Environmental Toxicology and Chemistry 39, no. 11 (September 22, 2020): 2325–35.
NAKAYAMA, Shouta M.M., Ayuko MORITA, Yoshinori IKENAKA, Hazuki MIZUKAWA, and Mayumi ISHIZUKA. “A Review: Poisoning by Anticoagulant Rodenticides in Non-Target Animals Globally.” The Journal of Veterinary Medical Science 81, no. 2 (February 1, 2019): 298–313.
Nelson, Angela . “Understanding the Risks of Rodent Poisons to Birds of Prey | Tufts Now.” now.tufts.edu, September 16, 2020.
Niedringhaus, Kevin D., Nicole M. Nemeth, Samantha Gibbs, Jared Zimmerman, Lisa Shender, Kate Slankard, Heather Fenton, et al. “Anticoagulant Rodenticide Exposure and Toxicosis in Bald Eagles (Haliaeetus Leucocephalus) and Golden Eagles (Aquila Chrysaetos) in the United States.” Edited by Benito Soto-Blanco. PLOS ONE 16, no. 4 (April 7, 2021): e0246134.
Okoniewski, Joseph C., Christine VanPatten, Ashley E. Ableman, Kevin P. Hynes, Angela L. Martin, and Peter Furdyna. “Anticoagulant Rodenticides in Red-Tailed Hawks (Buteo Jamaicensis) from New York City, New York, USA, 2012–18.Journal of Wildlife Diseases 57, no. 1 (January 6, 2021).
Popov Aleksandrov, Aleksandra, Dina Tucovic, Jelena Kulas, Dusanka Popovic, Dragan Kataranovski, Milena Kataranovski, and Ivana Mirkov. “Toxicology of Chemical Biocides: Anticoagulant Rodenticides – beyond Hemostasis Disturbance.” Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP 277 (March 1, 2024): 109841..
Raptors Are the Solution. “RATS Home.” Accessed June 23, 2024.
Regnery, Julia, Pia Parrhysius, Robert Schulz, Christel Möhlenkamp, Georgia Buchmeier, Georg Reifferscheid, and Marvin Brinke. “Wastewater-Borne Exposure of Limnic Fish to Anticoagulant Rodenticides.” Water Research 167 (December 15, 2019): 115090–90.
US EPA, OCSPP. “Restrictions on Rodenticide Products.” US EPA, March 4, 2014.
Vatcher, Deborah. “‘Prey for Wildlife; Casualties of the Chemical War on Rats,’ (with English Closed Captions, April, 2023).” Vimeo, April 13, 2023.
W, Christina. “When Pest Control Poisons Wildlife: Why It Happens and How to Help.” Mass Audubon – Your Great Outdoors, May 6, 2021.
Weir, Scott M., Jeffrey F. Thomas, and David N. Blauch. “Investigating Spatial Patterns of Mercury and Rodenticide Residues in Raptors Collected near the Charlotte, NC, USA, Metropolitan Area.” Environmental Science and Pollution Research 25, no. 33 (September 25, 2018): 33153–61.
www.audubon.org. “City Life Is Hard for Raptors. Can Removing Rat Poison Make It Easier? | Audubon,” June 6, 2024.