Wildlife Health comes to New York City – Investigating Lead Levels in Pigeons

Credit: Jennifer Morrow, https://www.flickr.com/


Wildlife in New York City. It sounds like an oxymoron, but every year, concerned New Yorkers find thousands of injured animals lying on the sidewalk. They take to Google and end up at the only wildlife rehabilitation center in NYC – the Wild Bird Fund. I was one of those people.

In 2009, two children brought a sparrow into the dog & cat clinic that I worked at. The bird wasn’t putting any weight on its right leg. After my shift was over, I made the two-hour subway ride to the Upper West Side and stepped through the front door of the Wild Bird Fund. Hens roamed freely in the lobby. A gull honked from its perch on the chair next to me. Mourning doves cooed from huge window aviaries, and a rehab worker bustled by cradling a swan, one hand supporting its long neck. I was instantly hooked. The very next week, I attended orientation to become a volunteer.

Although the Wild Bird Fund accepts all animals, more than half of its patients belong to just one species. It’s the most commonly sighted animal in New York City – the infamous pigeon, Columba livia, or, “rat with wings”.  There are over a million in NYC alone. That means thousands of sick pigeons arrive at the Wild Bird Fund every year. After volunteering for a while, I became interested in learning more about lead poisoning, one of the most common ailments among our patients.

Map of pigeon mean blood lead levels in Manhattan by zip code.

For my undergraduate senior thesis project, I decided to compile all of the blood lead levels for pigeons measured at the Wild Bird Fund from 2011 onwards. Then, I mapped these results across different neighborhoods in NYC. Sorting through and geolocating thousands of hand-written records took me the better part of an entire summer. Turns out it wasn’t in vain – I found consistently high levels of lead poisoning in small pockets of the city, areas such as Lower Manhattan and the Gowanus Canal in Brooklyn. My results also matched child lead poisoning reports published by the US Department of Health in 2010 and 2014. Sick children and sick pigeons live in the same neighborhoods.

It’s still unclear where this lead is coming from, although it’s most likely a combination of several different sources, including leaded paint, leaded gasoline, and small airplane fuel. The Wild Bird Fund data also revealed another trend: lead poisoning is significantly higher in the summer. This correlates with lead poisoning studies done on human children; Laidlaw et al. (2005) suggest that soil humidity is lower in the summer, leading to increased suspension of and exposure to lead dust.

In the end, it’s hard to look past some of the similarities between human and animal pathology, especially when we live in the same neighborhoods, breathe the same air, and eat the same food. (If you’ve never seen a pigeon chowing down on a discarded pretzel, have you truly seen New York City?) Mine is just one of many studies being published every year about human-ecosphere interaction. One emerging field involves the use of animals as bioindicators for human health. The bioindicator is the proverbial canary in the coal mine; if the wildlife falls ill, we may expect humans to fall ill as well.

Just like any other time science happens, I submitted my paper with more questions than I had answers. Wildlife is suffering, and it is by no uncertain terms our doing. It’s hard not to notice this when three of the most common problems treated at the Wild Bird Fund are lead poisoning, collision with windows, and cat attacks. Shortly after my study was published in Chemosphere, it was picked up by The New York Times and a slew of other online papers. In particular, The New York Times debated the true efficacy of predicting human disease using pigeon lives. As I read the news article, my heart sank.

I’d written a paper on pigeon health, but I was getting the impression that very few people cared if it didn’t have immediate applications to human medicine. It wasn’t entirely their fault — I had, after all, dedicated many pages of my study to drawing comparisons between pigeon and human child lead toxicity. But as accurate as these comparisons were, I’d done them in part because I hadn’t been confident that anyone would notice a study on just pigeon lead poisoning. I thought my results were important, and I wanted them to be published; writing about human medicine would help that process.

It’s not that I don’t care about human medicine — far from it. We should raise our voices, loudly and clearly, when a human is poisoned. And we should raise our voices, loudly and clearly, when an animal is poisoned as well. Lead toxicity or otherwise, it’s becoming more and more obvious that connections between human and animal health exist everywhere we turn. I guess this is a call to everyone to care just a bit more about what happens to the life that we’re surrounded by: the earthworms tunneling underfoot, the warblers migrating south, and yes, maybe that pigeon strutting past too, even if it just pooped on your windshield.


The paper published from Fayme’s research can be found here.  Click here to read the New York Times article about it.


Fayme Cai, class of 2022, was born and raised in NYC and graduated from Columbia University with a Bachelor’s in Ecology & Evolution and a minor in Psychology. Although it’s still up in the air for now, she’s mostly interested in small animal and companion exotic animal medicine.

The Price of Freedom: How our Choice to use Lead is Killing the Bald Eagle (Part 2)

This post was originally published at Science@CornellVet on August 2, 2017 by Melissa Hanson, third year Cornell DVM student.  

juvenile bald eagle

A juvenile bald eagle receives treatment at the Janet L. Swanson Wildlife Health Center

Last week offered a glimpse into the work the Animal Health Diagnostic Center and Wildlife Health Team has done to quantify the impact of lead on our native wildlife, but what does the story look like from the perspective of Cornell’s clinicians? Dr. Sara Childs-Sanford, a veterinarian at the Janet L. Swanson’s Wildlife Health Center, a clinical service of the Cornell University Hospital for Animals (CUHA), shared her experience treating local wildlife directly impacted by the toxic element.

“A typical patient presenting with lead toxicity is a raptor species (bird of prey) or waterfowl. These animals are weak, and often have neurologic signs and ileus (failure of food to pass through the digestive tract),” says Childs-Sanford. “Concerned members of the public usually bring the animal to CUHA after observing it unable to fly or walk.”

She explains that the primary treatment of these animals involves supportive care for dehydration and emaciation, and a blood draw to screen for serum lead values. Her team uses an in-house lead analyzer is to detect lead concentration in the blood, giving them a rapid answer regarding lead toxicity in a patient.

With the help of the analyzer, virtually every raptor or waterfowl species patient that comes through the door is screened for lead toxicity, allowing treatment to begin immediately. To target the lead, the Wildlife Health Center team uses chelation therapy, which involves the introduction of compounds that bind lead and thus allow it to be excreted by the patient. Chelation therapy is completed in five day increments for a minimum of two weeks, but many patients need to remain under the care of Childs-Sanford’s team or a wildlife rehabilitator for much longer.

What harm can a little lead do? When ingested by an animal, lead is absorbed through the blood stream where it disrupts heme synthesis, a process required for oxygen delivery. The toxin is then distributed throughout the body where it deposits in soft tissue, organs, and bone, degenerating nerves and interrupting signaling pathways necessary for neurologic and gastrointestinal function. The prognosis for patients is widely variable and dependent upon the levels of lead detected, the organ systems affected, and most importantly, how long the toxicity has been present. In general, acutely affected animals carry a better prognosis than those with chronic exposure. Unfortunately, for waterfowl and piscivorous raptors, continually eating from a contaminated body of water often results in the latter.

radiograph of a common loon with a lead sinker in its digestive tract

Radiograph of a common loon with a lead sinker visible in the digestive tract

So, what can you do to help? For Childs-Sanford, part of the solution is clear: don’t use lead bullets or sinkers, and don’t cut fishing lines into the water. “Lead in the wild comes from people,” she stated, noting that its inexpensiveness and the lack of public awareness of its effects are likely to blame for its continued use. While the Wildlife Health Center is capable of treating animals on an individual basis, the true answer to the lead problem lies in addressing its source—us. Increased education for hunters and fishermen is vital, and eliminating the use of lead materials in our environment is the only way to save our wildlife from its devastating effects. Until then, Childs-Sanford and her team will take it one patient at a time.


Melissa is a third-year veterinary student from Cortlandt Manor, New York. She received her Bachelor of Science degree from Duquesne University where she majored in biology and minored in biochemistry and history. Her interests are in clinical zoo and wildlife medicine and particularly rescue, rehabilitation, and release. She works as student technician at the Janet L. Swanson Wildlife Health Center, a service of the Cornell University Hospital for Animals.

The Price of Freedom: How our choice to use lead is killing the bald eagle (Part 1)

This post was originally published at Science@CornellVet on July 27, 2017 by Melissa Hanson, third year Cornell DVM student.

bald eagle

Photo credit: Animal Health Diagnostic Center

The bald eagle is an American icon, a symbol of freedom, and for conservationists, one of the nation’s greatest success stories. Restored from near extinction, the species has been thriving once again—or so we thought. As it turns out, mankind may be placing unnecessary pressure on America’s best known bird.

Cornell University’s Animal Health Diagnostic Center (AHDC) employs some of the brightest minds in ecology and wildlife health. Dr. Krysten Schuler, a wildlife disease ecologist, has been leading the research effort exploring the role environmental lead plays in bald eagle health. Schuler partnered with the New York State Dept. of Environmental Conservation to analyze two decades’ worth of data collected from New York State to identify sources of mortality. Their results are disturbing: 17% of bald eagle carcasses examined revealed death due to lead poisoning, and 80% had measurable lead levels in their blood, tissues, or bone. Schuler reports that adult eagles are more likely to die from lead poisoning than juveniles, posing a serious threat to the reproductive success of the species because adults nest and rear young.

Where is all this lead coming from? A likely significant source is ammunition. Lead bullets are commonly and traditionally used for game hunting, which can leave trace levels in meat as well as in the environment. When carcasses or offal are left on the landscape, eagles will scavenge from them, consuming lead bullet fragments. Lead is toxic to all animals, including humans, and eating venison shot with lead bullets may pose a risk to consumers. Schuler explains that the bullet fragments when it hits its target, and small shards can travel more than a foot from the wound channel where they are less likely to be removed during the butchering process. Pregnant women and children are particularly sensitive to the toxic effects of lead, as developing tissues are vulnerable and easily damaged by the toxin.

So, how can we protect our families and our wildlife? Consider alternative ammunition. Modern non-lead bullets are inexpensive and do not foul firearms, as was once widely believed in the hunting community. These alternatives are safe and effective, and when combined with proper hunting etiquette, such as recovering carcasses and properly disposing of entrails, can make a real impact in the levels of lead present in the environment. Even recreational shooting with lead contaminates the environment, and participants should also consider alternatives. Lead bullets may be traditional, but they are also replaceable.

While 80% of bald eagles with measurable lead is a startling figure on its own, it is important to recognize that this species serves only as a snapshot of the entire picture. Lead is toxic to all wildlife and humans, and shared sources of food are the common denominator. “This is a problem that is both man-made and solvable,” says Schuler, emphasizing that humans have introduced lead into the environment and therefore hold the responsibility of removing it as well. Research conducted by the AHDC brings to light the severity of lead toxicity in New York State, exposing it as a true threat to wildlife health where it otherwise may have persisted as a silent killer. Schuler adds, “Just because we don’t see piles of dead eagles doesn’t mean it’s not a problem.” Thanks to her contribution, both problem and solution are now quite clear.


Melissa is a third-year veterinary student from Cortlandt Manor, New York. She received her Bachelor of Science degree from Duquesne University where she majored in biology and minored in biochemistry and history. Her interests are in clinical zoo and wildlife medicine and particularly rescue, rehabilitation, and release. She works as student technician at the Janet L. Swanson Wildlife Health Center, a service of the Cornell University Hospital for Animals.