Our friends at Raptors Are The Solution shared a story with us about a flock of parrots dying because of rodenticide poisoning in the Telegraph Hill neighborhood of San Francisco.
We wrote a story a few weeks ago asking our readers to ditch using rodenticides because it kills our birds of prey – ‘Save Our Raptors, Don’t Use Rodenticide.’
Besides killing rodents, rodenticide kills wildlife that comes in contact with the poisoned rats or mice and contaminated soil and water.
It’s just bad stuff. Period.
Famous Parrots Victim of Rodenticide Poisoning
And now a new study led by the University of Georgia (UGA) Infectious Diseases Laboratory and funded by Mickaboo Companion Bird Rescue adds to the growing list of wildlife victims of rodenticide.
Researchers say bromethalin, a common rat poison, is the culprit.
It’s the agent responsible for a neurological disease that’s making birds sick or killing birds from a popular flock of naturalized parrots residing primarily in the Telegraph Hill area in north San Francisco.
The parrots and their plight gained notoriety after being featured in a book, and a documentary both titled “The Wild Parrots of Telegraph Hill.”
And are now the subject of a study published in PLOS ONE.
The findings cap a multi-year effort to determine the cause of the disease, which has been observed in parrots from this flock since 1999.
“The investigation, inspired and funded by Mickaboo, required a team of veterinarians, pathologists and researchers,” says study author Fern Van Sant.
She says the condition was so thoroughly investigated because the poisoned birds were feral parrots.
Van Sant’s clinic, For the Birds, in San Jose California provided care for many of the affected parrots.
“The findings offer us an opportunity to assess the true risk of this rodenticide to pets and feral animals and to clarify the risk of potential soil and water contamination,” she adds.
Bromethalin, a Common Rat Poison
The study focused on four parrots in 2018 that exhibited the same types of neurologic signs to varying degrees: ataxia, circling, seizures and tumbling.
Three of the parrots, like many before them, were euthanized when their condition worsened and they could no longer self-feed.
The team looked for bromethalin, or its active metabolite desmethyl-bromethalin, based on their findings in 15 historic cases from 2013 through 2017.
The historic cases lacked evidence of viruses known to cause neurologic disease in parrots, as well as of exposure to lead or other toxins.
But pathologists found consistent lesions in the central nervous system that suggested bromethalin poisoning.
Bromethalin is difficult to detect, especially in living animals, and particularly in free-ranging birds.
Birds Ingesting Sublethal Doses of Bromethalin
In this study, the UGA-led team screened fecal samples from live birds and brain samples from deceased parrots.
Co-author Sayed M. Hassan, director of the UGA Laboratory for Environmental Analysis in the Center for Applied Isotope Studies, detected both bromethalin and desmethyl-bromethalin in the samples.
Findings suggest that parrots don’t metabolize the potent neurotoxin in the same way described in other species, and/or that the parrots are ingesting a sublethal dose.
Researchers don’t know how the parrots are being exposed to bromethalin, and are planning a follow-up study to determine the source.
Funding Needed to Understand Lethal Toxin
Researchers need funding from individuals and groups interested in protecting our environment.
It’s important to understand if this toxin is accumulating in a space where it could pose a health risk in other free-ranging animals, or in companion animals and people.
The birds affected primarily reside in neighborhoods near the San Francisco-Oakland Bay Bridge area and frequent the area’s parks.
But affected birds have been found throughout San Francisco, including on busy streets and downtown sidewalks.
The total number of birds affected to date is difficult to estimate.
Mickaboo Companion Bird Rescue’s records show that from 2003 through 2018, there were 158 San Francisco parrots affected.
Fifty-five died, 53 were adopted, 22 were released – including three that escaped, and 25 remain in foster care.
The birds in foster care or adopted have persistent neurologic deficits, including paresis and ataxia, that require special care.
Coming in Contact with an Affected Bird
If you come in contact with a possibly affected parrot, report the bird and its location to San Francisco Animal Care and Control.
The poisoned birds need professional help and should not be handled or harmed.
If necessary, a towel can be used to move the bird to a secure box or dog kennel.
Rat poison presents great dangers wherever it’s used.
Think of the consequences before using rat poison and the perils of creating a toxic food web.
Let’s all coexist.