Varying levels of rat poison have been found in a number of the wild parrots that reside in San Francisco parks, and scientists are now trying to figure out the source of the toxin.
Over 100 of the wild birds have turned up with apparent neurological damage in recent years, and a local nonprofit devoted to caring for and adopting out the birds wants to get to the bottom of the mystery.
A new study in the journal PLOS ONE comes at the end of a multi-year effort spearheaded by the University of Georgia Infectious Diseases Laboratory and funded by the non-profit Mickaboo Companion Bird Rescue. As Science Daily reports, the study looked at the liver and brain matter of deceased parrots as well as fecal samples from live birds and found detectable levels of the rat poison bromethalin and its metabolite desmethyl-bromethalin.
Many of the birds that Mickaboo rescues exhibit symptoms that are consistent with bromethalin poisoning, including circling, tumbling, seizures, and ataxia. The organization collected records on 158 San Francisco parrots between 2003 and 2018, and of those 55 have died, 53 were adopted, 25 remain in foster care, and 22 were released back into the wild (including three that escaped).
The source of the poison remains a mystery, and Mickaboo and the researchers are now hoping to secure funding for a next phase of their study to track down the source. The fear is that the birds may be accessing and ingesting the bromethalin from a water- or soil-borne source, and that the poison could ultimately be harming other species as well. The study also suggests that parrots do not metabolize the toxin in the same manner as other species, and/or they are ingesting sub-lethal doses.
These wild South American conures (or parrots) have been around in the city for several decades, and they were made famous by a 2003 documentary that centered on one of their early caretakers, an eccentric Telegraph Hill denizen named Mark Bittner. No one knows for sure how the first parrots arrived on Telegraph Hill, but they multiplied over the years and there are now several flocks of them that reside in different SF parks, as well as one that lives down in Brisbane. (The original flock still spends part of their day on Telegraph Hill, and part of it down by the Embarcadero in Sue Bierman Park and Sydney Walton Square.) Their common distinctive feature, in addition to bright green plumage, is a red cap on their heads, which appears once they reach adulthood.
SFist last talked about the birds when Mickaboo put a call out for donations in 2017 — some of the funds from which obviously went to this study. At the time they estimated the wild parrot population to be around 300 in the city. Then, as now, Mickaboo had several dozen "San Francisco conures" available for adoption, including several bonded pairs. You can see the current crew here.
Members of the public who find parrots on the street acting strangely should immediately report the bird and its location to San Francisco Animal Care and Control at 415-554-9400.