The United States Geological Survey study found that an analysis of liver tissue samples from dead California condors reveals that a large portion of the giant raptors have consumed carcasses that contain second generation anticoagulant rodenticides.
Those chemicals are potentially harmful and can have the potential to exacerbate health issues the birds face from issues such as lead poisoning.
“There are a lot of opportunities for the rodenticides to move through the food web,” Garth Herring, an ecologist with the U.S. Geological Survey said, according to Wildlife.org.
Second generation anticoagulant rodenticides originally came into focus back in the 1970s, a time when the pests reportedly began developing a resistance to older types of poison, and the newer chemicals have been designed to be more toxic for the organisms.
It certainly aides in eliminating the target rodent, but the negative impact is that the chemicals don’t break down as quickly after those rodents die, which can lead scavengers to inadvertently ingest the rodenticides when eating the carcasses of rodents that had eaten them.
California condors (Gymnogyps californianus) are already suffering a huge challenge due to consuming lead and the new study revealed a new potential danger.
Herring and his team aimed to find out if they might also be eating carcasses contaminated with rodenticide.
According to a study published in Environmental Pollution, the team analyzed the livers of 65 condors that had died from 2006 to 2018 and were subsequently given necropsies, all of which were collected from the Pinnacles National Park area, Southern California and Arizona.
The study showed that 42% of them had traces of second-generation rodenticides in their systems.
Herring said that while the source of some of these rodenticides may be legal, it’s also possible that illegally applied rodenticide may be getting into the condors’ systems.
Additionally, the team analyzed the livers of turkey vultures (Cathartes aura) as a substitute with 71 turkey vultures sampled and analyzed in Northern California and southern Oregon, with 93% of them having traces of rodenticide in their livers.
“The larger proportion of turkey vultures contaminated with rodenticide could be an indication of there being more illegal marijuana plantations in that area. Or it could mean that turkey vultures just feed on smaller carcasses more likely to contain rodenticide than condors do” Herring said.
There is more research being done to determine any potential danger to condors.