I received a phone call this fall from a concerned citizen reporting a couple of dead Canada geese near his property around the Rathdrum prairie. After taking notes regarding the situation I told him to keep an eye on things and let me know if any more dead animals turn up.
The following day my co-worker received a phone call about a goose that appeared to be sick near Hayden. The goose was reported to have a large bulge at the base of its neck, was acting lethargic and would not fly. My co-worker and I went out to examine the goose and determined that indeed something was not right.
At this point we decided if we received more phone calls about dead geese we would ask for them to be brought into the IDFG office. Sure enough, a few days passed and more phone calls of dead geese came into the office, again from the Rathdrum prairie area. In all, we could account for about 20 geese that died.
Four geese were brought into the office and prepped to be sent off for a full necropsy (an autopsy for animals) and lab tests at the USGS National Wildlife Health Center in Madison, WI. Every goose appeared to be emaciated even though they had a crop that was packed full of food. A few weeks passed and I learned the geese tested negative for lead poisoning and avian influenza, but that still didn’t answer why the geese died…so more lab tests continued.
A few more weeks went by with no word, but then I received an email from the USGS lab with results indicating phosphine poisoning as the cause of death. Phosphine gas is a result of the breakdown of Zinc Phosphide, a bait used to control rodents like mice, gophers, and ground squirrels. It is used throughout the United States.
I still don’t know how the geese got into the Zinc Phosphide, but this brings up an important message about how crucial it is to properly apply all rodenticides and pesticides near your home or business. Be conscious of where and when you place rodenticides in the environment, making sure you are following label instructions for application, or see if there are alternative ways to solve your issue. Proper application of these substances is extremely important to protect people, pets and wildlife.
Zinc Phosphide is a relatively short lived toxin and at this point IDFG has not received any more calls regarding deceased geese. For more information regarding Zinc Phosphide click this link.