Confused Yankton, SD, residents saw streets and sidewalks covered with dead starling birds after a mass bird death this week- a recent recurring phenomenon that is alarming the nation. Thousands of black birds fell from the sky in Arkansas on New Year’s eve, followed by similar occurrences in Nebraska, Louisiana and worldwide.

Scientists have proposed several theories as to the cause of recent bird deaths, none providing clear answers. Recorded 911 calls reveal resident speculation as to the cause of death. One resident testified that they were “bleeding out of the mouth” and that “some of them were not dead,” concluding that “they’ve been poisoned,” according to ABC News.

Bird deaths in Yankton, South Dakota on Monday were explained to media officials by animal control officer Lisa Brasel. The U.S. Department of Agriculture contacted Brasel by telephone to explain that the birds were intentionally exterminated with DRC 1339 as an agricultural safety measure. Over 2,000 starling birds ingested the poison after posing sanitation problems for a Nebraska farmer’s cattle feed lot. DRC 1339, often referred to as “Starlicide,” is a highly toxic avicide administered to targeted bird species.

Government bird poisoning is not an uncommon practice. A similar government bird kill-off in Griggstown, New Jersey in 2009 was responsible for the death of over 5,000 birds, which spurred public confusion and mass media investigation that mirrors the present bewilderment.