A shocking number of endangered vultures died last week after being poisoned by poachers in northern Botswana. After feeding on three elephant carcasses laced with a poisonous chemical, a total of 537 vultures and two tawny eagles were found dead, reports the Botswana government. According to conservationists, the vultures were targeted because their scavenging activities (circling around carcasses) can often alert authorities to the presence of poached animals and, consequently, poachers.

Since it’s currently vulture breeding season, many of the vultures were certainly new parents, leaving behind orphaned babies. Kerri Wolter, CEO and founder of conservation charity VulPro, said to The New York Times, “[Since] vultures are late maturing and slow breeders, the magnitude of losing just under 600 vultures in one week is incomprehensible. The species cannot withstand these losses and it is impossible to recover the disappearance of these individuals and breeding pairs in our lifetime.”

Vultures are vital to a healthy ecosystem, helping keep the environment clean and minimizing the spread of diseases.

The vultures poisoned included 10 cape vultures, 14 lappet faced vultures, 468 white-backed vultures, 17 white-headed vultures, and 28 hooded vultures. All of them are endangered and critically endangered according to the IUCN Red List and their population numbers are decreasing.