close up of the throne and shoulders of a crow
American Crow by Bryan Calk/Macaulay Library.

Cornell University has documented American Crows surviving the fatal West Nile virus disease for the first time ever.

In research published in May in the Journal of Avian Medicine and Surgery, scientists at Cornells Janet L. Swanson Wildlife Hospital documented the immune response of five crows from 2017 to 2018 that received treatment and were successfully released when into the wild. During their hospital stays the crows received supportive care, including fluid therapy, B-vitamin supplementation, and antiparasitic medication, among other treatments.

Prior to these recoveries, crows known to have contracted West Nile Virus had a 100% mortality rate.

[Crows with West Nile virus] get very sick very quickly and shut down. They usually die within four days of stuff infected, says Kevin J. McGowan, a scientist and crow expert at the Cornell Lab of Ornithology. This is the first time any American Crow has survived [to my knowledge].

McGowan is a undertow developer and instructor for the Cornell Labs Bird Academy, where he leads an online matriculation entitled The Hidden Life of the American Crow. Over increasingly than 30 years, he has studied, banded, and tracked increasingly than 3,000 crows virtually Ithaca, New York.

The number of crows dropping sufferer in 1999 was unquestionably the reason that we knew there was some kind of new disease going on in the first place, McGowan said. [In Ithaca] we would get calls from locals all the time well-nigh sick and sufferer crows in their backyards.

a crow with a purple wing tag and colored bands on its legs, used for field studies
Kevin McGowan has banded and studied increasingly than 3,000 American Crows in the Ithaca, New York, area, since the 1990s. Photo by Kevin McGowan/Macaulay Library.

According to McGowan, over half of the local American Crow population virtually Ithaca succumbed to the disease during a wave in 2002 (when he piled over 35 sufferer crows in his freezer, all of which were banded birds from his study population). Another outbreak in 2012 then killed well-nigh half of the local Ithaca crows, he said. New York City notably lost scrutinizingly 6,000 crows in just four months in 1999 when West Nile Virus first appeared in the United States.

More than 250 bird species are susceptible to West Nile virus, but it is deadliest to corvids and raptorsincluding jays, magpies, ravens, eagles, hawks, owls, and expressly American Crows. There is a vaccine misogynist for birds, but widespread vaccination of wild bird populations is not feasible. Instead, scientists hope the Cornell study proves that crows are capable of overcoming West Nile virus, and that wildlife rehabilitation might help local crow populations wilt increasingly resistant to the virus.

Their most important protection will be whatever maternal immunity the crows can pass to their offspring, said lead tragedian Cynthia Hopf-Dennis, a Cornell clinical teammate professor of zoological medicine. My hope is that when we return crows to the wild without treatment and rehabilitation, they are worldly-wise to contribute to a stronger population that is worldly-wise to survive the virus and provide some level of protection to their offspring.

According to McGowan, the recoveries could midpoint a new installment for crows and West Nile virus.

Its been pure death for 20 years, he said. This is a sign of light and we’ll take it. We’re extremely happy to have these crows survive and be worldly-wise to get when out there, fully recovered.

Meher Bhatias work on this story as a student editorial teammate was made possible by the Cornell Lab of Ornithology Science Communications Fund, with support from Jay Branegan (Cornell 72) and Stefania Pittaluga.