INDIANAPOLIS — The Department of Natural Resources is asking residents across the state to take down their bird feeders as they investigate the mysterious deaths of songbirds statewide.

Earlier this week, Indiana DNR said birds – including cardinals, robins and blue jays – were getting sick or dying across the state, but it was unclear why. Investigators say the birds have shown signs of neurological illness, as well as eye swelling and a crusty discharge.

The sick or dead birds have been found in 15 counties across Indiana, including Delaware, Hamilton, Jackson, Johnson, Marion and Monroe counties in central Indiana, as well as Clark, Jefferson, LaGrange, Lake, Newton, St. Joseph, Union, Washington and Whitley counties.

The samples tested so far have come back negative for avian influenza and West Nile virus.

As the department works with the Indiana Animal Disease Diagnostic Laboratory and the USGS National Wildlife Health Center to determine what is causing the bird deaths, they’re asking all Hoosiers to remove feeders from their yards.

That includes hummingbird feeders, Indiana DNR told 13News Friday evening.

In addition to removing bird feeders, Indiana DNR recommends the following steps for Hoosiers statewide:

(Editor’s Note: This story initially reported Indiana DNR requested feeders to be removed in 15 counties. The recommendation is for all bird feeders to be taken down statewide.)