Student Research Saves Crows and Trees

By Shruti Mungi '19

A tree once destined for removal has come off the chopping block, and wildlife may be saved, thanks to a recent Knox College graduate's Honors research.

Elena Prado-Ragan '18 conducted her research on the use of crow effigies to deter crows from roosting in trees in and around the Knox campus. Crow effigies are three-dimensional representations of the birds—often made of plastic and positioned so the (fake) crows appear to be dead. The concept was later implemented by the Knox County Board, saving a tree located near the main entrance of the Knox County Courthouse from being cut down.

The tree, a common roosting site for crows, had been scheduled to be cut down in 2017 as a solution to the bird droppings that littered the nearby courthouse parking lot. 

The Knox County Board was able to find an alternate solution by talking to the Knox College biology department. Having mentored Prado-Ragan’s research the previous year, Associate Professor of Biology Jim Mountjoy and Professor of Biology Jennifer Templeton were in talks with the board about the use of crow effigies.

The county was eventually able to acquire crow effigies to put on the courthouse trees. This method of crow deterrence has kept the area clean and has also been implemented on the Knox College campus.

Interested primarily in bird behavior, Prado-Ragan focused on crows for her Honors project because they congregate in such large numbers on and around the Knox campus. She based her research on a series of studies that had been published by John Marzluff of the University of Washington, which investigated how crows avoid areas where their dead are present.

“This method is unique because it is using what we already know about the behavior of crows to keep them from coming back,” said Prado-Ragan, who noted that other methods to get rid of crows often involve poisoning, trapping, or shooting them. “It's safe for them and will not result in any crow deaths.”

To avoid being seen by the crows, Prado-Ragan hung plastic crow effigies in front of the roosting sites in the mornings. She then tracked how many crows were present before the presentation of the "dead" crow, and how many were there in the trees 24 hours later.

Her research ultimately revealed there was a 79% decrease in crow numbers at all the sites where a "dead" crow was visible to the incoming crows.

Prado-Ragan currently works as an assistant field ecologist to a Ph.D. student in Bocas del Toro, Panama. She is assisting on a project looking at the hybridization of the white collared and orange collared manakin, a bird found in the American Tropics. She hopes to gain experience in the field before pursuing a master's in ornithology.