[Note: this story has been modified since its original posting. The link to the MU Veterinary Diagnostic Laboratory was incorrect.]
Julie Aber was at work at the Central Missouri Humane Society on Tuesday when she got a call that a pigeon had just fallen from the sky in mid-flight. It lay dead and bloated downtown on Cherry Street, the caller said.
For Aber, the call came as no surprise. While the society could not provide an exact number of reports of sick and distressed pigeons, it cited a noticeable increase in recent days.
The cause is unknown, but one possibility is MU’s use of Avitrol, a chemical pigeon deterrent, which the school is licensed to use, according to documents provided by the Missouri Department of Conservation.
Julaine Kiehn, the director of MU’s Campus Dining services, said Avitrol-laced corn was last applied to the roof of Bingham Dining Hall on Aug. 8.
She said Avitrol-laced corn is one of several deterrents MU uses to limit potentially harmful pigeon droppings on its buildings and equipment. She added that the department has no plans to discontinue the use of Avitrol as its sole method of deterring pigeons.
Derek Collier, facilities manager for Campus Dining Services, said the roofs of Rollins and Bingham dining halls are baited with Avitrol-laced corn as needed. He said the corn is spread on the roof because pigeons tend to roost and eat in above-ground locations.
Collier said Avitrol is meant to be a nonlethal deterrent.
“We always want to use it sparingly,” he said, “but pigeons are very stubborn.”
Campus Dining Services tried using plastic owls to deter pigeons before using Avitrol, Collier said, but the owls proved ineffective. Collier said he believes Avitrol has produced better results.
One reason the pigeon population is stubborn, a 1998 University of Barcelona study found, is that pigeons are in constant competition for food. Because of this competition, starvation kills about 70 percent of younger birds. If adult pigeons are poisoned and die, however, young pigeons will eat the newly available food and fewer will die of starvation. This method keeps the population relatively constant.
When birds eat enough Avitrol, they begin showing symptoms that include distress calls, flapping about and flying in unusual ways.
This behavior works as a deterrent by frightening other members of the flock, according to the
at Cornell University.
MU uses chemicals in an effort to ensure the health of its employees who may come into contact with the birds’ droppings, Kiehn said.
Workers who touch infected droppings and forget to wash their hands could infect themselves with salmonella, said Alex Bermudez, director of the MU Veterinary Diagnostic Laboratory.
Another concern is Histoplasmosis, caused by inhalation of a fungus, which can be fatal if left untreated. The fungus can grow on bird or bat droppings alone, but it is most dangerous when combined with soil, Bermudez said.
Philip Shocklee, campus facilities director for MU, said the department stopped using Avitrol several years ago in favor of non-chemical deterrents.
The department now uses a variety of methods depending on which is most effective for each facility.
An ultrasonic sound device emits a sound that annoys pigeons but is inaudible to humans on the roof of Jesse Hall, for example.
Elsewhere, rubber snakes sit on out-of-sight window ledges to discourage roosting, and plastic owls perch on buildings to frighten flocks. Stainless steel mesh covers the openings around the bell tower at Switzler Hall.
“If we can use something other than poison, that’s what we try to do,” said Shocklee. “It’s a different approach, but I believe it’s providing an effective pigeon control.”