A consultant's report on Niabi Zoo shows that eight of the zoo's wallabies have died.
Zoo director Marc Heinzman said Wednesday that the deaths were not publicly announced because they occurred over a period of more than a year. Most of the animals, which are small members of the kangaroo family, succumbed to a disease called toxoplasmosis, he said.
Cats are the primary carriers of the parasitic disease, and Heinzman said he suspects feral cats, or possibly raccoons, infected the Australian Walkabout exhibit with fecal droppings.
The last surviving wallaby was returned to the zoo that loaned it to Niabi, he said.
The wallabies died over a period of time and not all at once, Heinzman said. A necropsy, or animal autopsy, was performed on each of the animals, and toxoplasmosis was deemed the cause of death in most of the eight cases.
"It's one of those things that's hard to determine when it's happening," he said of the spread of the disease. "Had there been some big incident ... obviously, that's what we'd say is newsworthy. We weren't trying to be secretive. It was just gradual."
In other deaths at the Coal Valley zoo, the public has been notified. But Heinzman and Jeff Craver, director of the Rock Island County Forest Preserve, said it is not always appropriate to announce animal fatalities.
"We've always left that up to the zoo director's discretion," Craver said, noting that all deaths are reported in county records, which are available to the public. "You put it out into the paper and, you know, people will be clamoring with their own opinions."
Heinzman said he makes a determination on which animal deaths are reported, in part, by how widely they are recognized.
"That decision is made on more of a case-by-case basis," he said. "Well-known animals, such as our giraffes — we announced the giraffe death."
Other deaths also have been reported to the media, including a lion cub's accidental death and the passing of original Niabi elephant Kathy Sha-Boom, among others.
As part of a recently commissioned 22-page report by zoo consultants Schultz & Williams, the issue of the wallaby exhibit is addressed.
"Unfortunately, toxoplasmosis, probably from feral cats and/or raccoons entering the exhibit (or from hay that was contaminated with 'barn cat' feces), killed eight wallabies," the report states. "We believe that there is a relatively inexpensive fix to improving this exhibit — specifically, remove the grass and some six inches of soil and put down disinfectant; refill with clean dirt and install new sod in Spring 2015 and bring back the wallabies."
Heinzman said cleanup and modifications to areas of the exhibit were completed several years ago when staffers noticed raccoons were getting in. The woodlands surrounding the zoo are flush with raccoons, which also carry toxoplasmosis.
Asked about the ages of the wallabies that perished, he said, "I believe they were all adults or at least juveniles."