"Put away your waste," say the rats' researchers

Rats. I can not live with them, I can not live without them – at least, it seems, in a city like Chicago. Researchers from the Urban Wildlife Institute and the Lincoln Park Zoo's Davee Center for Epidemiology and Endocrinology have begun to understand why. The results are published on November 28 in Borders in ecology and evolution.

Rats are a unique species in that they have a global distribution and are always close to humans. This combination creates risks to public health as well as property damage. Nearly 46,000 rat complaints were filed from April 2017 to April 2018 in Chicago and researchers investigated whether the complaints were accurate indicators of prevalence in rats.

"At Lincoln Park Zoo, we continually try to understand the conflicts between humans and wildlife and find solutions to alleviate stress on humans and animals," said Maureen Murray, Ph.D. ecologist, specialist in wildlife diseases. "Rats, whether we like it or not, are part of our ecosystem, they are a fascinating species that we have relatively little research on and we are looking to change."

Murray has teamed up with Landmark Pest Management, a research-based pest management company, for the ongoing study.

"Every city and every urban owner is required to manage rats, and our findings on rats in Chicagoland could also help wildlife managers and city planners in other cities," said Rebecca Fyffe, director of research at Landmark Pest Management.

Landmark verified that areas with higher numbers of complaints in rats also had more rats trapped in 13 community areas in Chicago. Then, zoo researchers compared rat trapping success rates (or the number of trapped rats per night) as a measure of rat abundance versus public complaint data, income, the rental properties and land cover of rats. The amount of waste, carry (clutter) and structural integrity of buildings adjacent to trapping sites were also measured to see if these rat problems were growing on a more local scale.

The results? The complaints of rats are indeed indicators of their abundance. Areas with a high rate of complaints did have a higher trap rate in rats. In addition, the availability of unconfined waste was a clear indicator of the abundance of rats – even more than other attractive ones such as crowding or access points. Surprisingly, another result surfaced: neighborhoods with high rental rates (relative to the number of homeowners) experienced an increase in the number of rats, while vacant or abandoned lots showed a decrease in number of rats.

"This discovery is very interesting," said Murray. "Additional research should be conducted, but it seems that neighborhoods where rents are high also have an increased number of garbage and potential access points for rats in the alleyways, probably because of the responsibility of the building. Maintenance of the owner rather than the tenant. "

The study between the Lincoln Park Zoo and Landmark Pest Management is underway. Future research questions include rat stress levels and disease prevalence, as well as risk indicators for public health.

The moral of the story, "Put away your garbage," says Murray. "The easiest way to ensure that rats stay at bay is to dump garbage in closed bins."

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More information:
Maureen H. Murray et al, Public complaints reflect the relative abundance of rats in various urban neighborhoods, Borders in ecology and evolution (2018). DOI: 10.3389 / fevo.2018.00189