Town overrun with ground squirrels

[Catherine]

They are being overrun with Richardson's Ground Squirrels, to be more precise. They are native to prairie areas like North Dakota. Outside of cities, there are natural predators that keep their numbers in balance. In the city, with nothing to stop them, they probably outnumber humans. With no predators and the grass all neatly mowed, things are out of balance. 

https://www.theglobeandmail.com/world/ar...squirrels/

The solution isn't really killing the existing ground squirrels. They just keep multiplying. The real solution is to restore ecological balance.
In a city like that, hawks and owls could probably restore balance. What species is missing right now and how can they bring it back. They need an environmental assessment, not an exterminator.