I live in S/E MIchigan 25 miles North of Detroit and while it is a good sized housing development with thousands of people, there are coyotes near us and some times they come into the neighborhoods. That is because of the farmland just across the street from the development. Their natural habitat is getting reduced and all those new people are providing lots of easy food...garbage and small pets. They will avoid you but not small pets and not a good idea to let a small child out by theirself.
Prior to retiring I lived and worked in Northern California in San Francisco area and when I was younger there were no problems with mountain lions....now they are everywhere. There have been a few cases of them attacking humans in California sadly and some cases of deaths. So don't tempt fate.
If you now go into San Francisco in areas like Twin Peaks and Lands End and the Presidio Park you will see signs...."Coyote Crossing". That is new also.
My astronomy buddy has a neighbor in Novato, Ca. that came home to a mountain line in their bedroom that climbed up on the lower level garage roof and patio and pulled a partially opened doorwall open and went in. Luckily when the lion saw the people it ran away.
I manage a large observatory for Scouts here in S/E Michigan and our battle has always been with mice getting in. We tried all kinds of electronic devices from cheap to expensive. None worked...finally we completely blocked the lower part of the building with metal sheathing to cover every possible crack and opening and prevent them from chewing the wood away to make an entrance. That MAY have worked....thus far it seems to work but give it a few more months. Those buggers are clever.
For all the possible critter encounters....I still rate mosquitos the worst for astronomy hobby ;-) Lots itching but scarier is the disease they can spread....Lyme, West Nile, etc. That is partially why I am now spending more time doing Solar astrophotography and less night time imaging...no mosquitos!