Just got back home, and noticed when I got out of my car that there was radiator fluid leaking out, no, pouring out. So I raised the hood, and the little container with yellow fluid behind the radiator was making a whistling noise, while pouring out it's fluid, I assumed this was radiator fluid.

I think it is from when I went to get my oil changed, I think they added it. Also, is this poisonous to animals?

 

Sounds like you overheated. And YES, radiator fluid will kill animals.

 

Thats funny, I noticed while cleaning my engine bay some dried yellow fluid on the same overfllow container...then today I heard a whistle coming from under the hood...
I think the cap is the like the cap on the brake booster...it leaks...