Well that's easy! Both varieties of foxes enjoy a good bug once in a while, and many creatures were gathering for a large Pest Picnic featuring many insect/arachnid varieties on he menu. They both showed up among with many skunks and bats and such and thus go to talking!
Lol I know I'm silly and I have yet to see Zootopia
But I am thinking I vaguely have the gist of how their world works from the trailer I saw and I want my bestie to take her DVD over soon!!