titmouse, also called tit, plural titmice, small cheery-voiced nonmigratory woodland bird. Along with the chickadees, titmice make up the family Paridae (order Passeriformes), with approximately 55 species throughout the world, mostly in the Northern Hemisphere.

Do you say Titmouses or titmice?

The bird is not related to Mickey, Mighty, or Stewart Little. Thus, if I've interpreted the book correctly, using titmice for the plural of titmouse is not proper. It should be titmouses, much the same way the plural of houses isn't, as it turns out, “hice.” But, saying titmice isn't totally wrong either.

What is a flock of titmouse called?

A group of titmice are collectively known as a "banditry" and a "dissimulation" of titmice.