The Carolina Wren is in the family Troglodytidae, which is in the Order Passeriformes.  It inhabits the eastern United States, with the range extending a little into Canada and Mexico.  In the US family, only the Cactus Wren is larger.  Their range has expanded, possibly due to climate change and milder winters. Domestic cats and snakes are among their top predators.  Some populations have shown higher mercury contents from eating spiders, which have concentrated it, being predators higher in the food chain than herbivorous insects.