Squirrel

The squirrel appears numerous times in the series as a supporting animal.

Theme Song
At the beginning of the song, a camera pushes a squirrel out of a hole in a tree. Soon after, squirrels are seen with DJ until a fish falls on him and all the animals, including the squirrel, attack him, even though he is supposed to be an animal lover.

The Sucky Outdoors
The squirrels make fun of Katie and Sadie by mimicking their argument by mouthing the words and making the faces.

X-Treme Torture
Early in the morning, an annoyed squirrel smacks a tweeting bird off a tree.

Camp Castaways
A squirrel is seen floating away from the island, on top of a submarine.

I Triple Dog Dare You!
A squirrel becomes "dramatic" after hearing Heather scream, in a parody of the famous "Dramatic Chipmunk".

Total Drama Action
Like almost everyone in the show, the squirrel seems to have a crush on Justin, as it has fainted due to his "powers" in some episodes.

Dial M for Merger
The squirrel falls in the tomato bath that the cast after smelling their stench.

Aftermath: Bridgette Over Troubled Water
The squirrel makes a brief appearance in the aftermath in a never before seen video about Harold "best" moments, when it punches Harold after it becomes annoyed with his stream of trivial facts.

Aftermath: Revenge of the Telethon
The squirrel is seen during the "DJ's World of Animals" segment, where DJ is feeding a squirrel food in Central Park, and suddenly a bicycle runs over the squirrel.

Trivia

 * The squirrels, a dolphin (in Justin's audition tape), the eagles, the chipmunks, and the sharks are the only animals that have been blown away by Justin's charm.
 * The squirrel is one of the few animals to be seen in the first three seasons.
 * The squirrel is shown to be able to knock Harold out.
 * Although Harold is considered very weak by his peers.