How did Hooter get the nickname "Hooter"?

Hooter's real name is Brian Melrose, but he does not look like a Brian Melrose, according to the author. He is large and goofy looking and, in Matt's mind, resembles the cartoon character Fred Flintstone. Hooter has a very good heart, and in third grade he took care of a baby owl with a broken wing. He put the owl into a box and hooted at it to keep it company. Eventually, his parents made him give the owl to an animal shelter, but the neighborhood kids had begun to call him "Hooter," and the nickname stuck to him.
Hooter is physically strong, and Matt says that Hooter will be the "strong man" in their Adventure Club because Hooter has more strength and muscles than the other members. At the same time, Matt says that they will turn to Hooter if they need to rescue any baby animals, as this is one of Hooter's talents. Hooter is both strong and caring; he is a gentle giant.