From the Super Mario Wiki, the Mario encyclopedia

Squabbles are gull enemies in Wario: Master of Disguise. Their method of attacking is biting their enemy. While Wario is on the S.S. Caviar, many Squabbles attack him. They can be easily defeated by shooting using Cosmic Wario or some other form of attack.

In-game description[edit]

"This chubby seagull has a taste for the good life. He circles luxurly lines, hoping for a quick nibble on some rich, fatty passengers."