Modifiers matching duck:

• aggressive,
• smaller,
• tenacious,
• brash,
• jealous,
• here,
• insecure,
• slobbery,
• breeding,
• large,
• determined,
• domestic,
• wild,
• lisping,
• optimistic,
• boastful,
• paranoid,
• zany,
• indigenous,
• larger,
• marine,
• bullying,
• unusual,
• common,
• small,
• native,
• rare,
• daffy,
• pushy,
• short-tempered,

Simple categories matching here:

• duck,
• process,
• activity,