I looked up your website reference, and realized that the site was using the different terms, as though they were synomonous. Let's use the dictionary to define each of the groups. Hens lay eggs. A group of eggs laid at the same time is a clutch. When born, the young fowl are called chicks. The collective group of chicks raised together are called a brood. Peep when used with birds is a VERB, not a noun, therefore 'peep' is the small, weak sounds of young birds. A flock of birds is defined as a group of birds that live, travel and / or eat together.
Sep 11 2000, 5:40 PM