The seagull is appropriately identified as the "herring gull." This North American bird belongs to the genus "Larus" alongside many other gull types. These other gull types, including the very similar California gull and ring-billed gull, are often incorrectly referred to as seagulls. However, most birds belonging to genus Larus possess quite similar characteristics, habitats and feeding habits. Appropriately referencing more than one herring gull depends upon the group's life stage.
A female seagull builds her nest on the ground, using vegetation, litter or other scraps to line and hide the eventual eggs. A seagull lays up to three eggs. These eggs are collectively referred to as a "clutch." The word "clutch" is used to identify the eggs, though it is often used to reference the chicks after hatching. This is technically incorrect, but usually acceptable.
Once hatched, the group of baby birds are generally called "broods," "hatchlings" or "chicks." These terms are usually acceptable when referencing newly-hatched seagulls, although the most correct word referencing a group of newly-hatched seagulls is "chicks." If the chicks cannot fly, the young, injured seagulls are a group of "fledglings."
As adults, seagulls are social creatures. A group of seagulls is a "flock." Flocks are usually found scavenging open areas, like beaches or man-made areas such as car parks or dumps.
The terms "clutch" and "chicks" appropriately identify groups of other gull species belonging to the genus "Larus." The word "flock" is only used when referencing a group of herring gulls. For all other non-seagull species within "Larus," the term "colony" is the correct way to identify a group. In casual environments, however, the terms are often interchanged without sacrificing the meaning or the speaker's intention.