Competition and Predation: Herring Gulls versus Laughing Gulls

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Abstract
Interactions between herring and laughing gulls were examined on Clam Island, New Jersey [USA]. In the last 3 yr, the number of breeding herring gulls has increased from 800 to 1200 pairs, while laughing gulls have decreased from 5000 to 500 pairs. Herring gulls arrive on the nesting areas in late Feb. or early March and begin egg-laying in mid-April. Laughing gulls arrive in early or mid-April and begin egg-laying in early May. Direct aggressive encounters between the 2 spp. occur in areas of overlap. Herring gulls win most of these encounters and displace laughing gulls. Over a 2 wk period laughing gulls gradually abandon areas of overlap. Herring gulls prey on the eggs of laughing gulls in proportion to the distances these nests are from the herring gull nesting area. Adjacent areas suffered 100% predation; areas 1000 m from herring gulls suffered only 19% predation. Areas farther from nesting herring gulls suffered still lower predation rates (6%) but were vulnerable to flood and storm tides.