Caspian Tern (Sterna caspia)

Status: State Endangered (1989).

Occurrence: Common migrant north and east, uncommon summer resident east. Occur during spring and summer along the shoreline of Lake Michigan and Lake Superior.

Aid to ID: This white gull-sized tern has a black cap, coral-red bill, black legs and feet, and short, slightly forked tail. Is easily distinguished from other tern species by their greater size, thicker bill, and low-pitched, harsh calls.

Habitat: Nest on open, unvegetated islands.

Food Habits: Plunge-dive for small fish. Also feed from surface, sometimes eating eggs or young of other birds.

Natural History:

Breeding: Caspians nest at 2-3 years of age. Clutch size: 2-3 grayish or buffy eggs with irregular spots; laid from May to July. Incubation: 20-22 days. Young fledge at 28-35 days old. One young typically fledges from a successful nest.
Nest: Eggs laid in shallow depressions in the ground or in nests lined with grasses, seaweeds, or mosses.

Management Considerations: Colony instability, poor reproduction, and the low number of nesting pairs have contributed to its endangered status. Declining nesting success and colony abandonment may be due to the effects of chemical contaminants, human disturbance at colony sites, competition for nesting sites with Ring-billed Gulls and Herring Gulls, and predation by Great Horned Owls and other predators. Conservation measures include controlling public access to the nesting colonies to minimize disturbance, eliminating predators from colony sites, and monitoring all potential nesting habitat, especially dredge spoil islands.