One of the most widespread waterbird species, the Caspian Tern is found on all continents except Antarctica.  Breeding habitat can be diverse, but all sites share some commonalities: open, fairly flat islands or similar environment with low vegetation and an absence of ground predators.  In Texas, the species breeds near sea level on barren dredge spoil, islands and shell beaches. Caspian Terns may nest in colonies with other species, but will remain segregated in one area.

The species utilizes coastlines, shorelines, inland lakes, rivers, lagoons, estuaries and sloughs for foraging, often within 100 m of shore.  A recapture study on banded Caspian Terns discovered that individuals tended to nest at the colony where they bred the previous year if they had raised a chick successfully. Terns that experienced reproductive failure tended to nest at a new colony site on their next attempt. Reproductive success is heavily impacted by predation and human disturbance;  the primary limiting factor limiting populations is availability of high-quality nest sites protected from storms and free of mammalian and avian predators.

For more information on Caspian Terns, including identification information, visit their page on the Cornell Lab of Ornithology. 

Text References

1. Cuthbert 1988
2. Cuthbert and Wires 1999
3. Oberholser 1974