Priorities for Future Research

Threats to and the biology of all populations of the Caspian Tern during winter remain largely unknown. Exact wintering sites for birds from several geographic regions are not known. Little information exists on migration, especially important stopover sites and habitats used.

Significant effort has gone into studying the levels of contaminants in Caspian Terns without yielding clear conclusions about effects of toxic chemicals on reproduction and survival. This work should be continued.

Despite extensive banding studies, more information is needed on population dynamics, espe-cially factors that favor population expansion and increase. There is no information on lifetime reproductive success.

Most Caspians nest in colonies of >100 pairs. In the Northwest Territories and elsewhere, however, some Caspians typically nest as single pairs. A comparative study of colonial and solitary nesting would contribute to knowledge of the evolution of colonial behavior in this and other colonial nesting species.

More detail is needed on the plumage descriptions of young birds and on the molt cycle of North American birds.

Although general behavior has been described, this species is ideal for studies of reproductive strategies and parental care because prey are visible and play an important role in courtship behavior and reproductive success.

No information is available on the genetic structure of the North American population. Given its disjunct distribution and strong fidelity to the general area of hatching, molecular studies are needed.

Postfledging parental care and the development of hunting skills are not well documented for any bird species. The Caspian lends itself to study of these behaviors because it has the longest parental care known for terns and logistics are feasible.

Additional topics in this account for which little or no information was found include fossil history, control and physiology of migration, metabolism and temperature regulation, nutrition and energetics, nest microclimate, intraspecific brood parasitism, and home range.