Priorities for Future Research

The relationship of the Roseate Tern to other Sterna species needs study by biochemical and molecular techniques. Long-term studies of individually marked adults are under way as part of a Metapopulation Study of the northeastern U.S. population (Spendelow et al. 1995); this study should be continued for at least a full tern generation (about 20 years). The role of food limitation and possible competition for small fish needs study, and food availability needs to be incorporated in the Metapopulation Study. Moreover, almost nothing is known about the behavior, feeding, and spatial and temporal patterns of movements of this species outside the breeding season.

The ability to sex individuals reliably by means of polymerase chain reaction (PCR) DNA techniques will open up many research opportunities in pairing behavior, parental care, and behavioral ecology of males and females of this monomorphic species. It will be important to investigate sex-specific demographic patterns and to establish the causes and consequences of the unusual female-biased sex ratio documented in some colonies. Determining the origin of clutches that have ≥3 eggs will be important; a combination of measurements and molecular techniques may establish parentage.

Despite different climatic regimes, Caribbean and northeastern Roseates breed at about the same time. Factors influencing migration and breeding phenology, as well as interactions with other species with which Roseates migrate and breed, require study.

Our understanding of the biology and sources of mortality on wintering areas remains poor. Study of these topics is particularly important for elucidating population dynamics, and formulating conservation and management plans. Many details are lacking—for example, the speed of migration and the location of stopping areas. Factors that influence migratory movements and the relation of movement to fish availability require study. Results of these studies will influence decisions about colony management and site restoration. Specifically, the migration patterns and wintering of Caribbean birds need investigation.

Physiologic data are lacking; they would be valuable to an understanding of factors controlling salt gland function and its maturation. Vocal behavior needs careful study. There are few recordings of calls other than mobbing and alarm calls, and recordings free of the loud background of Common Tern noise would be especially valuable. Vocal studies during feeding, staging, migration, and wintering are needed.