Priorities for Future Research

Research priorities lie with improving our knowledge of the movement of this species between breeding and wintering areas, obtaining better estimates of its demographic parameters, evaluating management practices that succeed, assessing the species’ behavioral and demographic responses to humans and other animals, and identifying contaminant threats. Coordination appears limited among numerous researchers across the wide range of the species, resulting in duplication of effort; improved regular communication seems necessary. Specific suggested research includes the following.

Movement And Distribution

Long-term studies of individually marked terns to detect movement between breeding areas, identify migration routes, and define wintering areas. Improved understanding of tern biology and the effects of predation by humans and other animals on the wintering grounds. Identification of habitat requirements and threats during migration and on the wintering grounds. Identification of nesting distribution and population status along the Pacific Coast of the Mexican mainland, where human activity likely is deleterious. Consensus on the distinctiveness of North American subpopulations and the extent of mixing on breeding and wintering grounds.

Demography

Protocols for periodic, standardized, rangewide surveys to estimate regional populations, trends, and reproductive outcomes. Estimate of age-specific and lifetime breeding success for populations other than the California Least Tern. Determination of levels of productivity needed for population stability, especially survival from fledging until first breeding. Researchers are cautioned to assess survival to fledging carefully as chicks are cryptic and mobile; many existing estimates likely are conservative.

Habitat Management

Determination of the amount of habitat necessary to maintain all subspecies and recover listed populations. Development of methods to restore, enhance, and create suitable breeding habitat across the species’ range, especially management of dam discharges and construction and maintenance of islands for interior populations. Identification of migration and winter habitat factors that may be limiting. Specific controlled assessments of management successes and failures. Enhanced understanding of how colonies respond to different types of predation; does the cost of human intervention for predator control provide substantively improved production?

Behavior

Evaluation of the effects of human activity (including pets, vehicles, and watercraft) on colony selection and behavior in the early stages of breeding. Detailed studies of behavioral ecology (especially during migration and on wintering areas) should focus on: dynamics of colony formation, especially new nesting areas; sex roles in raising young; how long the pair bond is maintained; mate fidelity between years and whether site fidelity is related to mate fidelity; extent of postfledging parental care; and whether young migrate independently of parents or as family units.

Contaminants

Verification of levels of chemical contaminants (DDT, PCB). Determination of the implications of heavy-metal deposits in feathers and eggs. Assessment of the impact of all these on individual breeding and survival.