CANCELLED - Whooping crane migration and stopover decision, a conceptual model

Background/Question/Methods

The endangered Whooping Crane (Grus americana), had increased from 15 birds in 1941 to 281 individuals by the winter of 2010-2011.  The population that migrates from Canada to Texas, has exhibited exponential growth over the past seven decades, notwithstanding a few short periods of decline.  Recent studies have shown that “bad” years have been partially attributed to climatic and abiotic factors in the wintering and breeding grounds (extreme temperature, freshwater inflow, pond water depth, PDO). However, an analysis of all possible variables affecting whooping cranes during migration and along the central flyway has not been developed. We built a conceptual model for the entire life cycle of the whooping crane including migration where we established a hierarchical structure of abiotic and biotic factors that could be correlated to the historical population dynamics and also to their decision on stopover selection. We reviewed all databases and information available on historical migration records from 1943 to 2010, identifying all variables and attributes collected for each sighting and sight evaluation: habitat (location, water depth, stopover size, wetland type, potential food), and attributes of whooping crane (age class, social structure, site fidelity, staging days, mortality), however environmental conditions (local and regional climate, wind) were not recorded (only few records during telemetry study).

Results/Conclusions

The conceptual model shows scenarios where: whooping crane, habitat and climate (during migration time), are associated. We establish that periods of population decline and decisions of stopover use could be responding to a combination of these variables. We developed this model for understanding migration ecology of the Whooping Crane, as a tool for a decision support system and management of wetlands along the central flyway, to identify missing information from 67 years of records, to suggest a suit of statistics analyses with information collected and to be collected (path analysis,and spatial explicit simulation models) from historical records, and finally we suggest key research activities on this endangered species that have not been developed during the last decades and need to be done in addition to the current telemetry project on this species.