Apparent breeding success drives long-term population dynamics of a migratory swan ...

• Main Authors: Nuijten, Rascha, Vriend, Stefan, Wood, Kevin, Haitjema, Trinus, Rees, Eileen, Jongejans, Eelke, Nolet, Bart
• Format: Dataset
• Language: English
• Published: Dryad 2020
• Subjects: Animal Ecology; Cygnus columbianus
• Online Access: https://dx.doi.org/10.5061/dryad.g1jwstqpj; https://datadryad.org/stash/dataset/doi:10.5061/dryad.g1jwstqpj

The ability of a species to adapt to environmental change is ultimately reflected in its vital rates – i.e., survival and reproductive success of individuals. Together, vital rates determine trends in numbers, commonly monitored using counts of species abundance. Rapid changes in abundance can give rise to concern, leading to calls for research into the biological mechanisms underlying variations in demography. For the NW European population of Bewick’s swan (Cygnus columbianus bewickii), there have been major changes in the population trends recorded during nearly five decades of monitoring (1970-2016). The total number of birds increased to a maximum of c. 30,000 in 1995 and subsequently decreased to about 18,000 individuals in 2010. Such large fluctuation in population numbers is rare in long-lived species and understanding the drivers of this population change is crucial for species management and conservation. Using the integrated population model (IPM) framework, we analysed three demographic datasets ... : Encounter history -- data was collected over 47 years of mark-resighting research with both legrings and neckbands. In the csv, the years of the study (1969 - 2015) are indicated with they year index as the column header (1-47) and the individual ID as the rows. When an individual was resighted that year, a '1' is present in the matrix 'encounter-history.csv', otherwise a '0'. Counts -- internationally coordinated counts of Bewick's swans take place every 5 years in January. The results of these counts are imputed to fill missing years based on a lineary imputation (see Methods section in Manuscript). Census years are indicated with 'TRUE' in the CensusYear column in the csv 'counts-jp.csv'. Juvenile percentage (jp) -- every year, the proportion of juveniles on the total population are done in the Netherlands and the UK in December/January as a proxy for breeding success. The average of the estimates for both countries are presented in the csv 'counts-jp.csv' in the column 'JuvenilePercentage'. Output IPM -- ...