Management options for a resident Barnacle Goose (Branta leucopsis) population in Flanders. A comparison of different scenarios using population modelling

In Flanders, Barnacle Goose wintering numbers have drastically increased over the last decades. Simultaneously, a local breeding population has emerged, probably of mixed feral and wild origin. This has raised concerns, mainly in the light of diminishing Canada Goose numbers as a result of management, where an increase in breeding Barnacle Goose numbers could potentially counter the benefits gained from the Canada Goose management.
This study examines different Barnacle Goose life-history parameters in the Flanders’ breeding population. Demographic data were derived using detailed monitoring and standard capture-recapture analyses and further used to construct a stage-based population model. This model allows examination of the expected development of the breeding population and the evaluation of different management scenarios.
Results showed that neither reproductive output nor population growth rate exceeded those of other Barnacle Goose populations, both migratory and non-migratory. The yearly average growth rate of the population was 1.12, which meant that, at the current breeding population level and expected thresholds
for acceptance of goose damage, we estimate a 5 to 10 year time frame for implementation of a management scheme.
Elasticity analysis shows adult survival has the greatest impact on population growth rates. Therefore, a management scheme aimed at the reduction or entire removal of the local Barnacle Goose breeding population, should consider methods that impact adult survival.
A simulation of three different management scenarios (nest destruction, culling and a combined scenario) showed that culling birds through moult captures is currently the most effective method to affect population growth rate. Also, this method is practical to implement and has immediate effect on population numbers.