Setting population-size targets for geese causing socio-economic conflicts

Abstract

Most European goose populations have increased exponentially, and this has increasingly brought them into conflict with human activities. To manage this conflict, we used multi-criteria decision analysis to help set population targets for a super-abundant population of greylag geese (Anser anser). We relied on expert elicitation to assess the consequences of varying goose abundance on nine ecological, economic, and societal objectives. Representatives from national governments and from non-governmental organizations then weighted the objectives based on their perceived relative importance, and we used a consensus-convergence model to reach stakeholder agreement on the tradeoffs among objectives. The preferred population targets for two management units represent about a 20% reduction from current abundances, which from a management perspective would require considerable effort above and beyond current population-control measures. We believe that multi-criteria decision analysis can provide a systematic and transparent framework for building consensus among diverse stakeholders in a wide array of human-wildlife conflicts.

When and where to count? Implications of migratory connectivity and nonbreeding distribution to population censuses in a migratory bird population

“…For the calculation of the daily MCPs, data were merged from the years 2014 to 2021. periods for population size assessment. Comparing satellite tracking and data indicated that current autumn and spring count schemes likely underestimate true population size, even though spring and autumn counts generally exceed the corresponding winter counts (Johnson et al, 2021). Our findings provide important perspectives to be considered when studying migratory connectivity and assessing the population size of the taiga bean goose population and migratory animal populations in general.…”

“…These are probably caused by birds moving further south (especially to Germany) during cold winters and the lack of any available count data from Germany (Heldbjerg et al, 2019). As results from the Swedish mid-winter counts are used in the integrated population model (Johnson et al, 2021) to monitor the taiga bean goose population size for the purposes of international management, it would be important to study their performance in the future. In addition, it would be vital to develop mid-winter counts also in Germany and to merge these data with the Swedish count data.…”

“…It was suspected (but never verified) that at these times the vast majority of the flyway population was present, because these spring and autumn counts always far exceeded those counted in mid-winter (Johnson et al, 2021). Currently, estimates generated by the integrated population model are used to monitor the status of the population, using data from October, mid-winter and March as inputs in the model (Johnson et al, 2021). However, the optimal time of the year for making the most accurate count of the taiga bean goose population remains to be investigated.…”

“…In addition to the mid-winter counts, large-scale, coordinated counts of taiga bean geese were carried out in Swedish staging areas in October (autumn counts; see Nilsson & Kampe-Persson, 2020) and March (spring counts; see Skyllberg, 2015). It was suspected (but never verified) that at these times the vast majority of the flyway population was present, because these spring and autumn counts always far exceeded those counted in mid-winter (Johnson et al, 2021). Currently, estimates generated by the integrated population model are used to monitor the status of the population, using data from October, mid-winter and March as inputs in the model (Johnson et al, 2021).…”

Using the R package popharvest to assess the sustainability of offtake in birds

“…Finally, we used estimates of population size of 40.96 thousand (SD = 3.33) and a harvest of 7.26 thousand (SD = 0.131) from 2000 based on an update of an integrated population model (IPM) by Johnson et al. (2020). We also examined estimates from 2020 after population size had increased to 62.16 thousand (SD = 2.02) and harvest had been reduced to 3.56 thousand (SD = 0.14).…”