Literature type: Scientific
Journal: Biological Conservation
Full reference: Marolla, F., Aarvak, T. Hamel, S., Ims, R.A., Kéry, M., Mellard, J.P., Nater, C.R., Schaub, M., Vougioukalou, M., Yoccoz, N.G. & Øien, I.J. 2023. Life-cycle analysis of an endangered migratory goose to assess the impact of conservation actions on population recovery. Biological Conservation 281. https://www.dx.doi.org/10.1016/j.biocon.2023.110028
Evaluating the effectiveness of conservation actions is challenging for migratory species because a population can be impacted anywhere along its route. Conservation actions for the critically endangered Fennoscandian lesser white-fronted goose population include culling of red foxes in the breeding area and habitat improvements and reduction of illegal hunting in the non-breeding areas. One goal of the predator control strategy is to prevent adult birds from using an autumn migration route through western Asia, where mortality is believed to be higher than on the migration route through eastern Europe. We used 23 years of count data obtained at different staging areas to parameterize a seasonal state-space model describing the full-annual cycle dynamics of this population and evaluate whether the recent population recovery was linked to these conservation efforts. The results did not provide evidence that predator control influenced population recovery, as survival on the European route did not appear higher than on the allegedly riskier Asian route. However, adult survival at staging areas on both routes and at wintering sites may have improved in the last decade, suggesting a positive effect of the other conservation initiatives. These results emphasize the importance of including the non-breeding dynamics in population assessments of migratory species and highlight the challenge of evaluating the efficacy of separate conservation actions when a proper experimental design is unfeasible. Our study, which is a unique case of cross-national, coordinated conservation efforts, exemplifies how to model complex population dynamics to assess the influence of costly conservation initiatives.
Literature type: Thesis
Full reference: Mandila, J.M. 2015. Problems of translocation: case study Lesser White-fronted Goose. , B.Sc. Thesis. Faculty of Environment and Natural Resources, Freiburg, Germany.
In order to prevent extinction of the endangered Fennoscandian Lesser White-fronted Goose (LWfG) population, several translocation attempts have been conducted since 1981. Reintroductions prior to 2010 were based on captive birds. By altering the species migration route, the birds were led from former breeding grounds of the Fennoscandian population to safer wintering grounds in Western Europe. The subsequent detection of introgression from other goose genes among the source population led to further releases being put on hold. However, hybridization may be a natural phenomena among LWfG, although research supporting such a view is scarce and the data used questionable, probably relying on samples from escapees. Furthermore, reintroduction by means of using a non traditional route has been criticised due to the change in habitat selection and feeding behaviour of the released population. More recently, releases have been carried out with pure bred LWfG using the traditional route to Western Europe. Although this supports the view that the migration route used is an earlier traditional one which got lost as a result of the decline in the Fennoscandian population, analysis of the supporting data shows that the evidence is too scarce to make such an assumption. Since reintroduction is threatening the wild LWfG genetically and ecologically due to the adoption of genetic traits and behaviour caused by inter-breeding with the released population, the restricted resources of suitable birds should be kept for possible future supplementation of the Fennoscandian population in accordance with the IUCN Guidelines. Furthermore, in order to maintain the wild population and lead to its recovery to a favourable conservation status, efforts should concentrate on the reduction of threats along the traditional migration route and the restoration of its natural habitats.
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