Portal to the Lesser White-fronted Goose

- by the Fennoscandian Lesser White-fronted Goose project

Literature type: Report

Language: English


Full reference: Schekkerman, H. & Koffijberg, K. 2019. Annual survival in the Swedish Lesser White-fronted Geese. , Sovon-report 2019/63, Sovon Vogelonderzoek Nederland, Nijmegen. 22 pp.

Keywords: reintroduction, farming, releases, survival, Sweden


This report presents the first effort to estimate annual survival rates in the LWfG from the Swedish breeding population. It is among the first studies at all to quantify annual survival probabilities in this highly threatened species. An extensive dataset with live resightings was used as input in a mark-recapture survival analyses in MARK. At present, resighting probabilities of the marked birds are very high, i.e. >95%, thus reflecting nearly the entire ringed population. This is made possible by a large number of volunteer ring readers and dedicated effort of the project to facilitate ring reading at key staging sites (see Figure 1). Figure 4 summarises the survival rates described in chapter 3. The main conclusions that can be drawn from the analyses are: 1) During the first project phase (period 1, releases until 1999) there was an overall increase in annual survival probabilities in all age-classes in the course of the project, i.e. between 1984-2003. Survival was lowest in birds that had been released as yearlings, without any parental care, followed by first-year survival in birds that had been released as juveniles with Barnacle Goose as forster parents. Remarkably, survival was slightly higher in the 2nd year after release for birds released as juveniles than in adult birds (3 years and older, birds released as juveniles and yearlings combined); 2) During the second project phase (period 2, after 2010) there was no trend in survival rates over time (but note that this period spans just five years). Birds released as yearlings had rather similar (low) survival probabilities as those in the first project phase. However, first-year survival in birds released as juveniles was lower (and now comparable with birds released as yearlings) than in the first project phase, likely because juveniles were now released without parental care. Again, survival in the 2nd year after release for birds released as juvenile was somewhat higher than adult survival. Adult survival in the second period was lower than in the first period, but also subject to some variation (note standard error). Again note that the period for which this could be calculated is rather short, as only data from 2012-2017 were taken into account.

Number of results: 1