BRANTA — Pratik Rajan Gupte
Spatial ecology and movements of wintering White-fronted Goose (Anser albifrons): Family size dynamics in wintering geese
Institution: Christian-Albrechts-Universität zu Kiel (University of Kiel), Germany
Supervisors: Andrea Kölzsch, Kees Koffijberg, Stefan Garthe
Details: MSc, 2017
TB04 Macrophysiology Lab,
Centre for Ecological Sciences,
Indian Institute of Science,
Bangalore 560012, India.
Subject Keywords:Spatial ecology, population dynamics, family sizes, long-term data, GPS telemetry
Species Keywords: White-fronted Goose, Anser albifrons
The ecology of migratory Arctic-breeding birds on their wintering grounds is affected by many factors. Hypotheses of interactions between family size, flock size, foraging site, and age-ratio of wintering geese have emerged from field observations in western Europe, but are not well tested. We gathered long-term observation data on flocks of wintering greater white-fronted geese Anser albifrons albifrons from the Netherlands and northern Germany, and tracked a total of 13 whole families of the species over three winters (2013, 2014, 2016) with GPS transmitters. Taking into account effects carried over from the summer, we explored how the distance of the wintering site from breeding grounds on Kolguyev Island (69°N, 49°E), number of juveniles in a family, number of individuals in a flock, and the age-ratio of flocks develop over time. We related the probability of a family splitting to the number of times, and the distance that it flew. Families with more juveniles winter farther west after the first 60 days following autumn arrival, where flocks are smaller. The number of juveniles in a family, flock size, age-ratio and the number of families in flocks were well correlated with the number of days since arrival. Families that undertook more flights in winter were more likely to split. Our data suggest that juvenile white-fronted geese separate from their parents during the winter, and that this species is differentially migratory by age and social class in both autumn and spring.