Timing and duration of spring staging of the Eurasian Greater White-fronted Goose (Anser albifrons albifrons) in relation to sex, age and progress of migration season

Among Arctic-breeding waterfowl species, spring stopovers are critical to individuals as a means to accumulate fat and nutrient stores to invest in both migration and their breeding attempt in the tundra zone. We studied the influence of possible factors (age, sex, progress of migration season) on the stopover duration of one such species, the Eurasian Greater White-fronted Goose (Anser albifrons albifrons), by analysing records of 1,115 neck-banded birds spotted at their Biebrza Basin stopover site on spring migration in Poland. As expected, because most mature birds are paired, there were no differences between the sexes in stopover duration. Generally, adults stayed for shorter periods than immatures and stopover duration was shorter later in the season. Data from individuals of known age showed that the rate of decrease in stopover duration with season was faster among older than younger geese. Immature birds, still not ready to breed, do not face the pressure to attain breeding condition and therefore may stay longer in the stopover areas. We think these patterns may reflect the greater experience of older birds, as well as the stronger pressure on them to reach the breeding grounds as early as possible. As the breeding season approaches and foraging opportunities at migration sites further up the flyway become more accessible and of higher quality, geese stay for shorter periods later in the season.