Abstract
BackgroundMigration theory suggests, and some empirical studies show, that in order to compete for the best breeding sites and increase reproductive success, long-distance avian migrants tend to adopt a time minimization strategy during spring migration, resulting in shorter duration spring migration compared to that in autumn.MethodsUsing GPS/GSM transmitters, we tracked the full migrations of 11 Greater White-fronted Geese (Anser albifrons) between southeast China and the Russian Arctic, to reveal the migration timing and routes of the East Asian population, and compare the difference in duration between spring and autumn migration of this population.ResultsWe found that migration in spring (79 ± 12 days) took more than twice as long to cover the same distance as in autumn (35 ± 7 days). This difference in migration duration was mainly determined by significantly more time spent in spring (59 ± 16 days) than in autumn (23 ± 6 days) at significantly more stopover sites.ConclusionsWe suggest that these geese, thought to be partial capital breeders, spent almost three quarters of total migration time at spring stopover sites to acquire energy stores for ultimate investment in reproduction, although we cannot reject the hypothesis that timing of the spring thaw also contributed to stopover duration. In autumn, they acquired necessary energy stores on the breeding grounds sufficient to reach Northeast China staging areas almost without stop, which reduced stopover times in autumn and resulted in the faster autumn migration than spring.
Highlights
Migration theory suggests, and some empirical studies show, that in order to compete for the best breeding sites and increase reproductive success, long-distance avian migrants tend to adopt a time minimization strategy during spring migration, resulting in shorter duration spring migration compared to that in autumn
Data from the full spring migration routes (Fig. 1a) showed that the Greater White–fronted Geese (n = 11) wintered mainly in the middle and lower Yangtze River, most of them wintering in Poyang Lake (n = 8)
The distances the tagged birds travelled during spring migration and autumn did not differ significantly (t16 = 2.0, p = 0.062; Fig. 3b, spring: 6111 ± 477 km, range = 5457–7295 km, n = 11; autumn: 5733 ± 363 km, range = 5155–6146 km, n = 9)
Summary
Some empirical studies show, that in order to compete for the best breeding sites and increase reproductive success, long-distance avian migrants tend to adopt a time minimization strategy during spring migration, resulting in shorter duration spring migration compared to that in autumn. Earlier nesting contributes to increased clutch size (Rowe et al 1994) and fledging of better quality offspring, which better survive their first migration (Perrins 1970; McNamara et al 1998), as well as providing improved opportunities for females to adjust reproductive investment to maximize fitness (Van Noordwijk et al 1995) For this reason, spring migration is predicted to be faster than in autumn, when resources are generally more abundant after a summer season of biological productivity, making it less imperative to reach specific goals in time and space. The quality of, and access to, such sources of exogenous resources to breeding female geese during spring migration will potentially affect their ability to accumulate energy and nutrient stores for ultimate investment in reproduction (e.g. Drent et al 2006; Hübner et al 2010) and affect their rate of progress along the flyway in spring
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