The onset of spring and timing of migration in two arctic nesting goose populations: the pink‐footed goose Anser bachyrhynchus and the barnacle goose Branta leucopsis

Abstract

An earlier onset of spring has been recorded for many parts of Eurasia in recent decades. This has consequences for migratory species, both in changing the conditions encountered by individuals on reaching migratory sites and in affecting cues regulating the timing of migration where decisions to migrate are influenced by local environmental variables. Here we examine the timing of spring migration for two arctic goose populations, the pink‐footed goose Anser brachyrhynchus (during 1990–2003) and barnacle goose Branta leucopsis (during 1982–2003), which both breed on Svalbard. The satellite‐derived Normalised Difference Vegetation Index (NDVI) was used to express the onset of spring at their wintering and spring staging sites. Pink‐footed geese use several sites during spring migration, ranging from the southernmost wintering areas in Belgium to two spring staging areas in Norway, and distances between sites used along the flyway are relatively short. There was a positive correlation in the onset of spring between neighbouring sites, and the geese migrated earlier in early springs. Barnacle geese, on the other hand, have a long overseas crossing from their wintering grounds in Britain to spring staging areas in Norway. Although spring advanced in both regions, there was no corresponding correlation in the timing of onset of spring between their wintering and spring staging sites, and little evidence for barnacle geese migrating earlier over the whole study period. Hence, where geese can use spring conditions at one site as an indicator of the conditions they might encounter at the next, they have responded quickly to the advancement of spring, whereas in a situation where they cannot predict, they have not yet responded, despite the advancement of spring in the spring staging area.

Migration timing and stopover selection for barnacle geese Branta leucopsis

“…An earlier start to the growing season at higher latitudes would have meant that the geese were more likely to catch the later phenological stages of plant growth along their flyway in 2010 if they had started migrating at their normal time. As shown by Tombre et al (2008), if the geese cannot predict the conditions they might encounter at the next stopover, they are unable to respond quickly to the advancing spring. For instance, the lack of correlation in the onset of spring between the Solway Firth and Helgeland stopovers meant the geese were unable to migrate earlier if spring was early at both sites (Tombre et al, 2008).…”

“…As shown by Tombre et al (2008), if the geese cannot predict the conditions they might encounter at the next stopover, they are unable to respond quickly to the advancing spring. For instance, the lack of correlation in the onset of spring between the Solway Firth and Helgeland stopovers meant the geese were unable to migrate earlier if spring was early at both sites (Tombre et al, 2008). Moreover, the timing of the Russian geese migration from the Baltic Sea was not linked to the advancement of plant growth, most likely because of the low correlation in the weather patterns between the Baltic Sea and White Sea (van der Graaf, 2006).…”

“…Also, environmental parameters at the stopover site are expected to play a major role to adjust the migration timing of the geese (Bauer et al, 2008). In particular, environmental parameters at the last staging site are important since they may help the geese in predicting conditions at the breeding site and move on to their nesting location when it becomes snow free (Bety et al, 2004;Hübner, 2006;Owen, 1980;Tombre et al, 2008). Despite the importance of environmental parameters at the last stage, existing knowledge on the relations between these parameters and the migration timing of the geese necessitates further investigations.…”

“…Relatedly, changing day length is a reliable cue for migratory birds to time their migration for proper arrival at the reproductive area with respect to favourable environmental conditions (Pulido, 2007a). This has been found to be an important parameter for the geese especially when the correlation in temperature between consecutive stopover sites along the flyway is low (Tombre et al, 2008). For instance, during their spring migration, barnacle geese rely on day length to leave Baltic Sea towards the White Sea, which is perhaps related to low correlation of weather pattern between these two sites (van der Graaf, 2006).…”

“…Satellite NDVI time-series data has also been widely adopted as a proxy for plant phenology in ecological studies (Beck et al, 2006;Tombre et al, 2008;White et al, 1997;Zhang et al, 2003). The plant phenology itself has been recognized as a good proxy for plant quality, as young plants are generally of high nutritional value, with low levels of secondary plant chemicals (Demment & Van Soest, 1985).…”