Do Arctic breeding geese track or overtake a green wave during spring migration?

Yali Si,Willem F De Boer,Qinchuan Xin,Herbert H T Prins,Peng Gong,Ronald C Ydenberg

doi:10.1038/srep08749

Yali Si, Willem F De Boer + Show 4 more

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https://doi.org/10.1038/srep08749

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Abstract

Geese breeding in the Arctic have to do so in a short time-window while having sufficient body reserves. Hence, arrival time and body condition upon arrival largely influence breeding success. The green wave hypothesis posits that geese track a successively delayed spring flush of plant development on the way to their breeding sites. The green wave has been interpreted as representing either the onset of spring or the peak in nutrient biomass. However, geese tend to adopt a partial capital breeding strategy and might overtake the green wave to accomplish a timely arrival on the breeding site. To test the green wave hypothesis, we link the satellite-derived onset of spring and peak in nutrient biomass with the stopover schedule of individual Barnacle Geese. We find that geese track neither the onset of spring nor the peak in nutrient biomass. Rather, they arrive at the southernmost stopover site around the peak in nutrient biomass, and gradually overtake the green wave to match their arrival at the breeding site with the local onset of spring, thereby ensuring gosling benefit from the peak in nutrient biomass. Our approach for estimating plant development stages is critical in testing the migration strategies of migratory herbivores.

Highlights

Geese breeding in the Arctic have to do so in a short time-window while having sufficient body reserves
As migration progressed from the southern stopover site 1 to the breeding site 5, we found an increasing difference with the peak in nutrient biomass (RMSD 5 6, 10, 25, 27 and 28) (Fig. 3a) and a decreasing difference between the goose arrival time and the onset of spring (RMSD 5 20, 23, 12, 6, and 4 days) (Fig. 3b)
Similar plant development levels were found in the stopover site 4 and the breeding site 5 (Fig. 4)

Summary

Introduction

Geese breeding in the Arctic have to do so in a short time-window while having sufficient body reserves. The green wave hypothesis posits that migratory geese track a successively delayed spring flush of plants on their way from the wintering grounds in the temperate zone to their Arctic breeding site[6,21] Previous studies investigating this food effect mostly interpreted the green wave as the onset of spring[22,23,24,25,26,27], whereas a field study[28] demonstrated that the peak in nutrient biomass (i.e., plants with the highest amount of nitrogen per unit area) is a www.nature.com/scientificreports key factor driving the timing of spring migration, but that geese skip ahead of this peak at the breeding site to benefit gosling rearing later in the season

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