Habitat use during spring migration: Remote sensing meets movement ecology

Abstract

Forage availability during spring migration is crucial for the survival and successful reproduction of many migratory species. With careful timing in relation to spring growth and small-scale selection of suitable food sites, large avian herbivory migrants are known to maximise foraging rate during spring. However, especially for Arctic breeders, the recent levels of climate and habitat change alter the conditions that they meet at their spring stopover and breeding sites. In the EO-MOVE project we examine the habitat use of greater white-fronted geese (Anser albifrons) along their spring migration route between central Europe and northern Russia. This species is known to be sensitive to land-use intensity, phenology and landscape configuration, which calls for the exploitation of high resolution tracking and remote sensing technologies. To characterise the movement of geese within their spring stopovers, we use over 150 highly resolved GPS tracks of individual adult geese from the years 2006-2017. Since 2014 we have additionally collected acceleration data to classify the animals' behaviour and energy expenditure. We select within-stopover GPS positions that are classified as flight or feeding and overlay the movements connecting different small-scale feeding sites with optical and SAR time series data (20Ã-20m) from the Sentinel 1 and 2 satellite missions using step selection functions. Habitat preference outcomes are then set into context with vegetation indices and compared between individuals, years and stopover sites. First results indicate that white-fronted geese generally select for highly green, low and young vegetation, but also that there are large differences between stopovers. We expect to reveal in detail how the birds select for suitable feeding sites in relation to availability and recent levels of habitat change, potentially allowing for site selection prediction, an important prerequisite for spatially or temporally targeted conservation schemes.