Using pressure and activity to better understand where birds migrate

    Geolocators are small 1g tags which can be attached to migrating birds. They measure daylight to estimate where a bird might be in the world at a given time. However, geolocators can have an error range of tens of kilometres (depending on the angle of the earth relative to the sun at that time of year).

    Recent technological developments have allowed us to add activity and pressure sensors to geolocators. We know for instance that when pressure decreases that altitude increases and can therefore tell when a bird is flying. This information can be used to create migration timetables (using the R package PAMLr), and these timetables can in turn be used to increase the precision of geolocation estimates (using the R package SGAT). There are three ways this can be done. Firstly, we can add a movement model, which assumes that if a bird has been flying a long time, it will have travelled further than if it was only flying a short period. Second, we can use a stopover model, which uses known stopovers to analyse multiple sunrises and sunsets to estimate one location from multiple data points. Finally, we can use a spatial model, which uses global weather maps as predictors for where a bird might have stopped, based on the pressure levels that were recorded on the bird.

    Because all of these methods are newly developed, we do not know which is best for improving geolocation estimates. We are looking for a student who will run these three analyses and compare the precision of each method. They will do so with hoopoes (Upupa Epops) which were tracked from Valais/Wallis and migrate to West Africa.

    We are looking for a student who is comfortable both with developing skills in R and writing in English. Supervision language is English or French. Most of the code is set up and documented. The supervisors are specialised in these types of analyses and will provide the student with the support and guidance needed.

    Contact and further information

    Main supervisor: Dr Kiran L. Dhanjal-Adams

    Secondary supervisor: Dr Felix Liechti

    Swiss Ornithological Institute

    Seerose 1

    CH-6204 Sempach

    email: Dr Kiran L. Dhanjal-Adams