Bird Migration

Our Aeroecology group uses predominantly radar technology to record the flight movements of birds, bats, and insects around the clock and around the year.Using vertical-looking small scale radars and other technology, we gain insights into macroecological migration patterns, weather influences, barrier crossing, altitudinal distribution, and aerial biomass flows. One radar continously observes the skies above our institute in Sempach

Our focus is on studies in Europe but we currently extend radar monitoring to Africa, where aerial movements of birds and insects remain largely undescribed. The group also invests in developing new methods and adopting new technologies for studying aerial migratory movements, from next-generation radar to automated species recognition and nocturnal flight call analysis. To foster collaboration, we also coordinate an international community of radar researchers, the Birdscan Community. Towards conservation, radar data provide clues on the effects of light pollution on migratory birds and for predicting and reducing collision risks with buildings and wind turbines.

Migration of individual birds is the focus of our sub-group using tracking and laboratory technologies. We strive to find out where birds go, where they come from, what condition they are in, and how their migrations and body functions are shaped by environmental conditions and evolutionary change. Our interest ranges from local species, such as European Starlings, to worldwide migration studies with international partners. A main tool are multi-sensor loggers built in-house that record light, acceleration, air pressure, and other features of the birds’ environment.

Using analytical methods developed within the unit, we obtain increasingly deeper insights into the migratory behavior of small landbirds, such as crossing of migration barriers, flight altitude, energy costs, and day and night behaviour. While briefly capturing the birds to apply tags, we often take samples, such as feathers and droppings, which we analyse using molecular and geochemical methods to infer the birds’ origin, health, and diet. Genomic analyses help us to establish where breeding birds spend the non-breeding time and where non-breeders, including vagrants, originate. We also use genomics to reconstruct the evolution of migration strategies. Our studies indicate sensitive phases of the annual cycle, and provide stepping stones towards the protection of stopover and wintering areas.

Our sub-group with focus on Africa engages with the ecology, behaviour, and conservation in the non-breeding range. Many long-distance migrants that breed in Europe spend more time on migration and on the wintering grounds than in their breeding grounds. Studies of the non-breeding grounds are therefore crucial to understand the threats and opportunities birds face throughout the year. Our fieldwork mostly uses key stopover and wintering areas where large numbers of migrants converge

We identify these sites based on tracking data, local observations and citizen-science records, and utilise state-of-the-art technologies to investigate the birds’ ecology. Stable isotopes, mainly in breath and feather samples, provide information about the birds’ nutrition, water balance and provenience, while circulating metabolites reveal how fast individuals are refuelling. Metabarcoding of the DNA in droppings, indicates the birds’ diet and thereby also habitat features. Across the continent, we collaborate locally with research partners and charities to strengthen the ornithological community. To help conserve the avifauna, we target cocoa farming in West Africa, where we support farmers in the planting of shade trees.