The patterns of animal migration are influenced by various factors such as seasons, time of day, topography, wind drift, weather conditions, age and sex. In Lund, bird migration patterns have been studied for many years using different and complimentary methods. For tracking migratory birds we for instance use tracking radar (short ranges), satellite telemetry and geolocators . Stopover duration and migration departure are studied by using radio-tags and a stationary system for automatic recording at the Falsterbo peninsula, south west Sweden. Within CAnMove, we have also initiated studies of the much less known migration patterns of bats and butterflies. In addition to tracking devices, we also use stable isotope analysis to determine geographical origin.
When it comes to exceptionally small organisms, many questions, easily addressed for larger animals such as birds, bats or fish, cannot be asked since tracking devices are too heavy to allow for the organism to act naturally. Recent advances in nanotechnology have, however, made it possible to track millimeter sized animals without affecting their behavior, and within CAnMove we have made some initial and successful experiments of daphnia tracking using this technology.
The approaches of modeling the process of migration by using simple analytical equations or by more complex models (stochastic dynamic programming) embrace the term “optimal migration”. In simple analytical models migration strategies are derived on the basis of optimization of a performance measure, such as survival, time (overall speed) or energy, or some combination of such currencies. The starting point is usually the “flight range” equation that describes how far the animal can potentially move as a function of added fuel. It is assumed that natural selection works as an optimization process where the maximum speed, survival or minimum energy cost is related to fitness. Fundamental behavioural components of the migration strategy are fuel deposition rate, stopover duration, and time of departure from a stopover and flight speed. The other class of models, annual routine models, use dynamic programming to calculate the optimal scheduling and effort of the main annual processes breeding, moulting and migration. The latter models are useful in the context of theoretically exploring consequences of migration in scenarios of climate change and are used by CAnMove scientist