A mimicked bacterial infection prolongs stopover duration in songbirds – but more pronounced in short- than long-distance migrants

1) Migration usually consists of intermittent travel and stopovers, the latter being crucially important for individuals to recover and refuel to successfully complete migration. Quantifying how sickness behaviours influence stopovers is crucial for our understanding of migration ecology and how diseases spread. However, little is known about infections in songbirds, which constitute the majority of avian migrants. 2) We experimentally immune-challenged autumn migrating passerines (both short- and long-distance migrating species) with a simulated bacterial infection. Using an automated radio-telemetry system in the stopover area, we subsequently quantified stopover duration, ‘bush-level’ activity patterns (0.1-30m) and landscape movements (30-6000m). 3) We show that compared to controls, immune-challenged birds prolonged their stopover duration by on average 1.2 days in long-distance and 2.9 days in short-distance migrants, respectively (100 – 126 % longer than controls, respectively). ...