Departure, routing and landing decisions of long-distance migratory songbirds in relation to weather

Abstract

Migrating birds flexibly adjust their individual migratory decisions, i.e. departing, routing and landing, based on intrinsic (e.g. energy stores) and extrinsic (e.g. landscape features and weather) factors modulating the endogenous stimuli. So far, these decisions have mostly been studied separately. Notably, we lack information on which factors landing decisions during active flight are based on. Therefore, we simultaneously recorded all three decisions in free-flying long-distance migratory songbirds in a coastal stopover area via regional-scale radio-telemetry and related them to the prevailing weather. Birds departed under favourable weather conditions resulting in specific nights with increased departure probability. Once departed, birds could either fly offshore or take a route along the coast, which was predicted by wind support. Radio-tracking revealed that departed individuals more likely interrupted their migratory endurance flight under overcast or headwind conditions. Studying departure, routing and landing decisions in concert, we highlight the importance of weather as a common driver across all migratory decisions. By radio-tracking individuals between stopovers, we provide evidence that avoidance of adverse weather conditions is an important function of stopover. Understanding how birds adjust migratory decisions and how they affect the timing of migration and survival is key to link migration performance to individual fitness.

A conceptual framework on the role of magnetic cues in songbird migration ecology

“…However, since we are only just beginning to study and understand when, where and how birds decide to land (e.g. Rüppel et al ., 2023), our current knowledge on the biological importance of magnetic cues on these decisions is very limited. We speculate that geomagnetic signposts may contribute to identifying crucial stopover landscapes before crossing ecological barriers, although evidence for this hypothesis is not yet available.…”

Time of year and weather influence departure decisions of sandhill cranes at a primary stopover

“…For example, wind speed and wind assistance both have been cited as important in the departure decisions of many species (Schaub et al, 2004;Mellone et al, 2012;Gill et al, 2014;Panuccio et al, 2016;O'Neal et al, 2018). Higher wind speeds, increased tailwinds, and reduced crosswinds may all speed up migration and reduce energy use (Pennycuick et al, 1979;Panuccio et al, 2016;O'Neal et al, 2018;Roques et al, 2021;Rüppel et al, 2023). Temperature changes are often associated with arrival and departure during migration, where migration usually occurs in spring with rising temperatures and in autumn with falling temperatures (Richardson, 1990;Bauer et al, 2008).…”