Influence of weather conditions on the flight of migrating black storks

Abstract

This study tested the potential influence of meteorological parameters (temperature, humidity, wind direction, thermal convection) on different migration characteristics (namely flight speed, altitude and direction and daily distance) in 16 black storks (Ciconia nigra). The birds were tracked by satellite during their entire autumnal and spring migration, from 1998 to 2006. Our data reveal that during their 27-day-long migration between Europe and Africa (mean distance of 4100 km), the periods of maximum flight activity corresponded to periods of maximum thermal energy, underlining the importance of atmospheric thermal convection in the migratory flight of the black stork. In some cases, tailwind was recorded at the same altitude and position as the birds, and was associated with a significant rise in flight speed, but wind often produced a side azimuth along the birds' migratory route. Whatever the season, the distance travelled daily was on average shorter in Europe than in Africa, with values of 200 and 270 km d 21 , respectively. The fastest instantaneous flight speeds of up to 112 km h 21 were also observed above Africa. This observation confirms the hypothesis of thermal-dependant flight behaviour, and also reveals differences in flight costs between Europe and Africa. Furthermore, differences in food availability, a crucial factor for black storks during their flight between Europe and Africa, may also contribute to the above-mentioned shift in daily flight speeds.

Energy Landscapes Shape Animal Movement Ecology

“…Some of the greatest savings in movement energy will occur when particular locomotion options allow animals to negotiate what is otherwise an impenetrable object, such as a cliff or a body of water (Chevallier et al 2010). One of the selection pressures for flight illustrates this well and shows the dangers of comparing COT for animals moving through idealized landscapes in or on different media at a constant height.…”

Real-time weather analysis reveals the adaptability of direct sea-crossing by raptors

“…However, the adaptability of these routes is not fully understood, mainly because of the difficulty of measuring variables that may determine travelling patterns at sufficiently large time and spatial scales. For example, if weather conditions determine patterns of avian movement, we must accurately measure the spatiotemporal dynamics of weather conditions with high resolution, and then superimpose the routes of travel on these weather maps as well as statistically examine the effect of weather conditions on migration routes, body conditions of birds and flight strategies such as which flight style is adopted or when, where and how long a bird stops over (Shamoun-Baranes et al 2003, 2010Mandel et al 2008;Chevallier et al 2010;Mandel et al 2011).…”

Flight Paths of Migrating Golden Eagles and the Risk Associated with Wind Energy Development in the Rocky Mountains

“…By comparison, both early morning and late afternoon passage were low under weak winds, typically with NE winds; even though passage did increase by midday under these conditions, overall passage on these days was much lower than seen during high-wind conditions. Under such low-wind conditions, birds may not be able to initiate movement until thermal activity on the ridgelines, which is not present when strong winds dissipate warm, rising pockets of air (Shamoun-Baranes et al 2003, Ákos et al 2008, Chevallier et al 2010, Duerr et al 2012, begins to peak at midday. However, whether eagles respond to strong winds by taking flight earlier in the day or to weak winds and thermal activity by concentrating movement later in the morning, both scenarios attest to the overwhelming importance of documenting spatial and temporal patterns of movement to identify conditions of collision risk.…”