Jason W. 2013 Multi-generational longdistance migration of insects: studying the painted lady butterfly in the Western Palaearctic. Ecography, 36 (4). 474-486. 10.1111/j.1600-0587.2012.07738.x Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. (up to 60 degrees of latitude). The cycle comprises an annual poleward advance of the 73 populations in spring followed by an equatorward return movement in autumn, with returning 74 individuals potentially flying thousands of kilometres. We show that many long-distance 75 migrants take advantage of favourable winds, moving downwind at high elevation (from 76 some tens of metres from the ground to altitudes over 1,000 m), pointing at strong similarities 77 in the flight strategies used by V. cardui and other migrant Lepidoptera. Our results reveal the 78 highly successful strategy that has evolved in these insects, and provide a useful framework 79 for a better understanding of long-distance seasonal migration in the temperate regions 80 worldwide. 81 82 5

Despite the potentially strong effect of wind on bird orientation, our understanding of how wind drift affects migrating birds is still very limited. Using data from satellite-based radio telemetry, we analysed the effect of changing winds on the variation of the track direction of individual birds. We studied adults and juveniles of two raptor species, osprey Pandion haliaetus and honey buzzard Pernis apivorus, on autumn migration between North Europe and Africa, and demonstrate an important difference between the age categories of both species in the extent of wind drift. For juveniles, side-and following-wind components affected the rates of movement perpendicular to and along the mean direction, respectively, to a similar degree, suggesting full wind drift. By contrast, for adults the rate of crosswind displacement was significantly smaller than the effect of wind on forward movement, showing much reduced wind drift (29%). This indicates that adults have acquired a more sophisticated orientation system, permitting detection of and compensation for wind drift, than juveniles. These drift effects are likely to reduce the ability of juveniles to locate species-specific wintering areas in case of rapid climatic wind change.

Six adult and three juvenile honey buzzards Pernis apivorus were radio‐tracked by satellite during autumn migration from southwestern Sweden. All adults crossed the Mediterranean Sea at the Strait of Gibraltar and continued across the Sahara desert to winter in West Africa, from Sierra Leone to Cameroon. Analysing three main steps of the migration, (1) from the breeding site to the southern Mediterranean region, (2) across the Sahara and (3) from the southern Sahara to the wintering sites, the adults changed direction significantly between these steps, and migrated along a distinct large‐scale detour. In contrast, the juveniles travelled in more southerly directions, crossed the Mediterranean Sea at various places, but still ended up in the same wintering areas as the adults. Average speeds maintained on travelling days were similar for the two age groups, about 170 km/day in Europe, 270 km/day across Sahara and 125 km/day in Africa south of Sahara. However, as the adults used fewer stopover days en route, they maintained higher mean overall speeds and completed migration in a shorter time (42 days) than the juveniles (64 days). Although the juveniles set out on more direct courses towards the wintering grounds, they did not cover significantly shorter distances than the adults, as they tended to show a larger directional scatter between shorter flight segments. The results corroborate previous suggestions that adult and juvenile honey buzzards follow different routes during autumn migration, and that the birds change migration strategy during their lifetime. While juveniles may use individual vector orientation, social influences and learning may be of great importance for the detour migration of adults. The remarkable and distinct age‐dependent shift in migratory route and orientation of the honey buzzard provides a challenging evolutionary problem.

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Breeding Ospreys were studied in southern Sweden and 13 birds were tracked by satellite telemetry on autumn migration to the African wintering grounds. This was supplemented with studies of migrating birds at Falsterbo and radar trackings from southern Sweden. Females generally left the nest site 2–3 weeks ahead of males and juveniles. Among males, failed breeders migrated significantly earlier than successful breeders. At Falsterbo, Ospreys passed in the order adult females (median 22 Aug), adult males (26 Aug) and juveniles (30 Aug). Birds tracked by radar achieved cross‐country speeds of 18–47 km/h. Most of our birds wintered in an area from The Gambia to the Ivory Coast, with one juvenile in Cameroon and one female in Mozambique. Ospreys spent on average 45 days travelling an average distance of 6742 km with no significant differences between sex and age categories. Between 0 and 44 days were used for stopovers en route. Females generally made more stopovers at northerly latitudes than males. Average speed on migration was 174 km/d, which is similar to speeds reported for other large raptors followed by satellite. Speed on travelling days was on average 257 km/d with males generally moving fastest. There was a clear tendency for lower speeds and more stopovers in Europe than during the crossing of the Sahara. Migratory activity generally took place between 8 a. m. and 5 p. m. local time and we have no indications of birds flying at night. With 9 hours travelling time the expected cross‐country speed, derived from the theory of thermal soaring flight and assuming thermal climb rates of 1–2 m/s, varies from 251 to 360 km/d, which is similar to the observed mean speed on travelling days. Even so, one male travelled 746 km/d between Sweden and Spain. Some Ospreys need a much larger fraction of travelling days than expected from theory, suggesting that they deposit fuel on the breeding grounds before departure. This is supported by a correlation between the observed fraction of days spent travelling and departure date. In late departing Ospreys, especially males and juveniles, a major part of the energy for migration is probably deposited on the breeding grounds.