Aims Different aspects of soaring-bird migration are influenced by weather. However, the relationship between weather and the onset of soaring-bird migration, particularly in autumn, is not clear. Although long-term migration counts are often unavailable near the breeding areas of many soaring birds in the western Palaearctic, soaring-bird migration has been systematically monitored in Israel, a region where populations from large geographical areas converge. This study tests several fundamental hypotheses regarding the onset of migration and explores the connection between weather, migration onset and arrival at a distant site.Location Globally gridded meteorological data from the breeding areas in north-eastern Europe were used as predictive variables in relation to the arrival of soaring migrants in Israel. MethodsInverse modelling was used to study the temporal and spatial influence of weather on initiation of migration based on autumn soaring-bird migration counts in Israel. Numerous combinations of migration duration and temporal influence of meteorological variables (temperature, sea-level pressure and precipitable water) were tested with different models for meteorological sensitivity. ResultsThe day of arrival in Israel of white storks, honey buzzards, Levant sparrowhawks and lesser spotted eagles was significantly and strongly related to meteorological conditions in the breeding area days or even weeks before arrival in Israel. The cumulative number of days or cumulative value above or below a meteorological threshold performed significantly better than other models tested. Models provided reliable estimates of migration duration for each species. Main conclusionsThe meteorological triggers of migration at the breeding grounds differed between species and were related to deteriorating living conditions and deteriorating migratory flight conditions. Soaring birds are sensitive to meteorological triggers at the same period every year and their temporal response to weather appears to be constrained by their annual routine.

Aims Different aspects of soaring-bird migration are influenced by weather. However, the relationship between weather and the onset of soaring-bird migration, particularly in autumn, is not clear. Although long-term migration counts are often unavailable near the breeding areas of many soaring birds in the western Palaearctic, soaring-bird migration has been systematically monitored in Israel, a region where populations from large geographical areas converge. This study tests several fundamental hypotheses regarding the onset of migration and explores the connection between weather, migration onset and arrival at a distant site.Location Globally gridded meteorological data from the breeding areas in north-eastern Europe were used as predictive variables in relation to the arrival of soaring migrants in Israel.Methods Inverse modelling was used to study the temporal and spatial influence of weather on initiation of migration based on autumn soaring-bird migration counts in Israel. Numerous combinations of migration duration and temporal influence of meteorological variables (temperature, sea-level pressure and precipitable water) were tested with different models for meteorological sensitivity. ResultsThe day of arrival in Israel of white storks, honey buzzards, Levant sparrowhawks and lesser spotted eagles was significantly and strongly related to meteorological conditions in the breeding area days or even weeks before arrival in Israel. The cumulative number of days or cumulative value above or below a meteorological threshold performed significantly better than other models tested. Models provided reliable estimates of migration duration for each species. Main conclusionsThe meteorological triggers of migration at the breeding grounds differed between species and were related to deteriorating living conditions and deteriorating migratory flight conditions. Soaring birds are sensitive to meteorological triggers at the same period every year and their temporal response to weather appears to be constrained by their annual routine.

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ÐåзюìåМèрîâая ïîïуляцèя ñòåïнîгî îрла (Aquila nipalensis) èмååò ñòаòуñ угрîжаåмîé è бûñòрî òåряåò ÷èñлåннîñòь ïî âñåму арåалу. Эéлаò, раñïîлîжåннûé â южнîм Иçраèлå -эòî òаê наçûâаåмîå «буòûлî÷нîå гîрлûшêî» на ïуòè âåñåннåé мèграцèè эòîгî âèда èç Àфрèêè. Мû ïрîâåлè ñåрèю ïîлåâûõ èññлåдîâанèé ñ 2015 ïî 2018 гг., âåдя ïîдñ÷ёò ïрîлåòаюùèõ ñòåïнûõ îрлîâ, è ñîбèрая даннûå îб èõ âîçраñòå. Ïîлу÷åннûå даннûå мû ñраâнèлè ñ аналîгè÷нûмè, ñîбраннûмè çа 4 âåñåннèõ ñåçîна â ïрîмåжуòêå мåжду 1977 è 1988 гг. Мû нå âûяâèлè дîñòîâåрнûõ раçлè÷èé мåжду дâумя âûбîрêамè ïî êîлè÷åñòâу ñòåïнûõ îрлîâ, ïрîõîдяùèõ над Эéлаòîм на âåñåннåé мèграцèè. Эòî îçна÷аåò, ÷òî çèмîâêè ñòåïнîгî îрла â Àфрèêå è åгî ïуòè мèграцèè â Àфрèêу è îбраòнî îòнîñèòåльнî бåçîïаñнû. Мû òаêжå îбнаружèлè, ÷òî 75% ïрîлåòаюùèõ îрлîâ -эòî âçрîñлûå îñîбè, è ÷òî èõ îñнîâнîé ïрîлёò ïрèõîдèòñя на òрåòью нåдåлю фåâраля. Эòа èнфîрмацèя ñïîñîбñòâуåò улу÷шåнèю мåр ïî îõранå âèда.