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Calls for urgent action to conserve biodiversity under global change are increasing, and conservation of migratory species in this context poses special challenges. In the last two decades the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has provided a framework for several subsidiary instruments including action plans for migratory bird species, but the effectiveness and transferability of these plans remain unclear. Such laws and policies have been credited with positive outcomes for the conservation of migratory species, but the lack of international coordination and on-ground implementation pose major challenges. While research on migratory populations has received growing attention, considerably less emphasis has been given to integrating ecological information throughout the annual cycle for examining strategies to conserve migratory species at multiple scales in the face of global change. We fill this gap through a case study examining the ecological status and conservation of a migratory raptor and facultative scavenger, the red kite (Milvus milvus), whose current breeding range is limited to Europe and is associated with agricultural landscapes and restricted to the temperate zone. Based on our review, conservation actions have been successful at recovering red kite populations within certain regions. Populations however remain depleted along the southern-most edge of the geographic range where many migratory red kites from northern strongholds overwinter. This led us to a forward-looking and integrated strategy that emphasizes international coordination involving researchers and conservation practitioners to enhance the science-policy-action interface. We identify and explore key issues for conserving the red kite under global change, including enhancing conservation actions within and outside protected areas, recovering depleted populations, accounting for climate change, and transboundary coordination in adaptive conservation and management actions. The integrated conservation strategy is sufficiently general such that it can be adapted to inform conservation of other highly mobile species subject to global change., Financial and logistic support were provided by GREFA, IREC, UCLM (Universidad de Castilla-La Mancha), CSIC and MITECO.

Three black kite (Milvus migrans migrans) pulli (siblings, BK1, BK2, and BK3) from the same nest in eastern Slovakia were tagged with telemetry (GPS/GSM) loggers on 1 July 2016. BK1 (female), BK2 (male) and BK3 (female) occupied post-fledging areas until 12 August 2016 when they began to migrate southeast. BK1 wintered in Libya, returned to Turkey in the summer, then wintered in Israel. After spending the winter there, it returned to Europe, looped the Baltic Sea and stayed in western Russia throughout the summer. During the autumn, it passed Ukraine and travelled along the Black Sea and wintered in Syria then it moved again to Europe. It used 18 temporary settlement areas (TSA) during its journey until 12 June 2019 when it was roadkilled in Norway. BK2 migrated to the northern tip of the Red Sea and crossed the sea where positions of the bird spatiotemporally coincided with a position of transcontinental cargo ship. It is expected that the bird died whilst on the cargo ship and its body was passively carried on-board and discarded on the west coast of the Red Sea. BK3 reached the northern outpost of the Red Sea in Saudi Arabia. It then continued southeast along the east coast of the Red Sea to Yemen and crossed the Strait of Bab-el-Mandeb to Africa. It wintered mainly in Sudan, Southern Sudan and Uganda, then returned along the west coast of the Red Sea and the east coast of the Mediterranean Sea arriving to the Turkey/Syria border area. Only two TSA were revealed on its route. The migration behaviour among these floaters during natal dispersal was substantially different and covered surprisingly large parts of Europe and North and East Africa.

We characterized the spatiotemporal activities in winter grounds of Red Kites originated from central Europe and wintering in south-eastern Europe. We found not only Red Kites at these places but often also Black Kites Milvus migrans. Birds arrived to winter grounds in Hungary, Croatia, and Greece from 10 July to 12 December (median 22 October) and departed from winter grounds between 14 February and 22 May (median 14 March), thus staying at winter grounds from 121 to 229 days (median 145, mean 161 ± 43 SD, n = 14 cases). We usually found a number of Red Kites wintering together at winter grounds, although some Red Kites wintered alone. We found Black Kites wintering together with Red Kites at the same winter grounds in 6 out of 14 cases. The numbers of Black Kites wintering together with Red Kites were higher than the number of Red Kites at all Greek winter grounds. At winter grounds in Hungary and Croatia, the numbers of Black Kites were lower than the numbers of Red Kites or Black Kites were wholly absent. If we regarded kernel density estimate 80% (area of main foraging and roosting activities) as the best indicator as to the size of home range, we revealed that the size of a home range for birds staying at one place through the entire winter was from 10 to 108 km2 (median 72, mean 60 ± 36 SD, n = 12 cases) and that the size of home range for birds with local shift(s) in winter grounds was from 344 to 620 km2 (median 434, mean 466 ± 115 SD, n = 3 cases) which is substantially larger than the size of home ranges published to date for Red Kites wintering in central and south-western Europe.

A total of 13 Red Kites Milvus milvus fitted with GPS/GSM telemetry loggers in central Europe were tracked in Serbia from 10 July 2014 until 31 March 2018. These birds remained in Serbia for 138 days (counted as number of one bird/one day stays). Red Kites occurred mostly in the Vojvodina Province (NW Serbia). They were registered most often in April and October, which corresponded to their spring and autumn migrations. It is possible that Red Kites occur in Serbia more often than formerly, and this could in future result in this threatened European raptor’s more frequently wintering and breeding within the country.