942 C. Böhm et al.


migration starts at the beginning of August, but birds regu- larly remain north of the Alps up to mid September. In the unusually mild winter of 2014 most of the birds delayed mi- gration to late December, resulting in significant mortality (Fritz et al., 2016). In 2018, 20 juveniles followed conspecifics to the wintering site, and one group of seven juveniles and two adults reached the wintering area within 24 days. On one day the birds covered over 400 km. In 2014 the feasibility study evolved into a 6-year rein-


troduction project involving eight partners from Germany, Austria and Italy, with significant co-financing from the European Union under the LIFE+ programme. The aim was to establish three migratory breeding colonies with a total of at least 120 birds (Fritz et al., 2017). A follow-up pro- ject has been proposed, aiming to achieve a viable popula- tion by 2026. By the end of 2018, there were 100 free-flying, migrating


northern bald ibises (10 breeding pairs; Table 5), belonging to two established breeding colonies at Burghausen, south- ern Germany, and Kuchl, Austria, with a third breeding colony establishing from 2017 in Ueberlingen at Lake Constance, southern Germany. A major challenge for the project are losses caused by illegal hunting during the au- tumn migration (Fritz, 2015). During the feasibility study (2002–2013)up to 71%of the annual losses were attributable to illegal hunting in Italy (Fritz, 2015; Fritz et al., 2016). Since 2014, illegal hunting accounts for 17% of the annual losses, with electrocution at medium voltage power poles caus- ing 31% of the mortality (Supplementary Table 1). Criminal and civil cases brought against an Italian northern bald ibis hunter raised awareness of the issues in Europe (Fritz et al., 2016, 2017). Since 2011 a total of 104 juveniles fledged in the wild at the two breeding sites (Table 5), a mean of 2.2 per nest. Details of annual releases of 7–30 birds are presented in Supplementary Table 1. Overall annual post-release survival in the first year is c. 69%. All released birds are individually marked and tracked (Fritz et al., 2017).


Spain: reintroduction of a sedentary population


In 2004 a joint project between Zoobotánico Jerez and the Andalusian government established Proyecto Eremita, to develop techniques for the release of captive-bred northern bald ibises (López & Quevedo, 2016), with the aim to estab- lish a sedentary, free-flying colony in southern Spain. The release area in south-western Cádiz province has coastal and inland cliffs, and extensive foraging areas, allowing the birds to feed all year round. Birds are hand-reared by human foster parents wearing black shirts and ibis-shaped cycle-helmets (Quevedo et al., 2004; Quevedo, 2016). Once a free-flying hand-reared group of ibises was established in the area, groups of parent-reared juveniles were kept in a


neighbouring release aviary for several months (October– January), then released to join the free-flying birds. This technique facilitates the integration of additional birds coming from collaborating zoos that are members of the European Endangered Species Programme for the northern bald ibis. Annual releases of 17–52 birds during 2004–2018


(Table 6) demonstrated the ability of captive bred northern bald ibises to survive after release and to establish a wild col- ony in the region of La Janda, Cádiz, south-west Spain. At present post-release survival in the first year is c. 44%, with the main causes of mortality being predation by eagle owls Bubo bubo and electrocution (Supplementary Table 3; López & Quevedo, 2016). The first nesting of released birds was in 2008 at Tajo Barbate, a coastal cliff 5 km from the release site, where breeding occurred annually until 2010.In 2011 a new breeding site was established beside a busy road at Barca de Vejer, 15 km from the release site, and this has be- come the main colony (López & Quevedo, 2016). In 2014 a new breeding site was established in Castilnovo, a coastal tower, 23 km from the release site. By 2018 there were two active breeding sites (Table 6) within 23 km of the release site, with a total of 90 birds in the wild, including 20 breed- ing pairs (Supplementary Table 3). The four breeding sites were naturally colonized by northern bald ibises; no boxes or ledges were provided. All birds are individually marked, and some carry transmitters. From the hand-reared groups, some juvenile dispersal, mainly southwards, has been re- corded, in contrast with the wild-hatched juveniles that have remained in the area with their parents and the rest of the group. In July 2013 the Environment Ministry of Spain formally approved the work as a northern bald ibis reintroduction project. The project has two phases: (1) the consolidation of the existing colonies, and (2) applying the techniques refined by Proyecto Eremita to establish a second population of northern bald ibises in Cabo de Gata Natural Park, 200 km away, also in Andalusia. To date, Proyecto Eremita has succeeded in establishing a sedentary popula- tion without supplementary feeding or other intensive in- terventions. The population is not yet self-sustaining, so supplementationwith additional birds is continuing, improv- ing genetic variability and aiming for a minimumof 120 birds and 35 breeding pairs by 2020.


Conservation progress


Management of the remaining population in coastal Morocco has generated the first sustained increase in the natural wild population in historical times. Although the northern bald ibis was categorized as Critically Endangered in the IUCN Red List up to 2018, the positive trend in Morocco since 1997 justified recategorization from Critically Endangered to Endangered (BirdLife, 2018). Management by


Oryx, 2021, 55(6), 934–946 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605320000198


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