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The Sacred Ibis in Europe: ecology and management Pierre Yésou, Philippe Clergeau, Suzanne Bastian, Sébastien Reeber and Jean-François Maillard Abstract The Sacred Ibis Threskiornis aethiopicus is common and widespread in its native range. The species’ adaptability means that it thrives in landscapes modified by human activity. In recent decades, non-native populations have become established in several areas of Europe as a result of escapes or deliberate releases from collections. Such populations have the potential to become established and increase quickly, and thus to have a significant impact on native species. This paper summarises the current situation in Europe, with particular reference to France. The largest non-native populations in Europe became established in France between about 1990 and 2005, prompting a costly eradication programme, the progress and results of which are described. The Sacred Ibis in its native range The Sacred Ibis is a social breeder, in The Sacred Ibis Threskiornis aethiopicus is colonies from a few tens up to c. 2,000 pairs. common and widespread throughout much Nests are built on a variety of supports, of sub-Saharan Africa, and a small, isolated mostly in trees and bushes but sometimes on and decreasing population persists in the ground or among rocks (Urban 1974; southern Iraq (Bonn 2005). The world popu- Brown et al. 1982; Hancock et al. 1992). lation, estimated at some 200,000–450,000 Around Cape Town, ibises breed in reedbeds, individuals, is thought to be stable or on the ground, in trees and bushes and even declining (Wetlands International wpe. on artificial breeding platforms. In all cases, wetlands.org; BirdLife www.birdlife.org), and breeding sites are completely surrounded by it is treated as a species of Least Concern water or on an offshore island, and the under IUCN criteria (iucnredlist.org). species will breed almost anywhere provided In South Africa, where most studies have that the ‘island’ criterion is met (Doug Hare- been carried out, the Sacred Ibis bred only on bottle in litt.). coastal islets near Cape Town at the begin- Ibises are similarly social when feeding, ning of the twentieth century, moving to mostly foraging in groups, often with other inland marshes in winter. Subsequently, it long-legged species such as Yellow-billed benefited from irrigation, agriculture intensi- Stork Mycteria ibis, African Spoonbill fication, and conservation measures, and Platalea alba and Little Egret Egretta garzetta progressively established colonies as far (Hancock et al. 1992). In Africa as a whole, inland as Zimbabwe (Harrison et al. 1997; the main foraging habitats are farmland, wet- Kopij 1999). Although it is nominally resi- lands, and rubbish dumps (Brown et al. dent, over 50% of ring-recoveries are more 1982), while in South Africa over 80% of than 100 km from the ringing site (Hockey et records are from grassland habitats, the al. 2005), while post-breeding movements of remainder mainly from freshwater wetlands up to 1,000 km occur, and some consider the and estuaries (Harrison et al. 1997). The Sacred Ibis to be more accurately described species will also use a wide variety of man- as nomadic (Clark & Clark 1979; Harrison et modified and artificial habitats (Clark & al. 1997; Underhill et al. 1999). Clark 1979). © British Birds 110 • April 2017 • 197–212 197 Yésou et al. Sébastien Reeber 94. Sacred Ibises Threskiornis aethiopicus, Lac de Grand-Lieu, France, May 2011. The Sacred Ibis feeds mainly on locusts, reports from Egypt (Egyptian Ornithological grasshoppers, and aquatic beetles; it will also Rarities Committee http://chn-france.org/ take a variety of other aquatic and terrestrial eorc), and none has reached Morocco invertebrates, in addition to fish, amphibians, although it is common in Mauritania lizards, birds and small mammals. Carrion, (Thévenot et al. 2003; Moroccan Rarities vegetable and animal refuse, offal and seeds Committee www.go-south.org). Conse- are also taken. In addition, breeding birds can quently, any Sacred Ibis recorded in the wild raid neighbouring nests for eggs and chicks, in Europe can be regarded as a former and some individuals specialise in raiding the captive, released either deliberately or acci- nests of other birds, sometimes pulling adult dentally. Such escapes remained a rare sight birds out of their nest to take the eggs or until it became more common for zoological young. Victims include pelicans, herons, collections to house free-flying groups of spoonbills and cormorants, gulls and terns ibises (Clergeau & Yésou 2006; Fàbregas et al. on offshore islands, and two Endangered 2010). In recent decades, the number of species (African Penguin Spheniscus demersus escapes has led to the establishment of signif- and Cape Cormorant Phalacrocorax icant non-native populations in some areas. capensis), and they will even take eggs of the Non-native species that become estab- Nile Crocodile Crocodylus niloticus (Clark lished in the wild may have a negative impact 1979; Brown et al. 1982; Harrison et al. 1997; on native species, potentially with a signifi- Hockey et al. 2005; Williams & Ward 2006). cant loss of biodiversity as well as economic impacts, and are termed ‘invasive species’ The Sacred Ibis as a non-native (e.g. Mooney & Cleland 2001, Vilà et al. 2010, The Sacred Ibis is absent from the paleonto- Martin-Albarracin et al. 2015). Accordingly, logical and archeo-zoological record in the European Parliament and the Council of Europe (Mourer-Chauviré 1993), and there is the European Union adopted a regulation to no evidence for natural vagrancy out of ‘prevent, minimise and mitigate the adverse Africa. In the early nineteenth century the impact on biodiversity of the introduction species still bred in Egypt, in the Nile Valley, and spread within the Union of invasive alien but disappeared within a few decades (del species’ (European Commission 2014). This Hoyo et al. 1992). There are no modern-day required the Commission to adopt a list of 198 British Birds 110 • April 2017 • 197–212 The Sacred Ibis in Europe: ecology and management invasive alien species of Union concern, Introductions in Europe and which came into effect in August 2016 (Euro- elsewhere pean Commission 2016). The list contains 37 Free-flying Sacred Ibises have been reported species, including three bird species: House from several European countries. Breeding Crow Corvus splendens, Ruddy Duck Oxyura has occurred in the wild in France, Spain, jamaicensis and Sacred Ibis. In addition, a Portugal, Italy, the Netherlands and possibly pan-European research programme has iden- other nations. A number of free-ranging tified the Sacred Ibis among the invasive colonies have become established; the situa- species of main European concern (DAISIE tion in France is treated in more detail below, 2009 www.europe-aliens.org). These three but a brief summary of breeding status in species are now the subject of control and other European countries is given first. eradication programmes throughout the EU. The House Crow has established popula- Spain and Canary Islands tions in over 20 countries outside its native Sacred Ibises that escaped from Barcelona range and often rapidly attained pest status, Zoo settled in a nearby public park, where for example through predation of native breeding first occurred in 1974. This con- species and as a carrier of human and animal tinued throughout the 1980s and 1990s, after disease (GISD 2017). The threat posed by the which the colony was controlled, and Ruddy Duck to the conservation of the breeding was last recorded in 2001. The endangered native White-headed Duck O. breeding birds also visited nearby wetland leucocephala in southern Europe and the con- areas including the Llobregat and Ebro deltas sequent eradication programme in the UK (Jordi Clavell in litt.). In the Canary Islands, are well known (e.g. Henderson 2009, where the species was first recorded in 1989, Holling et al. 2017). The remainder of this free-ranging ibises have nested regularly on paper considers the potential problems of Fuerteventura since at least 1997, with 2–5 established non-native Sacred Ibis popula- pairs nesting in the early 2000s (Yésou & tions. Focusing on the situation in France, Clergeau 2005) and unknown numbers since where the largest introduced population in then. the world has spread, we highlight the diffi- culties encountered in setting up an eradica- Portugal tion programme to deal with such a large and Three Sacred Ibises escaped from a zoo near widespread population. When not otherwise Coimbra in 1998; a pair nested nearby and stated, the information presented here reared three young that year, after which they has been collected by the authors and their disappeared. Since 2009 the species has been institutions. observed almost year-round in the Algarve Jérôme Cabelguen 95. Sacred Ibises Threskiornis aethiopicus, Banc du Bilho, Loire estuary, France, April 2005. British Birds 110 • April 2017 • 197–212 199 Yésou et al. with up to six birds together, but breeding The Netherlands has so far not been recorded (de Juana & Free-flying Sacred Ibises that escaped from a Garcia 2015; Gonçalo Elias in litt.). zoological park in Zuid-Holland attempted to breed in 2001, and successful breeding Italy occurred in 2002. Numbers increased to ten Breeding in the upper Po Valley, Piedmont, breeding pairs in 2003 and 15 pairs in 2007. began in 1989, and 26 pairs nested there in Eradication measures began in 2008 and only 2000, when approximately 100 individuals 4–5 pairs remained in 2009. A few birds are were present. In 2003 breeding occurred at a still at large, possibly new escapees or birds second site in the same area, with possibly arriving from Germany (Smits et al. 2010; 25–30 pairs, and a few more pairs were found Robert et al. 2013; www.cr-birding.org). at a third colony in 2004 (Yésou & Clergeau Sporadic reports of breeding birds continue, 2005).

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