The status and recent breeding performance of the critically endangered Northern Bald Ibis Geronticus eremita population on the Atlantic coast of Morocco

Abstract

The main wild population of the Northern Bald Ibis Geronticus eremita breeds on the Atlantic coast of Morocco in the Agadir region. This paper describes the numbers of breeding pairs over the last two decades, the recent breeding performance, the causes of egg and chick losses and their conservation implications. Since 1980 there has been no overall decline in numbers with, over the last 5 years, 59–74 pairs breeding and a peak prebreeding population of around 220 birds. In contrast with the now extinct Northern Bald Ibis populations in Turkey and elsewhere in Morocco, the birds are present in the Agadir region throughout the year and do not appear to migrate from the area outside the breeding season. Breeding performance is highly variable from one year to the next but does not appear to be related to rainfall in the vicinity of the colonies as has been reported elsewhere. It is suggested that coastal fogs in this region may buffer the adverse impacts of low rainfall and may in part account for the year‐round residency of the birds. The main causes of breeding failures have been loss of eggs to predators and, most importantly, poor chick survival as a result of starvation and predation. Conservation action to date has focused on reducing the negative influences on breeding success but it is recognized that for such a long‐lived bird adult survival is also likely to be an important limiting factor on the population size.

Breeding ecology and behaviour of the last wild oriental Northern Bald Ibises (Geronticus eremita) in Syria

“…Probable causes of this dramatic decline in Syria were identified as chick collection for food by locals, uncontrolled hunting, human disturbance during incubation and also habitat degradation (Serra et al 2003). The feeding ecology of the relict Syrian colony has been recently described by Serra et al (2008), while the breeding ecology of the species in Turkey and in Morocco is quite well known (Kumerloeve 1967;Hirsch 1976;Hirsch 1979;Ş ahin 1982Ş ahin , Sahin 1983aPegoraro 1992;Bowden and Smith 1997;Bowden et al 2003).…”

“…Until 2002, the Northern Bald Ibis was known to survive in the wild, globally, in the western range only, with about 92 breeding pairs scattered in a few colonies in coastal Morocco (Bowden et al 2003). That same year, a relict colony of seven individuals was unexpectedly discovered in Syria (Serra et al 2003).…”

“…This bird, traditionally revered in the Middle East and historically elusive (Kumerloeve 1984), has undergone a continuous decline over the last four centuries throughout its original distribution range; this decline accelerated during the twentieth century, with an estimated 98% of the species global population vanishing (Hirsch 1979;Collar and Stuart 1985). The decline of the species within the whole range seems linked to habitat loss, persecution, pesticides and climate change (Collar and Stuart 1985), but, according to some (Hirsch 1979;Bowden et al 2003), the real reasons are still unclear.…”

“…Human disturbance was recorded as having negative effects on the Northern Bald Ibises breeding both in Turkey and in Morocco (Hirsch 1976;Collar and Stuart 1985;Bowden and Smith 1997;Bowden et al 2008), along with raven depredation (Bowden et al 2003(Bowden et al , 2008. A marked sensitivity to human disturbance at breeding sites versus at roosting sites outside the breeding season was described by Bowden and Smith (1997).…”

“…Gesner (1555) recorded breeding of Northern Bald Ibises on the ''rocky walls'' of the Danube valley at Kelheim and Passau, while Schenker (1977) reported historical records of ibises nesting on the castle rocks of Salzburg. The breeding cycle, breeding performance and behaviour of Birecik's colony until 1989 and of Moroccan colonies over several years have been described in detail (Hirsch 1979;Bowden and Smith 1997;Bowden et al 2003Bowden et al , 2008Akçakaya 1990).…”