Northern Bald Ibis in Morocco since 1900: Analysis of ecological requirements

How Northern Bald Ibis managed to survive in Morocco? In other words, which are the most important factors that determine the survival of the Northern Bald Ibis colonies in Morocco? A recent study gave us some good answers.

Northern Bald Ibis (Geronticus eremita) named ‘Aylal’, Souss Massa National Park, October 2019 (Abdeslam Rihane)
Northern Bald Ibis (Geronticus eremita) named ‘Aylal’, Souss Massa National Park, October 2019 (Abdeslam Rihane).

Historically widespread, now reduced to a small restricted area

Northern Bald Ibis (Geronticus eremita) had once a wide breeding range extending from Morocco to the Middle East. It also bred in Southern and Central Europe where it disappeared no later than mid-17th century.

The species survived into the 20th century in two isolated breeding populations: a western population in Morocco and Algeria (now extinct in the latter), and an eastern population in Turkey and Syria. The Turkish population at Birecik is now semi-captive (or semi-wild). The relic breeding population discovered in Syria in 2002 is most likely extinct. So, at present Morocco holds the only surviving wild population of the Northern Bald Ibis.

Two reintroduction projects have been initiated in Europe: the first aims to establish a migratory population in Austria and Germany, and a second aims to create a sedentary population in Andalusia, southern Spain (Despite the objective of the project, some birds from Spain – probably hand-reared – do reach Morocco).

In 2018, the species was downlisted from ‘Critically Endangered’ to ‘Endangered’ on the IUCN Red List of Threatened Species.

Past and present of Northern Bald Ibis in Morocco

About 70 breeding colonies of Northern Bald Ibis were originally known in Morocco. In 1940, the Bald Ibis population in the country consisted of about 1,500 birds. However, the population declined to about 600 individuals in 1975, including 198 breeding pairs dispersed over 13 breeding sites. Thus, only four colonies have survived on the Moroccan Atlantic coast: three in the Souss-Massa National Park and one in Tamri.

The creation of the Souss-Massa National Park in 1991 and conservation measures implemented since 1993 resulted in an increase of the Northern Bald Ibis population from 59 breeding pairs in 1997 to 147 breeding pairs and a total of 708 individuals in 2018.

In 2017, two new small breeding colonies were discovered on the Atlantic coast north of Tamri and in 2018 two additional new sites were found in the Souss Massa National Park.

Northern Bald Ibis breeding colony at Aoulouz, Souss region, in April 1977 (Richard Fairbank). The colony now deserted.
Active breeding colony of Northern Bald Ibis at Aoulouz, Souss region, in April 1977 (Richard Fairbank). The colony now deserted.

Ecological requirements of Northern Bald Ibis colonies

Andre Schenker and his coauthors analyzed the ecological conditions of the 72 breeding colonies of the species known in Morocco since 1900 using qualitative and semi-quantitative parameters. The authors also carried out a more detailed analysis of the 28 breeding colonies known to exist in Morocco after 1977. Examples of the parameters taken into account in the analysis include the physical and climatic conditions, land use, vegetation cover, human settlements and roads. The study has been published online in the journal Bird Conservation International.

From the analysis, two factors emerged as the most important conditions for the maintenance of the breeding colonies: a low level of disturbance at the breeding sites and good suitable feeding areas at a reasonable distance of 5–15 km.

The 28 breeding colonies known in Morocco after 1977 are/were often located in remote, less disturbed areas in semiarid regions (low rainfall) or in the Middle Atlas (good rainfall). However, the four remaining breeding colonies today are all located in a semiarid area. In general, these colonies must be considered as refuge sites with reduced habitat quality due to the high variability of annual rainfall. This appears to be the case not only in Morocco but also in Algeria (the last breeding colony was located at El Bayadh which is an arid area) and Syria (Palmyra desert).

Comparing the current breeding colonies showed however a difference between the three colonies located in the Souss Massa National Park and the colony of Tamri. The latter has a much better annual rainfall (240 mm on average) while the colonies in the Park have a much lower annual rainfall (140 mm on average). Mainly because of this, the three colonies located in the Park must be “living under rather marginal ecological conditions” the authors wrote.

Another good point from the study is that some of the former breeding sites are still suitable for the Northern Bald Ibis (no human disturbances in the immediate vicinity of the nesting sites and suitable feeding habitats within a short distance). Therefore these former sites should be considered in any future reintroduction/translocation project (to increase the species’ range and reinforce the population at the national level).

The article concludes by some recommendations centered mainly on how to make any possible translocation project succeed.

Reference:

Schenker, A., Cahenzli, F., Gutbrod, K. G., Thévenot, M. & Erhardt, A. 2020. The Northern Bald Ibis Geronticus eremita in Morocco since 1900: Analysis of ecological requirements. Bird Conservation International 30: 117-138.  doi:10.1017/S0959270919000170

Real also:

Fritz, J., Eberhard, B., Esterer, C., Trobe, D. & Scope, A. 2019. Unilateral corneal opacity as a result of GPS tracking in a European Northern Bald Ibis (Geronticus eremita) population released in the context of a LIFE+ reintroduction project. Waldrappteam, Austria

2 thoughts on “Northern Bald Ibis in Morocco since 1900: Analysis of ecological requirements”

  1. You surely know that NBI in the Middle East died out because of pesticide poisoning. I wonder whether NBI has real preference for semidesert away from human habitations, or it is a refuge habitat because of low pesticide use. Direct data about the local pesticide use could be very helpful for conservation.

    1. Thanks for your comment and sorry for the late reply.

      The life history of the NBA in the Middle East is more complex because the population is migratory which means additional threats along the route and in wintering areas.

      Historically, the NBA has no preference for semi-desert habitats neither in Morocco nor in its former range elsewhere (in has bred in the Balkan region and central Europe, both of which are not semi-deserts). In Morocco, it has bred for example in the Middle Atlas (over 700 mm of annual rainfall) and other humid or semi-humid regions (see the map of all known colonies in the cited paper, or see the map in this blog-post). So, yes semidesert is a refuge habitat, and despite its low quality (less rain), the species managed to survive there because the threats are minimal (low pesticide use, less disturbance,…).

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