POPULATION SIZE AOO EOO TREND
100-200 mat. ind. 56-100 km2 9,698 km2
NORTH AFRICA REGIONAL ASSESSMENT: CRITICALLY ENDANGERED (CR) C2a(ii) (IUCN version 3.1) This species has a small and declining population in North Africa estimated at 100–200 mature individuals in a single subpopulation. Based on historical localities, it is estimated that its extent of occurrence (EOO) has been reduced by 50 to 70% in the last 22 years as a consequence of the elimination and degradation of marshlands, its main suitable habitat. Its area of occupancy (AOO) is estimated to be less than 100 km2 and its EOO 9,698 km2. Recent observations indicate the species could be colonising new habitats, but more research is needed to in-crease knowledge of its current distribution, ecological requirements and population status. However, based on the small and declining population, the species is listed as Critically Endangered under criterion C2a(ii).
DISTRIBUTION
This is a widespread Afrotropical owl occurring over large areas of sub-Saharan Africa, with isolated populations of the endemic subspecies A. c. ssp. tingitanus in North Africa. The Marsh Owl currently occurs in Morocco, though it formerly also bred in Algeria (Thévenot et al., 2003; Isenmann and Moali, 2000).
In Morocco, the species used to be found from Tangier to Essaouira and Fez, but currently it occurs on the plains and hills of northern and central parts of the Atlantic coast, between Tangier and Essaouira and inland around Meknès, where it almost exclusively inhabits marsh vegetation in coastal wetlands (Bergier and Thévenot, 1991;
Thévenot et al., 2003). To date, five breeding localities have been identified: the wetlands of Merja Zerga, Lower Loukkos, Sidi-Boughaba and the Tahaddart estuary (MaghrebOrnitho, 2014b, 2018e), and an unknown forest habitat in the Mamora Forest, which could be a newly colonised site (Hanane and Cherkaoui, 2014).
CR
© Brahim Bakaas
POPULATION
In the late 19th century, marsh owls were considered common in Morocco (Reid 1885), but the population has undergone a considerable decline since the end of the 19th century (Hanane and Cherkaoui, 2014), and especially since the 1970s in most areas, due to the increase in the human population and the resulting modification, distur-bance and destruction of wetlands (Bergier and Thévenot, 1991; Thévenot et al., 2003). By 1991, the population in Morocco was estimated at 50–140 breeding pairs (Bergier and Thévenot, 1991), a number which was repeated by El Agbani and Qninba (2011). However, Qninba et al. (2008) found a decline of 40% from the 1980s to 2008 in the second most important location in Morocco, Lower Loukkos. Thus, if the decline is assumed to be the same across the country, and considering the threats that wetlands are facing (Franchimont and Saadaoui, 2001;
Sayad, 2007; MaghrebOrnitho, 2012), the breeding population in the country may be estimated to be around 50–100 breeding pairs (100–200 mature individuals).
HABITATS AND ECOLOGY
The typical habitat of the species in Morocco is permanent wetlands surrounded by well-developed marsh vegetation (Bergier and Thévenot, 1991), especially in coastal wetlands (Thévenot et al., 2003), but also in cereal fields (El Agbani and Qninba, 2011), rice fields (K. Rousselon, pers. obs., 2019) and forest habitats (Hanane and Cherkaoui, 2014). The breeding season in the area lasts from the end of February to the end of May (Thévenot et al., 2003). The marsh owl nests on the ground or, exceptionally, in trees in old corvid nests, and lays an aver-age clutch of 3.22 eggs with a hatching rate of 78%; with young birds recorded from April to June (Bergier and Thévenot, 1991).
The species’ diet varies from one site to another and includes micromammals and invertebrates, but in largely unspoilt wetlands it consists mainly of insects (Bergier and Thévenot, 1991). The species is mainly sedentary but some birds disperse over long distances (Bergier and Thévenot, 1991), even as far as Spain (De Juana and García, 2015). The habitat of the recent breeding record from the Mamora forest consists of dense Quercus suber forest with tall Chamaerops humilis and Cistus sp. shrubland (Hanane and Cherkaoui, 2014).
THREATS
The marsh owl is very vulnerable to habitat loss resulting from drainage of marshland (due to the increasing human population and the expansion of agriculture) and to disturbance by farmers, pastoralists and especially birders at their main breeding sites (Bergier and Thévenot, 1991; Franchimont and Saadaoui, 2001; Thévenot et al., 2003; Sayad, 2007; MaghrebOrnitho, 2012). Nests are vulnerable to fires (Olsen, 1999), which have occurred a few times at breeding sites (MaghrebOrnitho, 2012), as well as vandalism, such that very few broods succeed at the species’ best breeding site in Morocco (A. Qninba, pers. comm., 2020). Increasing populations of wild boars may also be having a negative impact on breeding success (I. Cherkaoui, pers. comm., 2020).
Rodenticides used on farmland may also be adversely affecting the population but there are no available data (K. Rousselon, pers. comm., 2020). Marsh owls are also killed by traffic (Bergier and Thévenot, 1991;
MaghrebOrnitho, 2014b). Finally, all owl species are illegally traded in North Afri-ca (Brochet et al., 2016), and in MorocAfri-can popular belief, all nocturnal birds of prey are used for magic rituals. Overall, this small, isolated population could suffer a reduction in genetic diversity over time, which could influence breeding success and the long-term survival of the population unless the sites are carefully managed.
© IUCN
Distribution range of the Marsh owl, Asio capensis - (Smith, 1834) in North Africa. Source: The IUCN Red List of the breeding birds of prey of North Africa.
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CONSERVATION
Conservation and research actions in place: CITES Appendix II.
Conservation and research actions needed: A Conservation Action Plan must be developed to conserve and restore breeding locations, including a population and habitat viability assessment and prospection to find new populations. Strict and effective protection of all known breeding sites is required, and the destruction of wetland vegetation for agricultural purposes or by fire must be prevented. Local ornithological guides should be trained to avoid disturbing the breeding and wintering population, and best practice guidelines for birdwatching should be established, including a ban during the breeding season. Populations should be monitored to deter-mine, protect and manage key breeding, wintering and dispersal sites. Road signage should be installed in areas of high traffic collision risk (e.g. near breeding sites) alerting drivers to the presence of marsh owls and warning them to reduce speed. Research is needed into the feasibility of a captive breeding programme to reinforce existing populations and to reintroduce individuals to suitable localities where the species has become extinct.
Assessor(s): Cherkaoui, I., Rousselon, K. & Monti, F.
Reviewer(s): Garrido López, J.R. & Qninba, A.
Contributor(s): Gyenge, P., Bakass, B., BirdLife International & Qninba, A.
Date: 2020–09–08