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Circus maurus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES ACCIPITRIFORMES ACCIPITRIDAE

Scientific Name: Circus maurus
Species Authority: (Temminck, 1828)
Common Name(s):
English Black Harrier
French Busard maure
Spanish Aguilucho Negro

Assessment Information [top]

Red List Category & Criteria: Vulnerable D1 ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Taylor, J. & Butchart, S.
Contributor(s): Curtis, O., Jenkins, A. & Simmons, R.
Facilitator/Compiler(s): Benstead, P., Butchart, S., Ekstrom, J., Pilgrim, J., Robertson, P., Symes, A., Taylor, J.
Justification:
This species is classified as Vulnerable, despite its huge range, because it has a very small population. This and its virtual disappearance from agricultural lowlands make it highly reliant on protected areas in its core breeding range.

Geographic Range [top]

Range Description: Circus maurus is restricted to southern Africa, where it is concentrated in the Western Cape (its core range), and occurs in the Eastern Cape, the Northern Cape and Free State (where it is irruptive in both areas), in South Africa (R.E. Simmons in litt. 2004), and is also found in Lesotho (non-breeding birds) (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004), with a tiny isolated population in northern Namibia (less than 50 birds including about five pairs [Simmons 2005]). It is considered a vagrant in Botswana and Swaziland, where non-breeding birds occasionally occur (Hancock 2008). An unknown proportion migrates between South Africa and Namibia (Simmons 2005). It is widespread and can be locally common within its breeding range (Thiollay 1994), with high concentrations of breeding pairs (up to 10 pairs/0.7 km2) at suitable sites (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004), such as West Coast National Park in South Africa (Thiollay 1994, Harrison et al. 1997). The total population is estimated at 1,000-1,500 individuals (R.E. Simmons in litt. 2007), although the number of mature individuals is likely to be less than 1,000. Although there has been some debate on its status and trends, with breeding birds now known to irrupt into grasslands in some areas (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004, R.E. Simmons in litt. 2004), populations have probably been stable overall and its range has not changed markedly during the 20th century. Recently, the population is thought to have experienced a slight decline due to the loss of some patches of renosterveld vegetation in Overberg (R.E. Simmons in litt. 2007). Future declines may occur in reaction to a predicted decrease in rainfall in the western parts of its range (R.E. Simmons in litt. 2007).

Countries:
Native:
Lesotho; Namibia; South Africa
Vagrant:
Botswana; Swaziland
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The total population is estimated at 1,000-1,500 individuals (R.E. Simmons in litt. 2007); however, it is thought that the number of mature individuals does not exceed 1,000, thus the range 250-999 mature individuals is retained for the population estimate.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: It is a cool, dry-country species, frequenting coastal and montane fynbos(Curtis et al. 2004, (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004), highland grasslands, Karoo subdesert scrub, open plains with low shrubs and croplands. It often breeds close to coastal and upland marshes with tall shrubs or reeds, occurring in dry steppe and grassland areas further north in the non-breeding season (Brown et al. 1982, Thiollay 1994, R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). In the western cape of South Africa it is most abundant in coastal and montane fynbos(Curtis et al. 2004), whilst in Namibia it favours coastal river floodplains(S. Braine and J. Paterson per Simmons 2005). It prefers open ground with low vegetation for hunting, where it feeds on a diet comprising mainly of small mammals, especially Otomys and Rhabdomys species (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). Whilst mammals make up the vast majority of prey taken at coastal sites, with reptiles and birds also taken, birds make up a slightly greater proportion than mammals in the diet of pairs nesting in montane habitats (Curtis et al. 2004). Local fluctuations in breeding numbers may be related to population cycles in its prey base (Thiollay 1994), such as mice whose numbers fluctuate with rainfall, especially in the more arid regions (R.E. Simmons in litt. 2007). Damp sites, near vleis, marshes or streams, are preferred for breeding (Brown et al. 1982), while south-facing slopes are preferred in montane areas (R.E. Simmons in litt. 2007). Nests are built on the ground and usually hold three to five eggs (Brown et al. 1982, Curtis et al. 2004, R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). In south-western South Africa, egg-laying takes place in June-November, with peaks in July and September (Curtis et al. 2004).

Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): The species has conceivably lost 50% of its preferred breeding habitat over the last century (Curtis et al. 2004), and present rates in the Overberg may be over 1% per annum (R.E. Simmons in litt. 2007). Habitat is primarily lost to agriculture, and this is compounded by the uncontrolled burning of fynbos and grassland, which renders these habitats unsuitable for breeding for about five years (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). Alien vegetation and urbanisation are also cited as causes of habitat loss (Curtis et al. 2004). In south-western South Africa, it is thought that breeding birds have been displaced from prime lowland habitats (renosterveld and fynbos) by the spread of cereal agriculture, with breeding pairs presently occupying only coastal areas, with high productivity, and montane habitats, where breeding success is low and levels of nest predation are high (Curtis et al. 2004). Rodent populations in areas of wheat cultivation may be as low as 33% of those found in renosterveld vegetation (R.E. Simmons in litt. 2004), and remnant patches of renosterveld, which continue to be degraded R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004), hold lower numbers of rodents than coastal strandveld vegetation (R.E. Simmons in litt. 2004). Low hatching rates, possibly as a result of high pesticide residues, is an increasing threat now that many remaining breeding habitats are surrounded by agricultural areas R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). The ingestion of herbicides and pesticides may account for the death of some adults in South Africa (Simmons 2005), while road deaths adjacent to west coast breeding grounds numbered six birds over one breeding season in 2007 (R.E. Simmons in litt. 2007). Drainage, impoundment and inappropriate management of vleis, marshes or streams near breeding grounds could prove detrimental. Climate change in South Africa is predicted to cause a decrease in overall winter rainfall in the core breeding areas, which is likely to lead to a reduction in mouse populations and disruption to breeding (R.E. Simmons in litt. 2007). The same threats may apply to the species in Namibia, and the favoured habitats of the migrant population may be overgrazed, particularly in southern Namibia (Simmons 2005). Overgrazing in southern Namibia is attributed mainly to resident pastoralists and 'emergency grazing' by farmers from elsewhere, which is offered during years of good rainfall (R.E. Simmons in litt. 2007).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
CITES Appendix II. CMS Appendix II. There are fewer than 100 individuals in protected areas (Siegfried 1992). The resident Namibian population occurs within the Skeleton Coast Park and is protected from fires and grazing (Simmons 2005).

Conservation Actions Proposed
Closely monitor the population, including those in the north-western rivers of Namibia (Simmons 2005). Investigate the possible occurrence of breeding in the northern Namibian population (likely in October-November) (Simmons 2005). Study the causes of population fluctuations (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). Carry out research into its foraging ecology and the availability of rodent prey around habitat fragments (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). Provide incentives to landowners to manage fynbos, renosterveld and grasslands beneficially (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004). Instigate education programmes to raise awareness of the value of this species. Study direct interactions and potential competition between the species and African Marsh Harrier C. ranivorus where they occur in sympatry (Curtis et al. 2004). Promote the species as an icon of Cape conservation needs (R.E. Simmons, O. Curtis and A. Jenkins in litt. 2004).


Citation: BirdLife International 2012. Circus maurus. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 21 September 2014.
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