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Black Harrier Circus maurus

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.

Taxonomic source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

Identification
48-53 cm. Medium-sized harrier. Adult striking, with black plumage plus boldly striped black-and-white tail, white rump and yellow legs, eye and cere. White undersides to primaries and secondaries give huge white wing panels, contrasting with black coverts and body. Immature dark brown and heavily mottled and streaked, but has obvious white rump and banded tail. Similar spp. Juvenile and immature much darker and more blotched on underparts than the warm brown streaking of similar-age Pallid Harrier C. macrourus and Montagu's Harrier C. pygargus; which also have large white underwing panels. Voice A pi pi pi pi pi food call by females, also a squeeling wheep aerial display call and harsh chuckling chak chak chak when alarmed.

Distribution and population
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).

Population justification
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.

Trend justification
Recently, the population is thought to have experienced a slight decline owing to the loss of some patches of renosterveld vegetation in Overberg (R.E. Simmons in litt. 2007). Future declines may occur because of a predicted decrease in rainfall in the western parts of its range, which could lead to a reduction in mouse populations (R.E. Simmons in litt. 2007). However, the trend is maintained as stable until further data are obtained.

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).

Threats
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 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).

References
Barnes, K. N. 2000. The Eskom Red Data Book of birds of South Africa, Lesotho and Swaziland. BirdLife South Africa, Johannesburg.

Brown, L. H.; Urban, E. K.; Newman, K. 1982. The birds of Africa vol I. Academic Press, London.

Curtis, O.; Simmons, R.E.; Jenkins, A. R. 2004. Black Harrier Circus maurus of the Fynbos biome, South Africa: a threatened specialist or an adaptable survivor? Bird Conservation International 14: 233-245.

Harrison, J. A.; Allan, D. G.; Underhill, L. G.; Herremans, M.; Tree, A. J.; Parker, V.; Brown, C. J. 1997. The atlas of southern African birds. BirdLife South Africa, Johannesburg.

Siegfried, W. R. 1992. Conservation status of the South African endemic avifauna. South African Journal of Wildlife Research 22: 61-64.

Simmons, R.E. 2005. Declining coastal avifauna at a diamond-mining site in Namibia: comparisons and causes. Ostrich 76(3-4): 97-103.

Simmons, R.E. 2005. Reviewing the conservation status of the Black Harrier, Circus maurus. Gabar 16: 29-31.

Thiollay, J.-M. 1994. Family Accipitridae (Hawks and Eagles). In: del Hoyo, J.; Elliott, A.; Sargatal, J. (ed.), Handbook of the birds of the world, pp. 52-205. Lynx Edicions, Barcelona, Spain.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Butchart, S., Ekstrom, J., Pilgrim, J., Robertson, P., Symes, A., Taylor, J.

Contributors
Curtis, O., Jenkins, A., Simmons, R.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2014) Species factsheet: Circus maurus. Downloaded from http://www.birdlife.org on 29/08/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 29/08/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Black harrier (Circus maurus) 0

Key facts
Current IUCN Red List category Vulnerable
Family Accipitridae (Hawks, Eagles)
Species name author (Temminck, 1828)
Population size 250-999 mature individuals
Population trend Stable
Distribution size (breeding/resident) 494,000 km2
Country endemic? No
Links to further information
- Additional Information on this species
- Projected distributions under climate change