| Pallid Harrier | |
| Circus macrourus | |
| Status: | Near-Threatened |
Distribution and abundance
 Click to see distribution map |
A rare non-breeding visitor to s Africa with most records widely scattered from se and n Botswana grasslands, Zimbabwe and n S Africa (Simmons 1997, S Tyler in litt). While it is more widespread than the Montagu's Harrier - occurring farther west into Namibia and farther s into South Africa (Steyn 1982) - it is less common. Its centre of migration appears to be central and e Africa, especially the Sahel and w African grasslands where locusts are common (Clarke 1996). The Eurasian distribution has become highly fragmented (Gallo-Orsi et al. 2002) leading to a decline in world numbers which were estimated at 20 000 prs in the early 1990s (del Hoyo et al. 1994) and are presently 9,000-15,000 pairs (Gallo-Orsi et al. 2002). In Namibia, it is slightly less common than Montagu's Harrier with an overall reporting rate of 4.6% from 15,543 km2 of which 25% lies within protected areas (Simmons 1997, Jarvis et al. 2001). It arrives in November, peaks from December - February before leaving in March-April (Steyn 1982, Simmons 1997). It was once locally common in Botswana grasslands from the Savuti marsh in the west to the Makgadikgadi Pans in the east (Penry 1994), but its numbers have decreased in the decade since 1994 in these grasslands and the Pitsane grasslands in se Botswana with only 1 bird for every 10-15 Montagu's Harriers (S Tyler in litt).
Numbers are unknown but it is unlikely that >500 birds over-summer in southern Africa. Numbers may be higher than this when high rainfall gives rise to increased locust and small mammal populations. Of 150 harriers estimated in the dry Lake Liambezi, East Caprivi, Pallid Harriers appeared in the ratio of 3:2:25 (Pallid : European Marsh : Montagu's : C Hines unpubl data). Other areas in Namibia that hold substantial numbers at times are the adjacent Salambala Conservancy (on the Chobe floodplain) the Bushmanland (Tsumkwe) pans (RE Simmons pers obs) and the grasslands in the Witvlei-Gobabis region (Hines 1998).
Ecology
Prefers dry to damp grasslands associated with open pans or flood plains, or open areas in woodland where it quarters the ground at 1-5 m catching prey such as insects and birds. These are mainly taken on the ground but locusts may be taken on the wing (Steyn 1982, RE Simmons pers obs). Flies less buoyantly than Montagu's Harrier and travels faster during direct flight (Clarke 1996). Attracted to rodent populations that have reached plague proportions in dry lake beds in Namibia (C Hines unpubl data); these are its main prey in e Europe (Gallo-Orsi et al. 2002). Breeding is extralimital. Often roosts communally with other harriers in large numbers (Clarke 1993) but none have ever been located in southern Africa.
Threats
Threats are considered to be degradation of wetlands among remaining islands of natural or semi-natural grasslands (critical in Eurasia), and in Africa, the use of pesticides used on locust outbreaks (high threat). Other threats are recent drying of the climate (medium) and disturbance and shooting (low or local threats: Gallo-Orsi et al. 2002). In w Africa the bird was formerly the most common harrier but now it is out-numbered by Montagu's Harrier (Brown et al. 1982). The extreme frequency of grassland burning in n Namibia (Mendelsohn & Roberts 1997) may assist this species as it opens up otherwise bushy or treed landscapes; it is also attracted to grass fires where prey may be more vulnerable (Steyn 1982). This is tempered by the effects of global climate change and increased carbon dioxide levels which are expected to increase treed savannas at the expense of C4 grasslands (Bond et al. 2003).
Conservation status
This species is designated Near-Threatened in Namibia because of its globally threatened status and small but significant summering population in grasslands of n Namibia. It is the most threatened harrier in Eurasia and declining because of a highly fragmented distribution due to agriculture (Gallo-Orsi et al. 2002). Because declines have been long-term it has been designated as globally Near Threatened (Stattersfield & Capper 2000). A species action plan has been recently been formulated (Gallo-Orsi et al. 2002). In s Africa it appears to have generally declined, based on reduced sightings in Zimbabwe (A Tree in Simmons 1997), and reduced range compared with historical sightings in the former Transvaal (Tarboton et al. 1987) and elsewhere (Steyn 1982). It is treated as NearThreatened in South Africa (Barnes 2000) because of the declines in southern Africa.
Actions
Conservation measures are being implemented in Russia and e Europe and should be implemented in southern Africa; these include control on the excessive use of pesticides to combat locusts. Research should focus on finding and protecting roost sites (Gallo-Orsi et al. 2002), where significant numbers of the southern African population probably congregate. Pellets may also be collected from such roosts revealing the poorly documented diet in southern Africa. The conservation of grassland areas which may be under threat from agriculture such as cattle ranching, is necessary within its range in southern Africa. All sightings of this species should be reported to local authorities and conservancies promoted in any core concentration areas uncovered. Witvlei east of Windhoek is one such area that requires further survey work following good rains in January-February.
From: Simmons RE & Brown CJ 2006. Birds to watch in Namibia: red, rare and endemic species. National Biodiversity Programme, Windhoek, Namibia
References
Barnes KN (ed) 2000. The Eskom Red data book of birds of South Africa, Lesotho and Swaziland. Birdlife South Africa, Johannesburg.
Bond WJ, Midgley GF, Woodward FI 2003 The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas. Global Change Biology 9: 973-982.
Brown LH, Urban EK, Newman K 1982 The Birds of Africa, Vol. 1. Academic Press, London.
Clarke R 1993 Velavadar: largest harrier roost in the world? Sanctuary Asia 13:32-35.
Clarke R 1996 Montagu's Harrier. Arlequin Press, Chelmsford, UK.
Del Hoyo J, Elliott A, Sargatal J (eds).1994 Handbook of the Birds of the World, Vol. 2. Lynx Edicions, Barcelona.
Gallo-Orsi U, Galushin V, Clarke R, Davygora A 2002 Action Plan for the Pallid Harrier (Circus macrourus). IUCN.
Hines C 1998 Short Notes [Pallid Harrier] Lanioturdus 31: 31
Hines, Christopher unpublished data (pririt@yahoo.com)
Jarvis AM, Robertson A, Brown CJ, Simmons RE 2001. Namibian avifaunal database. National Biodiversity Programme, Ministry of Environment & Tourism, Windhoek.
Mendelsohn J, Roberts C 1997 An environmental profile and atlas of Caprivi. Directorate of Environmental Affairs. Gamsberg MacMillan, Windhoek.
Penry H 1994 Bird Atlas of Botswana. University of Natal Press, Pietermaritzburg.
Simmons RE 1997 Montagu's Harrier. In: Harrison JA, Allan DG, Underhill LG, Herremans M, Tree AJ, Parker V, Brown CJ (eds). The Atlas of Southern African Birds. Vol. 1:239. BirdLife South Africa, Johannesburg.
Simmons RE Dr Ornithologist, FitzPatrick Institute, UCT (harrier@botzoo.uct.ac.za)
Stattersfield AJ, Capper DR (eds) 2000. Threatened Birds of the World. Birdlife International, Cambridge, UK.
Steyn P 1982 Birds of Prey of Southern Africa. David Philip, Cape Town.
Tarboton WR, Kemp MI, Kemp AC 1987 Birds of the Transvaal. Transvaal Museum, Pretoria.
Tyler, Stephanie Dr ornithologist, Botswana (steph_tyler2001@hotmail.com)