Grey crowned-crane  (Balearica regulorum)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Standing at over a metre tall, this large, yet elegant crane graces many of Africa’s wetlands. Its predominantly grey plumage contrasts sharply with black and white wings, and a crest of golden feathers sitting on top of the head, and a bright red gular pouch that hangs from the throat (4). The head is black with large white cheek patches, while the neck is pale grey (2) (4). Males tend to be marginally larger than females but are otherwise indistinguishable. Juveniles have a brownish plumage, with a darker crown and nape, while the face may be feathered and buffish (4).

Two subspecies are often recognised, with the East African crowned crane (Balearica regulorum gibbericeps) the more abundant of the subspecies, found in the central and northern ranges of the species distribution and the South African crowned crane (Balearica regulorum regulorum) which is restricted to South Africa and Zimbabwe (5) (6). The two subspecies can be visually distinguished by the possession of a larger area of red skin above the white cheeks on the East African crowned crane (4).

The grey crowned-crane is a resident of eastern and southern Africa, ranging from Kenya and Uganda in the northern extremities of the species distribution to South Africa and Zimbabwe in the south (7). The grey-crowned crane is a non-migratory species; however, local movements may occur in response to the seasonal availability of water, food and nest sties (7) (8).

The grey crowned-crane is associated with a mixture of wetland and open grassland habitats, including flood-plains, marshes, rivers and savannah. Medium-height open grassland near wetlands is preferred foraging habitat, while tall trees are required for nesting. Populations in East Africa have adapted to man-made landscapes and can be particularly abundant around agricultural land with artificial wetlands (2) (5).

As with all cranes, the grey crowned-crane is omnivorous and will consume a multitude of different prey types including insects, lizards, amphibians, fish, grasses and seeds (4). The grey crowned-crane prefers to forage in short to medium height grasslands but will also enter cultivated land to forage for crops (5). This generalist diet allows the grey crowned-crane to inhabit various habitats and adapt to environmental changes, and as a result the species has proven adept to colonising human altered landscapes (4) (7).

The breeding season peaks between December and February, but varies hugely between localities in response to rainfall, and may occur year round (2). The nests are constructed along the peripheries of wetlands and consist of uprooted grasses arranged to create a circular platform, usually in an area of dense vegetation, approximately one metre above the ground (2) (4). However, the grey crowned-crane will occasionally nest in trees; one of only two crane species demonstrating this ability, the other being the black crowned-crane (Balearica pavonina) (5). The grey crowned-crane has the largest average clutch size of a crane species at two to three, with eggs incubated for 28 to 31 days, and chicks fledging after 56 to 100 days (5).

The importance and extent of seasonal movements varies between grey crowned-crane populations. The abundance and distribution of food and nesting sites appear to be the main determinant of the timing and extent of migrations, with larger home ranges and seasonal movements in drier regions and areas with low abundance of nesting sites and food (5). 

The principal threat to grey crowned-crane populations is the loss or degradation of suitable wetland habitat, due to an increasing human population accelerating the demand for agricultural land and freshwater sources. Increased grazing pressures subtly alter wetland habitats and influence the abundance of insect prey and the availability of nest habitat (5). Increasing human populations also threaten grey crowned-crane habitat via wetland damming, drainage, increased sedimentation through deforestation and the use of agricultural pesticides (2) (7) (9). Further threats to the grey crowned-crane include the removal of live birds and eggs and this activity has been attributed to a recent rapid decline throughout much of the species’ range (7).

The grey crowned-crane is listed under Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that trade in this species requires permits and must be carefully monitored (3). It is also listed as Vulnerable by the IUCN, suggesting that the species faces a risk of extinction in the wild unless conservation initiatives are developed (1). Conservation projects currently being undertaken include: community-based wetland conservation in Kenya, Uganda and Zimbabwe, African crane and wetland training workshops in Botswana, the development of wetland action plans and increased frequency of count surveys (2) (4) (5) (7). The grey crowned-crane is protected by law in Kenya, South Africa, Uganda and Zimbabwe, while wetland habitat is protected by various range countries that have ratified the Ramsar convention and the African-Eurasian Waterbird Agreement (10) (11). Further conservation measures that have been proposed include: listing the species under CITES Appendix I, development and standardisation of surveys to evaluate the species total population and make assessments of trends, the monitoring of hunting and habitat loss and discouraging the use of pesticides through public awareness projects (5) (9). The grey-crowned crane also breeds successfully in captivity and this would help facilitate re-introduction programmes if required (2).

For more information on crane conservation, see:

• The International Crane Foundation: 
  http://www.savingcranes.org/ 

• The IUCN/SSC Crane Specialist group: 
  http://www.wetlands.org/Aboutus/Specialistgroups/CraneSpecialistGroup/tabid/1142/Default.aspx

• The International Crane Foundation/Endangered Wildlife Trust Partnership for African Cranes: 
  http://www.ewt.org.za/workgroups_overview.aspx?group=sacrane&page=overview

• Amphibians: cold-blooded vertebrates of the class Amphibia, such as frogs or salamanders, which characteristically hatch as aquatic larvae with gills. The larvae then transform into adults with air-breathing lungs.
• Gular pouch: a large distensible pouch below the beak of some birds.
• Omnivorous: feeding on both plants and animals.
• Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

1. IUCN Red List (January, 2010)
   http://www.iucnredlist.org/
2. del Hoyo, J., Elliott, A. and Sargatal, J. (1994) Handbook of the Birds of the World - New World Vultures To Guineafowl. Vol. 2. Lynx Edicions, Barcelona.
3. CITES (January, 2010)
   http://www.cites.org/
4. The International Crane Foundation (January, 2010)
   http://www.savingcranes.org/
5. Meine, C.D. and Archibald, G.W. (Eds) (1996) The cranes:- Status survey and conservation action plan. IUCN, Gland, Switzerland, and Cambridge, U.K and Northern Prairie Wildlife Research Centre Online. Available at: http://www.npwrc.usgs.gov/resource/birds/cranes/index.htm
6. Integrated Taxonomic Information System (ITIS) (January, 2010)
   http://www.itis.gov/
7. BirdLife International (January, 2010)
   http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=2785&m=0
8. Global Register of Migratory Species (January, 2010)
   http://www.groms.de/
9. Ellis, D.H., Gee, G.F. and Mirande, C.M. (1996) Cranes: Their biology, husbandry and conservation. U.S. Department of the Interior, national Biological Service, Washington, DC and International Crane Foundation, Baraboo, Wisconsin. Available at: http://www.pwrc.usgs.gov/resshow/gee/cranbook/cranebook.htm
10. The Ramsar Convention on Wetlands (January, 2010)
    http://www.ramsar.org/
11. The African-Eurasian Waterbird Agreement (January, 2010)
    http://www.unep-aewa.org/