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The regional population of Grey Crowned Crane Balearica regulorum has undergone a continuous decline of greater than 30% over the past 45 years (three generation period) satisfying the criterion for regionally Vulnerable. The key threats to the species are still present and in many cases are escalating in scale. The species is however listed as globally Endangered and the global status is also adopted as the regional status.
The range of the Grey Crowned Crane stretches from eastern Democratic Republic of Congo, Uganda and Kenya to south-eastern South Africa (Walkinshaw 1964). The South African subspecies occurs in Angola, Namibia, Botswana, Zimbabwe, and South Africa (Allan 1997a). Within the region, the range of the species is divided between three core areas: the Eastern Cape and Transkei area; KwaZulu-Natal; and eastern Free State (van Niekerk 2011). Atlas records do not indicate occurrence in Lesotho with birds recorded there being considered non-breeding vagrants (Osborne and Tigar 1990). The EoO of the species has declined by 28.74% between the two atlasing periods while the AoO has declined by 24.24% from 174 642 km2 to 132 310 km2. The species is well represented in the regional IBA network. Grey Crowned Cranes are non-migratory, but undertake variable local and seasonal movements (Morrison and Bothma 1998).
The global population was quantified at 50 000-64 000 individuals in 2004 (Beilfuss et al. 2007) with the East African population gibbericeps making up the majority of the global population (Meine and Archibald 1996). The South African subspecies appeared to be relatively stable with 3 500 individuals counted in the 2001 National Crane Census (2003), and an estimated population of greater than 4 000 present in the country (Beilfuss et al. 2007). Confidence in this population estimate is medium.
The global population is in decline with the species experiencing a steady, long-term decline across much of its range (Beilfuss et al. 2007). The East African gibbericeps has declined significantly within its range where status surveys have been conducted. Regionally, the nominate subspecies has experienced declines of greater than 30% in the past three generations (45 years), noted by McCann and Wilkins (1995) who estimated a 15% decline in the KwaZulu-Natal population between 1982 and 1994. Comparing reporting rates from SABAP1 and SABAP2, the data indicate that Grey Crowned Cranes have declined over the two reporting periods, i.e. 1987-2015 with reporting rates in Mpumalanga/north-eastern Free State and north-western KwaZulu-Natal being lower during SABAP2 than SABAP1 and the species apparently no longer occurs in some grid cells in which it was reported in SABAP1. This indicates that the cranes are less frequently reported and infers that populations in this region have declined or that birds have moved away from existing or known breeding and feeding sites. The regional population is suspected to be undergoing a continuous decline of greater than 30% over three generations. The confidence in this population trend is medium.
The primary threat to the species in South Africa is the widespread degradation and loss of breeding habitats, most often caused by the draining or damming of wetlands (Johnson and Barnes 1986, McCann and Wilkins 1995, McCann 2003). In the future, open-cast coal mining will most likely significantly impact upon habitat availability within Mpumalanga grasslands. Birds utilise agricultural lands extensively and intensively, particularly when flocking in winter and into spring (van Niekerk 2011). Damage on maize lands occurs within the first 2-3 weeks of planting when the plants and seeds are easy to extract (van Niekerk 2011). The crane's presence in agricultural lands, and the real or perceived damage they cause, often brings them into conflict with farmers, increasing the risk of persecution through poisoning or shooting (Johnson and Barnes 1986, McCann 2003). Illegal removal of chicks from the wild for illegal trade is a significant threat to the species in Africa, including South Africa (McCann and Wilkins 1995, Morrison et al. 2007a). The majority of chicks taken are destined for the zoo and pet trade, and are seldom kept for eating. In the illegal trade, chicks taken from the wild are often legalised through legal pairs or birds that traders have on permit. Power-lines pose a collision hazard to young, inexperienced birds and adults on misty days, and transformer boxes pose an electrocution risk when cranes attempt to roost (Martin and Shaw 2010). Other threats include disturbance at nesting areas, entanglement in fences, collision with other overhead lines and hunting by dogs, coordinated or not (Beilfuss et al. 2007).
The Endangered Wildlife Trust's African Crane Conservation Programme has full-time Field Officers covering the greater part of Mpumalanga, KwaZulu-Natal Midlands and southern KwaZulu-Natal. Conservation efforts in these areas include monitoring, securing key sites through the National Biodiversity Stewardship Programme, and proactive involvement in development applications at key crane sites. The Endangered Wildlife Trust's Wildlife and Energy Programme works closely with Eskom to proactively reduce the potential of power-line collisions and electrocutions, and to reactively mitigate high-risk power-lines.
Grey Crowned Cranes opportunistically forage in agricultural lands and come into conflict with land-owners during the germination phase of maize and other crops. A study was recently completed on the damage caused by Grey Crowned Cranes on maize in Eastern Cape, investigating methods of quantifying crop damage and influence of seed treatments to control insect pests (van Niekerk 2011). The Endangered Wildlife Trust is currently exploring the registration of a crop deterrent that has been used effectively in USA by the International Crane Foundation to deter Sandhill Cranes Grus canadensis from eating germinating crops.
The International Crane Foundation/Endangered Wildlife Trust Partnership is currently addressing the illegal trade through the African Crane Trade Project. This project works at the supply side of the market where cranes are removed from the wild, on the compliance and legislative areas, and with the demand sector both in Africa and internationally. Notably, Grey Crowned Cranes have been included in the CITES Significant Trade Review process and are currently under review. The Grey Crowned Crane is currently included in a Biodiversity Management Plan for Species being developed for all three crane species in South Africa.
Ongoing maintenance of all Endangered Wildlife Trust projects that involve the conservation of the Grey Crowned Crane, including the Crane Conservation Programme, Wildlife and Energy Programme, and African Crane Trade Project, in partnership with the International Crane Foundation, is essential. An improved understanding of the habitat characteristics of wetlands that Grey Crowned Cranes use for nesting is important and is a possible research topic.
Proposed research questions and conservation recommendations are based primarily on McCann (2000) and van Niekerk (2010).
* Conduct a bio-energetics study to determine the total biomass of crop consumed by cranes and calculate projections to estimate the economic impact of cranes foraging on commercial crops.
* Political pressure for land reform and agricultural intensification has been predicted to result in wide-scale transformation of agricultural landscapes in the region. Investigate what the impact of land-use changes would be on the foraging and breeding success and long-term conservation of the species.
* Investigate the beneficial effects of Grey Crowned Cranes on agricultural operations, for example through depredation of pests such as locusts and cut worms.
* Research avenues for developing sustainable management alternatives to allow coexistence of cranes and humans in an agricultural matrix, such as the potential of excluding cranes from croplands during sensitive crop stages, or establishment of crane restaurants to discourage feeding on crops.
* Investigate the cultural significance of the species, and assess the scale of utilisation, harvesting and trade and its potential impacts on crane conservation.