Grey Crowned Crane
The grey crowned crane is closely related to the black crowned crane, and the two species have sometimes been treated as the same species. The two are separable on the basis of genetic evidence, calls, plumage and bare parts, and all authorities treat them as different species today. There are two subspecies. The East African crested crane occurs in the east of the Democratic Republic of the Congo and in Uganda, of which it is the national bird represented in its national flag, and Kenya to eastern South Africa. It has a larger area of bare red facial skin above the white patch than the smaller nominate species, (South African crowned crane), which breeds from Angola south to South Africa. The grey crowned crane is about 3.3 ft tall, weighs 3.5 kg, and has a wingspan of 6.5 ft. Its body plumage is mainly grey. The wings are predominantly white, but contain feathers with a range of colours, with a distinctive black patch at the very top.
The head has a crown of stiff golden feathers. The sides of the face are white, and there is a bright red inflatable throat pouch. The bill is relatively short and grey, and the legs are black. They have long legs for wading through the grasses. The feet are large, yet slender, adapted for balance rather than defence or grasping. The sexes are similar, although males tend to be slightly larger. Young birds are greyer than adults, with a feathered buff face. This species and the black-crowned crane are the only cranes that can roost in trees, because of a long hind toe that can grasp branches. This trait is assumed to be an ancestral trait among the cranes, which has been lost in the other subfamily. Crowned cranes also lack a coiled trachea and have loose plumage compared to the other cranes.
Habitat
It occurs in dry savannah in Africa south of the Sahara, although it nests in somewhat wetter habitats. They can also be found in marshes, cultivated lands and grassy flatlands near rivers and lakes in Uganda and Kenya and as far south as South Africa. Birds in more arid areas, particularly Namibia, make localised seasonal movements during drier periods. The species inhabits wetlands such as marshes, pans and dams with tall emergent vegetation, riverbanks, open riverine woodland, shallowly flooded plains and temporary pools with adjacent grasslands, open savannas, croplands, pastures, fallow fields and irrigated areas. It shows a preference for short to medium height open grasslands adjacent to wetlands for foraging , and breeds within or at the edges of wetlands especially in marshes with water 1 m deep and with emergent vegetation 1 m above the water. It roosts in water along rivers or in marshes, or perches on nearby trees. A Maxent-modelling study showed that while wetlands are important for the species in Uganda, temperature seasonality can also be important.
Diet
They are omnivores. The species is a generalist, its diet consisting of seed heads, new tips of grasses, agricultural pulses, nuts and grain, insects (, frogs, lizards and crabs. They eat plants, seeds, grain, insects, frogs, worms, snakes, small fish and the eggs of aquatic animals. Stamping their feet as they walk, they flush out insects which are quickly caught and eaten. The birds also associate with grazing herbivores, benefiting from the ability to grab prey items disturbed by antelopes and gazelles. They spend their entire day looking for food. At night, the crowned crane spends its time in the trees sleeping and resting.
Breeding
Grey crowned cranes time their breeding season around the rains, although the effect varies geographically. In East Africa the species breeds year-round, but most frequently during the drier periods, whereas in Southern Africa the breeding season is timed to coincide with the rains. During the breeding season, pairs of cranes construct a large nest; a platform of grass and other plants in tall wetland vegetation. The grey crowned crane lays a clutch of 2-5 glossy, dirty-white eggs, which are incubated by both sexes for 28–31 days. Chicks are precocial, can run as soon as they hatch, and fledge in 56–100 days. The nest is a circular platform of uprooted grasses and sedges concealed in tall emergent vegetation (greater than 1 m in height) in or along the margins of wetlands such as marshes with water 1 m deep. The species may also rarely nest in trees.
Population
The current population size has recently been estimated at 26,500-33,500 and is placed in the 20,00-49,999 range. This roughly equates to 17,700-22,300 mature individuals. Overall estimates suggest that the species’s global population has declined from over 100,000 individuals in 1985 to 50,000-64,000 individuals in 2004. This implies that the species may have declined by over 50% in 19 years, and when these data are extrapolated to a period of 45 years in the past (1967-2012) or past and future (1985-2030), assuming an exponential trend, the calculated rate of decline is 65-79%. Declines are attributed primarily to habitat loss and fragmentation and illegal removal of birds and eggs from the wild for food, traditional use, domestication and the international illegal trade market.
Threats
The species is threatened by the loss and degradation of wetland breeding areas through drought-related changes in land-use (such as for cultivation), drainage and overgrazing, as well as through the heavy use of agricultural pesticides, declines in fallowing practices, high sedimentation rates(due to deforestation), uncontrolled grass and deep litter fires in the breeding season, dam construction(for hydroelectric power generation) and groundwater extraction, leading to changes in hydrological regime like unseasonal flooding. The species is also threatened by live-trapping (for trade), egg-collecting and hunting, and by indirect disturbance from the hunting of large mammals or ducks in wetlands and the activities of fisheries. Due to human population pressure, the cranes are increasingly living in closer proximity to people, exposing them to disturbance and making them more vulnerable to hunting. It is also persecuted in some areas (e.g. southern Africa) due to its use of agricultural land for foraging, as it will destroy maize crops at their early stage of germination. Research has found that large numbers of Grey Crowned-cranes are killed annually by poisoning in Kenya, mainly as retaliation or to prevent of crop damage. In South Africa in particular, an increase of coal mining is threatening much of the grassland/wetland habitat where the species breeds. Mortality of birds due to electrocution and collision with overhead power lines is a serious threat in Uganda, South Africa and Tanzania and is likely to increase significantly in the future, across its entire range.
Conservation
Conservation Actions Underway
Community-based wetland conservation projects have been undertaken in Kenya, with some captive breeding populations established. The current single species action plan is undergoing revision by Wetlands International / IUCN Crane Specialist Group, and a new plan was endorsed at the AEWA MoP in November 2015. Monitoring occurs in at least parts of its range by the International Waterbird Census in Botswana by BirdLife Botswana; in South Africa, Grey Crowned Cranes are monitored through the Avifaunal Road Counts coordinated by the Animal Demographic Unit at the University of Cape Town and through annual aerial surveys conducted by the EWT and Ezemvelo KwaZulu-Natal Wildlife over the range of the species in KwaZulu-Natal, and in Zambia regular surveys for cranes are conducted in Lochinvar, Blue Lagoon, Kafue, South Luangwa, Chikuni, Nsumbu and Liuwa National Parks. In Zimbabwe Local Community Conservation Groups/Site Support Groups in Driefontein Grasslands are actively involved in raising the awareness of this species, and in Rwanda conservation efforts of the International Crane Foundation have started around Rugezi Marsh. This species is listed as Endangered in South Africa, Lesotho and Swaziland, and Uganda, and Critically Endangered in Namibia.
Conservation Actions Proposed
Conduct standardised and coordinated surveys to assess the species's total population size. Monitor population trends through regular standardised surveys and extend captive breeding efforts. Monitor rates of habitat loss and degradation, and attempt to restore the habitat. Raise awareness of this species and land use practices that would be more beneficial for this species. Monitor levels of hunting pressure. Discourage hunting and irresponsible pesticide use through awareness campaigns. Improve species protection and increase enforcement of hunting legislation.