Wattled Crane
The wattled crane is a large bird with a long white neck, gray body, black undersides, and a bare red face with a black “cap.” Their name comes from the white wattles that dangle from its throat. Their secondary, inner-wing feathers are elongated and look like a tail when the crane is standing. Their height ranges from 150-175cm, it is the largest crane in Africa and is the second tallest species of crane in the world, after the sarus crane. The wingspan is 230–260cm, the length is typically 110-140cm and weight is 6.4–8.28kg in females and 7.5–9kgin males. Going on standard measurements, it is the second largest proportioned crane after the sarus crane, outsizing in these respects even the heavier red-crowned crane.
The back and wings are ashy gray. The feathered portion of the head is dark slate gray above the eyes and on the crown, but is otherwise white, including the wattles, which are almost fully feathered and hang down from under the upper throat. The breast, primaries, secondaries, and tail coverts are black. The secondaries are long and nearly reach the ground. The upper breast and neck are white all the way to the face. The skin in front of the eye extending to the base of the beak and tip of the wattles is red and bare of feathers and covered by small round wart-like bumps. Wattled cranes have long bills and black legs and toes. Males and females are virtually indistinguishable, although males tend to be slightly larger. Juveniles have tawny body plumage, lack the bare skin on the face, and have less prominent wattles.
Habitat
In South Africa this species was found to occupy large grasslands with a small core of essential wetland breeding habitat. They nest in shallow sedge-dominated wetlands, often above 2,000m altitude. In South Africa and Zimbabwe it breeds on undisturbed small permanent wetlands surrounded by grassland or miombo woodland in high rainfall areas with plateau topography, where human disturbance is minimal. In South Africa it relies on relatively undisturbed mid-altitude wetland-grassland mosaics. Elsewhere in its range it breeds on large low-lying tropical, seasonal flood plains such as the Okavango Delta where wetlands are bordered by grasslands. It may use man-made habitats such as dams. The Ethiopian population uses high-altitude wetlands in the Bale Mountains.
Non-breeding During the non-breeding season the species continues to rely on wetland habitats surrounded by grassland. It congregates at large wetlands on riparian floodplains, but also requires pristine or semi-pristine, high-altitude wetlands and grasslands in some places. It frequents dambos (depressions), permanently isolated wetlands and vleis as well as using grasslands, pastures, and occasionally cultivated fields for foraging. Dams and pans are used as roosting sites during the non-breeding season. The Ethiopian population is less dependent on wetlands during this season, generally moving to drier, lower elevation habitats including ploughed fields. Birds that breed in the Okavango Delta often move to recently burnt ground in the dry season.
Diet
They are Omnivores. The species feeds on rhizomes, roots and bulbs of sedges, and grass sward and seed. It will also take animals including small aquatic snails, fish and frogs. Chicks are reported to eat insects. Roughly 90% of foraging done by this species occurs in shallow waters. They typically forage by digging vigorously with their bill into the muddy soil. On occasion, it will eat grain and grass seed as well, but does so much less often than the other three African crane species.
Breeding
Breeding season for the wattled crane starts in around April. Three weeks after a messy nest is made of crushed grass on a marsh bank, the female lays one to two eggs. In the case of two eggs being laid, one is usually neglected, so that only one chick survives. The chick becomes a fledgling at between 100 and 150 days old, which is the longest fledging period of all cranes. Interestingly, these birds learn to fly before they can walk. The young stay with their parents until the next year’s breeding season starts.
Population
Its present world population has been variously estimated at 7,700 individuals or fewer, fewer than 8,000 individuals and 6,000-8,000 individuals. More recent estimates though suggest that the population is currently placed in the range of 9,000-10,000. This increase though may not be a true increase in the population and further research to better understand the movements between the key flood plains in south-central Africa and the seasonal movements whereby cranes come together in large flocks in the drier season needs to be explored further. This estimate roughly equates to 6,000-6,300 mature individuals. When estimates from the 1980s are compared with those from 2006, the species is judged to have declined significantly, indicating declines in the last three generations. The comparison of 2002 estimates with those from 1993 suggests marked declines in Mozambique, Zambia and possibly Botswana . The total population was recently stated to be in decline in nine range states. The overall rate of decline is estimated to be rapid.
Threats
The main threat is loss and degradation of wetlands as a result of upstream river regulation, intensified agriculture, mining, drainage, invasive species such as Mimosa pigra, and rice cultivation. Other threats include nest disturbance; grass-burning regimes, though in the non-breeding season burnt floodplains are used for feeding in some areas; poisoning; collision with utility lines; direct consumption of chicks; persecution, and traditional medicine. Increasing livestock farming, wars, desertification and agrochemicals are additional threats to the species's habitats. Nest destruction through trampling by livestock is believed to be a problem. The population is threatened by the illegal removal of eggs and chicks for international trade. Adults are also taken for trade and are hunted. The destruction of vegetation by fires probably leaves adults more susceptible to predation and hunting, and flood levels in turn influence the extent and intensity of fires. Recent potential threats that could extensively affect a large portion of the Okavango Delta include the proposed hydroelectric scheme at Popa Falls in Namibia, papyrus cutting, channel modification, and the extensive aerial spraying of pesticide to eradicate the tsetse fly. The extent of suitable breeding habitat in the Zambezi Delta (Mozambique) and Kafue Flats (Zambia) and the suitability of remaining habitat for feeding is believed to have declined as a result of the interruption of the natural flooding regime by the Cahora Bassa (Tete province), Kariba (Zambia/Zimbabwe), and Itezhi-tezhi (Zambia) dams upstream, and hunting is also a threat in this country.
Conservation
Conservation Actions Underway
Protected areas have been established in several key wetlands, in Zambia, Namibia, Zimbabwe and Botswana. A major environmental flows initiative is underway for the Zambezi River basin, addressing the restoration of natural flooding patterns, conservation of basin wetlands, and control of invasive species in the Zambezi River basin. Key wetlands targeted by the program include the Kafue Flats, Zambezi Delta, Liuwa Plain, Busanga Swamps, and others, covering about 40% of the global Wattled Crane population. In South Africa, and some other countries, action has included legal protection, marking and relocation of powerlines, awareness programmes, and encouragement of habitat protection, security and management by private landowners. Invasive of Mimosa pigra was eradicated through aerial spraying and community-involvement in manual cutting, although much of this has regrown due to a lack of follow up action. A conservation group conducted aerial surveys, field research and a community awareness programme in the Kafue Flats. Aerial surveys, nest monitoring and monitoring of adult:juvenile ratios took place annually on the Okavango Delta in the early 2000s. Surveys and monitoring occur in several countries in south-central Africa (Zambia[International Crane Foundation (ICF)/Endangered Wildlife Trust(EWT) Partnership, in partnership with the Zambian Department of National Parks and Wildlife; African Parks Foundation], Zimbabwe[BirdLife Zimbabwe], Namibia [Namibia Crane Working Group], South Africa [ICF/EWT Partnership; Ezemvelo KwaZulu-Natal Wildlife, in partnership with the Endangered Wildlife Trust; KwaZulu-Natal Crane Foundation]), and also aim to drive more awareness amongst local communities. A continent-wide programme for the species was launched in 2001 to monitor the species's status and threats, and help develop effective conservation programmes for the management of wetland systems. National conservation plans have been developed for Botswana, Namibia, South Africa and Zimbabwe. Following a workshop in July 2000, the Wattled Crane Recovery Programme was initiated for the South African population. There are currently five partners in this South African programme, one aim of which is to establish a viable captive population and supplement the wild population. The Johannesburg Zoo has also built a dedicated chick-rearing facility, and several captive management facilities throughout South Africa now participate in the breeding programme. In 2005, it was announced that a veterinary fence would be constructed to the east of the Makgadikgadi Pans National Park in Botswana, effectively extending the park boundary and protecting grasslands used by the species from the high density of livestock in the area (BirdLife Botswana 2006). Status surveys are underway in Ethiopia to better understand the current status of the species there, and its genetic differences from the south-central African populations.
Conservation Actions Proposed
Develop a coordinated range-wide action plan. Re-operate large dams to restore flooding in key Wattled Crane habitats, including Kafue Flats and Zambezi Delta. Coordinate range-wide surveys and long-term monitoring, partly in order to understand population movements between sites and countries. Continue and expand ecological research and support the establishment of a captive breeding population. Strengthen key protected areas, especially in the Kafue Flats, Liuwa Plain and Bangweulu Swamps (Zambia), and the Zambezi Delta (Mozambique), and attempt to secure protection for more key sites for the species. Improve protection of birds outside of protected areas such as the Jao/Boro rivers of Botswana. Increase educational campaigns, targeting landowners with breeding cranes, as well policy makers. Employ satellite tracking to study the species's movements across its range (BirdLife Botswana Crane Working Group 2004). In South Africa, work with farming communities to conserve natural grasslands that surround wetlands. Investigate whether the South African and Ethiopian populations represent separate subspecies. Assess the levels of legal and illegal trade in the species. Continued (second phase) aerial spraying and manual control of Mimosa in the Kafue Flats , and develop a long term managment plan for Mimosa. Assess the impacts of fire and management on the species. Study the impact of indigenous game compared with domestic cattle. Plan and conduct research into semen cryopreservation, genetic fingerprinting, eggshell membrane sexing and nutrition. In South Africa, supplement existing wild populations with captive-bred fledglings of South African origin. Assess the current status of this species in Ethiopia.