Named for its crown of stiff golden feathers, the grey crowned crane (Balearica regulorum) rules over the savannahs of Southern and Eastern Africa. They may also be found in wetter habitats such as marshes and around lakes. Although its plumage is mainly grey, it exhibits shades of white, gold, red and black. They reach around 1 metre in height and even wander around like royalty – with their entire body postured upright.
African crowned cranes (which includes the closely related black crowned crane) are the only cranes that can grip branches, enabling them to roost up in trees. Grey crowned cranes have a spectacular breeding display. Jumping, dancing and bowing are just some of the tactics used to attract a mate. They also deploy a booming call by inflating their red gular sac (the bit of red skin beneath their chin). Once they have successfully mated and created their nest, grey crowned cranes will lay a clutch 2-5 eggs.
Omnivorous, these birds have a varied diet. Examples include grasses, seeds, insects, frogs, snakes, worms and small fish. They have adopted an effective hunting mechanism, stamping their feet as they walk to flush out insects and other invertebrates. A similar strategy is used when they follow larger grazing herbivores such as antelopes and rhinos, except they don’t have to do any work. They simply follow these mammals and swiftly devour any small creatures turned up by the passing grazer. This is an example of commensalism. Commensalism is a form of symbiosis (a biological interaction between two organisms) in which one organisms benefits whilst the other is unaffected. In this case, the grey crowned crane benefits and the grazing mammal is unaffected.
Sadly, these royal birds are endangered. Grey crowned cranes face a plethora of ongoing threats. Drainage of the natural wetlands in their habitat is leaving them with fewer places to nest. Overgrazing by livestock is limiting their availability of food. Pesticide pollution is interfering with the delicate ecological balance of Africa. Live capture and egg collection for commercial trade is also a detrimental threat to these cranes. However, organisations such as the International Crane Foundation are helping to conserve this species. By improving and enforcing harsher policies that strengthen the consequences of the illegal wildlife trade, they hope to reduce the atrocity of this trade. Moreover, they are encouraging methods to minimise the conflict between grey crowned cranes and traditional farmers.
One of the things I can do is to spread a wider awareness for the status of these cranes and the threats they face. As the national animal of Uganda, the grey crowned crane even appears on the country’s flag. They are unique in both appearance and behaviour and play a great ecological role. Their reign is not yet over.
Hennessy, K., Wiggins, V. (2014) Animal Encyclopedia: The Definitive Visual Guide. 2nd edn. London. Dorling Kindersley.