Le martin-chasseur géant ou kookaburra (Dacelo novaeguineae) est un oiseau d'Australie de la famille des alcédinidés (sous-famille des halcyoninés ayant temporairement constitué la famille des dacélonidés). Oiseau mythique dans la culture aborigène, son chant ressemble à un rire rauque. Son nom australien (de la langue morte wiradjuri) est d'ailleurs Laughing Kookaburra (littéralement « Kookaburra rieur »).

Description
C'est un oiseau trapu de 45 cm de long, d'environ 500 grammes, avec une grosse tête, un œil marron saillant et un très grand bec pointu. Le mâle se distingue facilement de la femelle par le bleu des ailes et le bleu foncé de la queue. La femelle a un peu de bleu clair sur les ailes mais n'a pas de bleu sur la queue.

Distribution et habitat
On le trouve dans toute la partie est de l'Australie et il a été introduit à l'heure actuelle dans le sud-ouest de l'Australie-Occidentale, en Tasmanie, dans les îles Flinders et Kangaroo Island. Un certain nombre d'entre eux ont été introduits en Nouvelle-Zélande entre 1866 et 1880 mais seuls ceux qui ont été libérés dans l'île Kawau par sir George Grey ont survécu. On en trouve encore des descendants à l'heure actuelle. Il habite dans toutes les zones boisées où il peut trouver à proximité des zones dégagées pour pouvoir chasser. Il ne craint pas la proximité de l'homme.

Alimentation
Comme tous les martins-chasseurs, il se nourrit en attendant patiemment installé sur une branche qu'une proie passe à proximité pour se précipiter dessus : carnivore, il mange ainsi souris et autres petits mammifères analogues, gros insectes, lézards, petits oiseaux et oisillons, et, surtout serpents. Il s'attaque de préférence à des proies plus petites que lui mais il n'est pas rare qu'il s'attaque par surprise à des animaux nettement plus gros que lui, en particulier des serpents venimeux. Les proies les plus petites sont avalées vivantes, les proies plus grosses sont d'abord tuées en les frappant vivement sur le sol. Cet animal produit des pelotes de réjection.

Reproduction
La saison des amours est au début de l'été (octobre, novembre). Les couples sont fidèles et couvent et s'occupent des petits à deux. La femelle pond généralement un œuf tous les deux jours et la couvée est généralement de trois œufs. Les petits ont un crochet sur la partie supérieure du bec qui disparaîtra en vieillissant mais ce harpon peut être utilisé dans des combats entre oisillons si la nourriture n'est pas suffisante. Le plus fragile des oisillons peut ainsi être tué par ses frères et sœurs. Par contre, on peut voir les oisillons des couvées précédentes aider leurs parents pour chasser et nourrir leurs plus jeunes frères et sœurs.

Kookaburra albinos
En 2010, un fermier australien a découvert, au pied d'un arbre, deux kookaburras de seulement quelques semaines, ayant la particularité d'être albinos (plumes blanches, yeux et bec roses). C'est la première fois que de tels spécimens sont observés.

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The Laughing Kookaburra (Dacelo novaeguineae) is a carnivorous bird in the kingfisher family Halcyonidae. Native to eastern Australia, it has also been introduced to parts of New Zealand, Tasmania and Western Australia. Male and female adults are similar in plumage, which is predominantly brown and white. A common and familiar bird, this species of kookaburra is well known for its laughing call.

Taxonomy
Scientific name: The Laughing Kookaburra was first described in western knowledge systems by French naturalist Johann Hermann in 1783, its specific epithet novaeguineae refers to New Guinea. For many years it was known as Dacelo gigas. Vernacular name: The species was previously known as the Laughing Jackass and Giant Kingfisher. Its current name comes from Wiradhuri, an Aboriginal language now effectively extinct.

Distribution
The Laughing Kookaburra is native to eastern mainland Australia, and has also been introduced to Tasmania, Flinders Island and Kangaroo Island. Some were also introduced to New Zealand between 1866 and 1880, but only those released on Kawau Island by Sir George Grey survived. Descendants of these individuals are found there today. Remnants of this population have been seen on the New Zealand mainland near Matakana. Individuals were released at Perth, Western Australia, in 1898 and can now be found throughout southwest Australia.

Description
The Laughing Kookaburra is a stocky bird of about 45 cm (18 in) in length, with a large head, prominent brown eyes, and a very large bill. The sexes are very similar, although the female averages larger and has less blue to the rump than the male. They have a white or cream-coloured body and head with a dark brown stripe through each eye and more faintly over the top of the head. The wings and back are brown with sky blue spots on the shoulders. The tail is rusty reddish-orange with dark brown bars and white tips on the feathers. The heavy bill is black on top and bone coloured on the bottom.

Call
The name "Laughing Kookaburra" refers to the bird's "laugh", which it uses to establish territory amongst family groups. It can be heard at any time of day, but most frequently shortly after dawn and after sunset to dusk. One bird starts with a low, hiccuping chuckle, then throws its head back in raucous laughter: often several others join in. If a rival tribe is within earshot and replies, the whole family soon gathers to fill the bush with ringing laughter. Hearing kookaburras in full voice is one of the more extraordinary experiences of the Australian bush, something even locals cannot ignore; some visitors, unless forewarned, may find their call startling. The Kookaburra is also the subject of a popular Australian children's song, the Kookaburra.

Behaviour
Kookaburras occupy woodland territories (including forests) in loose family groups, and their laughter serves the same purpose as a great many other bird calls—to demarcate territorial borders. Most species of Kookaburra tend to live in family units, with offspring helping the parents hunt and care for the next generation of offspring.

Feeding
Kookaburras hunt much as other kingfishers (or indeed Australasian robins) do: by perching on a convenient branch or wire and waiting patiently for prey to pass by. Common prey include mice and similar-sized small mammals, large insects, lizards, small birds and nestlings, and most famously, snakes. Small prey are preferred, but kookaburras sometimes take large creatures, including venomous snakes much longer than their bodies.

Breeding
During mating season, the Laughing Kookaburra reputedly indulges in behaviour similar to that of a Wattlebird. The female adopts a begging posture and vocalises like a young bird. The male then offers her his current catch accompanied with an "oo oo oo" sound. However, some observers maintain that the opposite happens - the female approaches the male with her current catch and offers it to him. Either way, they start breeding around October/November. If the first clutch fails, they will continue breeding into the summer months. They generally lay three eggs at about 2-day intervals. If the food supply is not adequate, the third egg will be smaller and the third chick will also be smaller and at a disadvantage relative to its larger siblings. Chicks have a hook on the upper mandible, which disappears by the time of fledging. If the food supply to the chicks is not adequate, the chicks will quarrel, with the hook being used as a weapon. The smallest chick may even be killed by its larger siblings. If food is plentiful, the parent birds spend more time brooding the chicks and so the chicks are not able to fight.

Interaction with humans
Laughing Kookaburras are a common sight in suburban gardens and urban settings, even in built-up areas, and are so accustomed to humans that they will often eat out of their hands. It is not uncommon for kookaburras to snatch food out of people's hands without warning, by swooping in from a distance. People often feed them pieces of raw meat.