The struggle chick maleo
Maleos are communal nesters and on the largest known site at Bakiriang on the south coast of the north-east peninsula, more than 600 birds nest early in the year with the holes only two or three metres apart. Two hundred of the birds nest on just 1 ha of sand (Watling 1983).
The surface of a sandy beach can become extremely hot, over 50 celcius degree and 80 celcius degree on white and black sand respectively (MacKinnon 1978), yet just a few centimeters below the surface, the temperature is relatively stable at about 36 celcius degree. It seems as if most eggs, on beachs or elsewhere, are laid in positions where the temperature is between 32 celcius degree and 38 celcius degree (MacKinnon 1978, Wiriosoepartho 1980). The depth of the hole might be thought to be critical, and it has been suggested that the bare head of the maleo is efficient at sensing temperature but, in reality, the exact depth and temperature (within certain limits) are not so critical. Instead it seems that the eggs are laid as deep as possible for protection against predators.
Hatching takes about three months and if the chicks survive the one or two day scramble to the surface, for ants are a major predator of chicks in the ground (R. Dekker pers. Comm.), they are able to fly away immediately, already having adult plumage the manner in which they ‘explode’ from the sand and rush away is probably an adaption to avoid the attention of predators (Watling 1983). The great size of the egg is related to the need to produce a chick strong enough to struggle up to the surface (Guillemard 1889).
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Maleo Birds (Macrocephalon maleo)
Maleo birds
The maleo (Macrocephalon maleo) is a member of small family of mound builders, or incubator birds (megapodiidae), which with one exception is confined to eastern Indonesia, new Guinea, Australia and Polynesia. The maleo itself, however, is found only in north, central and southweast Celebes. It is about the size of a domestic hen, weighing around 1,6 kg (Guillemard 1889), with striking black and rose-white plumage, an erect tail, and a head with a bare, helmeted cranium which may serve to keep the brain cool when it is on hot beaches 9watling 1983).
The bill is pale green and red at the base. Maleo are primarily inhabitants of forest, but only lay eggs where the ground is sufficiently hot for incubation-that is near hat springs (Wiriosoepartho 1979), near volcanic vents, or on sandy beaches. The megapodes and the Egyptian plover (Pluvianus aegyptius) are the only living birds which do not use the heat of their own for incubation.
Pairs arrive at a nesting area the night before eggs are laid. The following morning, amid much duck-like quacking and turkey-like gobbing, the birds examine holes and make trial digs. When a suitable spot is found, both male and female start digging, throwing earth or sand behind them using their strong legs and claws. The toes are slightly webbed at the base which must help when scratching away loose sand (Wallace 1869). As the hole becomes cleeper, so the birds take it in turns to dig and drive away other maleos that venture too close.
This digging can take over three hours, particularly where the sand is loose, after which the female lays her enormous egg, 11 cm long and 240-270 egg g in weight (Guillemard 1889), in the bottom of the pit. Subsequent eggs are laid and is lengthened by the digging of false pits near the real one to divert predators such as monitor lizard and pigs. Against human who value maleo eggs as a delicacy, however, these precautions are of little use. During the nesting period the maleos seek food such as figs, and fruit of macaranga (Euphorbiaceae) and Dracontomelum (Anacardiaceae) in the beach forest and roost primarily in Casuarina (Casuarinaceae) trees (Wiriosoepartho 1980).
The maleo (Macrocephalon maleo) is a member of small family of mound builders, or incubator birds (megapodiidae), which with one exception is confined to eastern Indonesia, new Guinea, Australia and Polynesia. The maleo itself, however, is found only in north, central and southweast Celebes. It is about the size of a domestic hen, weighing around 1,6 kg (Guillemard 1889), with striking black and rose-white plumage, an erect tail, and a head with a bare, helmeted cranium which may serve to keep the brain cool when it is on hot beaches 9watling 1983).
The bill is pale green and red at the base. Maleo are primarily inhabitants of forest, but only lay eggs where the ground is sufficiently hot for incubation-that is near hat springs (Wiriosoepartho 1979), near volcanic vents, or on sandy beaches. The megapodes and the Egyptian plover (Pluvianus aegyptius) are the only living birds which do not use the heat of their own for incubation.
Pairs arrive at a nesting area the night before eggs are laid. The following morning, amid much duck-like quacking and turkey-like gobbing, the birds examine holes and make trial digs. When a suitable spot is found, both male and female start digging, throwing earth or sand behind them using their strong legs and claws. The toes are slightly webbed at the base which must help when scratching away loose sand (Wallace 1869). As the hole becomes cleeper, so the birds take it in turns to dig and drive away other maleos that venture too close.
This digging can take over three hours, particularly where the sand is loose, after which the female lays her enormous egg, 11 cm long and 240-270 egg g in weight (Guillemard 1889), in the bottom of the pit. Subsequent eggs are laid and is lengthened by the digging of false pits near the real one to divert predators such as monitor lizard and pigs. Against human who value maleo eggs as a delicacy, however, these precautions are of little use. During the nesting period the maleos seek food such as figs, and fruit of macaranga (Euphorbiaceae) and Dracontomelum (Anacardiaceae) in the beach forest and roost primarily in Casuarina (Casuarinaceae) trees (Wiriosoepartho 1980).
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