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Saturday, 1 September 2012

Galliformes 2: Palawan Peacock-Pheasant

Male Palawan Peacock-pheasant
Scattered through the forests of south east Asia and related islands are a group of six or seven species of small pheasant in the genus Polyplectron. Most of the species have the wings of the males ornamented with eye spots reminiscent of those on a peacocks tail, from which they get their English name of Peacock-pheasant. In fact, recent DNA analysis has shown that they are indeed related to their much larger cousins, and also other pheasants with highly ornamented wings and tails such as the Great Argus pheasant Argusianus argus, the Congo Peafowl Afropavo congensis and the Crested Argus Rheinartia ocellata.

Congo Peafowl (male on left)
At Bristol we keep the most ornamental of the group, the Palawan Peacock-pheasant Polyplectron napoleonis. We have been quite successful with them and parent rear birds in outside aviaries most years. Aside from heated quarters they have access to during the winter months, they manage in the Bristol climate quite well.

As with many rainforest birds, their behaviour in the wild has not been much studied. From surveys, the wild population in Palawan is in reasonable shape, although deforestation has undoubtedly affected the population. For this reason the IUCN Red List classes it as Vulnerable.

Palawan Peacock-pheasants are solitary in the wild, except for the few weeks a mother is caring for her chicks, and males during the breeding season are territorial. Males clear a patch of forest floor as a display site and call from there to attract females. After mating, the female lays a clutch of 2-5 eggs in a typical pheasant scrape on the ground. After an incubation period of 19 days, the chicks hatch and immediately leave the nest to follow the mother around her home range. Unusually for pheasants, she does not just scratch up food for her chicks but actively catches food for them and presents the food item to the chicks in her beak. As a result, artificial rearing of Peacock-pheasant chicks requires more hands-on care than is usual, as the chicks have to be either hand-fed for at least the first few days or otherwise taught to feed themselves.
Female Palawan Peacock-pheasant
As with most rainforest pheasants, Peacock-pheasants feed on a high proportion of invertebrates, especially when young, but will also feed on various plant parts and forest fruits. For a diet used for rearing Peacock-pheasant chicks and feeding adults, a diet sheet can be found here: http://www.gbwf.org/pheasants/Polyplectron_emphanum_HRG.pdf

Peacock-pheasants take some time to reach maturity, with males needing at least three years to attain full colour. In captivity they have been known to reach the age of 15 years, but in the wild it is certainly a lot less than that.

Although the various species of Peacock-pheasant are quite similar in general appearance, it is possible that there is more variation in behaviour than one might expect between the species. Two forms, P.inopinatum and P.chalcurum, have much reduced ornamentation, and were originally considered to be closest to the ancestral form. In fact, the Palawan P.napoleonis is the most basal branch of the genus, and this implies there has been a tendency to lose ornamentation over time rather than increase it. Whether this has anything to do with habitat (both the unornamented species tend to live at higher altitudes) or changes in breeding strategy is not clear. As a group, Peacock-pheasants lay small clutches (some just a single egg) which suggests there may be more parental investment and higher success rate in raising young than more familiar species. Unfortunately, this also makes them more vulnerable to population loss, as they cannot rapidly build up their numbers after natural or man-made disasters as more prolific species can.

Next week, the last of the pheasants we currently have on show – the Satyr Tragopan.

(images from wikipedia)

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