Geophaps

Taxonomy

Pigeons and doves are placed in their taxonomic groups based predominantly on structural characteristics. Pigeons feed their young by regurgitation and suck water while their beak is immersed. Males and females divide incubation duties.

Geophaps pigeons are members of the family Columbidae, who's distribution is spread between three defined areas around the globe: the Americas; Africa, the Middle East and Central Asia; and Asia, Australasia and Oceania. Australia and Oceania are home to almost two-thirds of all living species of Columbidae, which also includes three-quarters of all threatened species globally.

Evolution

Pigeons in the genus Geophaps are believed to have evolved from bird fossils which were found at Riversleigh, north-west Queensland. The fossils were described as a new genus and species of pigeon and are the oldest Columbia fossils to have been found globally. The fossil species has been most closely linked to the Australian bronze wings, including Geophaps species and suggests that pigeons may have evolved in the southern hemisphere. The fossil find indicates that the ancestry of Australian bronzewings goes back to the end of the Paleogene era.

Description

All species of Pigeons and Doves are described as having short necks and legs, and a short, slender bill.

All four species within the Geophaps genus are endemic to Australia and are generally described as Bronzewings. They are closely related to pigeons from the genus Phaps. Geophaps species share partridge-like flight patterns and show no differences in plumage between the sexes. Aside from the Crested pigeon, who roosts and nests arboreally, all members of the genus Geophaps are terrestrial. Geophaps scripta and Geophaps smithii are closely related terrestrial species both with recognisable facial patterns. Geophaps plumifera and Geophaps lophotes both have long, erect crests and are considered reasonably different from G.scripta and G.smithii. G.plumifera and G.lophotes are placed occasionally within their own genera (Ocyphaps lophotes for the Crested pigeon, and Lophophaps plumifera for the Spinifex pigeon).

Table 1.1, shows the following information- Common name, scientific name/s, sub-species, size, distribution and IUCN (International Union for Conservation of Nature and Natural Resources) Red List Status,

Feeding

Geophaps species are ground feeding granivores, with studies finding that seeds make up their diet almost entirely, with a small number of insects found in the crops of Geophaps smithii. While the Spinifex pigeon is found in arid tussock/spinifex grasslands, the spinifex grass seeds have not been found to make up a large portion of their diet.

Breeding

All Geophaps pigeons exhibit a bowing display during courtship. The Spinifex pigeon and Crested pigeon's display is performed with a raising and fanning out of the tail with their folded wings partly opened to display their iridescent wing marks to their potential partner. The other members of the Geophaps genus displays and bows in a very similar manner.

G.scripta has been recorded to have performed its courtship ritual where it stood fully erect on an exposed branch, with plumage slightly fluffed out. The male then bobs up and down rapidly and rhythmically, he displays alone and waits for a female to fly from cover to pair with him. Rainfall and food abundance has been shown to effect breeding cycles

Crested pigeons have been observed to build nests on a platform of branches, with both sexes collecting nest building material. The female builds the nest, lacing thin twigs through the substructure. They are thought to learn to build nests through trial and error.

Parasites

Pigeons and doves are parasitised by two major groups of lice; wing lice and body lice. Most birds are host to both groups, which eat the downy parts of feathers that are close to the body. Body lice have been found to be more likely to be host specific than wing lice, possibly due to their host ecology where terrestrial pigeons feeding on the ground may create an easier transfer of lice and therefore be more likely to carry host specific body lice than arboreal birds.

Threats to conservation

Columbidae species are amongst the most threatened bird families around the world. Geophaps species' conservation is largely threatened by habitat loss and fragmentation caused predominantly by agriculture and human interference as well as by predation by introduced predators, namely cats.

As arid environments are naturally changing, it is difficult to gauge the extent of change caused by pastoralisation, however, grazing by livestock is considered incompatible with natural succession of ecosystems. Overgrazing by livestock causes alteration and degradation of soil and flora. Very few arid species have been recorded as declining in numbers since European settlement and some species, including the Spinifex pigeon and the Crested pigeon have increased in population size, possibly due to the increase in permanent water sources created for livestock

Cultural links

Species within the Geophaps genus have been named in Aboriginal stories and songs.

The Partridge pigeon (Geophaps smithii) has been listed as a bird species which features as a Morrdjdjanjno song subject. Morrdjdjanjno is a genre of song from the Arnhem Land plateau in the Northern Territory top end, they are sung only by men and passed down as 'open domain' songs. Morrdjdjanjno songs' subjects are discussed in relation to mythological events of religious significance and are believed to bring the singer into contact with the animal being sung about or to increase numbers of certain species.

The Spinifex pigeon and Crested pigeons have been recorded in versions of an Aboriginal Children's story from Central Australia, conveying rich symbolic meanings between the Geophaps species and associations by the Arandic people with 'kurdaitchas' (a person who sets out to kill or harm someone, often in revenge, and who leaves no trace.