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Description
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Plumage variation between
the sexes is closely related to breeding system. The manucodes and
Paradise-crow, which are socially monogamous, are sexually monomorphic. So are
the two species of Paradigalla, which are polygamous. All these species have
generally black plumage with varying amounts of green and blue iridescence.
Habitat
and distribution
The centre of
bird-of-paradise diversity is the large island of New Guinea; all but two
genera are found in New Guinea. The two that are not are the monotypic genera
Lycocorax and Semiptera, both of which are endemic to the Moluccas, to the west
of New Guinea. Of the riflebirds in the genus Ptiloris, two are endemic to the
coastal forests of eastern Australia, one occurs in both Australia and New
Guinea, and one is only found in New Guinea. The only other genus to have a
species outside New Guinea is Manucodia, one representative of which is found
in the extreme north of Queensland. The remaining species are restricted to New
Guinea and some of the surrounding islands. Many species have highly restricted
ranges, particularly a number of species with restricted habitat types such as
mid-montane forest (like the Black Sicklebill) or island endemics (like the
Wilson's Bird-of-paradise). The majority of birds-of-paradise live in tropical
forests, including rainforest, swamps and moss forest, nearly all of them
solitary tree dwellers. Several species have been recorded in coastal
mangroves. The southernmost species, the Paradise Riflebird of Australia, lives
in sub-tropical and temperate wet forests. As a group the manucodes are the
most plastic in their habitat requirements, with in particular the
Glossy-mantled Manucode inhabiting both forest and open savanna woodland.
Mid-montane habitats are the most commonly occupied habitat, with thirty of the
forty species occurring in the 1000–2000 m altitudinal band.
Behaviour
Diet and feeding
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Breeding
Most species have
elaborate mating rituals, with the Paradisaea species using a lek-type mating
system. Others, such as the Cicinnurus and Parotia species, have highly
ritualised mating dances. Males are polygamous in the sexually dimorphic
species, but monogamous in at least some of the monomorphic species.
Hybridisation is frequent in these birds, suggesting the polygamous species of
bird of paradise are very closely related despite being in different genera.
Many hybrids have been described as new species, and doubt remains regarding
whether some forms, such as Rothschild's Lobe-billed Bird of Paradise, are
valid. Despite the presence of hybrids, some ornithologists hypothesise that at
least some putative hybrids are valid species that may be extinct. Birds-of-paradise
build their nests from soft materials, such as leaves, ferns, and vine
tendrils, typically placed in a tree fork. Clutch size is somewhat uncertain.
In the large species, it is almost always just one egg. Smaller species may
produce clutches of 2–3. Eggs hatch after 16–22 days, and the young leave the
nest at between 16 and 30 days of age.
Taxonomy
and systematics
For many years the
birds-of-paradise were treated as being closely related to the bowerbirds.
Today while both are treated as being part of the Australasian lineage Corvida,
the two are now only thought to be distantly related. The closest evolutionary
relatives of the birds-of-paradise are the crow and jay family Corvidae, the
monarch flycatchers Monarchidae and the Australian mudnesters Struthideidae. A
2009 study examining the mitochondrial DNA of all species to examine the
relationships within the family and to its nearest relatives estimated that the
family emerged 24 million years ago, older than previous estimates. The study
identified five clades within the family, and placed the split between the
first clade, which contains the monogamous manucodes and Paradise-crow, and all
the other birds-of-paradise, to be 10 million years ago. The second clade
includes the parotias and the King of Saxony Bird-of-paradise. The third clade
provisionally contains a number of genera, Seleucidis, the Drepanornis
sicklebills, Semioptera, Ptiloris and Lophorina, but support values for some of
these is inclusions is low. The fourth clade includes the Epimachus
sicklebills, Paradigalla and the astrapias. The final clade includes the
Cicinnurus and the Paradisaea birds-of-paradise. The exact limits of the family
have been the subject of revision as well. The three species of satinbird (the
genera Cnemophilus and Loboparadisea) were treated as a subfamily of the
birds-of-paradise, Cnemophilinae. In spite of differences in the mouth, foot
morphology and nesting habits they remained in the family until a 2000 study
moved them to a separate family closer to the berrypeckers and longbills
(Melanocharitidae). The same study found that the Macgregor's Bird-of-paradise
was actually a member of the large Australasian honeyeater family. In addition
to these three species, a number of systematically enigmatic species and genera
have been considered potential members of this family. The two species in the
genus Melampitta, also from New Guinea, have been linked with the
birds-of-paradise, but their relationships remain uncertain, more recently
being linked with the Australian mudnesters. The Silktail of Fiji has been
linked with the birds-of-paradise many times since its discovery, but never
formerly assigned to the family. Recent molecular evidence now places the
species with the fantails.