“When seen in this attitude, the Bird of Paradise really deserves its name, and must be ranked as one of the most beautiful and most wonderful of living things.”

--  Alfred Russel Wallace

BOP display-forms are without precedent among birds and are, at times, bizarre almost to the point of absurdity.  The process of sexual selection has operated to the extreme, producing a beautiful, bizarre, and unprecedented evolutionary radiation.  The BOP are special among the worlds biodiversity because they are to sexual selection what Hawaiian Honeycreepers (Drepaniidae) and Galapagos Finches (Fringillidae) are to natural selection: an example of the diversifying ability of evolution.

How did this phenotypic diversity arise and diverge over time?  How did closely related species get to be so disparate in form?  These questions lie at the core of my research.

No doubt, Wallace was right.  The birds of paradise (BOP) truly are the most beautiful and wonderfully diverse birds on the planet .  Depending on how you count them, there are between 38-88 species in 14-18 genera.  Most of which we still know very little about.  The plates below, from Birds of New Guinea, by John Gould (1877), highlight the diversity of just six species and six genera (click to enlarge).

Today, one of the most incredible things about the birds of paradise is how geographically restricted the radiation is.  The map to the right shows the entire global distribution of birds of paradise (area shaded yellow).  By far, most species and most of the diversity, are found on the New Guinea mainland.  Australia has only four species, three of which are riflebirds (see plate above).

Geography, at many scales, has played an important role in bird of paradise evolution.  At one end of the continuum is the deeper history of the Austrlao-papuan region and at the other end is the extremely dissected geography of New Guinea, with its massive (formerly glacier covered) central cordillera, numerous isolated island-like mountain ranges, and the many real satellite islands just offshore.  All of these factors have promoted the kind of population subdivision and geographic isolation necessary for speciation and the pronounced phenotypic evolution for which the birds of paradise are renown.

Ecology has played an important role in BOP evolution as well.  For instance, different species occupy different elevational zones from near sea level to nearly 3000 m above it.  The figure to the left (from Frith and Beehler 1998) illustrates this phenomenon and shows how different genera are partitioned within and among elevational zones.

Although different BOP species eat different foods depending on where they live (i.e. geography and elevation) and what’s available at the time, overall diet is not tremendously variable within the family.  All eat fruit most of the time (frugivory) and most eat insects at least some of the time.  Most species (30 of 38, or 79%) have a very generalized bill shape and eat a wide range of fruits and insects.

Above are representatives of four species from four different genera (Lophorina, Astrapia, Diphyllodes, and Parotia) with very similar bill morphology (specimens from the American Museum of Natural History).

There are several spectacular exceptions however.  The photographs at right show the most specialized bill morphology of the genera Drepanornis and Epimachus.  The genera Ptiloris and Selucidis also  have more specialized bill morphology.  The general

thinking is that the species with specialized bill morphology forage more for insects and eat less fruit.  The evidence for this in Drepanornis is fairly strong, but not so much for the other species.

Yet, most BOP diversity centers around the form (shape, size, and color) of male courtship displays.  It is this aspect of their biology that earned them their family name and what makes the group of so much interest to birders, ornithologists, behaviorists, and evolutionary biologists.

BOP plumage diversity is quite spectacular and has been the subject of interest for centuries as the the plate by Barraband (from Levaillant 1801-06) to the left illustrates.  The images below show more (specimens from AMNH).

But Wallace wasn’t the first western naturalist to be enamored with the birds of paradise, he was just the first to see them display in the wild (no small feat at the time).  More than three centuries before, in 1522, the first preserved specimens arrived in Europe in the cargo holds of only ship to survive Magellan's circumnavigation of the globe. 

They were given as special gifts to the King of Spain from the Sultan of Batchian (present day island of Tidore); the Portugese sailors they were told they were “the birds of the Gods”.  The species were Paradisaea apoda, Greater Birds of Paradise, from the lowland forest of mainland New Guinea hundreds of miles to the east.  They were an unusual sight, like nothing anyone had ever seen before because they had been prepared in the traditional way by native New Guineans, with legs and wings removed and the skins carefully dried over a fire to shrink them and accentuate the wonderful yellow plumes.  The exotic beauty of these birds,

Ferdinand Magellan

coupled with the way they had been preserved (no feet, no wings) and the belief that lived in the heavens, caused a stir among 16th century European naturalists.  It was thought that the birds must have come from Eden, the earthly paradise believed to exist and they were christened “The Birds of Paradise.”

In the decades following discovery, more specimens arrived in Europe, and people began to realized that these extraordinary birds were very unique but, in fact, they were of the Earth and not the heavens.  Nonetheless, they were highly regarded and sought after by experts from many areas of study.  Around the year 1640 for instance, the artist Rembrant made a charcoal study (at left) of two preserved specimens.  In time, more species were discovered and naturalists began to actively seek to collect more.  By the early 19th century, it was widely known that the real earthy paradise and home to the BOPs was the great Pacific island of New Guinea.