Moa's Ark: Why the Female Giant Moa Was About Twice the Size of the Male

Apr. 9, 2013 — Some of the largest female birds in the world were almost twice as big as their male mates. Research carried out by the Zoological Society of London (ZSL) shows that this amazing size difference in giant moa was not due to any specific environmental factors, but evolved simply as a result of scaling-up of smaller differences in male and female body size shown by their smaller-bodied ancestors.

The paper is published April 10 in Proceedings of the Royal Society B.

Sir Richard Owen with skeleton of Dinornis.

In an environment lacking large mammals, New Zealand's giant moa (Dinornis) evolved to be one of the biggest species of bird ever, with females weighing more than two hundred kilograms -- the same as about 3 average sized men.

Male and female birds often show differences in body size, with males typically being larger. However some birds, like many ratites -- large, flightless species such as emus and cassowaries -- are the opposite, with the females towering over the males.

Moa were huge flightless ratites. Several different species inhabited New Zealand's forests, grasslands and mountains until about 700 years ago. However, the first Polynesian settlers became a moa-hunting culture, and rapidly drove all of these species to extinction.

Dr Samuel Turvey, ZSL Senior Research Fellow and lead author on the paper, says: "We compared patterns of body mass within an evolutionary framework for both extinct and living ratites. Females becoming much larger was an odd side-effect of the scaling up of overall body size in moa.

Continued: http://www.sciencedaily.com/releases/2013/04/130409211939.htm

What a Bunch of Dodos! Catastrophic Mass Extinction of Birds in Pacific Islands Followed Arrival of First People

Mar. 25, 2013 — Research carried out by the Zoological Society of London (ZSL) and collaborators reveals that the last region on earth to be colonised by humans was home to more than 1,000 species of birds that went extinct soon after people reached their island homes.

The paper was published today (March 25th) in the journal Proceedings of the National Academy of Sciences.

Almost 4,000 years ago, tropical Pacific Islands were an untouched paradise, but the arrival of the first people in places like Hawaii and Fiji caused irreversible damage to these natural havens, due to overhunting and deforestation. As a result, birds disappeared. But understanding the scale and extent of these extinctions has been hampered by uncertainties in the fossil record.

Professor Tim Blackburn, Director of ZSL's Institute of Zoology says: "We studied fossils from 41 tropical Pacific islands and using new techniques we were able to gauge how many extra species of bird disappeared without leaving any trace."

They found that 160 species of non-passerine land birds (non-perching birds which generally have feet designed for specific functions, for example webbed for swimming) went extinct without a trace after the first humans arrived on these islands alone.

"If we take into account all the other islands in the tropical Pacific, as well as seabirds and songbirds, the total extinction toll is likely to have been around 1,300 bird species," Professor Blackburn added.

Continued: http://www.sciencedaily.com/releases/2013/03/130325160509.htm

Chick Magnet? Nest Diet Has Big Impact On Attractiveness of Hihi Birds

Feb. 12, 2013 — Published February 12 by the Zoological Society of London (ZSL) and University of Cambridge, the study reveals that male hihi birds develop more colourful and attractive breeding feathers if they receive a nest diet rich in carotenoids -- natural pigments found mainly in fruit and vegetables.

Scientists looked at the effects of newborn nutrition on male plumage in the rare New Zealand hihi (Notiomystis concta) over the course of a year. The paper was published in Proceedings of The Royal Society B.

ZSL and University of Cambridge PhD student Leila Walker says: "We first hand-fed baby hihi birds either a carotenoid supplement -- natural pigments used to colour yellow, orange and red -- or a more complete dietary supplement. Then we looked at the effect this had on male breeding feather colour once those chicks had grown and moulted into their adult plumage."

All nestlings initially develop female-like plumage and fledge at around one month old. Youngsters then moult their body feathers at about four months old, during which time the males obtain their breeding features. Colourful plumage is an important factor in a bird's breeding success as it demonstrates the strong health of a bird to females.

Continued:  http://www.sciencedaily.com/releases/2013/02/130212210118.htm