The Alan Sondheim Mail Archive

March 26, 2013

Joseph Bennington-Castro

What Happened to All the Birds in the Most Recently Colonized Regions of 

The numerous islands scattered throughout the Pacific Ocean comprise the 
last habitable region of Earth that humans colonized. Beginning about 3500 
years ago, people settled the eastern islands, such as the Samoan islands, 
Fiji and the Marianas. By 700 years ago they made their way to the more 
remote locations of Hawai.i and Rapa Nui (Easter Island). These islands 
once held hundreds of species of birds that disappeared when humans 
arrived. Now we have a clearer picture of what happened.

The Pacific islands experienced a massive die-off of bird species not long 
after human colonization, but just how many of the feathery creatures went 
extinct has remained a bit of a mystery to scientists. Now, a new analysis 
suggests that some 1000 nonpasserine landbird species (birds that don't 
perch) disappeared due to hunting and habitat loss between the time people 
first settled the Pacific islands and the arrival of Europeans.

These tropical landscapes were once dominated by numerous bird species, 
many of which became extinct in a relatively short time after humans 
arrived. Some conservative estimates say 800 species disappeared, while 
others place the number at over 2000. The main reason for this large 
extinction uncertainty is the spotty fossil record available, says Richard 
Duncan, an ecologist at the University of Canberra in Australia and lead 
author of the new study.

"Relatively few fossils have been collected from a lot of the islands that 
have been studied," Duncan told io9. Fossils will only preserve in certain 
types of sites . these "specialized habitats" are often difficult to find. 
"And a lot of the work on collecting raw data and fossils [in the Pacific] 
has been done by just a few people," he adds. The large differences 
between the islands, including area, topographic diversity and rainfall, 
further complicates getting an accurate rate of species loss, since these 
features would've affected how easily people could hunt and clear out 

So Duncan and his colleagues used the available data to refine the Pacific 
islands' extinction estimates. The team focused only on nonpasserine 
landbirds, which are better represented in the fossil record than sea 
birds and passerine birds. The large-bodied landbirds preserve as fossils 
easier than smaller birds and were likely the prime target of hunters, who 
left the remains in more accessible sites.

The team looked at the extinction question as a "mark-recapture" problem. 
Ecologists use this method to estimate the size of an animal population . 
it involves capturing and marking a portion of a population, then later 
collecting another group and counting the number of individuals that have 
been previously marked (recaptured). In this case, the landbird species 
recorded after the arrival of Europeans were the so-called marked species, 
which were available for recapture in the fossil record.

One way to think about it, Duncan explains, is to imagine you have an 
island with various species of birds. Say you count 10 species on the 
island, but find only five of them in the fossil record. The other five 
species should be there, you just haven't found them yet. This information 
can give you an idea about your ability to detect birds in the fossil 
record, and when combined with the number of extinct species discovered, 
it can help you to estimate the number of extinct species that remain 
missing and the associated rate of extinction. Though the researchers' 
model involves a bit more than this, it's basically "the idea of using the 
information we have on our ability to detect birds and extrapolating out 
to see how many species must be missing," he says.

The team performed their calculations for 41 Pacific islands. They found 
that the large, flightless birds were most likely to go extinct. And 
islands that are small and have little rainfall suffered the highest rates 
of extinction (about 90 percent). Overall, a whopping two-thirds of the 
nonpasserine landbird populations on the islands died off between 
colonization and European contact . this means that at least 983 bird 
species became extinct, an estimation that doesn't even include all of the 
seabird and passerine bird extinctions.

There are currently only 10,000 extant bird species today, so this event 
was quite significant in terms of the global bird diversity, Duncan notes. 
"To put it in context: This is probably the largest extinction event we've 
witnessed that was caused by humans," he says.

The researchers findings were published today in the journal PNAS.

- Alan

Heritage (best)

with Chris Diasparra, tenor, Alan Sondheim
electric saz, oud, saz

and heritage, because there is mindful remembrance here, and
falls victim to warfare and ecstasy and national heritage, and
folding and entropic and this bored language and this sequence
concerned with probing and defining the fibres of roots, and
cultural heritage among the tribe of tribes, and intellectual
heritage, and strangers, other than people, than other people,
and be it known, inescapable, thinking this is it, that this is
given to the human, and that my heritage is wood and silk and
goodbye, it may be known,

and the end, these are the heritage of humanity, and that
humanity is the heritage of silk and wood, being silk and wood,
and living within and without, and speaking, and touching these
folding, unfalling, and rescued, this unboring language, this
sequence, this forming and unforming

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