Where have all the birds gone?
Humans behind extinction of hundreds of bird species over the last 50,000 years

Date:
August 11, 2021
Source:
Tel-Aviv University
Summary:
A new study has revealed that over the last 20,000 to 50,000 years,
birds have undergone a major extinction event, inflicted chiefly by
humans, which caused the disappearance of about 10 to 20 percent of
all avian species. According to the researchers, the vast majority
of the extinct species shared several features: they were large,
they lived on islands, and many of them were flightless.



FULL STORY ==========================================================================
A new study from Tel Aviv University and the Weizmann Institute
revealed that over the last 20,000-50,000 years birds have undergone a
major extinction event, inflicted chiefly by humans, which caused the disappearance of about 10%-20% of all avian species. According to the researchers, the vast majority of the extinct species shared several
features: they were large, they lived on islands, and many of them
were flightless.


==========================================================================
The study was led by Prof. Shai Meiri of the School of Zoology at the
George S.

Wise Faculty of Life Sciences and the Steinhardt Museum of Natural
History at Tel Aviv University, and Amir Fromm of the Weizmann Institute
of Science. The paper was published in the Journal of Biogeography.

Prof. Meiri: "We conducted a comprehensive review of scientific
literature, and for the first time collected quantitative data on
the numbers and traits of extinct species of birds worldwide. Those
that became extinct in the last 300 years or so are relatively well
known, while earlier species are known to science from remains found
in archaeological and paleontological sites worldwide. Altogether we
were able to list 469 avian species that became extinct over the last
50,000 years, but we believe that the real number is much higher."
The researchers think that the vast extinction was caused primarily by
humans, who hunted the birds for food, or by animals brought to islands
by humans - - that fed on the birds and/or their eggs. This assumption
is based mainly on two facts: First, the greater part of bird remains
were found on human sites, apparently belonging to birds consumed by the inhabitants. Second, in most cases the extinctions occurred a short time
after the arrival of humans.

The researchers also found that extinction was not random, as most
extinct species shared three major features:
* About 90% of them lived on islands. When humans arrived on the
island,
the birds were hunted by them, or fell victim to other animals
introduced by humans, such as pigs, rats, monkeys, and cats.

* Most extinct bird species were large, some very large. Consequently,
since each bird provided humans with a great quantity of food,
they were a preferred target for hunters. In fact, the body mass
of the extinct species was found to be up to 10 times as large as
that of surviving species. Previous studies have found a similar
phenomenon among mammals and reptiles, especially lizards and
turtles that lived on islands: the larger ones were hunted by
humans and became extinct.

* A large portion of the extinct bird species were flightless,
and often
unable to escape their pursuers. The study found that the number of
flightless bird species that became extinct is double the number
of flightless species still existing today; all in all, 68% of
the flightless bird species known to science became extinct. One
of the better-known examples is the moa bird in New Zealand: 11
species of moa became extinct within 300 hundred years, due to
hunting by humans
Prof. Meiri: "Our study indicates that before the major extinction
event of the past millennia, many more large, even giant, as well as
flightless avian lived on our globe, and the diversity of birds living
on islands was much greater than today. We hope that our findings can
serve as warning signals regarding bird species currently threatened
with extinction, and it is therefore important to check whether they
have similar features. It must be noted, however, that conditions have
changed considerably, and today the main cause for extinction of species
by humans is not hunting but rather the destruction of natural habitats." ========================================================================== Story Source: Materials provided by Tel-Aviv_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Amir Fromm, Shai Meiri, Jenny McGuire. Big, flightless, insular
and dead:
Characterising the extinct birds of the Quaternary. Journal of
Biogeography, 2021; DOI: 10.1111/jbi.14206 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210811113120.htm

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