Tuesday, May 01, 2007
End of the Line
I started with this article about a Galapagos tortoise, then I went to bird extinctions and then back to the tortoise. It seems there were 14 different subspecies (or races) of Geochelone nigra. Some are on the same island, some on different islands. Three are extinct and unless there is a breeding female (or a first generation hybrid) out there, when Lonesome George (pictured above left) dies there will only be 10. George is from the Island called Pinta in Spanish (Abingdon in English) and he is a Geochelone nigra abingdoni. The difference between the subspecies is merely a visible but superficial changes in the shape of the carapace. The two two real distinctions are between domedback and saddleback, but there are intermediate types and some called tabletops. George is a saddleback. A domedback one (a Geochelone elephantopus) is pictured below right. If the shape change is extreme enough, perhaps mating between different subspecies will be impossible (and then we have moved from subspecies to species).
The bulk of the bird extinctions were on islands where a new species--rat, mosquito with avian malaria, brown tree snake, etc. was introduced. One of the big exceptions was the Passenger pigeon, here in North America, which went from being among the most numerous birds on the planet to extinct in just a few decades of commercial hunting. Of course, the pigeon was destructive to crops, and it is doubtful we could have co-existed with them in any numbers.
UPDATE: Things may be looking up for George.
Labels: Species extinctions
# posted by Roger Fraley @ 9:13 PM 
Comments:
<< Home
R,
On the subject of extinctions, I highly recommend David Quammen's "The Song of the Dodo: Biogeography in an Age of Extinctions."
Habitat destructuion in the form of deforestation of hardwood forests in the midwest also played a crucial role in the extinction of the passenger pigeon.
One particularly cruel method of hunting passenger pigeons was to blind a single bird by sewing its eyes shut. the bird was then tethered to a circular stool that could be raised 5 or 6 feet in the air by means of a stick. as the tethered bird attempted to land, it would flutter its wings attracting other pigeons flying overhead which would land near the decoy bird and be netted by hunters who crush their heads between thumb and forefinger. This is the origin of the term "stool pigeon."
T
On the subject of extinctions, I highly recommend David Quammen's "The Song of the Dodo: Biogeography in an Age of Extinctions."
Habitat destructuion in the form of deforestation of hardwood forests in the midwest also played a crucial role in the extinction of the passenger pigeon.
One particularly cruel method of hunting passenger pigeons was to blind a single bird by sewing its eyes shut. the bird was then tethered to a circular stool that could be raised 5 or 6 feet in the air by means of a stick. as the tethered bird attempted to land, it would flutter its wings attracting other pigeons flying overhead which would land near the decoy bird and be netted by hunters who crush their heads between thumb and forefinger. This is the origin of the term "stool pigeon."
T
# posted by 
: 9:50 AM
: 9:50 AM
Very interesting. I never knew that. And of course habitat destruction couldn't have helped. Still from a few billion to zero in just a few generations. Thaere was some killing going on.
Post a Comment
<< Home
