New take on why the passenger pigeon went extinct
The adage that there is safety in numbers didn’t help the poor old passenger pigeon.
New research reveals it was the birds’ vast numbers that eventually caused their total demise.
Four billion passenger pigeons once darkened the skies of North America, but by the end of the 19th century, they were all gone. Although the pigeons evolved quickly, they did so in a way that made them more vulnerable to hunting and other threats.
Hunting and deforestation have long been held responsible for the pigeons’ extinction, but the birds were so abundant that they destroyed the very trees in which they nested.
So why did they disappear so quickly – and so completely?
Because their huge population and lack of genetic diversity made them vulnerable, according to Beth Shapiro, a paleogenomicist at the University of California, Santa Cruz. She says that although the birds were able to adapt faster to their environment, that also caused all of them to be fairly genetically similar.
And when new threats like human hunters and habitat loss arrived, the pigeons suddenly found their physiology and behaviour were poorly suited for their declining numbers.
Their population went from being super-big to super-small so fast they didn’t have time to adapt – in part because they lacked the diversity to cope with this new way of living, says Shapiro.