Atlantic puffins are breeding
once again on a Scottish island after the eradication of rats that preyed
on them for more than a century. Puffins hadn't successfully bred on
Ailsa Craig for more than 50 years, according to researchers from the
University of Glasgow.
From thousands to virtually gone
Rat predation beginning in 1889 drastically reduced
the puffin population on Ailsa Craig. That was when the rodents were
first seen there, while a lighthouse was being built. Rats made their
way onto the island from supply ships or possibly from the many ships
wrecked on the rocks off the island before the lighthouse was built.
Puffins numbered in the tens of thousands on Ailsa
Craig before the influx of brown rats. Their population plunged to mere
hundreds by the 1930s. A few decades later, puffin breeding on the island
ceased.
Rats are particularly threatening to puffins.
While rats threatened many seabird species on the island, puffins were
especially vulnerable due to their burrow nesting.
In a massive 1991 operation, the University of
Glasgow, in cooperation with the owner of Ailsa Craig and with advice
from a pest control company, eradicated the rodents from the small island.
Several tons of rodenticide was airlifted to the island and distributed
by a team of workers. Follow-up baiting took place in 1992, and no rats
have been seen on the island since.
A decade for renewal
There was no evidence of renewed puffin breeding
on Ailsa Craig until last summer, ten years after the rats were removed.
The few chicks observed on the island were a sign of hope for the return
and flourishing of the seabird.
"At least two pairs were seen carrying fish
to their chick on Ailsa Craig this summer," said Dr. Bernard Zonfrillo
of the University of Glasgow, who has studied seabirds on the island
for more than 20 years. "Given time and left to their own devices,
I hope that their numbers will gradually increase."
"The return of burrow nesting seabirds like
the puffin is just what we had hoped would happen following rat eradication,"
said Professor Pat Monaghan, of the UniversityÕs Division of Environmental
and Evolutionary Biology. "The loss of bio-diversity that occurs
when predators like rats are introduced to offshore islands is tragic.
Seabirds originally bred on such offshore islands because they were
free of predators like rats."