the clash | 181harvesting continues, it is, from a worldwide perspective, no longer a
primary cause of seabird decline. More significant is the continuing dev-
astation wrought by alien species introduced to seabird nesting islands.
The impacts may be direct and brutal. Introduced cats and rats eat sea-
birds, their chicks, their eggs. Once thriving colonies have been mas-
sively reduced or totally extirpated. The main islands of New Zealand,
formerly mammal- free (except for bats), once held huge seabird colo-
nies. These have gone forever thanks to the impacts of Maori and then
European settlers, their attendant mammals, and associated wider hab-
itat changes.
Focussed examples are more vivid still. In order to be stripped of
their furry skins and provide high value coats, blue foxes were intro-
duced to more than 400 islands off Alaska from the early 18th century
onwards. The foxes devastated seabird colonies, notably auk colonies.
As they colonised Polynesia, so the Polynesians introduced Pacific Rats to
numerous islands, sometimes accidentally, sometimes deliberately since
they had no cultural aversion to a lunch of grilled rat. I have watched the
consequences on Henderson Island where the Pacific Rats, the Polyne-
sian legacy, routinely snatch a one- day-old fluffy petrel chick from be-
side its parent. To its shame, the parent makes scant effort to defend its
young. Once dragged a metre away, the still- living chick continues to
cheep weakly as it is chewed open and eviscerated by the rat. And, very
startlingly, mice on Marion Island in the Southern Ocean, accidentally
introduced to the island by sealers, have recently been reported to ‘scalp’
albatross chicks.^2 The mice, which have probably developed this ‘skill’
only recently, clamber onto the neck or head of the young albatross
where they are safely beyond the reach of the chick’s snapping bill. There
they begin to strip the albatross’s flesh, resulting in a bloody scalp and
sometimes causing the chick’s death.
Other introduced species can affect seabirds ashore via indirect path-
ways. In the Juan Fernández Islands off Chile,* rabbits and goats con-
tribute to erosion, thereby reducing opportunities for petrels to burrow.
- (^) Goats were essential for the lifestyle of Robinson Crusoe, whose story Daniel Defoe was in-
spired to write after hearing about the real- life adventures of Alexander Selkirk, marooned at
his own request on the Juan Fernández Islands from 1704 to 1709.