Extinction and endemism in the New Zealand avifauna


*Correspondence: Richard P. Duncan, Bio-Protection and Ecology Division, PO Box 84, Lincoln University, Canterbury, New Zealand. E-mail: duncanr@lincoln.ac.nz


Aim  Species belonging to higher taxa endemic to islands are more likely to go extinct following human arrival. This selectivity may occur because more highly endemic island species possess features that make them uniquely vulnerable to impacts associated with human arrival, specifically: (1) restricted distribution (2) reduced predator escape response, including loss of flight, and (3) life history traits, such as large body mass, associated with greater susceptibility to hunting or habitat loss. This study aims to identify which of these features can explain the selective extinction of more highly endemic bird species in New Zealand.

Location  North and South Island, New Zealand.

Methods  Bird species breeding in New Zealand prior to human arrival were classified according to whether they became extinct or not during two periods of human settlement, prehistoric (post-Maori but pre-European arrival) and historic (post-European arrival). We modelled the relationships between extinction probability, level of endemism and life history traits in both periods.

Results  The prehistoric extinction–endemism relationship can be explained entirely by the selective extinction of large-bodied species, whereas the historic extinction–endemism relationship appears due to increased susceptibility to introduced predators resulting from the loss of predator escape responses, including loss of flight.

Conclusions  These features may explain extinction–endemism relationships more generally, given that human hunting and predator introductions are major impacts associated with human arrival on islands.