Download AEBR 242 Estimated population size of the Westland petrel, 2007–2011

A survey of high-density breeding colonies of Westland petrels Procellaria westlandica, an endemic New Zealand seabird, undertaken between 2007 to 2011, conservatively estimated the population size to be 2827 (95%CI, 2143–3510) annual breeding pairs. The population may have been underestimated by up to 10% but is unlikely to have exceeded 4000 annual breeding pairs at the time of this survey. This estimate is the first detailed population estimate for all known breeding areas of this species.