breed. Each family tends to be colonial in its breeding habits and nests in burrows, rock crevices or in a shallow scrape (larger fulmars). In general, petrels have a 20-plus-year life-expectancy (potentially to 50+ years), diving petrels being the exception with a shorter lifespan. They lay one egg per breeding season that is incubated and cared for by both parents. If the egg is damaged or lost then it is not replaced. The incubation period lasts 40-75 days and rearing of the chick takes 50-280 days. The majority of petrel species do not begin breeding until 3-6 years of age. Diving petrels begin earlier at 1-2 years due to their shorter lifespan. Of the 80 world species of the family Procellariidae, there are 28 species that breed in New Zealand and another 11 species are visitors to the region. Of the Hydrobatidae, 5 of the 22 species in the world breed in New Zealand, while an additional 2 species are visitors. For the diving petrels, the Pelecanoididae, 2 of the 4 species in the world breed in the New Zealand region. This diversity of petrels, prions and shearwaters represents about 49% of the global diversity of the family Procellariidae, 35% breeding in the region, and 14% breeding exclusively in the region. Of the storm petrels, Hydrobatidae, 32% of the global species occur within the region, 23% forming breeding colonies in the New Zealand region. Taxonomically, the breeding Procellariidae fauna of New Zealand are represented by six genera, with the most