page_title: Procellariidae
section_title: Threats and conservation
hierarchical_section_title: Procellariidae / Relationship with humans / Threats and conservation
context_page_description: The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes, which also includes the albatrosses, the storm petrels, and the diving petrels.
  The procellariids are the most numerous family of tubenoses, and the most diverse. They range in size from the giant petrels, which are almost as large as the albatrosses, to the prions, which are as small as the larger storm petrels. They feed on fish, squid and crustacea, with many also taking fisheries discards and carrion. All species are accomplished long-distance foragers, and many undertake long trans-equatorial migrations. They are colonial breeders, exhibiting long-term mate fidelity and site philopatry. In all species, each pair lays a single egg per breeding season. Their incubation times and chick-rearing periods are exceptionally long compared to other birds.
  Many procellariids have breeding populations of over several million pairs; others number fewer than 200 birds.
context_section_description: While some species of procellariid have populations that number in the millions, many species are much less common and several are threatened with extinction. Human activities have caused dramatic declines in the numbers of some species, particularly species that were originally restricted to one island. According to the IUCN 43 species are listed as vulnerable or worse, with 11 critically endangered. Procellariids are threatened by many threats, but introduced species on their breeding grounds, light pollution, marine fisheries particularly bycatch, pollution, exploitation and climate change are the main threats measures as the number of species involved.
  The most pressing threat for many species, particularly the smaller ones, comes from species introduced to their colonies. Procellariids overwhelmingly breed on islands away from land predators such as mammals, and for the most part have lost the defensive adaptations needed to deal with them (with the exception of the oil-spitting fulmarine petrels). The introduction of mammal predators such as feral cats, rats, mongooses and even mice can have disastrous results for ecologically naïve seabirds. These predators can either directly attack and kill breeding adults, or, more commonly, attack eggs and chicks. Burrowing species that leave their young unattended at a very early stage are particularly vulnerable to attack. Studies on grey-faced petrels breeding on New Zealand's Whale Island (Moutohora) have shown that a population under heavy pressure from Norway rats will produce virtually no young during a breeding season, whereas if the rats are controlled (through the use of poison), breeding success is much higher. That study also highlighted the role that non-predatory introduced species can play in harming seabirds; introduced rabbits on the island caused little damage to the petrels, other than damaging their burrows, but they also acted as a food source for the rats during the non-breeding season, which allowed rat numbers to be higher than they otherwise would be, resulting in more predators for the petrels to contend with. Interactions with introduced species can be quite complex. Gould's petrels breed only on two islands, Cabbage Tree Island and Boondelbah Island off Port Stephens (New South Wales). Introduced rabbits destroyed the forest understory on Cabbage Tree Island; this both increased the vulnerability of the petrels to natural predators and left them vulnerable to the sticky fruits of the birdlime tree (Pisonia umbellifera), a native plant. In the natural state these fruits lodge in the understory of the forest, but with the understory removed the fruits fall to the ground where the petrels move about, sticking to their feathers and making flight impossible.
  Larger species of procellariid face similar problems to the albatrosses with long-line fisheries. These species readily take offal from fishing boats and will also steal bait from the long lines as they are being set, risking becoming snared on the hooks and drowning. In the case of the spectacled petrel this has led to the species undergoing a large decline and its listing as critically endangered. Diving species, most especially the shearwaters, are also vulnerable to gillnet fisheries. Studies of gill-net fisheries show that shearwaters (sooty and short-tailed) compose 60% of the seabirds killed by gill-nets in Japanese waters and 40% in Monterey Bay, California in the 1980s, with the total number of shearwaters killed in Japan being between 65,000 and 125,000 per annum over the same study period (1978–1981).
  Procellariids are vulnerable to other threats as well. Ingestion of plastic flotsam is a problem for the family as it is for many other seabirds. Once swallowed, this plastic can cause a general decline in the fitness of the bird, or in some cases lodge in the gut and cause a blockage, leading to death by starvation. Procellariids are also vulnerable to general marine pollution, as well as oil spills. Some species, such as the Barau's petrel, the Newell's shearwater or the Cory's shearwater, 
caption: Northern fulmars (Fulmarus glacialis) flocking at a long-lining vessel in the north Pacific.
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