Birds also ingest small plastic particles while at sea which may limit the birds ability to maintain condition and contribute to deaths during migration. Feral cats are also a problem, as they find shearwater chicks easy prey. Trampling of burrows by humans can also cause their death. Similarly, erosion caused by recreational vehicles can destroy suitable sites for burrowing. It is important to keep off colonies.
Natural mortality occurs mainly during the first migration due to exhaustion and starvation.
The average lifespan is 15-19 years but birds can live up to 38 years. Both countries monitor the shearwater population while the birds are in their area. In Tasmania harvesting limits are imposed to prevent over-harvesting and a number of wildlife sanctuaries protect shearwater colonies. Japanese and other countries are attempting to minimise the number of birds drowned by their fishing operations. It is hoped that these conservation methods will ensure the survival of one of the world's most amazing migratory birds.