Shearwaters: Rakiura Tïtï Restoration
Mitigation of the
Command oil spill injury
Restoration of Sooty Shearwater
breeding colonies in New Zealand
The Rakiura Tïtï Restoration Project sought to repair the injury to Sooty Shearwaters (Puffinus griseus, titi) caused by the 1998 Command Oil Spill in California through the eradication of introduced black rats and Polynesian rats or kiore, and predatory weka rails from shearwater breeding colonies in the southern Tïtï Islands, New Zealand.
The project was led by Rakiura Mäori, New Zealand’s most southerly group of indigenous people who manage these migratory birds as taonga (treasured species) which they call tïtï (pronounced “tee-tee”). The restoration team combines the traditional knowledge of Mäori environmental stewards, called Kaitiaki, with technical and scientific expertise of the New Zealand Department of Conservation, a University of Otago team of ecologists, and United States environmental education and seabird experts.
Sooty Shearwaters are the most abundant seabird off central California during May to September (Briggs et al. 1986). They are a highly abundant species; there is estimated population of 21.3 million individual birds (19.0–23.6) in the New Zealand region (Newman et al. 2009), 4+ million in Chile, and ~2,000 in Australia (Reyes-Arriagada et al. 2007). While feeding in coastal waters, they aggregate in immense flocks, which may extend for many kilometers and number in the 10,000-100,000s, which makes them vulnerable to oil spills. On September 26, 1998, Tank Vessel Command leaked oil off central California coast within the migratory corridor of Sooty Shearwaters which occurred in flocks with densities ranging from 11 to 346 birds km-1 at the time of the spill (Hampton and Boyce, 2002). Moller et al. (2003) estimated the damage to the Shearwater population was 1,489 – 29,606 birds killed.
- Eradicate the non-native introduced rodents and weka birds
- Establish quarantine to prevent reintroduction of rodents and ensure long-term benefits
- Monitor and predict restoration success
- Create educational outreach to inform the people of New Zealand and California about the project
Threats to Migratory Shearwaters
Sooty Shearwaters face multiple threats throughout their range. In the Northern Hemisphere, shearwaters are killed by oil spills, fisheries entanglement, predators, disease, marine pollution. Perhaps one of the most unpredictable threats to the population is the effects of climate change. El Niño ocean conditions decrease food supplies for shearwaters, leading to greater mortality. At Southern Hemisphere nesting colonies, the threats are mainly land-based including introduction of invasive mammals, over-exploitation, and habitat destruction.
The best possible solution was found to be the elimination of rat and weka predation of eggs and chicks on the four target islands. We estimated that is this would be the most reliable and rapid method of replacing about 15,000 tïtï estimated to be lost because of the Command oil spill. Rat eradication occurred in July 2006. Because of the longevity of these birds and relatively slow reproductive rate (e.g. one egg per year; five to seven years to maturity), complete population-level recovery may take four decades.
International and Cross-cultural Collaboration
The Rakiura Tïtï Restoration Project promulgates a model for international and cross-cultural collaboration to mitigate the effects of a significant oil spill. Education effort will bring lasting benefits for conservation. The Rakiura Titi Restoration Project will build confidence that enlightened research, management and litigation can combine to restore environmental injury resulting from this negligence.
Rakiura Tïtï Islands
The breeding colonies for Sooty Shearwaters in the Titi Islands surrounding Rakiura off the South Island of NZ (map, below). The four islands in this group targeted for rodent eradications included Taukihepa, Pukeweka, Rerewhakaupoko, and Mokonui Islands. The banded shearwater killed during the Command oil spill was captured on Whenua Hou (Codfish Island).
Taukihepa (“Big South Cape”) is the largest (929 ha) of all the Tïtï Islands and the main target for restoration through rat eradication. It is fringed by steep cliffs and so in many places is accessible only by helicopter. This is ancestral land of scores of whänau (birding families) that continue their culture and livelihoods by a customary 6-10 week ‘heke hao kai tïtï’ (harvesting expedition). This customary practice and cultural identity is threatened by global pollution and catastrophes like the Command oil spill.
The Rakiura Titi Islands were also identified for their cultural and historical significance and multiple ecological benefits (Nevins et al. 2009). In 1964, a shipwreck was responsible for introducing ship rats to Taukihepa resulted in a globally-significant ecological disaster. This “rat spill” had a huge impact on the fragile island ecosystem —the rat introduction caused the extinction of three endemic land birds (Stewart Island Snipe), and Stead’s Bush Wren (Xenicus longipes variabilis) a large flightless beetle (weevil), and a rare ground-dwelling bat (Greater short-tailed bat, Mystacina robusta). After the rat spill, a last ditch effort was made to translocate 36 individual South Island Saddlebacks or Tïeke (Philesturnus c. carnuculatus) from the rat-plagued islands to a nearby predator-free island (Poutama or Evening Island). The current population of over 700 birds is descended from the survivors of the 36 Tïeke rescued in 1964. Restoring the Rakiura Tïtï Islands for reintroduction of endemic species, such as the Tïeke, was a major long-term ecological goal of this project.
This wide-scale destruction was a very rude awakening for New Zealand – no one had suspected the enormous havoc introduced predators could wreak upon our ecosystems until that catastrophe.– Dr. Henrik Moller
Ecosystem Monitoring – indicators of success
Many island species benefited from the rat removals – insects, birds, and plants. This multi-species benefit was one of the main reasons this project was undertaken. We conducted surveys of shearwater nesting areas prior to and after the 2006 eradication.
In 2008, just 2 years after the eradication, biologists reported great increases in land birds abundance. These surveys were key in documenting restoration success. Burrow density (number of burrows km-1) was the metric used for comparisons as occupancy may change greatly depending on inter-annual changes in food available to the breeding birds and may not be reflective of population-level changes.
The recovery of endemic Saddleback or Tieke to the last islands where they occurred in the wild is of utmost conservation value. These outcomes bring a long-lasting benefit to the islands.
Quarantine – an ongoing community effort
A major future challenge is to prevent re-infestations of rodents to these islands.
The objective of establishing quarantine measures was to (1) provide outreach to people traveling to the islands through main ports of entry (e.g. harbors, airports) to prevent reintroduction of rats and other pests to the Rakiura Tïtï Islands to ensure long-lasting benefits of the project and (2) to establish contingencies on targeted islands in the case of an pest introduction.
Rats are likely to be re-introduced from boats traveling to the Tïtï Islands to offload passengers and gear, originating from either the South Island at Bluff, or from Stewart Island at Halfmoon Bay. Fishing vessels may also pose a problem, as they may originate from various southland ports and occasionally visit the islands, but may not stop at a local port (i.e. Halfmoon Bay) prior to transiting to remote Tïtï Island. Helicopters also are used to transport gear directly from personal homes to island sites.
The implementation of quarantine measures included providing information to the island-traveling community regarding staging and preparing “rat-free” gear by means of yearly calendars, signs at loading/departure areas, brochures and public displays. Ka Mate Nga Kiore quarantine personnel target quarantine efforts with both the helicopter and boat charters at the most likely points of re-introduction.
South Coast Productions, NZ, produced two full-length documentary videos about this project. The first was entitled “The Tïtï Islands: a Paradise Restored (2008)” documented the story of the shearwaters killed by the Command Oil Spill and the unique restoration plan to eradicate rats on shearwater nesting islands in New Zealand. A second 45-minute video ass entitled, “The Tïtï Islands: the Return of the Taonga (2009)” highlighted the international partnership, and the unique conservation action to return the South Island Saddleback/Tieke to its former islands. Oikonos has a limited number of these videos for distribution see project contact below for copies.
Californian filmmakers, Karen and Kennan Ward produced “River of Birds” as a short educational video on the amazing feeding phenomenon of Sooty Shearwaters in a feeding frenzy in Monterey Bay, California. We hope that the film will enhance educational displays in state visitor centers and classroom audiences and ensure the longevity of the conservation message this project strives to communicate.
- “River of Birds” – Kennan Ward Productions
- Learn more about the “Endless Summer” birds
- Ocean Stewardship – Educational Materials
- Collaborators follow birds from California to New Zealand – Link to view maps
The Rakiura Tītī Islands Restoration Project: Community Action to Eradicate Rattus rattus and Rattus exulans for Ecological Restorationand Cultural Wellbeing
J. McClelland, R. Coote, M. Trow, P. Hutchins, H. M. Nevins, J. Adams, J. Newman, and H. Moller pgs. 451-454 Island Invasives: Eradication and Management.
Hannahrose M. Nevins, Josh Adams, Henrik Moller, Jamie Newman, Michelle Hester, and K. David Hyrenbach. 2009. Journal of the Royal Society of New Zealand: Volume 39, Number 4, 183–185; 1175-8899 (Online); 0303-6758 (Print)/09/3904–0183.
Reyes-Arriagada R, P Campos-Ellwanger, RP Schlatter, C Baduini. 2007. Sooty Shearwater (Puffinus griseus) on Guafo Island: the largest seabird colony in the world? Biodiversity and Conservation 16: 913–930.
Boyce, J.; S. Hampton 2002. Command Bird Injury Report. 14 May 2002, Command Oil Spill Trustee Council, 19 pp. Available: http://www.dfg.ca.gov/ospr/NRDA/command-oil.aspx
Harper, G. 2006. Weka (Gallirallus australis) depredation of sooty shearwater/titi (Puffinus griseus) chicks. Notornis 53: 318-320.
Lyver,P, H Moller, C Thompson. 1999. Changes in Sooty shearwater Puffinus griseus chick production and harvest precede ENSO events. Marine Ecology Progress Series 188: 237-248.
McClelland, PJ, R Coote, M Trow, P Hutchins, HM Nevins, J Adams, J Newman and H Moller. 2011. The Rakiura Titi Islands Restoration Project: community action to eradicate Rattus rattus and Rattus exulans for ecological restoration and cultural wellbeing. Pg. 451-454 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.) 2011. Island Invasives: Eradication and management. IUCN, (International Union for Conservation of Nature), Gland, Switzerland.
Moller, H.; Nevins, H. M,; Adams, J. 2003. The Rakiura Titi Restoration Project: Mitigation of the Command oil spill injury by eradication of rats from Sooty Shearwater breeding colonies in New Zealand. 78 pp. Unpublished Report for Rakiura Titi Islands Administering Body, January 2003.
Moller, H. Special Issue Forward: Matauranga Maori, science and seabirds in New Zealand. New Zealand Journal of Zoology, 2009, Vol. 36: 203–210; 1175-8821 (Online); 0301-4223 (Print)/09/3603–0203 © The Royal Society of New Zealand 2009
Nevins, HM, J Adams, H Moller, J Newman, M Hester, and KD Hyrenbach. 2009. Forum: International and cross-cultural management in conservation of migratory species. Journal of the Royal Society of New Zealand: 39(4):1175-8899 (Online); 0303-6758.
Newman, J, D Scott, H Moller, and D Fletcher. 2008. A population and harvest intensity estimate for Sooty Shearwater, Puffinus griseus, on Taukihepa (Big South Cape), New Zealand. Papers and Proceedings of the Royal Society Tasmania 142(1): 177-184.
Funding & Collaborators
- Command Oil Spill Trustee Council
- Ka Mate nga Kiore, Incorporated Society, Te Anau, NZ
- Rakiura Tïtï Islands Committee, NZ
- Rakiura Tïtï Islands Administering Body, NZ
- Southcoast Productions, Invercargill, NZ
- Kia Mau Te Tïtï Mo Ake Tönu Atu (“Keep the Tïtï Forever”) research team
- Dr. Henrik Moller, Centre for Sustainability, University of Otago, New Zealand
- New Zealand Department of Conservation – Te Papa Atawhai
- Karen and Kennan Ward,Wildlight Press and Photography, Santa Cruz, CA
- Deby Grosjean, Music