The Rakiura Tïtï Restoration Project: Mitigation of the Command oil spill injury by eradication of rats from Sooty Shearwater breeding colonies in New Zealand
Elimination of rat predation of eggs and chicks on Taukihepa, Pukeweka, Rerewhakaupoko and Mokonui islands is the most reliable and rapid method of replacing about 15,000 tïtï estimated to be lost because of the Command oil spill. Rat eradication was proposed for mid 2004 and occurred in July 2006 (see update). Computer simulations emphasize uncertainty in outcomes, but most likely scenarios predict complete recovery of the oil spill injury within a year after rat eradication. However simulations using extremely pessimistic assumptions predict that complete recovery may take four decades. Long-term benefits to tïtï and several other species and conservation of ecosystem processes will result.
Up to 15,000 adult Sooty Shearwaters may have been killed by the Command Oil spill in September 1998 during migration off the central California coast. The shearwaters (Tïtï) are a treasured species of Mäori (New Zealands indigenous people) and a keystone species on over 40 Nature Reserves in New Zealand. The kaitiaki (environmental guardians) of the tïtï request funding to repair the oil spill injury by eradicating rats from tïtï breeding colonies.
Sooty Shearwater (photo: Josh Adams)
(i) eradicate the non-native introduced rats,
(ii) establish quarantine to prevent reintroduction of rats,
(iii) monitor and predict restoration success, and
(iv) create educational outreach to inform the people
of New Zealand and California about the project.
Intensive study of the rate of loss of tïtï eggs
and chicks to introduced rats, and comparisons of productivity before
and after rat eradication, will allow computer simulation of rate of recovery
of the Command oil spill injury post-eradication. Longer-term monitoring
of tïtï abundance at fixed study plots 8 and 9 years after eradication
will then check model predictions and allow more definitive prediction
of ongoing restoration outcomes.
A large number of Rakiura Mäori visit the islands each
year and they transport considerable quantities of food and gear from
a variety of departure points. A concerted campaign to improve quarantine
precautions will be instigated by this project. Rakiura Mäori scientists
and managers will be employed to visit birders and urge care, to prepare
posters and place poison bait stations at landing island sites. A video
documentary about the restoration project will be used to heighten community
awareness and quarantine efforts. The television documentary will be supplemented
by CD-ROMS, interactive web-sites and a complete school educational package
to educate Americans and New Zealanders about the project and need for
All methods for eradication, managing risks and monitoring outcomes have been proven and refined. Experienced and expert teams will secure funders investment in the restoration effort and make the operation safe. Recovery of the injury to tïtï is most likely to be rapid. Multiple long-term benefits to four island ecosystems and several non-target endemic species are certain additional outcomes.
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.
Sooty Shearwater breeding habitat (Photo: Melanie Massaro)
This photo shows the understory of a typical Tïtï breeding habitat (manu). Thick well-developed peaty soil is pitted with breeding burrows under a tangled 3 7 m forest canopy. Tïtï lay an egg within burrows that can be up to 5 m long. Tïtï abundance, breeding success and productivity is determined by counting entrance holes and determining burrow occupancy using an infrared lit burrowscope inserted down the burrows in search of eggs, chicks and breeding adults.
(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.
(Photo: Darren Scott)
Taukihepa Island, looking toward the South end of Rakiura (photo: H. Nevins)
Tïtï Islands are one of the worlds treasures of endemic flora and fauna. Because the birds provide a rich nutrient supply, to the islands, the resulting vegetation is stunning. The islands edges are fringed with a canopy of silvery green-gray Teteaweka (Olearia oporina), tree daisies under which the tïtï nest. On the larger islands, such as Taukihepa larger canopy trees such as Rata (Metrosideros umbellata) occur along the semi-protected hillsides, and provide a shaded understory comprised of a diverse assemblage of ferns, hebe, punui, and climbing vines of supplejack (Ripogonum scandens). However, on islands were ship rats (Ratttus rattus) or Kiore (R. exultans) are present, there is noticeable damage to the native plants. As a result, on islands with rats the understory vegetation is less diverse than on rat-free islands.
Kakariki (photo: Jamie Newman)
This gorgeous kakariki or Red-fronted Parakeet (Cynanoramphus novaezelandiae), currently occurs in lower abundance than prior to the 1964 rat irruption on Taukihepa (Big South Cape Island). Kakariki are cavity-nesting species and thus vulnerable to disturbance from rats, also competition for food must be important in limiting the abundance of this species on rat-infested islands. Thus the tītī restoration project should benefit these birds.
Tieke or South Island Saddleback (photo: Jamie Newman)
The truly inspiring part of this conservation project is the potential for reestablishing the Tieke (Philesturnus carunculatus) on Taukihepa Island once rats are removed. Taukihepa Island was once the last strong hold for this species, which was only found here before the rat irruption and certain eminent extinction of this species was circumvented by conservationists who removed 36 individuals from Taukihepa and place them on nearby Kaimohu and Big Islands. Since 1986, Saddlebacks from this immigrant population have been translocated to several predator-free islands throughout the known historic range, including Breaksea and Ulva Islands.
Blessing of the project, March 2006
insects such as Weta and beetles were more abundant on Tïtï
Islands. Once ship rats invaded Taukihepa, a large flightless weevil (Hadramphus
stilbocarpuae) became locally extinct. Rodents depredate invertebrates
and are especially devasting to flightless forms. Rat-free islands offer
valueable refuges for these species.
Bait Deployment! - July 2006
On July 18, the Department of Conservation, working alongside
local muttonbirders, successfully spread more than 7 tonnes of bait over
the four rat-infested islands off the south-western corner of Stewart
Robert Coote, a birder and member of Ka Mate Nga Kiore says that all parties involved in the project have put in long hours of voluntary work to reverse a major past environmental catastrope.
It's not over yet however as we have just as great a challenge ahead gearing up to establish the quarantine procedure that will ensure the rats will never come back.
Keep the Titi Islands pest-free!
It is important for everyone to be vigilant - Inspect gear before departure to make sure no "stowaways" are on board. Store gear with bait stations. Unpack gear inside a closed room so that if one is there, it can be killed before escaping. Finally, notify a member of the island committee immediately when a rodent is detected on island.
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
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The trans-Pacific pre-breeding migration of 12 Sooty Shearwaters captured and outfitted with satellite radio-transmitters near Pismo Beach, CA Track lines show direct movements from California toward New Zealand and as far south as 60 degrees, near the Antarctic convergence. Tracks shown are from approximately 1 September 2004 to 3 December 2004 (data are ongoing, please visit www.seaturtle.org/tracking or www.signalsofspring.net for maps updated daily).
Courtesy of Collaborators: Josh Adams and James Harvey, Moss Landing Marine Laboratories, David Hyrenbach, Duke University, Cheryl Baduini, Claremont Colleges