Black Petrels: Winner or Loser in the Conservation Game

On 27 October 2015, Sanford CEO Volker Kuntzsch addressed the Hauraki Gulf Forum’s State of Our Gulf Seminar in Auckland. He opened with a picture of himself holding a black petrel chick – inconceivable five years ago when before the same audience, seabird scientist Matt Rayner presented his grim assessment of the risk for black petrels from fishing. The picture he painted then was one of a bird headed for extinction and led us to found the Black Petrel Action Group. Kuntzsch went on to offer to stop commercial fishing in the Hauraki Gulf, which grabbed headlines nationally. But he also said he was glad the black petrel population had stabilised – when in fact the evidence indicates a long-term trend of decline.

This article summaries recent research on black petrel (taiko) for 2014/15 and explores the indicators for long term population decline, looks at the impact of cat predation, and current efforts to reduce the deaths of black petrels through fishing. Finally, we ask the critical question: what more should the Department of Conservation (DOC) be doing to protect this iconic bird?

An average season but habitat literally slipped away and there are worrying trends
This year GBIET secured $15,000 from Auckland Council for ongoing research on taiko breeding site distribution and population, carried out by taiko expert Elizabeth Bell and the team from Wildlife Management International (WMIL). Bell has been working on Hirakimata (Mt. Hobson) monitoring black petrels as they return, breed and fledge chicks since 1996. The team monitors burrows throughout a 35-hectare study area all over this rugged terrain, banding chicks and adults, logging returning juveniles and breeding birds.

Bell reports that breeding success (a fledged chick) was 70% in the study burrows compared to an average of 74% since 1996 – a declining trend despite the number of burrows used for breeding increasing this year. This finding is concerning as all birds reaching the 3-4 year breeding age need to breed successfully for more than 25 years to hold the population stable.

In June 2014, a huge storm wiped out about 15 hectares of black petrel habitat – visible now as massive slips on the SE face of Hirakimata. Some new burrows were found in the study area and elsewhere as a result, possibly dug by displaced birds trying to find a new home, and fights arising over some burrows.

Fewer returned ‘chicks’ were caught compared to last season despite two intensive search periods with trained seabird dogs. Adult survival was higher than in the past, but juvenile survival (for birds 2-5 years old) was much lower. Bell thinks it’s likely that survival of chicks younger than two years is even lower; many do not survive to return to the colony. Of the 2500 chicks banded, only 204 have so far returned (others may have returned but not been recaptured).

Seabird specialists are concerned that the population may “go off a cliff” as breeding age birds die (the oldest recorded is 29 years) and the population is not sustained by returning juveniles.

On Little Barrier (Hauturu), search teams located 90 out of 97 burrows last monitored by researcher Mike Imber in 1997. Breeding occupancy in these burrows was 29.5% (compared to 40% in 1997) and another 13% had been taken over by Cook’s petrels. Twenty-five acoustic devices across Hauturu resulted in 4,230 hours of recordings. The incidence of taiko calls is low and tells us that Hauturu black petrels are likewise not doing well. Hirakimata remains the most important colony.

Getting around – are there black petrels in our back yards?
In early 2015, searches by Jo Sim and her seabird dogs Maddi and Rua covered Glenfern Sanctuary, Windy Canyon, Maungapiko, Whangaparapara, Te Ahumata, Coopers Castle and other areas. They detected active black petrel burrows at all sites, but predators had been there first in many cases. While reassuring to find birds away from the main colony, it was very frustrating to see so much evidence of feral cat impacts. Dead adult birds had wounds from claws or teeth and remains of fledging chicks were found along tracks or outside burrows. Bell reports that there was plenty of evidence of rat predation – eggshell fragments and remains of chicks with rat teeth marks. Disused burrows were also seen, suggesting taiko have been extirpated by rats and feral cats.

In “Bugger” (‘Weaving the Strands’ June 2015), Hauraki Gulf Forum Chair John Tregidga told the story of a chick killed by a cat at Windy Canyon. WMIL host many such visitors, this year including schools (Okiwi and Mulberry Grove), commercial fishing crews, industry leaders, a Labour MP Jacinda Ardern and media. Coverage of the visits was carried by TV3 and Maori TV news, the New Zealand Herald and Professional Skipper magazine.

In mid-November, a large gathering at Windy Canyon welcomed back the birds to Hirakimata. The airfares for Southern Seabirds Solutions (SSS), NGOs and visiting fishers totalled more than the $1,700 budget DOC had for cat control in the colony. The visit was just after two adult birds were discovered killed by a cat. Every breeding adult counts when there are 1200-1500 breeding pairs left. Cats are the biggest terrestrial threat to taiko, so the Trust asked the Minister to urgently look at a solution to control cats in the colony. Minister Barry’s response was disappointing – no funding for cat control this year from DOC – and contained some flawed interpretations of the threat.

Bell feels she was misquoted in the Minister’s response, which focused on the few cat predation events in the study area, and the low cat catch-rate. DOC may think it is doing enough and traps on the colony are not needed, but the data on which this thinking is based only includes Bell’s study burrows. Elsewhere in her report, cat predation is detailed for other burrows. She told us: “I’ve always said that cat trapping on Hirakimata should occur pre-season (Sept-Oct) and pre-chick fledging (April-May) …this is the most valuable use of funding and personnel time”. Bell will now create a dedicated section on cat predation in her reports, highlighting the recommendation she makes every year about continuing cat trapping at these times.

Feral cats killing black petrels: the real story
Cat trapping began on Hirakimata in 2011/12 when four cats were caught. Amelia Geary, the then Biodiversity Ranger on Great Barrier, set up traps on tracks around the summits of Hirakimata and Mt Heale with annual funding of around $4,000. In 2012/13 and 2014/15 no cats were caught and in 2013/14, just one cat was caught – which does not necessarily mean an absence of cats with factors at play such as difficulty in keeping bait fresh (cats like fresh rabbit), other baits used being less successful, and rats eating bait. Bell believes that DOC’s trapping to protect pateke/brown teal in Okiwi (below Hirakimata) has reduced cat numbers on the mountain. She believes feral cats from Okiwi travel up the mountain at fledging time to target chicks before they can fly. She supports the continuation of the Okiwi basin cat trapping programme but not as a replacement for protecting taiko breeding on Hirakimata.

How did DOC come to cease funding black petrel protection on GBI?
What we are seeing here are the consequences of current government policy for a vulnerable species in a unique, nationally significant ecosystem. We have a collaborative response from fishers, scientists, iwi, NGOs and conservationists, a local DOC office trying to do the right thing, and a community motivated to help. What could go wrong? The answers, overwhelming numbers of cats and rats and diversion of DOC’s Great Barrier biodiversity budget to “The Battle for the Birds” (1080 drops over South Island Beech Forests in 2015).

Hirakimata is a key biodiversity site for the Aotea Conservation Park. However there’s something very wrong with prioritisation at the regional level when it has no funding, manpower or a volunteer programme for predator control. For this reason, GBIET had already applied for funding to begin cat and rat control on Hirakimata under a project called Friends of Hirakimata. A big hurdle for a voluntary trust is the capability to manage the health and safety of volunteers or employees. The opportunity for partnership is clear, but DOC has not replaced the vacant partnerships officer role which could make this happen. We understand that local staff understand the need for, and preferred timing, of trapping and want to begin it again – but budget must be found.

Changing fishing practices continues to prevent black petrel deaths
On the positive side, Bell says it has been fantastic to involve the fishing industry. Raising the profile of black petrels helps fishers relate to what they see at sea. She is getting information directly from fishers, including sightings of black petrels and the problems fishers have with birds diving on baited hooks.

The effort going into changing fishing practices is encouraging. In October 2014, this culminated in fishers, NGOs, government, iwi and others pledging collaboration to help black petrels and other sea-birds thrive alongside fishing in FMA1 (North Cape to East Cape). The pledge includes measurable targets and milestones that organisations report on annually. Three work streams back up the pledge: commercial fishing, recreational fishing, and working with mana whenua (Ngati Wai, Ngati Rehua and Ngati Manuhiri). Actions government has taken include the appointment of two seabird liaison officers, roll out of vessel specific seabird management plans, mitigation monitoring and adherence checks, seabird training workshops and ongoing education. We are still waiting on a measurement framework to demonstrate where in the fleet this effort has been successful.

Southern Seabird Solutions (joint funded by MPI, DOC, WWF and industry) continues to target recreational fishers with the seabird smart message. This is challenging because there is little knowledge of the extent of the problem, a huge range of fishing methods, few known mitigation options, and a large, disparate sector. Trustee Emma Cronin has been working for Forest & Bird in this area on Aotea and boat ramp surveys continue via MPI.

It is incumbent on MPI and DOC to embed actions to protect black petrels in fisheries management and annual budgets. The next priority is to understand juvenile mortality when taiko winter in the east Pacific, and to increase engagement with the fishing fleets that operate there. Janice Molloy of SSS has been helping MPI and DOC on this front but we await a specific, outcome focused plan.

Future moves for taiko conservation
Bell’s team are doing more GPS tracking of birds to determine where and when they feed to understand overlaps with fishing fleets. Differences in food availability during the El Nino/La Nina oscillation is another issue Bell is keen to explore. Birds today are lighter than in 1996 with average bird weight falling over time. Birds were about 900-1000g in 1996 vs. 690-700g weights being recorded now. Key research gaps are to understand the reasons for this difference, and why so few young birds return to the colony to breed.

As we go to print, the Trust is using a grant from the Great Barrier Local Board to set up a stop-gap trap network around Hirakimata before chicks leave their burrows in March. This trapping will help protect the main colony, but won’t stop the levels of predation found by Bell’s team, there and in other sites across Aotea.

Taiko has moved the Chief Executive of one of our largest fishing companies. Let’s hope that Sanford’s enthusiasm is shared and that budgets and resource for DOC on Great Barrier start to reflect the importance that iwi, our community, MPI, and the Black Petrel Working Group are now placing on its survival.

References:
• Elizabeth Bell, personal communications 2015 Black Petrel Population Research 2014/5 season, WMIL (see DOC website for details)

• Report of the Black Petrel Working Group, September 2015 (Southern Seabird Solutions)

• ByCatch Bylines, Department of Conservation, Jan 2016.

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Environmental News Issue 35 Summer 2016