Dive, dig, fly thousands of miles

An update on our endangered Black Petrel

by Kate Waterhouse

Can you fly to Peru and back, dive 34m to get a feed, dig out a burrow with your bare beak and claws? All in a year’s work for Great Barrier’s little known hero. But what are we doing to make sure it survives our generation?If, at the age of 4 years, you are one of the one in ten black petrel chicks that ever makes it back to the colony high on Hirakimata/Mt Hobson to breed, then you are tough. Very tough. The latest population research tells us you are likely to be much lighter than birds who came before you – just why is not clear but it’s likely that lack of food is a factor. Adding to the odds against you, next October when you return to your potential burrow site it may not be there – thanks to the storm of June 10h which caused massive slips on the mountain. So you will have to search around for another, or make the decision not to breed this year. If you do find your mate, dig out a burrow and if an egg is laid, you’ll spend over a month incubating it, taking turns to fly out to the continental shelf, or even as far as Norfolk Island or the Australian coast to forage. Once the chick hatches it has a voracious appetite so you’ll need to make more and more foraging trips like these to feed it and yourself. Finally in about April or May it will be time for tough love. You leave your chick and your mate and fly east across the Pacific to the coastal waters of Peru and Ecuador for a winter holiday, until October. Your chick will spend its evenings stretching its wings until it is hungry and strong enough to lift off a launch rock in the bush and head east itself. It might crash land on a Barrier road on its way out and it has a 90% chance of never returning. Why, again, is not yet understood.

Updated risk assessment still puts black petrel at the top of the list.
In 2011 alarm bells rang when the first comprehensive risk assessment was completed for seabirds in New Zealand. Based on their interactions with fishing, black petrels were the most at risk bird we have. Black petrels chase or dive on squid baits used in longline fisheries and can be hooked and drown. The Ministry of Primary Industries (MPI) has just completed a revised risk assessment, which includes a number of alterations to the source data and parameters of the model. Despite this, the risk is still extremely alarming for black petrels – 20 times the PBR (Potential Biological Removal) or 20 time the rate of bycatch that the species can sustain. When combined with low juvenile survival (less than 90% survive to breeding age of 4 years), this means black petrels are on a path to extinction if no action is taken.

Not included in the risk assessment as yet, is spatial or gender data (anecdotally, male birds are thought to be more aggressive feeders around boats). This data is important to understand exactly where in our waters the likely overlap is between the foraging habits of black petrels and commercial fishing effort. Geospatial data collected this year shows concentrated foraging along the continental shelf between the Three Kings and East Cape during the critical early chick rearing stage in February and March. If a bird is caught at this time the adult and chick will both die as the remaining adult can’t provide enough food for the chick to survive.

To date, no changes to the risk assessment parameters have made any difference to the risk priority of black petrels – they remain number one.

Dying young – are black petrels heading for a population crash?

The overall population estimates based on the work of Elizabeth (Biz) Bell and others, show that black petrels are in slow decline. However there is concern amongst seabird specialists that the population may “go off a cliff”. This is because breeding age birds (the oldest recorded is 29 years) will slowly die off and the population will simply not be sustained. Bell’s view is that main risk is the sheer number of juvenile birds or “pre-breeders” killed at sea before they reach breeding age of 3-4 years. Return rates of these birds to the colony are very low – of the 2500 chicks she has banded only 225 have so far returned to breed.

In 2013/14, low numbers of returning birds and an average breeding season told a familiar story. Bell reports that her team monitoring the colony found overall lower numbers of returning birds and 72% breeding success vs a mean of 74% since studies began in 1996. Breeding success varies – between a low of 61% in 2011 and 81% in 2013. The team noted the large number of chicks that “disappeared” between February and April. The researchers found no evidence of predation so the causes are unclear.

In April Eli and I walked up Hirakimata with our packs on our backs to the DOC hut called the Rat’s Nest, where we stayed with two scientists Claudia and Calvin for the next three nights. We were going to assist them for the next few days to retrieve and band black petrel chicks. When we weren’t looking for koura in the mountain streams or talking back at camp we were working with Claudia and Calvin trekking around the never ending steep slopes, putting our arms into burrows to retrieve and band yet more endangered chicks. Over that period we discovered many awesome natural displays such as electric blue mushrooms and fuzz-covered chicks.
I hope I get to do this one more time before I go to high school. Eli and I would like to thank Claudia and Calvin for this great opportunity.
Taric Speir
P.S. My favourite thing about fledging chicks is that their hair style is never the same twice.

One trend that is evident to Bell is that birds now are lighter and the average bird weight is falling over time. She observes that birds were about 900g-1000g in the first years of study vs 690-700g weights being recorded now. Unfortunately weight data is not always recorded and this is an area of potential future research. Understanding the reasons for this and “poor juvenile recruitment” (why less than 10% of fledged birds return to the colony to breed) are key and both are big research needs.

Diving!
This year the research team recovered dive depth recorders attached to breeding birds. One female bird recorded a huge maximum dive depth of 34m – significantly higher than the previous 20m black petrels were thought to dive to – and for 75 seconds (don’t try that at home). But these deep dives are the minority, with 94% of dives to less than 5m depths. Most birds record lots of shallower dives (presumably for squid) and the odd deep dive, chasing larger prey. Daytime feeding was the norm, with 84% of dives made during the day and 16% at night. Some recorders are still on birds that have left the colony for winter and these will be collected next year to add to the research. This will help give guidance to fishers on how deep longline hooks need to be below the surface to ensure birds won’t reach them.

Black petrels return to old trees: Glenfern Sanctuary’s success and making connections with Peru.Recently some fishers have suggested that there might be an undiscovered colony of black petrels somewhere, thus accounting for the numbers of black petrels sighted off the North Island’s east coast. But such a colony would have to be in unmodified or mature forest, probably on ridgelines and likely where there are no cats, stoats or pigs (which are known to root up burrows and eat the contents). In fact while there may be perhaps 200 birds nesting on Little Barrier Island, which has been predator free for more than 10 years, there is very little of such forest left anywhere in the North Island and almost none that is predator free.

The importance of mature forests for black petrel breeding is clear, as the astonishing return of birds to old burrow sites at Glenfern shows, now that rats, cats and pigs are not present. Imagine how seabirds find such places – how they see the forest canopy from the air, marking out the puriri and other large trees with root systems and soils suitable for burrow sites.

This winter Emma Cronin of Glenfern Sanctuary, will travel to Peru on a Churchill fellowship to work with local schools to raise awareness of the plight of black petrels. It is thought many birds are killed in the fisheries of the East Pacific but very little is known about why or how. Emma has designed classroom materials and a game for kids that traces the life of black petrel chicks and juvenile birds as they grow from giant balls of grey fluff to sleek black instruments of the wind roaming the Pacific.

Collaboration improves between fishing industry and environmental groups Southern Seabird Solutions (a seabird advocacy body funded by DOC, WWF and the fishing industry) has set up a working group on seabirds and fishing in FMA1, (Northeast of Great Barrier Island) with representatives from all sectors which has met in March and June. The primary goals were to bring everyone up to a common understanding of the problem and to create better information flows between scientists, fishers, Forest and Bird, WWF and the Hauraki Gulf Forum, working on seabird conservation. The response from fishers to collaborative process was positive, but concrete results in terms of “back of the boat” changes to longline fishing practice are needed from this process for it to benefit black petrels. Meanwhile, SSS continues its engagement with fishers in the main ports around the gulf on seabird smart fishing.

So what is the government doing to save the black petrel — and is it a priority?

While progress has been made, the Ministry of Primary Industries (which manages our fisheries) appears to be inadequately resourcing reducing seabird mortality. Ongoing intent to change outcomes for black petrels is yet to be established. MPI’s Inshore fishery seabird coordinator left in May and has yet to be replaced, so external support has been sought from Janice Molloy of Southern Seabird Solutions (SSS) to maintain momentum. While response to black petrel risk has slowed in 2014, many building blocks are at least now in place. These include:

1. Intention to draft a Black Petrel Action Plan – to reduce black petrel deaths from fishing and increase use of better fishing practices in FMA1 (NE of the North Island) in the longline fleet, where most risk exists for black petrels. There is mixed news here – under the National Plan of Action for Seabirds (NPOA) Species Action Plans will now be prepared for all high and very high risk seabirds, including black petrels. Where there is significant overlap in range between species, multi-species plans will be developed. This means the long overdue Black Petrel Action Plan first promised a year ago will now be black petrel/flesh-footed shearwater plan. “Fleshies” as they are known, look very like black petrels in flight and have a colony on the Hen and Chickens but the population has dropped significantly in recent years. But unlike black petrels, fleshies breed elsewhere and are not as vulnerable to extinction, so this represents a backwards step for the black petrel if it causes further delays. Action plans are intended to address the cumulative effects of different fisheries on a species, but the majority of risk for black petrels is in one only – the bottom long line snapper fishery.  There is as yet no sign of a draft plan for black petrels.

2. Liaison officer programme – believed by MPI to be successful in their first trial season, two roles are improving awareness and knowledge across the fleet. Vessel Management Plans for 26 boats in the FMA1 fleet were completed, providing some guidance to skippers on avoiding and dealing with seabird mortality. 25 charter skippers were also covered from Gulf Harbour, Leigh and Whitianga. Measurement of outcomes from these plans is needed to assess what difference this will make for black petrel survival.

3. Observers on boats in fisheries at high risk to black petrels – where observers are on board a boat and record what interactions with seabirds occur while fishing and the mitigation used or not used. Actual days were lower than target and coverage was lowest in March which is a peak danger period for adults feeding chicks staying close to the colony. Only 18% of fishing effort was covered vs a target of 30%. Getting observers on smaller boats is an ongoing problem and MPI is looking at using cameras to address this. Skippers on some boats reportedly “turned around” (their attitudes to seabirds) following this season’s work and the reputation of observers improving in fleet. But observer days will fall in 2014/5 which with focus shifting to the politically sensitive SNA1 trawl fleet.

4. Camera trials on boats – these are happening on 10 trawlers to monitor mitigation and seabird interactions, extending 5 months from May 2014. Cameras are used in Australia and must be well positioned to cover bird captures - and well maintained. It may not be clear in FMA1 whether a bird caught on camera is a flesh footed shearwater or black petrel.

5. Research – risk assessment and population research continue to be funded by DOC, Ministry of Primary Industry and the fishing industry, but to some close to black petrel research, this is akin to shutting the door after the horse has bolted. The cost of the observer programme dwarfs the investment being made in known gaps in understanding that could materially change the numbers of birds caught. These include more comprehensive geospatial and dive depth research and crucially, causes of death for young black petrels – such as food availability, climate change and deaths in fisheries outside NZ waters.

Environmental News Issue 33 2016