Seabirds

Fifteen years ago I was very ignorant indeed about seabirds. When Sue and I helped with our first of I think 11 chick translocations, the first thing I learnt was that seabirds were not all just “seagulls’. Eventually I came to learn from the likes of Colin Miskelly and Helen Gummer that seabirds really are and ought to be pre-eminent in the New Zealand story.

New Zealand is still the centre for seabird endemism: 38 species breed nowhere else and 86 species breed here in total, out of 360 species worldwide. Populations-wise, however, they would once have been a much more dominant feature, before they were all but extirpated from the mainland by predators such as rats, stoats and pigs. Now we think of seabirds as perhaps belonging on rock stacks and little islands, despite a few happy mainland exceptions such as Hutton’s shearwater. I suppose this is yet another example of the shifting baseline idea expounded so well by George Monbiot in his book Feral: in our lifetimes we have thought of seabirds as breeding on islands, sometimes scarce; therefore it was always thus. In the recent past though, there would have been clouds of all sorts of seabirds, circling mainland high points, their nesting and burrowing and bringing food in from the sea and being eaten and dying and decomposing, having the biggest effect of anything on the ecology of the mainland.

We can see what it would once have been like by looking at their island strongholds today- vegetation modified by fertility changes, shrubs destabilised by burrowing, a profusion of life making use of their burrows and their leftovers. It’s no accident that there’s 300 mm of fertile topsoil across the formerly farmed piece of peneplain that is Mana Island, making it easy digging for today’s revegetation teams. A hundred thousand years of seabirds can do that. Ross Webber wasn’t confronted with barren rock on Puangiangi when he established his vege garden and orchard, rather a deep, free-draining, moisture-retentive soil.

Now, I see twenty-something Miss Canterbury on Petone beach (she is a red-billed gull banded red-black at her natal site in Kaikoura on the day of a big Ranfurly shield challenge by a naturalist with a sense of humour), resplendent in perfect plumage on a sunny winter’s day, standing aloof from the lesser of her species who eat chips, and reflect that even “common red-bills” have moved into the Vulnerable category now they have so few breeding sites left. And I’m well aware that there aren’t any petrel colonies on the windy hills around my home in Wellington, the last one possibly having gone about 60 years ago.

The present mainland colonies, natural and translocated, are often reliant on expensive predator management, including fences. We have an opportunity with the Puangiangi project to intervene inexpensively to create another seabird island, with its natural fence.

Puangiangi As a Seabird Island

There’s no doubt that Puangiangi would once have been a smaller version of Takapouwera/ Stephens Island, which even today holds two million fairy prions to name but one species. It was almost not even a discussion point to make seabirds the focus of our restoration efforts, but that decision does come at a cost and does limit what else we can do. Take weka (please): let’s say there were 500 weka on Puangiangi twenty thousand years ago, and 5 million of a mixed mega-colony of fairy prions, fluttering shearwaters, diving petrels, white-faced storm petrels, flesh-footed shearwaters and sooty shearwaters, with sundry outcroppings of half-a-dozen shag species, gannets, red-bills, black-billed gulls, terns, mollymawks, little blue penguins. The 500 weka would be very well-fed through grabbing unattended eggs, nestlings, weakened adults, but they wouldn’t make a huge difference to a population of 5 million birds. Contrast that with the situation in 2012. I estimated the population of weka on Puangiangi as 20 (that was a gross underestimate as it turned out, but 20 will suffice here). Let’s say we were able to re-establish  a colony of 20 pairs of sooty shearwater. If we left the weka there, it’s likely they would get many or all of the chicks each season. Weka are inquisitive with a good sense of smell and are constantly patrolling for new opportunities. Such a seabird colony would not go unnoticed.

Weka at sooty burrow, April 2014. It can just be seen at the end emerging with a piece of down.

If the burrow-nesting petrels lose an egg or a chick, there is no time to re-nest, and of course they can only afford the energy input of one per clutch. Sooties take several years before reaching breeding age also. Therefore, more or less any weka predation would send a nascent colony spiralling towards functional extinction, with only a few pairs of unsuccessfully breeding adults hanging on for any time. So if we were to have a go at re-creating Puangiangi as a seabird island, the weka would have to go. Weka are worthy of protection in their own right and ironically we have funded a project to re-introduce weka to an area of the upper south, so it’s not actually a no-brainer to choose seabirds over weka. However, there are more areas where weka are safe than there are islands where seabirds are safe, so we chose seabirds. Peter was able to secure a permit to catch weka and relocate them to the mainland, so the project was under way from our point of view.

Burrow-Nesters

Burrow-nesting seabirds were holding on on Puangiangi and on Tinui’s southern satellite Takawhero into the 1980s. Ross Webber was well aware of them, and indeed had found a chick and kept it at his house for a short time, trying to feed it on bacon scraps. Visiting field workers, including Peter, had found remnant sooty colonies in the southern and north-eastern forests and Peter brought out a predator trap for Ross to deploy in the southern colony. We found the remnants of the trap during May 2012. But, as the rats slowly got on top of Ross, they slowly got on top of the sooties. It’s highly predictable that sooties would be the last burrow-nester there: they are bigger and feistier than the fairy prions, fluttering shearwaters and diving petrels that are generally more common in Puangiangi’s latitude, and would be a match for a rat or a weka coming down a burrow, leading with its head. That protection would extend to incubated eggs, but after the egg hatches and the adults leave the nestling for longer and longer periods to go as far as the Polar Front to gather food, then the insidious numbers game of predation begins. That game was over perhaps a hundred years ago or more for the smaller and comparatively defenceless petrels and prions, but sooties hung on longest, before being wiped out or driven away.

Takawhero
Takawhero, centre left, from Puangiangi. Sooties present in 1980s, current status unknown.

Ross was pretty clear in conversation with Sue and me that he considered the sooties to be present to this day, but Peter and I looked for the old southern colony during what would be peak fledging week in May 2012. We should have found the old burrows to be clean, with squirts of bright white droppings away from the entrances, clean beaten ground from all the comings and goings and gardening, and a distinctive smell to the burrows. Instead we found cobwebby burrows, drifts of leaves blocking others, penguins in some others and weka following us around. We were to be starting from scratch, but of course the island was at least rat-free thanks to the efforts of 1999 described in another article.

So, let battle commence. It’s an important job every trip to catch as many weka as we can fit into the pen Dad built for them in the shed. Once in the pen, they get to forage for insects and worms in the leaf litter we bring in, and eat specially prepared meals and our leftovers- cheese, pasta, eggs, blue cod frames. In reality they mainly occupy themselves knocking over their water, trying to escape and staring balefully at us when they jump on to the top of the sacking we have hung as little refuges for the more timid weka to hide from their more aggressive brethren. We try to limit catching to near the end of a trip so we hold them for as short a time as possible, and they are largely very resilient. To start with, we transported them in cardboard or Corflute carry boxes, but after a near miss with one in its box almost being blown over the side of Aston’s barge, and the fact they just would not settle in the boxes, scrabbling around the whole trip into Garne and Saville Scenic Reserve, Claire made up some heavy canvas bags with tie tops. Like most birds, they settle well in the dark of the bags, even travelling two-up without incident if we run out of bags. At the release point they are tipped out of the bags and they orient themselves and run off impressively. We removed the 100th weka early in December 2015 and several times have thought we have gotten the last one. I’m still aware of a very few as I write though.

At the start of this article, I said we have helped with some chick translocations. These are intricate processes developed here by our endangered seabird scientists (ambiguity deliberate).  Almost every individual of each species of burrow-nesting seabird returns to nest in its natal colony, often coming back after however many years they spend at sea before beginning to breed, to within a few metres of where they were born. This fixing on their natal colony is thought to be learned during the nights (1-20 or more depending on the species) they emerge from their burrows to exercise wings and shed down and weight before they fledge. Only through over-population at a colony (unlikely these days) or in rare individuals with inclinations for wandering beyond the norm, or through some not-yet-understood at-sea interaction with others, will dispersal occur. The simple act of grabbing an adult and putting it in a hole somewhere else will in no way over-ride this loyalty to the natal site. People have tried- the adults fly back. However, moving chicks before they develop site loyalty, and feeding them until they fledge, might induce those birds to return as newly minted breeders to the new colony.

Chick translocations have been done with many species of petrels in New Zealand, many successfully. People like Brian Bell and Graeme Taylor practised on common species first, refining techniques so that endangered species like taiko and Chatham petrel could be tackled with justified optimism. Realising that canned sardines (whizzed up with water and fed by syringe) were a transportable, non-perishable means of approximating the chicks’ natural diet, expanded the type and remoteness of site which could be considered for the technique. People with attention to detail, like Helen Gummer, came to tailor the feeding regime individual by individual- not just sticking to a species template- by careful weighing and  measuring in the field as each project ran its course. Building up the numbers of trained people, such as Sue, means that chick translocation is now mainstream thinking for ecological restoration projects where common petrels are the target, and for work with the endangered ones too.

Chickfeeding
Sue feeds Chatham petrel chick, Sweetwater Conservation Covenant.

The typical three-year cycle of translocations is costing around $60,000 plus whatever notional price one wants to put on the volunteer chick-feeding labour. The maximum number of chicks that can be handled at a new site is about 240, with a target return rate of about 30% after however many years it takes for the species to reach breeding age. An analysis of the completed translocations around the country, however, indicates that many sites are going to need top-ups to give the new populations a statistically good chance of becoming self-sustaining. Funders and community groups should be thinking of a decent six-figure sum and bulk volunteer wrangling for a completed translocation project.  Puangiangi’s remoteness and difficulty of access and getting around suggests that chick translocation would be marginally achievable at best. Also, the community engagement plus of having large numbers of volunteers involved is not relevant for us. We have initially plumped for an alternative:

Speaker systems to attract seabirds are now a reality around the country. We’re up to our seventh I think, installed on the Kermadecs, Wakaterepapanui in the Rangitoto group, and now Puangiangi. A solar panel charges a hefty battery and, at night or in the daytime depending on the species being targeted, the solid-state electronics inside a waterproof case play the tracks on a sound card through 350-watt outdoor speakers. The systems now cost under $2500 and they require little, although not zero, maintenance. If they work, they attract adults, obviating waiting out the 2-8 years for translocated chicks to return as breeders.  We thought that Puangiangi would be a good candidate for the speaker method, what with a sooty colony not long gone with perhaps a few adults still alive that were born there, and large colonies of fairy prions to the north on Takapourewa, some of which might be enticed south.

The first site chosen was obviously to be near the bigger of the old sooty colonies, and we put up the speakers at the upper edge of the southern forest. It was a long, hot walk to carry in the heavy and awkward gear from the shed and we were grateful for the help of Roy Grose and Chris Birmingham from DOC, who were visiting us to catch up with Peter and to eyeball me. Sue and I were a bit worried that good intentions by DOC to assist us with the project might become subsumed by other priorities over time, but these immensely capable people gave me great confidence from the beginning of this project. Chris was at the time working nearby on Maud Island but has regrettably left for Te Anau to a dream takahe job along with his partner Linda Kilduff and new baby. Roy is sticking it out through the endless restructuring of DOC and still works in the region albeit with ever larger responsibilities.

Peter and I put in some starter burrows in the grass around the speakers and turned the system on, the sound card carrying recordings of sooty shearwater, fluttering shearwater, fairy prion and diving petrel. We gave visiting botanist Barbara Mitcalfe a demonstration and she thought it an awful cacophony, but it seemed to work for the birds. We also rigged up a trail camera and hooked it up to the cellular network through a big Yagi aerial fixed high up in a nearby akiraho. At 1 AM on 3 December 2012, a month after the system went in, I got the first photo (at the head of this article) sent to my phone back in Wellington, of a sooty shearwater on the ground.

The site saw quite a lot of activity. During March-April 2013 for example, the camera recorded birds on the ground on 15 of 56 nights monitored. We identified sooty shearwater, fluttering shearwater (two on the ground simultaneously several times) and probably diving petrel.

composite
Trail camera stills showing sooty shearwater, fluttering shearwater and diving petrel at the speaker site, 2012-13

One strange observation was a morepork/ruru having a go at a small petrel on the ground next to the speaker system. Did we encourage unusual behaviour or are ruru expected to be predators at seabird colonies?

Ruru attacks petrel on the ground, April 2013.

On the strength of these results we got another two sound systems. One was installed at lower altitude than the active one, at the edge of a tussock/ salt turf area which looks ideal for smaller petrels to dig burrows. The best we managed in two years there was some feathers and, separately, half a diving petrel. There was no sign at all of burrow construction and we have since shifted the speakers to above Boatshed Bay and put in a gannet tape.

A third system has been put in at the north end, within earshot of any of the millions of petrels on Takapourewa that might fly a few km south when  foraging. Cameras showed a good rate of visitation by fluttering shearwater, and we promptly added some shearwater decoys to help things along. The initial fluttering shearwater model was beautifully made for free by Richard de Hamel and then a two-piece fibreglass mould taken from that. Peter spent wet evenings in the shed on Puangiangi making resin shearwater halves, which were then glued together and painted. They look great, but to date neither they nor the speakers have enticed anything to occupy burrows at the site.

Decoys
Peter installs the decoys at northern speakers, January 2014.

In early December 2013 we returned to the original speaker site and found breeding sooty shearwater. There was a newly-refurbished look to the old natural burrows, and we found a couple of occupying birds at great cost to Peter’s arm. We installed some trail cameras on likely burrows.

A pair of sooties at their burrow entrance. Egg-laying season December 2013.

In January we went back with a burrowscope, courtesy of Nicky Nelson at Victoria University, and found 16 incubating birds.

After the chick hatches, the parents alternate between incubating and heading to sea to get food for themselves and their chick.

Adult sooty arrives presumably with food, March 2014.

As it grows, the chick is left by itself for longer periods. At the colony we recorded the longest time between feeds as 10 days.

First emergence, April 2014. This chick obviously survived the weka intrusion shown near the beginning of this article.

A few minutes later- had enough. Chick at maximum weight, fortunately.

The number of active burrows dwindled away during summer and autumn though, and three chicks got to the stage where they came to the surface at night-time, exercised their wings, shed down, lost weight and eventually took off in early May.

Exercising wings on a rainy night, April 2014. Most down has been shed. (The date on the camera was wrong).

Helen Gummer points out that this might be the first successful example of acoustic attraction of sooty shearwater which have gone on to (re-)found a breeding colony. The colony looked forlorn during 2012, and we first noticed adult sooties in December 2012, a month after the speaker system was installed. The burrows were obviously active the following season (beaten earth, smell, clear burrows and so on) and I don’t think I would have been so stupid as to miss such signs in 2012.  In possible support of this claim, we also found an old sooty burrow grouping elsewhere on the island away from any speakers, and there has been no activity there, despite weka pressure all but vanishing island-wide.

The 2014-15 season gave a similar low fledging rate from about as many nesting attempts. We can only speculate on the reason- inexperienced breeding birds seems likely, as they should be the ones pulled in by the speaker system. An undetected predatory animal on the island would surely have left a mess, which we did not ever see. At-sea factors may have also influenced the fledging rate; poor results have been seen elsewhere when possible changes in sea temperatures, say, have caused food supplies to dwindle or move to different areas.

As the 2015-16 season starts we can report 16 birds on eggs, from a total of 28 GPS-mapped burrows which have held birds at some point over the last three years.

We plan on disturbing the colony as little as possible and are not intending to band the chicks or the adults. We do want to know the fledging rates each year and to get an idea of the population trend. I guess we are also not completely certain that they are all sooties. Many of the larger petrels seen at sea nearby are flesh-footed shearwater, which breed at the same time, so a mixed colony may be possible. Either will do just fine. They are easily told apart but burrowscoping is limited to confirming that a sooty-sized petrel and not a penguin is in the hole.

Other Seabirds

Red-billed gulls live in the area seasonally, feeding on schools of small fish and concentrations of crustaceans. Once we saw a little bay on the eastern side with red-bills all but walking over one another to feed on some crustaceans which had filled the bay. Red-bills don’t breed on Puangiangi and we don’t have any idea which breeding colony they come from. They have contributed to the nesting success of the resident pair of karearea though. Their 2014 nest was littered with the beaks and feet of red-bills, the only pieces they didn’t seem to have eaten. Red-bills are not far short of the size of the smaller male karearea and if they had caught them close to the sea, it must have been a feat to carry them to the nest site at about 60 m altitude.

Black-backed gulls are quite common. A pair of reef heron is often seen, as are white-fronted tern, the occasional Caspian, and various shags such as king, little, pied and spotted. There is a thriving breeding colony of spotted shag, spread out from the northern tip of the island and along the eastern side, nesting adults and young being seen from the sea in crevices in the cliffs.

Little penguins seem to be common, and they are encountered at the sooty colony and all around the island. They also nest under various man-made structures such as Ross’ house and one of his old pottery kilns, which is housed in a converted mussel float.

None of these birds seems to need human interference, but we are trying to establish a breeding colony of gannets. Their regional breeding colonies are thought to be full and thriving and they are often seen fishing in the area. A grouping of generic fibreglass boobies, sourced commercially and painted up in Australasian gannet colours by Peter, has been set up above Boatshed Bay, on what we hope is an attractive, clear site. A speaker system broadcasts the sounds of a gannet colony from dawn to dusk, and indeed we did seem to have some early success. Peter was checking the speakers and I was looking down from the spur, frantically signalling to Peter that he should look behind him. A gannet was there and unconcerned at being a metre behind Peter. We took it as a sign that the decoys were good ones, on two counts. A gannet was also filmed staying overnight but there has been no nesting so far.

Gannets
Not a bad likeness. Spot the real one.