Riders of the storm – thousands of seabirds perish on New Zealand shores

It started as a trickle and soon developed into a flood of devastating proportions. On 11 July 2011 I received an email enquiry from a family at Waikanae seeking help with identifying an unusual seabird that they had found dead on their driveway. It was a Salvin’s prion, a not-too-unexpected discovery near the coast during a winter storm. But the next day a Department of Conservation colleague phoned from Masterton reporting a dozen live prions found scattered inland in the Wairarapa, on the sheltered (eastern) side of the Tararua Range. If that number had reached the leeside, what was happening of the exposed western coast? It didn’t take long to find out.

By 14 July over a thousand live prions had been handed in to wildlife care centres in Wellington and Manawatu, an alarming number given that during prion ‘wrecks’, only a tiny fraction of the birds are still alive by the time they reach land. But what is a prion? and why do they wreck?

Fig. 1. Some of the 660+ stranded prions delivered to Wellington Zoo. These are all broad-billed prions. Photo: Colin Miskelly. Copyright Te Papa

Prions (the singular is pronounced ‘pry-on’) are a group of six small closely-related seabirds that are hugely abundant in southern oceans. They are petrels, and like most petrels, typically breed in enormous colonies on remote islands free of introduced predators. They should not be confused with the other use of the word (in this case pronounced ‘pree-on’) used for a particularly nasty group of infectious proteins that cause the brain-wasting Creutzfeldt–Jakob disease in humans, plus mad-cow disease, and scrapie in sheep.

All prion (bird) species are very similar in size and plumage markings, with the most obvious difference being bill shape, which varies from broad through to narrow or chunky. Within this continuum of variation, some pairs of species are very difficult to distinguish from each other.

Fig. 2. Bill shapes of four species of prions. Left to right: broad-billed prion, Salvin’s prion, Antarctic prion and fairy prion. Photo: Colin Miskelly. Copyright Te Papa.

The three species with the widest bills have prominent lamellae (comb-like structures) along the edge of the upper mandible, used to filter tiny crustaceans and other small animals and their eggs from sea-water. When combined with a muscular tongue and an extendible pouch below the bill, these adaptations recall those of baleen whales, which feed in a similar way. Perhaps this is why prions are sometimes referred to as ‘whale-birds’.

Fig. 3. Lamellae (comb-like filters on the edge of the upper mandible) on a broad-billed prion. Photo: Colin Miskelly. Copyright Te Papa.

Prions are well known to New Zealand birdwatchers, even if they are frustratingly difficult to distinguish at sea. Members of the Ornithological Society of New Zealand have for many years patrolled the New Zealand coastline recording the numbers and identities of birds cast ashore. For many, this is the only way to become familiar with prions, particularly in those years when large multi-species wrecks occur. The results of these ‘beach patrols’ are occasionally published in the OSNZ’s journal Notornis. Between 1960 and 1996, over 86,000 prions were found dead on New Zealand beaches; large wrecks occurred in 1961, 1970, 1974, 1975, 1984-86 and 2002, with over 10,000 birds cast ashore in 1974, 1985 and 2002. Earlier wrecks occurred in 1878, 1918 and 1932.

Like all petrels, prions are true seabirds, spending their entire lives at sea apart from the 4 months when they are tied to a nesting burrow and the care of their single egg and resultant chick. At other times they are constantly on the move, often in vast flocks, skimming the waves of the southern oceans in search of productive upwellings. Although frail-looking, they thrive in a part of the globe renown for strong winds. Until they encounter land…

Fig. 4. A flock of Antarctic prions near South Georgia in the South Atlantic Ocean. Photo: Colin Miskelly. Copyright Colin Miskelly.

Prions move with the wind, using the varying airspeeds on the windward and leeward sides of waves to fly long distances with great energetic efficiency. There are few land masses in the southern ocean, and it is usually easy for flocks of prions to slide around the few obstacles that present. Except, that is, for the 1500 km coast of New Zealand. For ten consecutive days in July 2011, persistent westerly gales in the Tasman Sea pushed prions against New Zealand’s western shores. To start with, the birds moved effortlessly with the wind. Then as land loomed, they started to fight the wind, trying to stay offshore. But the relentless gale continued, consuming the birds’ energy until they were exhausted and driven ashore in tens of thousands.

Although there is a long history of prion wrecks on New Zealand beaches, the scale of the 2011 wreck is unprecedented. Far more prions have been killed in this single event than the 37-year total recorded by the OSNZ. Details are still being collected and collated, but large numbers have been found from at least Dargaville to Okarito, 900 km apart. In places they have stranded at rates over 400 birds per kilometre of coast. And that ignores the birds blown inland.

Even more alarming is that nearly all the birds are broad-billed prions (91% estimated), a locally-breeding species. The two previous largest wrecks of broad-billed prions were between 1100 and 1400 birds. It will be difficult to estimate the full extent of the 2011 wreck, but it is likely to be up to 250 times larger than either the 1961 or 1974 events.

Fig. 5. Beach-wrecked broad-billed prions, Paekakariki (Wellington west coast), 16 July 2011. Photo: Colin Miskelly. Copyright Te Papa.

Desperate efforts are being made to save some of the birds, including a combined total of over 1000 being hand-fed at Wellington Zoo and Massey University. As the birds are exhausted and emaciated from their struggle against the gale, it is terribly difficult to revive them, and hundreds of those delivered have since died.

Fig. 6. A rescued broad-billed prion being fed at Wellington Zoo. Photo: Colin Miskelly. Copyright Te Papa.

The 2011 prion wreck will have wreaked a terrible toll on the New Zealand broad-billed prion population. The species also occurs in the South Atlantic, but the birds in New Zealand waters are thought to come from the breeding populations on the Chatham Islands, Snares Islands, and islands around Stewart Island and off the Fiordland coast. Apart from the 330,000 pairs estimated on Rangatira Island in the Chatham Islands, none of these other populations are thought to number more than a few thousand pairs. The total New Zealand population is likely to be little more than a million birds, and so the tragic deaths of (probably) several hundred thousand of them will have a huge impact, especially if the birds in the Tasman Sea were mainly from the less numerous southern (non-Chatham) populations.

Fig. 7. The calm before the storm – healthy broad-billed prions on Kundy Island, off Stewart Island, March 2011. Photo: Colin Miskelly. Copyright Te Papa.

Other blogs on this topic:http://birdsnews.com/?p=264Riders of the storm – the severely depleted next generation

19 Responses

  1. Robin Elaine

    this is sad. i ran across this looking for an island near Stewart (can’t remember name right now) that an internet friend, dear friend, from queensland said his family owns some of the island. his name is colin too. well this is sad and they are adorable birds such cute heads and i see why they call them whale birds. just precious. awful weather to do these things. blessings to all who fight for nature and our planets future. it seems we’ll either make it or break it and time is running out if only a few are doers. seems it is time for humans to completely and collectively live up to their true abilities as guardians of this precious blue planet. are we that good? i hope so. awesome blogs!!!

    Reply
  2. About Snakes

    This is very sad..i hope this guys rebound soon

    Reply
  3. Colin Miskelly

    Kathy’s photographs were of a common diving petrel. Diving petrels were a minor component of the July 2011 seabird wreck, with about 1 bird picked up per kilometre of beach (cf. 200+ per kilometre for the prions). There are few data from West Coast (South Island) beaches, where Kathy found her bird, but it is likely that over 800 diving petrels perished on North Island beaches, compared to several hundred thousand prions.

    Diving petrels are often found dead in large numbers on New Zealand beaches, with the largest number found between 1943 and 1988 being 3593 in 1975. Typically 100-400 are found per annum, and so the 2011 mortality will be above average, but not exceptional.

    Reply
  4. Colin Miskelly

    Hi Kathy

    Thanks for the feedback. Please send me the photos. There were diving petrels affected by the same mortality event, but not to the same scale as the prions. I may add some more detail after I have seen your photographs.

    The Te Papa bird team has now received many hundreds of prion specimens from around the country to identify (some of the species are very difficult to distinguish), and to select specimens for long term preservation. It might be a few weeks before we complete this, but I intend to post another blog on this topic in due course.

    Reply
  5. Kathy Gilbert

    Yesterday I found a 20cm dead petrel on the beach 10km south of Ross in South Westland where I live. I don’t think that it is a prion as there is no white on the face above the beak. It looks more like a Common Diving Petrel but I am not skilled at giving identity. If anyone is interested I can send photos of it. I have never found one like this before. Would a Common Diving Petrel suffer from the same stormy sea conditions as these Prion? Very interesting blog thanks Colin. DoC Hokitika referred me to it. Kathy

    Reply
  6. R Bell

    Just read this:
    “The scale of the 2011 wreck in unprecedented,” said seabird scientist, Dr. Graeme Taylor from the Department of Conservation, who was carrying out research at a Grey-faced Petrel colony at Bethells Beach on the west coast at the time (he was reporting the event on Birding-NZ ).

    He picked up 589 dead birds over 2.5 km of Bethells and O’Neills beaches (west coast north of Auckland). All were prions except three Diving petrels and a Blue penguin.

    Read more at Suite101: Devastating Seabird Wreck Affects Prions in New Zealand | Suite101.com http://www.suite101.com/content/devastating-seabird-wreck-affects-prions-in-new-zealand-a381664#ixzz1TpmcZyOV

    Reply
  7. R Bell

    I found aat an estimate about one hundred at Bethells Beach west Auckland where I live. Didn’t think anything of it until i found the same birds in the same concentrations at Raglan beach Waikato a week later.

    Reply
  8. Gay Everitt

    A media message could be generated immediately an event like this occurs, to warn people of the danger of running over birds on roads, because they do not fly off as gulls do at an approaching car. So many more could have been saved if there was public awareness of their plight.

    Reply
  9. Colin Miskelly

    Thanks for persevering Viola – I am glad you found it eventually.

    We welcome feedback on ways to improve the Te Papa website. It would be very helpful if you could provide some more detail about what you were looking for, and where the barriers were.

    Firstly, did you know that you were looking for a blog? If so, did you find the blog page difficult to find on the Te Papa homepage?

    If you got to the blog page, did you find it difficult to search for the archived blog that you were looking for?

    And finally, if you did not know that you were looking for a blog, was the information that you wanted difficult to find from the Te Papa home page? If this was the case we could look into whether the generic home page ‘search’ tool also searches for words used in blogs, as well as the wider Te Papa content.

    If you would like to continue this discussion offline, please email me at:
    colin[dot]miskelly[at]tepapa[dot]govt[dot]nz

    Regards
    Colin

    Reply
  10. Viola Palmer

    Hi Colin,
    I tried to find this blog through the Te Papa web site, without success. It was not until Jean Luke told me to look under Te Papa broad-billed prions that I found it. Is there a way of making it easier to find on the Te Papa web site?
    Viola

    Reply
  11. Colin Miskelly

    Thanks for your comments Geoff

    There are many lessons that could be learnt from this severe mortality event in relation to conservation principles and practices, including the increased vulnerability to stochastic events (e.g. severe weather) as natural populations are reduced in size and distribution through human impacts.

    The challenge is telling the stories to the right audience, in a way that the message is heard.

    It will be difficult to estimate the number of birds killed during 5-14 July, as the only quantified data will be from short sections of coast, with no way of estimating numbers blown inland. Even on the coast, the sheer numbers of birds was overwhelming for the members of the Ornithological Society of NZ who contribute data to the Beach Patrol scheme, meaning that it often took all day to clear and identify birds from only 1-2 km of beach. Long stretches of coast weren’t even visited.

    Regards
    Colin

    Reply
  12. Geoff Davidson

    Hi Colin
    There are three broad-billed prion corpses that I have found in Oratia, West Auckland but east of the Waitakere ranges. Presuming they were blown over the ranges and landed 300 metres apart it is frightening calculating the loss over the whole country. I fear the 350,000 calculation may be way too conservative.
    Can the disaster be made more public and used to show the vulnerability of our bio-diversity?
    Regards
    Geoff Davidson

    Reply
  13. Colin Miskelly

    Thanks for looking Nikki
    Regards
    Colin

    Reply
  14. Nikki Peterson

    I’m so sorry. We did take some on my phone but I deleted them over the weekend when I first thought that they weren’t useful to anyone as people already knew they were there.

    I’ve tried to retrieve them but with no luck I’m afraid.

    Regards, Nikki

    Reply
  15. Colin Miskelly

    Thanks Nikki
    I would be interested to see photographs of the two different birds if you have any.
    Regards
    Colin

    Reply
  16. Nikki Peterson

    My partner and I were walking from Makara Beach on Sat 16th July 2011. We only spotted the dead birds at the base of the unsealed road leading from the hill top to Opau Bay. From there we counted 500 dead prions before we couldn’t count any longer around the point where Opau Bay turns into Wharehou Bay. We did see more from there right along to Makara Beach. Here the lady in the cafe confirmed that they were prions and had died after becoming exhausted trying to fly in the recent storms. A friend who works for DOC thought this would be useful information to share with you. There were 2 other birds amongst the 500 that looked different – possibly Gould’s Petrels.

    Reply
  17. Colin Miskelly

    Thanks for your comments Barbara. The only broad-billed prion population in New Zealand that receives any level of monitoring is the largest population, on Rangatira (South East) Island in the Chatham Islands. Ironically, the prions there are monitored solely in relation to their impacts on another rarer petrel species (Chatham petrel) that loses out to the much more numerous prions in competition for nesting burrows.

    To give some indication of the lack of monitoring of broad-billed prions, I would be astounded if a single banded (leg-tagged) broad-billed prion was found among the hundreds of thousands that have been killed in this mortality event.

    Regards, Colin Miskelly

    Reply
  18. Colin Miskelly

    Thanks for your comments Barbara. The only broad-billed prion population in New Zealand that receives any level of monitoring is the largest population, on Rangatira (South East) Island in the Chatham Islands. Ironically, the prions there are monitored solely in relation to their impacts on another rarer petrel species (Chatham petrel) that loses out to the much more numerous prions in competition for nesting burrows.

    To give some indication of the lack of monitoring of broad-billed prions, I would be astounded if a single banded broad-billed prion was found among the hundreds of thousands that have been killed in this mortality event.

    Regards, Colin Miskelly

    Reply
  19. Barbara Hammonds

    Thanks Colin, I knew it was bad, but I didn’t realise how bad – especially if as you say, the birds are from the smaller breeding populations. Are there any ongoing studies of populations at any of those sites that will help us understand the impact when this year’s breeding season starts?
    I was lucky enough to see the feeding of some of the 160 birds being looked after at the DOC office in New Plymouth last week – the ones I saw looked quite perky. Those that survived would be well out at sea by now – I think DOC staff were just waiting for the weather to settle before taking them out in the boat to release.
    Barbara

    Reply

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