Seabird discoveries in remote southern Fiordland

Te Papa scientists Alan Tennyson and Colin Miskelly recently joined a Department of Conservation-led survey of seabird colonies in remote Chalky Inlet and Preservation Inlet in southern Fiordland. The team made the most of an extended spell of fine weather to land on an astonishing 77 islands. Vertebrate curator Dr Colin Miskelly here summarises some of their more notable discoveries.

A plethora of islands

Most tourist impressions of coastal Fiordland are based on their experiences from cruises on Milford or Doubtful Sounds. But these two sites are many hours of steaming north of where we ended up in late November, surveying seabirds in southern Fiordland. We boarded the DOC vessel Southern Winds at Deep Cove in Doubtful Sound, and it was 6.5 hours later before the team landed on Cemetery Island in Preservation Inlet – an ironic ‘start’ to the survey.

Team members landing on outer Garden Island, Chalky Inlet. Photo by Colin Miskelly. Te Papa

Team members landing on outer Garden Island, Chalky Inlet. Photograph by Colin Miskelly. Te Papa

The four major fjords of southern Fiordland (from Breaksea Sound south) hold hundreds of islands, and the superb weather and sea conditions in late November allowed us to achieve more than expected.

The Zero Nuggets off Chalky Island, viewed from the top of Finger Rock. Photo by Colin Miskelly. Te Papa

The Zero Nuggets off Chalky Island, viewed from the top of Finger Rock. Photograph by Colin Miskelly. Te Papa

The purpose of the survey was to locate colonies of burrow-nesting petrels (seabirds), building on a highly successful Te Papa survey completed in Dusky Sound the previous November. The 2016 survey resulted in 49 colonies of three petrel species being found on 44 islands, with 42 of these colonies being previously unknown or unreported.

Colin Miskelly searching for petrel burrows on one of the ‘Fingers’ of Five Fingers Peninsula, Resolution Island, with the Southern Winds below. Photo by Alan Tennyson. Te Papa

Colin Miskelly searching for petrel burrows on one of the ‘Fingers’ of Five Fingers Peninsula, Resolution Island, with the Southern Winds below. Photograph by Alan Tennyson. Te Papa

The larger islands in southern Fiordland are important sites for many rare and threatened landbirds (e.g. kākāpō, little spotted kiwi, tīeke/South Island saddleback, mōhua, and kakaruwai/South Island robin), but it was the smaller islands that we focussed on for both the 2016 and 2017 surveys. Petrels do all their foraging at sea, and can breed at densities of three or more burrows per square metre, and so even tiny islets and stacks can hold large populations.

Islands in Chalky and Preservation Inlets surveyed for petrels in November 2017. Map derived from Google Earth, based on eBird records contributed by the expedition.

Islands in Chalky and Preservation Inlets surveyed for petrels in November 2017. Map derived from Google Earth, based on eBird records contributed by the expedition

Making sense of holes in the ground

The three petrel species known from Fiordland (sooty shearwater, mottled petrel, and broad-billed prion) have overlapping breeding seasons, with November being the best month to find all three species present at the same time.

A mottled petrel burrow on an islet in Isthmus Sound, southern Fiordland. Photo by Colin Miskelly. Te Papa

A mottled petrel burrow on an islet in Isthmus Sound, southern Fiordland. Photograph by Colin Miskelly. Te Papa

Our survey technique was to locate and count burrows on as many islands as possible, and to estimate the number of burrows on each island.

A broad-billed prion chick on an islet off the southern Fiordland coast. Photo by Colin Miskelly. Te Papa

A broad-billed prion chick on an islet off the southern Fiordland coast. Photograph by Colin Miskelly. Te Papa

The next challenge was to identify which species had made or was occupying the burrows we found, with the added complication that more than one species is often present on the same island.

An adult mottled petrel on a stack off South Passage Island, Chalky Inlet. Photo by Colin Miskelly. Te Papa

An adult mottled petrel on a stack off South Passage Island, Chalky Inlet. Photograph by Colin Miskelly. Te Papa

Sometimes an adult or chick might be within reach from a burrow entrance, but more often we had to identify the burrow occupants from feathers, skeletal remains, or failed eggs from previous seasons that had been dug out of burrows. Our task was aided by plucking sites left by predatory falcons, with both falcons and their feeding sites being found on many of the islands.

A New Zealand falcon on Round Island, Preservation Inlet. Photo by Alan Tennyson. Te Papa

A New Zealand falcon on Round Island, Preservation Inlet. Photograph by Alan Tennyson. Te Papa

Remains of an adult broad-billed prion partially consumed by a New Zealand falcon. Photo by Colin Miskelly. Te Papa

Remains of an adult broad-billed prion partially consumed by a New Zealand falcon. Photograph by Colin Miskelly. Te Papa

If we were unable to find birds, feathers, bones, or eggs, the petrel species present could usually be determined by characteristics of their burrows, including entrance diameter, location on the island, and the vegetation that they nested under or among.

By the end of the week-long survey, we had landed on 77 islands and had found 50 petrel colonies, 33 of which were previously unknown. All the colonies were of the three petrel species known to breed in Fiordland, but we also encountered three additional species at night.

A common diving petrel on the deck of Southern Winds while at anchor off Chalky Island. The nearest known breeding colony for this species is on the Green Islets, 30 km to the south-east. Photo by Colin Miskelly. Te Papa

A common diving petrel on the deck of Southern Winds while at anchor off Chalky Island. The nearest known breeding colony for this species is on the Green Islets, 30 km to the south-east. Photograph by Colin Miskelly. Te Papa

Fiordland’s mystery seabird

A fourth petrel species long suspected of breeding in Fiordland is one of New Zealand’s smallest seabirds – the grey-backed storm petrel. We encountered them while ‘spot-lighting’ at night at two sites in Dusky Sound last year, and were keen to find out whether they also occurred in Chalky and Preservation Inlets.

Grey-backed storm petrel in spotlight beam, Wet Jacket Arm, November 2016. Photo by Jean-Claude Stahl, Te Papa

Grey-backed storm petrel in spotlight beam, Wet Jacket Arm, November 2016. Photograph by Jean-Claude Stahl. Te Papa

Spot-lighting is a recognised survey technique for seabirds, and we undertook standardised surveys from the boat at five different overnight anchorages. Grey-backed storm petrels were seen at three sites, with at least two individuals (and probably more) at two of the sites.

A grey-backed storm petrel on the deck of Southern Winds while at anchor off Chalky Island. Photo by Colin Miskelly. Te Papa

A grey-backed storm petrel on the deck of Southern Winds while at anchor off Chalky Island. Photograph by Colin Miskelly. Te Papa

One grey-backed storm petrel was captured during a spot-lighting session, and was found to have a bare brood patch. Petrels normally have dense down under their belly feathers. However, they shed a large patch of this down when breeding, to allow effective transfer of body-warmth to their single enormous egg when incubating. The bare brood patch on this storm petrel was an indicator that it had a nest nearby – but we still don’t know where.

Grey-backed storm petrel records from Fiordland. Yellow = November 2017; red = November 2016; white = earlier August to November records; black = February to April records including 2 known fledglings; grey = undated records. Base map from Notornis volume 64 (p. 112), reproduced with permission of the editor.

Grey-backed storm petrel records from Fiordland. Yellow = November 2017; red = November 2016; white = earlier August to November records; black = February to April records including 2 known fledglings; grey = undated records. Base map from Notornis volume 64 (p. 112), reproduced with permission of the editor [article title ‘Do grey-backed storm petrels breed in Fiordland?]

The underside of the grey-backed storm petrel captured off Chalky Island in November 2017, showing its bare brood patch (indicating that it was likely to be incubating at the time it was caught). Photo by Alan Tennyson. Te Papa

The underside of the grey-backed storm petrel captured off Chalky Island in November 2017, showing its bare brood patch (indicating that it was likely to be incubating at the time it was caught). Photograph by Alan Tennyson. Te Papa

An oceanic wanderer a long way from home

An even bigger seabird surprise was that the first prion that we caught while spot-lighting was not the species we expected. We were anchored within a few hundred metres of a broad-billed prion colony, but the first prion captured was an Antarctic prion. The nearest known colony for this species is on the subantarctic Auckland Islands, 500 km to the south. The bird had a downy brood patch, and so was most likely a young bird not yet in breeding condition.

A broad-billed prion (left) and an Antarctic prion (right), Chalky Inlet, November 2017. Photo by Colin Miskelly. Te Papa

A broad-billed prion (left) and an Antarctic prion (right), Chalky Inlet, November 2017. Photograph by Colin Miskelly. Te Papa

An Antarctic prion on the deck of Southern Winds while at anchor off Chalky Island. Photo by Colin Miskelly. Te Papa

An Antarctic prion on the deck of Southern Winds while at anchor off Chalky Island. Photograph by Colin Miskelly. Te Papa

With many thanks to Colin Bishop (DOC) for organising the survey, Southern Winds skipper and crew Chris Pascoe and Pete Kirkman for getting us there and back safely and comfortably (and for skilfully getting us on and off so many islands), and Colin Bishop, Graeme Taylor, and Terry Greene (DOC), Riki Parata (Kāi Tahu), and Lawrie Mead for assisting with the field work on and off the boat.

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17 Responses

  1. Richard de Hamel

    What fun, I would have helped!! I seem to remember the burrows on the Snares had a differing smell depending on the species occupying it. Smell is hard to categorise I realise, but a useful indicator?

    Reply
    • Colin Miskelly

      Hi Richard
      Thanks very much for your comments – and great to hear from you.
      Smell is certainly a good indicator of an active, large petrel colony, and they can often be detected before even stepping ashore. But you would need a finer nose than mine to use odour as a species-specific identification method. I am sure that dogs could be trained to do so, but seabird dogs that I have observed in action have been just as ready to indicate a penguin burrow as a prion or a diving petrel.
      Cheers
      Colin

  2. Maureen Binns

    Well done, team. We really need the research that you are doing and publishing.

    Reply
    • Colin Miskelly

      Thanks very much Maureen
      Good to hear from you
      Kind regards
      Colin

  3. Colin Miskelly

    Thanks very much for your comments Ian. I am sure that there is a lot more to discover on the smaller Fiordland islands – this was very much an initial survey, with most of our island landings being brief, during daylight hours, and of course at only one time of the year. Plus there are many more islands waiting to be surveyed from Dusky Sound northwards.
    Cheers
    Colin

    Reply
  4. Peter young

    Well done. Awesome job we need to talk soon.

    Reply
    • Colin Miskelly

      Thanks very much Pete – and thanks also for your tips on where petrels might be in Chalky & Preservation Inlets
      Cheers
      Colin

  5. Olwen Mason

    Another very interesting tale of your travels. Thanks.

    Reply
    • Colin Miskelly

      Thanks very much for your feedback Olwen
      Kind regards
      Colin

  6. Euan Kennedy

    Exceptionally well done, Colin. Alan too. It’s so reassuring to see that the discovery instinct is still alive and well in some quarters.

    Any sign of four-footed furry intruders on any of these islands?

    Reply
    • Colin Miskelly

      Thanks very much for your kind words Euan, which must be shared with the whole team. At times we were split between up to 5 islands, which also meant long days with little down time for the boatmen.
      We are still assembling data on mammal presence on islands, but did find a few rat corpses under GoodNature A24 self-resetting traps on some of the larger islands (some of which had sooty shearwaters breeding on them, but not the two smaller petrel species).
      Kind regards
      Colin

  7. Sarah Jamieson

    Looking forward to reading the paper!

    Reply
    • Colin Miskelly

      Kia ora Sarah
      Great to see you keeping an eye on your former colleagues from afar!
      Best wishes
      Colin

  8. Susie Brown

    Wonderful work, team! Keep it up.

    Reply
    • Colin Miskelly

      Kia ora Susie
      Thanks very much for your feedback.
      Nga mihi
      Colin

  9. Tony Mooar

    Well done!!!
    I wonder if you could get this sort of information to RadioNZ or TVNZ children’s programmes?

    Reply

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