Colin Miskelly

Author Archives:

Critters of the Poor Knights Islands

16 February 2013 – 8.05pm

Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly recently visited the Poor Knights Islands Nature Reserve, off the Northland coast, as part of a research team tracking the at-sea movements of Buller’s shearwaters. The project is led by Graeme Taylor of the Department of Conservation, and is intended to identify the marine environments used by these elegant seabirds, both when raising young and when on migration. Here, Colin illustrates some of the large invertebrates that also occur on the islands.

The Poor Knights Islands are a treasure trove for large invertebrates, many of which have been wiped out by introduced predators on the mainland. The long isolation of the islands has also meant that some endemic species have evolved – i.e. species that only ever occurred on the Poor Knights Islands.

Flax snails were abundant under rocks and in seabird burrows, emerging on damp nights to graze on fallen leaves. It is thought that these large snails were introduced to the Poor Knights Islands from the Northland mainland by Maori.

Flax snails (Placostylus hongii), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Amborhytida dunniae is a medium-sized carnivorous snail that also occurs in declining numbers on the Northland mainland. We found one among leaf litter on a damp night.

Amborhytida dunniae, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

One of the most surprising finds of the trip was a previously unknown large leaf-veined slug (family Athoracophoridae). We found four large animals (10 cm long at rest) on the sunny northern side of a towai trunk on a hot summer afternoon. They had probably been caught in the open after climbing to the canopy during rain the night before. These impressive slugs proved to be a new record for the Poor Knights Islands, and are likely to be a new species in an as-yet unnamed genus. Two other similar species occur at Waipoua/Trounson in Northland, and Hikurangi in the Bay of Plenty.

Giant leaf-veined slugs sun-bathing on a towai trunk on Aorangi Island, Poor Knights Islands Nature Reserve. This species was previously unknown to science. Image: Colin Miskelly, Te Papa

Giant centipede (Cormocephalus rubriceps). This large centipede (up to 25 cm) is widespread in the North Island and also in Australia, but reaches its largest size on rat-free offshore islands. They were mainly seen on the forest floor at night, actively hunting for large insects and lizards. A few were seen in seabird burrows in the daytime, which we tried to block out of our minds as we reached in to extract shearwater adults and chicks.

Large, fast and venomous - a very good reason to keep your tent firmly zipped closed. Giant centipede on Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Large, fast and venomous – a very good reason to keep your tent firmly zipped closed. Giant centipede (Cormocephalus rubriceps) on Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Poor Knights giant weta (Deinacrida fallai). Second in size only to the Little Barrier giant weta, this is one of New Zealnd’s largest insects. One female we weighed was 49 grams. They stayed well-hidden during the day, but emerged at night to browse on leaves, and many females were seen laying their eggs in the soil of the forest floor.

A female Poor Knights giant weta sits on the author’s hand. Image: Colin Miskelly, Te Papa

A female Poor Knights giant weta laying eggs on the forest floor. Note the position of her long ovipositor (egg-laying appendage) compared to the previous photograph. Image: Colin Miskelly, Te Papa

Like all insects, weta have to moult their hard exoskeleton in order to grow. The moulting female shown here was suspended upside down from a flax bush when first found. She then turned around and ate every last scrap of her old skin, recycling the precious chiton while her new skin hardened. By the morning there was nothing left of the out-sized exoskeleton, and the still pale newly-moulted female was hiding nearby.

Female Poor Knights giant weta moulting, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

A freshly moulted Poor Knights giant weta consumes its old exoskeleton. Image: Colin Miskelly, Te Papa

Poor Knights giant jumping weta (Gymnoplectron giganteum). New Zealand’s largest jumping weta (or cave weta) is found only on the Poor Knights Islands, and has been measured at 45 cm from antenna tip to the tip of the hind leg (though the body makes up only 10% of this). We mainly saw them on damp nights, when they ran and jumped rapidly away from our lights.

Poor Knights giant jumping weta (Gymnoplectron giganteum), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Poor Knights ground weta (Hemiandrus sp. aff. anomalus). This yet-to-be-named endemic species emerged from its burrows in large numbers on damp nights, otherwise few were seen. With a body-length of 35 mm, and shorter appendages, it is much smaller than its more famous cousins mentioned above.

Poor Knights ground weta, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Clapping cicada (Amphipsalta cingulata). Common throughout the northern North Island and around Wellington, the clapping cicada spends most of its life as flightless nymphs living in the soil. The song of male clapping cicadas is one of the distinctive sounds of the New Zealand summer.

Clapping cicada (Amphipsalta cingulata) nymph, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Adult clapping cicada (Amphipsalta cingulata), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Flax weevil (Anagotus fairburni). These large flightless weevils feed only on flax (harakeke and wharariki), with the adults emerging at night to chew on the tough, fibrous leaves. Formerly found throughout New Zealand, they are now confined to rodent-free habitats, including a few mountain tops. They are most readily found on pest-free islands off northern New Zealand, in Cook Strait, and in Fiordland.

Flax weevil (Anagotus fairburni) feeding on flax/harakeke, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Turbott’s weevil (Anagotus turbotti). Slightly larger than its flax-eating relative, Turbott’s weevil has an even more restricted distribution – on the Poor Knights Islands, Three Kings Islands, and Muriwhenua Island in the Chickens Islands. All these islands have never had rats, whereas all the larger islands in the Hen & Chickens group had introduced Pacific rats (kiore) until they were eradicated from all but one of the islands. We saw about ten individuals, all at night, and mainly on karaka trunks. Three were seen feeding on ngaio leaves on the same bush, and one was on flax alongside its smaller cousins.

Turbott’s weevil (Anagotus turbotti) on ngaio, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Purple rock crab (Leptograpsus variegatus). These large crabs are widely distributed in rocky intertidal areas in northern New Zealand, but are extraordinarily abundant on the Poor Knights Islands. The full protection they receive from the combined (land-based) nature reserve and adjoining marine reserve gives a hint of the impacts human hunting pressure has had on our marine organisms elsewhere. At several points on the wave platform on Aorangi Island I was able to count over 50 purple rock crabs as they scuttled away from me. They were typically hyper-sensitive to movement, but one group were so intent on feasting on a dead shearwater that they allowed my close approach. Another was seen feeding on a dead bellbird at a brackish water hole on the edge of the forest, but it is not known whether it caught the bird or scavenged its corpse.

Purple rock crabs (Leptograpsus variegatus) scavenge the corpse of a Buller’s shearwater, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Acknowledgements: Thanks to Graeme Taylor of the Department of Conservation (DOC) for organising and leading the visit, and Bruce Marshall (Te Papa) and Gary Barker (Landcare Reasearch) for their thoughts on the giant slugs.

Posted in Biodiversity, Bugs, insects and spiders, Conservation, Crustacea, Field trips | Tagged centipede, cicada, crabs, molluscs, slug, snails, weevil, weta | Comments (4)

Reptiles of the Poor Knights Islands

16 February 2013 – 8.04pm

Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly recently visited the Poor Knights Islands Nature Reserve, off the Northland coast, as part of a research team tracking the at-sea movements of Buller’s shearwaters. The project is led by Graeme Taylor of the Department of Conservation, and is intended to identify the marine environments used by these elegant seabirds, both when raising young and when on migration. Here, Colin illustrates the nine reptile species that occur on the islands.

The Poor Knights Islands have a diverse, abundant and distinctive reptile fauna. It is diverse and abundant because the islands have never had introduced predators, other than pigs that were present on Aorangi Island until their eradication in 1936. It is distinctive as the islands are separated from the Northland coast by deep water, and so remained as isolated islands throughout periods of low sea-level during Pleistocene ice ages. This water barrier impeded lizard movements (and hence gene flow) to the extent that three Poor Knights Islands lizard species are considered to be distinct from their relatives on the mainland and nearby islands.

The Poor Knights Islands looking south, with Tawhiti Rahi in the foreground and Aorangi Island beyond. Image: Colin Miskelly, Te Papa

The top predator on the Poor Knights Islands is the tuatara, a large iguana-like reptile that is only distantly related to lizards. It lives in burrows, often in an uneasy truce with burrow-nesting seabirds. Our visit to the islands was focussed on one of the seabirds – the endemic Buller’s shearwater – and two of our study chicks were decapitated during our stay, almost certainly by tuatara.

Tuatara, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Tuatara (Sphenodon punctatus), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

A decapitated Buller’s shearwater chick, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Tuatara are considered sit-and-wait predators, waiting motionless for lizards, large invertebrates, or hapless seabird chicks to venture within striking distance of their jaws. As a consequence, their diet is recognised as comprising ground fauna only. It never occurred to anyone that tuatara could catch and eat fully-flighted forest birds – but they can! Many young bellbirds were feeding on fallen karaka fruit around our camp. On the last day of our stay, I was alerted by alarm-calls from the bellbirds, and a commotion in the leaf litter, and was able to snap this remarkable image of a tuatara carrying a freshly killed bellbird.

A tuatara holding a freshly killed bellbird, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The second largest reptile on the Poor Knights Islands is Duvaucel’s gecko. Growing up to 30 cm long, these are New Zealand’s largest and heaviest lizards. Introduced predators have confined them to islands off northern New Zealand and in Cook Strait, where they emerge at night to forage on the forest floor and over rocks and tree trunks.

Duvaucel's gecko, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Duvaucel’s gecko (Hoplodactylus duvaucelii), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The most abundant lizard on the Poor Knights Islands is the much smaller Poor Knights gecko. This species has yet to be given a scientific name, having only recently been recognised as distinct from the widely-distributed Pacific gecko. Poor Knights geckos are extraordinarily variable in their colours and markings, as shown in the following image of 15 that were clustered under a coastal rock.

Poor Knights gecko (Dactylocnemis undescribed species), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

A cluster of Poor Knights geckos, showing their variable colour and markings. Image: Colin Miskelly, Te Papa

The remaining six lizard species on the Poor Knights Islands are all skinks, only two of which were abundant and easy to find. The largest skink species there is the marbled skink, which also occurs on the Mercury and Alderman Island groups east of the Coromandel Peninsula. Marbled skinks are mainly nocturnal, hiding in seabird burrows and rock crevices during the day. However, we saw a few pregnant females basking in the sun, presumably to get extra warmth to increase the growth rate of their young.

Marbled skink, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Marbled skink (Oligosoma oliveri), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The as-yet unnamed Aorangi skink is much smaller than the marbled skink. It forages at night in leaf litter in areas with smaller rocks (and therefore smaller crevices), presumably to give protection from larger lizards and tuatara that might eat it. This skink is found only on the Poor Knights Islands, and has only recently been recognised as distinct from the ornate skink, which is found throughout the North Island.

Aorangi skink, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Aorangi skink (Oligosoma undescribed species), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Smaller still is another endemic species – Hardy’s skink, which is one of New Zealand’s smallest lizard species. We found Hardy’s skinks living among damp coastal vegetation, but they were secretive and hard to find.

Hardy's skink, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Hardy’s skink (Oligosoma hardyi), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The three remaining skink species present on the Poor Knights Islands are all widely distributed on northern offshore islands. Two of these (shore skink and moko skink) were ultra-wary, hiding among dense coastal vegetation, and scuttling away at the slightest disturbance.

Shore skink, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Shore skink (Oligosoma smithi), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Moko skink, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Moko skink (Oligosoma moco), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The ninth and final reptile species present on the Poor Knights Islands is Suter’s skink, which is New Zealand’s only egg-laying lizard. These sinuous skinks emerged at night to forage over coastal rocks, readily jumping into rock pools if disturbed. They are excellent swimmers, both on the water surface and along the bottom of pools.

Suter's skink, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Suter’s skink (Oligosoma suteri), Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Acknowledgements: Thanks to Graeme Taylor of the Department of Conservation (DOC) for organising and leading the visit, and DOC Northland staff for logistic support. David Boyle assisted with finding some of the more elusive lizard species.

Posted in Biodiversity, Conservation, Field trips, Reptiles | Tagged gecko, lizards, skink, tuatara | Comments (6)

Birds of the Poor Knights Islands

16 February 2013 – 8.04pm

Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly recently visited the Poor Knights Islands Nature Reserve, off the Northland coast, as part of a research team tracking the at-sea movements of Buller’s shearwaters. The project is led by Graeme Taylor of the Department of Conservation, and is intended to identify the marine environments used by these elegant seabirds, both when raising young and when on migration. Buller’s shearwaters breed only on the Poor Knights Islands, and migrate to the North Pacific after breeding.

The Poor Knights Islands are one of New Zealand’s least modified island groups. They are best known as New Zealand’s premier diving location, with the waters around the islands protected as a marine reserve. Few people, however, get the opportunity to step ashore, as the islands are protected as nature reserves, with access by permit only.

The Poor Knights Islands looking north, with Aorangi Island in the foreground and Tawhiti Rahi beyond. Image: Colin Miskelly, Te Papa

One of the hardships of camping on the Poor Knights Islands – having to bathe in tidal pools. Image: Colin Miskelly, Te Papa

We visited Aorangi Island to study Buller’s shearwater (rako), a burrow-nesting seabird that breeds only on the Poor Knights Islands, but that migrates over much of the Pacific Ocean. Graeme Taylor and his co-workers had attached geolocation tags to the legs of about 30 shearwaters on previous visits, and our main task was to recapture these birds, so that the data could be downloaded from the tags to reveal where the birds had been. We also established permanent burrow plots on the island, as part of a project to estimate the size of the population.

Buller’s shearwater, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Our visit was timed to be a few days after peak hatching of the Buller’s shearwaters’ eggs, when we hoped that both adults would be making frequent night-time visits to feed their single chick. The chicks are covered with dense down, and are left alone in their burrows when only a few days old, while both adults return to the sea to feed.

Buller’s shearwater chick, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Several other seabird species also breed in burrows on the Poor Knights Islands, but most of these (including little penguin, fairy prion, fluttering shearwater, little shearwater and diving petrel) had finished rearing their young and had returned to sea. One exception was the rare Pycroft’s petrel, which we heard most nights. They also breed on a few other island groups off northern New Zealand, particularly in the Mercury Island group.

Pycroft’s petrel, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

While Buller’s shearwaters dominated both the seabird and the nocturnal bird fauna, bellbirds (korimako) were by far the most common landbird, filling the forest with song from about 6 am each day. The bellbirds on the Poor Knights are considered a distinct subspecies from bellbirds elsewhere in New Zealand, differing slightly in colouration and measurements. Bellbirds are so abundant on the Poor Knights Islands that they exclude most other forest birds. We saw only a single fantail, and no tui, silvereyes, grey warblers or tomtits. It is likely that the bellbirds also prevent moreporks from establishing, as bellbirds mob moreporks, and there would be nowhere on the island for the owls to hide in the daytime.

Male bellbird, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Female bellbird, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

After bellbirds, the most abundant landbirds on the island were red-crowned parakeets (kakariki), plus there were a few New Zealand pigeons (kukupa / kereru) feeding on ripe karaka fruit, and kingfishers (kotare) feeding on lizards, insects and crabs. Perhaps the most interesting of the landbirds was the secretive spotless crake (puweto). These small rails live in dense wetlands on the mainland, and so are rarely seen. In the absence of predators they venture into more open habitats, occurring under open forest on the Poor Knights Islands.

Adult spotless crake, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Juvenile spotless crake, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Posted in Biodiversity, Birds, Conservation, Field trips | Tagged bellbird, Buller's shearwater, Pycroft's petrel, spotless crake | Comments (7)

Life through a burrowscope lens (Part 2) – subterranean Poor Knights Islands

16 February 2013 – 8.03pm

Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly recently visited the Poor Knights Islands Nature Reserve, off the Northland coast, as part of a research team tracking the at-sea movements of Buller’s shearwaters. The project is led by Graeme Taylor of the Department of Conservation, and is intended to identify the marine environments used by these elegant seabirds, both when raising young and when on migration. Buller’s shearwaters breed only on the Poor Knights Islands, and migrate to the North Pacific after breeding. They breed in rock crevices or in burrows that they excavate in soil. Here, Colin describes some of the wildlife they share their subterranean homes with.

An adult Buller’s shearwater on Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

A burrowscope is a field-hardened endoscope on steroids, used to view the interior of burrows. It can be used to determine whether a burrow is occupied or vacant, to identify what species is in a burrow, and to provide information on breeding success. At least seven species of seabirds excavate or breed in burrows and rock crevices on the Poor Knights Islands, and many other animals also inhabit the thousands of burrows there.

Buller’s shearwater burrows on Oneho hill, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The following images show some of the secrets of underground life on this pest-free nature reserve. During our visit (late January to early February), most of the breeding seabird species had finished breeding, but the Buller’s shearwaters had recently hatched their eggs.

An adult Buller’s shearwater inside its burrow, viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Buller’s shearwater egg viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Buller’s shearwater chick inside its burrow, viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Several species of reptiles live in burrows on the Poor Knights Islands, including tuatara, which occasionally kill and eat shearwater chicks. The smaller skinks and geckos usually move rapidly away from the light cast by the burrowscope, and rarely pose long enough for a photograph to be taken.

Tuatara inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

A marbled skink (the dark shape on the right) inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Duvaucel’s gecko inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Flax snails hide in seabird burrows and under rocks during the day, emerging on damp nights to graze on fallen leaves.

Flax snail (Placostylus hongii) inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

In addition to many seabird species, some landbirds also nest in burrows. We found a kingfisher nest in a low bank, with the entrance only 20 cm above the forest floor. The two large chicks inside froze statue-like when the burrowscope was inserted into their hole.

Kingfisher burrow entrance, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

Two fully-grown kingfisher chicks inside their burrow on Aorangi Island, viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Posted in Biodiversity, Birds, Bugs, insects and spiders, Conservation, Field trips, Reptiles | Tagged Buller's shearwater, burrowscope, gecko, kingfisher, lizards, skink, snails, tuatara | Comments (4)

The global penguin – Part 12. The final word?

17 January 2013 – 1.20pm

Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly tells the 12th, and probably final, instalment of the story of the emperor penguin that went where none had gone before. Previous blogs on the penguin were posted between 23 June 2011 and 24 April 2012.

For those of you interested in seeing the official account of the emperor penguin’s discovery, care, release and post-release monitoring, the following paper was published in the December 2012 issue of Notornis (the journal of the Ornithological Society of New Zealand):

Miskelly, C.M.; Simpson, P.M.; Argilla, L.S.; Cockrem, J.F. 2012. Discovery, care, and post-release monitoring of a vagrant emperor penguin (Aptenodytes forsteri). Notornis 59 (3&4): 116-122.

Abstract We report on the discovery, care, release, and post-release monitoring of the 2nd vagrant emperor penguin (Aptenodytes forsteri) recorded from New Zealand. An immature male emperor penguin came ashore at Peka Peka Beach (40° 50’ S) 56 km north-east of Wellington on 20 Jun 2011. Its condition deteriorated over the following 4 days, and it was taken into care at Wellington Zoo on 24 Jun. Following 72 days of rehabilitation, the bird was released at sea at 51° 42’ S, 78 km north of subantarctic Campbell I, on 4 Sep 2011. He was tracked, via satellite transmitter, moving south-east for 113 km until 9 Sep, after which no further signals were received. The arrival, care and release of this penguin attracted unprecedented levels of public and media interest for a vagrant bird to New Zealand.

The paper is accessible online to members of the Ornithological Society of New Zealand at http://notornis.osnz.org.nz/publications, and will be freely available to all 12 months after publication.

Previous blogs on this topic:

The global penguin – Part 1. How a lone emperor ventured into superstardom

The global penguin – Part 2. The young emperor penguin pushes the boundaries and is taken into care

The global penguin – Part 3. No latitude for error: a young emperor penguin a long way from home

The global penguin – Part 4. How to track a wandering emperor penguin

The global penguin – Part 5. The rocky road to fame

The global penguin – Part 6. Hitching a ride south

The global penguin – Part 7. The wandering emperor penguin enters the technological age

The global penguin – Part 8. Free at last!

The global penguin – Part 9. Heading home, or heading east?

The global penguin – Part 10. It’s only a game

The global penguin – Part 11. How old was the Peka Peka emperor penguin?

Posted in Biodiversity, Birds, Penguins | Tagged Emperor penguin, Happy Feet, Our Far South, Sirtrack | Comments (10)

Critters of Titi Island Nature Reserve, Marlborough Sounds

16 January 2013 – 4.28pm

Titi Island is a 32-ha reserve administered by the Department of Conservation and situated in the outer Marlborough Sounds. The island’s fauna was impacted by introduced Norway rats until these were eradicated in the early 1970s. The island has since been free of all introduced predators. Two species of large flightless insects plus tuatara were introduced to the island between 1995 & 2001 (see below). Te Papa researchers visited the island in January 2013 to attach tracking devices to breeding flesh-footed shearwaters, and to estimate the breeding population of these threatened birds. Our 3-day visit also provided an opportunity to encounter some of the island’s more cryptic wildlife.

The most well-known of Titi Island’s inhabitants are the tuatara introduced from North Brother Island and from captivity in 1995. At the time, tuatara from the Brothers Islands were considered to be a separate species from other tuatara. More recent genetic research has resulted in all tuatara being lumped back together as a single variable species. We encountered several tuatara inside shearwater burrows that we checked with a burrowscope.

Tuatara (Sphenodon punctatus) on Titi Island. Image: Colin Miskelly, Te Papa

Three lizard species are known from Titi Island. We found all three species to be present, but were surprised how few individuals we found. Rodent-free islands typically have abundant lizard populations.

Spotted skink (Oligosoma lineoocellatum) among iceplant on Titi Island. Image: Colin Miskelly, Te Papa

The two spotted skinks seen were among low coastal vegetation, as was the single common gecko found. Spotted skinks occur from Hawke’s Bay south to South Canterbury, but are most abundant on islands in the Marlborough Sounds and Wellington Harbour. They are a sun-loving species, and are most often noticed as they move back under cover when they detect someone approaching. Common geckos occur from Northland to Marlborough and Nelson, and are extremely abundant on many islands in the Marlborough Sounds and around Wellington. They are nocturnal, hiding during the day and emerging to forage at night.

Common gecko (Woodworthia maculata) on dead coastal flax/wharariki on Titi Island. Image: Colin Miskelly, Te Papa

The single brown skink seen was among a rock outcrop under forest. This species occurs from Taranaki south to north Westland, again being most abundant on rodent-free islands. It does not require as much access to sunlight as the larger spotted skink, and can be found under open forest as well as among grass and shrubland.

Brown skink (Oligosoma zelandicum) on Titi Island. Image: Colin Miskelly, Te Papa

Weevils are a group of beetles with a bad name, as some species are major pests of crops and stored food products. But they are an extraordinarily diverse group, with the weevil family containing more species than any other family of organisms on the planet. New Zealand has several large flightless weevil species that are mainly or entirely confined to sites that lack introduced rodents. These include the flax weevils introduced to Titi Island from nearby Maud Island in 2001. We found their characteristic feeding sign on flax plants all over the island, but the 2 cm-long animals were only visible at night when they emerged to feed.

Flax weevil (Anagotus fairburni) and its characteristic ragged feeding sign on a coastal flax/wharariki leaf on Titi Island. Image: Colin Miskelly, Te Papa

The most frequently encountered large beetle on Titi Island was a species of darkling beetle (genus Mimopeus). These also emerged at night, but were often found under rocks and in bird burrows during the day, and their larvae were common in the soil. Darkling beetles are a staple diet item for tuatara on many islands, though tuatara are partial to weta when they can catch them.

Darkling beetle (Mimopeus sp.) on a tree trunk on Titi Island. Image: Colin Miskelly, Te Papa

We failed to find any sign of the Cook Strait giant weta introduced to Titi Island from Maud Island in 2001, but did not have an opportunity to search the right habitats at night. The similarly-sized Wellington tree weta were very common, emerging at night and mainly staying in the trees out of reach of hungry tuatara.

Female Wellington tree weta (Hemideina crassidens) on Titi Island. Image: Colin Miskelly, Te Papa

We had been warned of tent-eating ground weta before our arrival. These voracious little (2.5 cm-long) weta live in tunnels in the soil and emerge at night to find other insects to eat. If anything is placed over their tunnel entrances, they simply chew through it. Rather than having our tent groundsheets wrecked, we devised the cunning plan of placing snow-foam bedrolls under the groundsheets. This was to little avail – the ground weta still chewed through them!

Ground weta (Hemiandrus sp.) on Titi Island. Image: Colin Miskelly, Te Papa

Sarah Jamieson eyeballing one of several holes chewed through her bedroll by ground weta on Titi Island. Image: Colin Miskelly, Te Papa

We also found several shells and one live animal of the medium-sized native landsnail Rhytida stephenensis. This carnivorous snail grows up to 34 mm across and is found on islands in the Marlborough Sounds and south to Kaikoura, with subfossil records from Takaka Hill.

The carnivorous snail Rhytida stephenensis on Titi Island. Image: Colin Miskelly, Te Papa

Posted in Biodiversity, Bugs, insects and spiders, Conservation, Field trips, Reptiles | Tagged gecko, lizards, skink, snail, tuatara, weevil, weta | Comments (3)

Life through a burrowscope lens – subterranean Titi Island

16 January 2013 – 4.27pm

By Sarah Jamieson & Colin Miskelly

Over the past two (southern hemisphere) summers, Te Papa seabird researchers have been investigating population trends and foraging behaviour of flesh-footed shearwaters. These all-dark seabirds are well known to recreational fishers around the North Island and in Cook Strait, as the birds have the annoying habit of sitting behind boats and diving after bait. This behaviour puts the birds at risk of being hooked and drowning on both commercial and recreational fishing lines. There is also evidence that some birds are deliberately killed by fishers, presumably after they become angry with the birds interfering with fishing. Added to this is the alarming revelation that some New Zealand flesh-footed shearwaters tracked on migration were found to have foraged within a few kilometres of the damaged Fukushima Daiichi nuclear power plant on the east coast of Japan. All this means bad news for flesh-footed shearwaters, which appear to be declining throughout their range.

Flesh-footed shearwater extracted from its burrow in order to be fitted with a tracking device. Image: Colin Miskelly, Te Papa

Our study has two main parts – estimating numbers on land, and tracking where the birds go at sea. Flesh-footed shearwaters nest in deep burrows that they excavate in soft soil, and both parts of the study require a means to see what is under the ground. Other animals also live underground on the islands where flesh-footed shearwaters nest, and so estimating numbers requires both counts (or estimates) of the number of burrows, and measurements of occupancy rates, i.e. what percentage of burrows is occupied by flesh-footed shearwaters. In addition, to track the birds at sea, we need to not only attach tracking devices to the birds, but to re-catch the same birds some weeks later to remove the device and down-load the data. This requires selecting birds that are incubating eggs, and will have a high motivation to return to the same site after having a tracking device taped to their back feathers.

A burrow on Titi Island – but what lies within? Image: Colin Miskelly, Te Papa

In order to see what species is in a burrow, and whether it is sitting on an egg, we use a device called a burrowscope. This is similar in principle to a surgeon’s endoscope, though of rather more robust design to cope with use in the field. A small camera lens surrounded by a cluster of lights is mounted on the end of a long flexible tube, which is carefully inserted into the burrow. An image from the camera is transmitted to a small video monitor screen, which allows the researcher to see what is in the burrow.

Te Papa researcher Dr Sarah Jamieson using a burrowscope on Titi Island. Image: Colin Miskelly, Te Papa

Flesh-footed shearwater egg inside a burrow on Titi Island, as seen on the burrowscope monitor. Image: Colin Miskelly, Te Papa

On Titi Island in the outer Marlborough Sounds we found three bird species and one large reptile species living in the burrows. The accompanying images show some of the views we had on the burrowscope screen. Our target species (flesh-footed shearwater) looks very similar to its cousin the sooty shearwater, which also nests on Titi Island. The main distinguishing character through the burrowscope is whether the bird has a slender dark bill (sooty shearwater) or a large pale bill with a dark tip (flesh-footed shearwater).

Flesh-footed shearwater inside a burrow on Titi Island. Image: Colin Miskelly, Te Papa

Sooty shearwater inside a burrow on Titi Island. Image: Colin Miskelly, Te Papa

Several burrows were found to contain little penguins, which had climbed up the steep slopes from the rocky shore below. These birds had finished breeding for the year, and had returned to shore for their annual moult. The presence of a moulting penguin in a burrow was usually evident from shed feathers at the burrow entrance even before the burrowscope was inserted.

Little penguin inside a burrow on Titi Island. Image: Colin Miskelly, Te Papa

The rarest of the burrow inhabitants was the tuatara – an iguana-like reptile unique to New Zealand, and with no close living relatives anywhere else on earth. Tuatara mainly eat large insects and also lizards, but occasionally take small seabirds and their chicks. They seemed to have an uneasy truce with the two large shearwater species, and we found some burrows occupied by both a tuatara and a shearwater.

Tuatara inside a burrow on Titi Island. Image: Colin Miskelly, Te Papa

Information on the Sextant Technology Ltd ‘Taupe’ burrowscope used

Posted in Biodiversity, Birds, Conservation, Field trips, Penguins, Reptiles | Tagged flesh-footed shearwater, little penguin, sooty shearwaters, tuatara | Comments (5)

Ruapuke Island – 1941 and 2012 – In the footsteps of Edgar Stead (Part 9)

8 January 2013 – 11.22am

Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly is researching the life and work of the Canterbury naturalist Edgar Stead (1881-1949). This includes re-taking Stead’s photos from the same photo-point, taking other images to illustrate his diaries, and describing how the ecology and wildlife of each of 10 islands has changed since Stead’s visits.

Edgar Stead, Robert Wilson and Percy Elworthy visited Ruapuke Island in eastern Foveaux Strait for a day at each end of their stay on nearby Green Island, in Nov-Dec 1941. They didn’t have time to explore much of this privately-owned 1600 ha island, with most time spent in the south-east between Old Ruapuke and Henrietta Bay. They did, however, visit the main podocarp / rata / kamahi forest patch in the hope of finding saddlebacks. I was privileged to be hosted on Ruapuke Island for 4 days at the very end of 2012, and also to visit Green Island.

Lagoon Bay on the west coast of Ruapuke Island. Image: Colin Miskelly

It is unclear what predators were on Ruapuke Island in 1941. Mice and weka were definitely present, and feral cats likely. Stead and his companions found a large colony of white-faced storm petrels in sand dunes along the east coast. This small seabird is highly vulnerable to rat predation, and the presence of a colony then indicates that rats were absent or recent arrivals. Rats are reported to be present now, and we found no sign of the storm petrels

Ruapuke Island from the south-east, with Bluff Hill in the distance. Image: Colin Miskelly

Forest birds were similar in 1941 and 2012, with bellbirds and tui widespread, and tomtits and red-crowned parakeets in the main forest. The brown creepers that Stead recorded appeared to have died out, but we recorded New Zealand pigeon / kereru, a species overlooked or absent in 1941.

The weka on Ruapuke Island are presumed to be Stewart Island stock. They are unusual for Stewart Island weka in having retained both the blackish and red-brown colour morphs. Although we saw more of the brown birds, several mixed pairs were seen, and both birds were black in one pair. The only other weka populations that have the black (or blackish) morph are in Fiordland. We also found both morphs present on nearby Green Island, but with fewer dark birds present.

A pair of weka on Ruapuke Island, December 2012. Dark morph female on left, brown morph male on right. Images: Colin Miskelly

A surprising find in 2012 was that fernbirds were common on Ruapuke Island. Stead did not record fernbirds in 1941, yet they are now present in areas that he visited. It is possible that they have sinced colonised from Bird Island 3 km away, where Stead found them during a brief visit at the end of his trip.

Fernbird carrying insects to its young, Ruapuke Island, December 2012. Image: Colin Miskelly

Both Ruapuke and Green Islands remain important breeding sites for the rare yellow-eyed penguin. The inaccessibility of the islands to anyone other than landowners is undoubtedly of ongoing benefit to this shy species.

A pair of yellow-eyed penguins on Ruapuke Island, December 2012. Image: Colin Miskelly

Posted in Biodiversity, Birds, Field trips, Mammals | Tagged fernbird, weka, yellow-eyed penguin | Comments (10)

Green Island (Papatea) – 1941 and 2012 – In the footsteps of Edgar Stead (Part 8)

8 January 2013 – 11.19am

Of all the islands that Edgar Stead visited, and for which his diaries exist, Green Island in eastern Foveaux Strait is the least well known. Green Island lies to the east of Ruapuke Island, and should not be confused with the much smaller homonymous Green Island near Dunedin. All the Ruapuke Island group are privately owned, mainly by descendants of the Kai Tahu chief Tuhawaiki. Some of the owners have huts on Green Island and harvest muttonbirds / titi (chicks of the sooty shearwater) each year. We were privileged to be granted access to the island, and were accompanied by two of the island’s owners during our 10 hours ashore.

Green Island from the south-west. Image: Colin Miskelly

It is not clear what motivated Stead to visit Green Island, other than the hope of finding rare birds on a ‘new’ island. He and his companions (Robert Wilson and Percy Elworthy) discovered that the island was free of introduced predators apart from weka, and this remains the case today. Birdlife was and is abundant, but there have been some notable changes over the ensuing 71 years.

Muttonbirding hut in Ruapuke Island, with Ruapuke Island in the background. Upper image taken by Edgar Stead in 1941 (courtesy of Canterbury Museum 2001_59_319); lower image by Colin Miskelly

Muttonbirding hut on Green Island, with Ruapuke Island in the background. Upper image taken by Edgar Stead in 1941 (courtesy of Canterbury Museum 2001_59_319); lower image by Colin Miskelly

Stead and Wilson estimated there to be 1.5 million pairs of fairy prions / titiwainui and broad-billed prions / parara breeding on the island in 1941, but we saw little evidence of them in 2012. They are both still present, but clearly in much reduced numbers. It is not clear why the population has crashed, as the weka population does not appear large enough to have caused such a massive decline. Perhaps the decline has been driven by at-sea conditions, rather than by conditions on the island.

Dark morph weka on Green Island, December 2012. Image: Colin Miskelly

Another species that has declined or disappeared on the island since 1941 is the southern skua, which should be the top predator on the island. About 10 pairs were present and breeding in 1941, but we saw none and found none of their distinctive middens of seabird remains.

Flowering southern rata and Stewart Island tree-groundsel (Brachyglottis stewartiae) on Green Island, December 2012. Images: Colin Miskelly

The landbirds on the island were much as Stead found them, with the brown creeper the most abundant species, and bellbird, tomtit and robin all being common. We also found tui to be numerous, probably attracted by the spectacular flowering of southern rata.

Brown creeper on Green Island, December 2012. Image: Colin Miskelly

We recorded over 20 New Zealand pigeons / kereru – a species not recorded by Stead. They are strong flyers and could easily cross the 2 km from Ruapuke Island. More surprising was that we found fernbirds to be common, when Stead specifically noted their absence. In 1941, fernbirds were found only on Bird island 3 km west of Ruapuke Island. Usually considered poor flyers and unlikely to cross water gaps, these furtive birds have apparently colonised both Ruapuke and Green Islands since Stead’s visit.

Fernbird photographed on Ruapuke Island, December 2012. Image: Colin Miskelly

One feature of the island that has not changed since Stead’s time was the abundance of geckos around the dwellings. We also saw several common skinks, but failed to find the green geckos reported from the island.

Geckos (Woodworthia ‘Otago large’) on Green Island, December 2012. Image: Colin Miskelly

The only seal species that Stead and his companions noted in 1941 was a single male sea lion. We did not see any sea lions, but there are now several hundred fur seals breeding on the island.

New Zealand fur seal cows and pups on Green Island, December 2012. Image: Colin Miskelly

Posted in Biodiversity, Birds, Conservation, Field trips, Mammals, Reptiles | Tagged brown creeper, edgar stead, fernbird, fur seal, weka | Comments (8)

Hunting henriettas on Ruapuke Island – on the tail of New Zealand’s first mice

8 January 2013 – 11.16am

Few people are aware of Ruapuke Island. Guarding the eastern approaches to Foveaux Strait, the 1600 ha island is large enough to appear as a smudge of colour at the very bottom of TV3’s weather map. Yet the island’s low relief means that passengers on the Stewart Island ferry 20 km to the west barely notice it compared to the imposing bulks of Bluff Hill and Mt Anglem.

Henrietta Bay on the south coast of Ruapuke Island. The cannon is claimed to have come from the Elizabeth Henrietta. Image: Colin Miskelly

Ruapuke Island is privately-owned, mainly by descendants of the Kai Tahu chief Tuhawaiki. Most of the island is rough farmland (sheep and beef cattle), with a large patch of rimu / rata / kamahi / miro / kahikatea forest in the centre. Long sandy beaches separate granite and basalt headlands, with shallow lagoons lying behind several beaches.

Ruapuke was an important site for two of New Zealand’s earliest industries – the harvesting of fur seal skins and flax (harakeke) fibre. But the island has another more furtive claim to historical fame – or infamy. It was the first New Zealand site to be colonised by mice.

The brig Elizabeth Henrietta was engaged in the flax trade when it ran aground in Henrietta Bay on 25 February 1824. It was eventually refloated in August that year, but some time during its enforced stay, mice made it to shore. This was 6 years before the second recorded presence of mice in New Zealand, at the Bay of Islands in 1830. The residents of Ruapuke Island did not know what the strange creatures were, and reportedly referred to them as ‘henriettas’ after the ship they came from.

A mouse caught on Ruapuke Island. Image: Colin Miskelly

I was privileged to be invited to stay on Ruapuke Island at the tail-end of 2012. My hosts knew the significance of the island’s mice, and had been involved in the collection of tissue samples (i.e. mouse tail tips) for a genetic study that has confirmed that Ruapuke’s mice are from a different lineage to the rest of New Zealand’s mice. Yet during 188 years of mouse presence on Ruapuke Island, no specimens had reached Te Papa’s extensive collection of New Zealand rodents. Prepared with a selection of traps and baits, I spent 3 days trying to rectify this. It took some effort, as the mice were scarce (or wary), with two only caught in 27 corrected trap-nights. The main challenge was hiding the traps from inquisitive weka, which took 4 cheese baits, and would have taken any mice if I didn’t beat them to it.

A weka on Ruapuke Island. Image: Colin Miskelly

Posted in Biodiversity, Field trips, History, Mammals | Tagged mouse, rodents | Comments (1)

Te Papa's Blog

Author Archives:

Critters of the Poor Knights Islands

Reptiles of the Poor Knights Islands

Birds of the Poor Knights Islands

Life through a burrowscope lens (Part 2) – subterranean Poor Knights Islands

The global penguin – Part 12. The final word?

Critters of Titi Island Nature Reserve, Marlborough Sounds

Life through a burrowscope lens – subterranean Titi Island

Ruapuke Island – 1941 and 2012 – In the footsteps of Edgar Stead (Part 9)

Green Island (Papatea) – 1941 and 2012 – In the footsteps of Edgar Stead (Part 8)

Hunting henriettas on Ruapuke Island – on the tail of New Zealand’s first mice

Pages

Recent posts

Categories

Search blog

Join the discussion

Follow us by email

Other blogs

Use of images

Te Papa Links

Te Papa Home - Fingerprint

Te Papa Homepage - Text

What's on

Plan your visit

Education

Collections

Shop

Venues

Follow “Te Papa's Blog”