Feeding our forests

I have begun doing some work with the Northern New Zealand Seabird Trust who invited me to come and help them with some field work on the Poor Knights Islands. My father had visited the Islands when he worked for DOC in the 1990’s, his stories about the reptile abundance really inspired me to do restoration work, and I jumped at the opportunity to go.

Landing on the Island is notoriously difficult and our first shot at it was delayed, we had to go back to Auckland to wait for better weather. The islands are surrounded by steep cliffs that made European habitation impractical, Māori left the area in the 1820’s. This means the island I visited has never had introduced mammals, not even kiore! I spent days cleaning my gear to get through the biosecurity requirements which are incredibly strict for good reason.

I have explored a few predator free islands including Hauturu / Little Barrier Island which has been described as New Zealand’s most intact ecosystem. However it was only cleared of rats in 2004. When I am photographing invertebrates at night in mainland sanctuaries or forests with predator control (like Tāwharanui Regional Park or parts of the Waitakere Ranges) I see one reptile every eight hours or so. On Hauturu / Little Barrier Island I see them every 20 minutes, but on the Poor Knights it was every two minutes! Bushbird numbers were lower than other islands, I expect this is because reptiles and birds compete over prey species. I wonder if reptile numbers on other islands might be slower to recover because they are preyed on by bushbirds. I reckon that the Poor Knights total reptile and bushbird biomass is much greater than the restored islands I have visited. One reason for this is that reptiles use less energy to hunt than bushbirds but the other reason might be because it has more seabirds.

While walking through the bush at night I would sometimes hear a crashing in the canopy followed by a soft thump on the ground. In an incredible navigational feat the seabirds somehow land only meters from their burrows. At night I heard Buller’s shearwater, grey-faced petrel, little penguins and diving petrel (fairy prion finish breeding in February). While monitoring birds at night I was showered with dirt by a Buller’s shearwater who was digging out a burrow. In my short time on the island I saw cave weta and three species of reptile using the burrows. Like a rock forest the burrows add another layer of habitat to the ecosystem. It was incredibly touching to see the care and compassion the researchers had for some of the chicks who were starving while waiting for their parents who often have to travel hundreds of kilometres to find enough food. The chicks who don’t make it die in their burrows and are eaten by many invertebrates, the invertebrates in turn become reptile or bushbird food. The soil on the island looked thick and rich, when it rains nutrients are bought down into the small but famous marine reserve which is teaming with life.

I was only on the island for three nights but I was very fortunate to experience a pristine ridge to reef ecosystem. Seabirds are incredible ecosystem engineers who were an integral part of New Zealand’s inland forests for millions of years. Communities are making small efforts to bring seabirds back to predator free island and mainland sites with no control over seabird food sources. If we really want intact ecosystems we will have to make sure our oceans have enough food for seabirds to feed our forests.

Pakiri horse mussel beds

For the last eight years I have been working on restoring green-lipped mussel (perna canaliculus) beds in the Hauraki Gulf. The main reason we started with that species was that there is a commercial supply. However there is a bigger native mussel that has even more potential than green-lipped mussels, both as a habitat and water cleaner. 

Horse mussels / Hururoa (atrina zelandica) are huge pumps, they are more than twice as big as green-lipped mussels (up to 400 mm in length) but have fragile shells which are vulnerable to fishing gear. They also  don’t move (unliked green-lipped mussels) and are sensitive to changes in substrate.

Last century horse mussel beds were some of the best fishing spots in the Hauraki Gulf. I regularly ask divers about horse mussels; Where did you see them? How dense was the bed? etc. There are spots with horse mussel in the Gulf but I don’t know of any significant beds left, if you do, please let me know about them.

I was recently sent these images of a stunning horse mussel bed in Pakiri.  They are from a report titled “Mangawhai – Pakiri Sand Study, Module 2: Technical Report, Marine Sands” by NIWA 1996. They show a large and dense horse mussel bed that has since been destroyed by sand mining. The beds ran the whole length of the embayment in depths of 15 -20m. I am posting them here to show the kind of seafloor we could have, if we treated it better.

We don’t yet understand the horse mussel lifecycle or what species / substates might attract juveniles. It’s interesting to note: presence of finger sponge and branching red algae, the hard edge to the bed and the way some of the shells align.

Overseas there have been attempts at restoring similar species (photos below). Seachange called for the “Initiation of a horse mussel restoration programme, with an initial focus on the Mahurangi and Whangapoua harbours.” But we could look at restoring any of the sites with historic beds. Wouldn’t it be awesome if we stopped smashing the seafloor, and bought back these giant pumps to clean the water, and create homes for fish.

Fairy tern models used as stand in parents

New Zealand Fairy Tern at Auckland Zoo

In December 2020 I jumped at the chance to help the Department of Conservation and Auckland Zoo with New Zealand’s most endangered bird. I provided 3D printed fairy tern models (that were designed for use as decoys) to Zoo staff who hand reared a chick through to fledging. A soft yellow tape was wrapped around the models beaks to make sure the valuable chick did not injure itself. The models stayed with the chick to its aviary bach until it learnt to fly and feed for itself.

What’s at the bottom of Jones Bay Lagoon?

I have driven past Jones Bay Lagoon many times and always wondered what’s down there. It was dredged for shingle from about 1870-1950 and would have had a stony seafloor like Jones Bay. I had heard that the mining might have made the lagoon 20 meters deep. Altho I knew there was sediment around the edges I imagined it was quite stable as most of the receiving catchment has been reforested including the regions best example of a wetland (albeit a small one).

Areas explored in green

I made a few transects at high tide. There was no noticeable current and the visibility above 4m was about 3m. However nearing the 5m mark the visibility dropped to .2m and was not much fun. I was able to easily plunge my hand into the seafloor about 30cm deep before it got uncomfortably sticky and heavy, the mud was very dark grey. The deepest spot I found was 7.5m with most of the lagoon at 5m. The contour of the seafloor varied and did not make sense with the odd ridge appearing in unexpected places.

I saw several fish including, a school of spotty, many yellow-eyed mullet in the shallows, a few snapper, and what I think were estuarine triplefin.

No Fishing. Marine pests found in this lagoon.

The biggest surprise however was the no fishing signs erected by Auckland Council. I was pleased to see them as it has always felt wrong to allow killing of native species in the Regional Park, which is supposed to be a safe place for nature. It was also a surprise given my recent request for Council to start managing the effects of fishing. This sign however is only here to manage a marine pest called Eudistoma or the Australian droplet tunicate.

Eudistoma are the little white things, the stalks belong to Mediterranean fanworm.

I knew that Eudistoma had reached the park because I was alerted by a member of the public on the 4th of February. It was no surprise as they were spreading fast and I documented dense areas of them on the other side of Kawau Bay in February 2019. The lagoon also had large numbers of Mediterranean fanworm (another marine pest) which interestingly often hosted native pleated sea squirts which I have not noticed on fanworm elsewhere. Mediterranean fanworm and Eudistoma are both present in the ocean, meters from the mouth of the lagoon. There was one small cockle bed in a sandy area and several areas with pacific oysters in the shallows. I have asked Auckland Council to comment on the closure which happened in spring 2020.

The Coastal Marine Area boundary on Unitary Plan viewer

Response from Auckland Council below.

The coastal marine boundary follows the South Coast/Jones Bay foreshore of Tāwharanui Regional Park, thus the lagoon is within the regional park, or at very least the land around it.

Fishing here is inconsistent with the general Regional Parks Management Plan to not take flora and fauna. The unwanted organism would be a threat to the Tāwharanui Marine Reserve. The regional parkland provides land based access to the periphery of the reserve and there is a real risk of transfer of organism in viable state on wet fishing gear between the two sites. The identification of the tunicate prompted a management response.

A short photogrammetric transect (4-5m)
Another slightly longer one, the fanworm are not as clear as I had hoped, I need to get much better at over-laping the frames.

I am making sure to decontaminate my dive gear, and I do not recommend the area for diving, in fact I think it might be with looking at the sediment inputs and, if they are low, considering the site for mussel bed restoration.

Birds of Auckland

Birds of Auckland

In 1980 the New Zealand Herald published a book called “Birds of Auckland” by Tim Lovegrove. It’s a great little book with great photos and detailed illustrations. I was only 5 years old in 1980 and lived in Whangārei so I found it interesting to read how these places have changed. However there are better datasets for a more robust analysis of population trends. I made some notes while I read it:

P7. “Tahuna Torea nature reserve at Glendowie is easily accessible from the city. Here many shorebirds gather to roost at high tide or feed on the nearby mud-flats at low water.” This site is also mentioned on page 57.

We know from other data that this roost has been compromised and species like godwit and knots no longer using the roost.

P15. “Giant petrels or nellies are common winter visitors to the Hauraki Gulf. These large, dark birds venture well into the Waitemata Harbour, often following ships. One can often see them from Tamaki Drive or Oarkie Wharf, if ships coming and going from the port are watched carefully with binoculars. Nellies follow in the wake of ships ready to scavenge upon any galley scraps tossed overboard.”

It’s good we no longer see giant petrel following ships, I expect this is because humans are now less likely to throw their waste overboard.

P33. [Pied shag] “Breeding colonies are located in the suburbs at the Panmure and Orakei Basins, and on the edges of Lake Pupuke.”

The colony at Panmure is probably 1/30th the size it was. I believe the Lake Pupuke colony has moved to the Chelsea Sugar factory but I am not sure.

P37. [Little shag] “There is a well-established colony in Hobson Bay where some 30 pairs of little shags breed.”

This colony is gone, tho I note a similar size colony has started at Point England in late 2019.

P39. “A number of spotted shags may be seen at high-tide roost on the rocks beside the Kawakawa Bay to Kailua road at Tarata Point. Another colony may be seen at Ihumoana Cliff at Bethells.”

We no longer see spotted shags at these locations or near the mainland.

P39. [White heron] “A regular visitor to the northern harbours of Manukau, Kaipara and Firth of Thames during winter.”

Observations of kotuku are now quite rare with less than 50 ever being recorded on eBird.org

P45. [Royal spoonbill] “… an occasional winter visitor to harbours and estuaries in the Auckland district”

Observations of Spoonbills are way up with more than 1,200 records on eBird.org

P45. [Canada goose] “… appears only as a straggler in the Auckland district.”

Observations of Canada geese are way up with more than 1,200 records on eBird.org

P52. [Weka] “… are also established around Middlemore Golf Course following a release of 18 birds at Kings College in 1971”

They didn’t survive but its interesting to hear about these early efforts.

P60. [Variable oystercatcher] “These days beach buggies pose the greatest threat to their breeding grounds. Only the odd variable is ever seen among the vast flocks of South Island pied oystercatchers in the Manukau, Kaipara and Firth of Thames.”

Beach buggies are no longer a significant threat. Observations of VOC are definitely up and the species is recovering.

P60. “Small flocks of up to 100 golden plover may occur in the South Manukau and Firth of Thames”.

Golden plover numbers have declined sharply.

P63. [Banded dotterel] Here over 100 birds are regularly found during the winter on the short cropped pasture of the freezing works holding paddocks on Hamlins Hill.

No waders are ever seen on Hamlin’s Hill anymore which has just been made a Regional Park.

P63. [New Zealand dotterel]. “It is a breeding bird near Auckland in the South Manukau and Firth of Thames.”

The strongest breeding grounds are now north east of Auckland from Shakespear Regional Park to Mangawhai.

P77. “Native pigeons still occur in reasonable numbers in the Waitakere and Hunua Ranges. Odd birds appear in the suburbs every year, especially in parks and gardens with fruiting trees”

This description sounds very sparse. They are rarely seen in eastern suburbs but are quite resident in many other suburbs. I’m sure Aucklands kereru numbers have risen strongly with predator control.

P78. [Kaka] “… are present in small numbers in the Waitakere and Hunua Ranges. These large parrots seem to be occasional winter visitors to suburban Auckland, as every year there are reports of birds from places like Cornwall Park and the Domain.”

It sounds like Kaka numbers have dropped in the Waitakere and Hunua Ranges and suburban Auckland, I would say that the Gulf Islands and Mainland Sanctuaries are now the best places to find Kaka.

From a handbook perspective, Aucklands avian populations have changed a lot with some significant improvements for many species which is impressive given Aucklands human population more than doubled in the last 41 years.

Tubeworms are awesome!

Tubeworm mound

I was pleased to read about Dr Mark Morrison’s 2020 discovery of tubeworms colonies in the Hauraki Gulf. The Marine Park has been heavily impacted by bottom impact fishing and epi-benthic biogenic habitat is now hard to find. I wanted to see what the tubeworm colonies looked like and how the wildlife differed from degraded seafloor.

I was therefore very excited to be invited on an expedition to inspect some tubeworm mounds discovered by Shane Kelly and Carina Sim-Smith near Moturua Island. They were relatively deep at about 25 meters whereas Mark Morrison’s ones were in the 12-22 meter range. The conditions were perfect with no wind and clear skies. We descended very quickly into the dark as we knew at that depth we would only have about half an hour to explore the area.

Scarlet tubeworm colony (Galeolaria hystrix)

I was stunned at the size of the mounds, they rose up to nearly a meter from the seafloor (much taller than any shellfish bed) and reminded me of coral reefs. Tubeworms grow in a similar way to coral, layering their calcareous skeleton homes upon each other as they filter feed and grow upwards. And just like some corals when I got about half a meter away from the tubeworms they retracted their red tentacles in a Mexican wave across the mound, it was really beautiful and I should have made a video of it.

The diversity was incredible, I was amazed at the amount of filter feeding colonial epifauna growing on the mounds. I wondered if the sponges, ascidians, anemones (which are also filter feeders) were competing with the tubeworms or if the relationships were commensal.

Conger eel

I don’t know the surrounding area but I was surprised to see so many fish including a young sandagers wrasse. This conger eel living in the mounds was a real highlight and I wish I had gotten a better photo. Goatfish were the most abundant fish species.

While the scientists collected a few specimens for identification I took two minutes to record a video which I later converted into an orthomoasic map using this technique (which I am still polishing). The map revealed an interesting pattern similar to that made by restored mussels as they clump together over time. It would be good to validate it by mapping more filter feeding structures.

The fragile mounds are easily damaged by dredges and trawlers, it’s likely that fear of catching gear on anchors from the adjacent mussel farm has protected the beds. The experience has me wondering what a huge protected tubeworm colony might look like, and how can we make more of these incredible structures.

UPDATE: July 2021. I was able to check our Dr Morrisons ones. Video from GoPro attached to my camera here.


I have spent a fair bit of time thinking about how citizen scientists can measure the health of their local streams using Macroinvertebrate Community Index (WIMP & SHMAK) and the index of biotic integrity (IBI) for New Zealand fish. The great thing about using stream life to measure stream health is that the animals act as 24/7 sensors that measure any of the countless pollutants that harm life. The problem with it is that finding and more importantly identifying species involves disrupting them.

eDNA (environmental DNA) sampling solves this by measuring the presence of stream life base on the tiny fragments all life constantly erode into water. Wilderlab have set up a testing system with relatively cheap kits available for citizen scientists. I found it easy to use on my local stream (which is very degraded). I am really excited about this technology, especially as the price comes down and results are benchmarked against existing stream health Indices.

Kelp gardening

Community groups and scientists have begun ‘Kelp Gardening’ in the Hauraki Gulf. The activity involves removing kina (se urchins) from rocky reefs to allow the kelp to regrow. It gives divers and snorkelers something to do on a reef (where they no longer have fish to hunt) and fits nicely with New Zealand pest management ethos (suppression).

However kina are not a pest, their numbers are artificially inflated by overfishing. See diagram of mine from the State of the Gulf report below.

Kina barrens are created by overfishing

Kelp gardening differs wildly from other active restoration techniques as it replaces a natural function with a human intervention. The activity may have a place in the creation of a marine protected area but it is not a smart long term reef management technique because it treats the symptom not the cause of a sick reef.

So why are well respected scientists and well intentioned volunteers doing it? I really think it’s just because calls for marine protection have fallen on deaf ears, and some people are so desperate to fix things they will try anything.

UPDATE: 11 March 2021: In a public seminar today Dr Nick Shears who is an expert on kina barrens in New Zealand said “kina removal can be incorporated into restoration / management but we want to make it clear it is not the answer on its own!