For the past few years, I’ve been supporting the campaign to raise awareness of the critically endangered Pukunui / Southern New Zealand Dotterel, and to see it recognised as New Zealand’s Bird of the Year. Unfortunately, the species is in a dire state and is on track for extinction within the next decade without urgent action.
Wanting to contribute in a meaningful way, I offered to produce decoy Pukunui eggs that the Department of Conservation (DOC) rangers could use to distract predators (primarily feral cats). However, DOC staff explained that decoy eggs would be most valuable during fertility checks, providing a substitute to keep adult birds settled on the nest while real eggs were removed for assessment. With only 12 nests found during the 2023/24 breeding season, it’s essential that each actively managed nest is as productive as possible. Ensuring birds aren’t incubating infertile eggs reduces wasted effort and limits their exposure to predators. Candling is only carried out when a bird has been sitting longer than the expected incubation period, suggesting the egg may not be viable.
Pukunui / Southern New Zealand dotterel nest. Photo Guy McDonald.
Using publicly available data on NZBirdsOnline, I 3D printed a set of six replica eggs, carefully matching the size, shape, and weight of real Pukunui eggs. Each egg was then airbrushed and speckled with acrylic paint to resemble the real thing as closely as possible. I also created custom protective cases for each egg to ensure they could be transported safely to Rakiura and carried in rangers’ backpacks during fieldwork.
Decoy pukunui eggs in protective cases. Photo Shaun Lee.
According to the rangers, the decoy eggs have been effective in keeping the birds settled during fertility checks, giving staff the time they need to carry out this crucial work without disrupting the breeding process.
A DOC ranger carefully candles a real Pukunui egg to check for signs of fertility. Photo Guy McDonald.
I’m proud to have volunteered my time to support the recovery of this remarkable species. You can help too by donating to the New Zealand Nature Fund.
Tarāpunga / red-billed gulls (Chroicocephalus novaehollandiae scopulinus) and tara / white-fronted tern (Sterna striata) nest on artificial structures in the Tāmaki Estuary, Auckland, New Zealand. The Department of Conservation ranks both species as At Risk / Declining (Robertson et al. 2021). Both species have also nested on moored boats in the estuary which creates human-wildlife conflict.
Piles under Waipuna Bridge (middle, photo taken from land). Photo by Shaun Lee.Piles under Waipuna Bridge (western end, photo taken at low tide). Photo by Shaun Lee.
Hypothesis
A nesting platform on the large piles (72cm diameter) that rise c2m above Mean High Water Springs (MHWS) under Waipuna Bridge. The piles are safe form mammalian predators who could not swim then climb to the nests. This area is less impacted by light pollution than Panmure Bridge where there is a tarāpunga colony.
Challenge
Solution
The nests are exposed to avian predators including the adjacent tarāpunga.
Using vertical canes to stop flying attacks on chicks. See Preston Dock Common Terns below.
The nest structures might be used by tarāpunga.
This is not a poor outcome but if the spaces are deep and small they might not be so suitable for tarāpunga. There is a small chance that nearby nesting feral pigeons are also interested in the structure.
Colonies are ephemeral (McLean 2018) with birds moving regularly.
This could be an advantage as species with higher site fidelity would be harder to attract. Suggest the addition of a 3D printed decoy to improve the chances of success I the first season.
The structure will attract human attention.
Clearly label the structure as a ‘trial bird nest for endangered terns’ include a phone number & URL to a blog post about the project. Centre the decoy to keep it less accessible / visible to humans. The height of the piles will help deter vandals. Even at low tide access requires a boat or a swim. Graffiti on the bridge may have been enabled by retired pontoons.
Installation difficulties
The piles are tall and using a ladder on a boat is tricky. A platform that connects the piles is visible 2.5hrs after high tide at the western end. A ladder could be used on the platform but it will be slippery.
Monitoring
There is no pedestrian access to the bridge. A land based site inspection from Finn Place identified the western piles as easy to monitor.
Preston Dock Common Tern nest boxes made by the Fylde Bird Club in Lancashire.
Tara do not use nesting material (NZBirdsOnline), a small amount of sand could cover the floor of the nests. The Preston Tern Nest Boxes use gravel. Drainage holes should be added to keep water out.
Proposed design
Based on the Preston Dock Common Tern nest boxes. Tara are not much larger than Common Tern but we have made the nest boxes smaller to dissuade tarāpunga form nesting here. Boxes dimensions made of ‘Radiata Premium Grade Smooth Decking 140 x 32mm’. The extra depth allows for a max of 40mm of gravel.
How the nest boxes might attach to a platform on top of the piles.
Timing
Tara tend to arrive at a prospective nesting location only a few days before laying, and there is a high degree of synchronisation of laying within a colony (NZBirdsOnline 2022). Eggs are laid between October-December (NZBirdsOnline 2022). Prospecting may begin weeks before egg laying. We plan to deploy the structure by mid September.
Deployment
The structure was deployed on the 14th of September 2022 (with a few modifications). I had a huge amount of help from a friend who is much more handy with an impact driver than me. The decoy is a bit odd looking as its just a scaled up tara iti with a different paint job. Five tara flew past while we were working and roosted on the piles in the center of the channel. We decided not to deploy the canes until we had active nests.
Update 15 Sep 2022. 10:00am-10:45am.
Four tara and three tarāpunga were roosting on the piles in the centre of the estuary. Every ten minutes or so they would be quite loud with both species calling and jostling for space but no confrontations observed. There were three close passes of the decoy and on at least two of these occasions it seemed like the terns were calling at it. No terns landed on the boxes but both species visited the piles near me. One tern was foraging from a pole which gave it a good view of any fish swimming above the platform in the shadow of the bridge, but it did not dive. One tern dived on in the centre area.
Update 18 Sep 2022. 5:15pm-6pm
About three gulls regularly on the piles in the centre of the estuary. Lots of gull movement and calls, more gull activity between the bridges than the 15th. No terns seen.
Update 28 Sep 2022. 2:15-2:20pm
Constant red-billed gull activity. Three gulls roosting on centre piles. Two pied shags feeding on the southern side.
Update 10 Oct 2022. 1:00-1:01pm
Low tide, no activity. Just a pied shag foraging under the bridge.
Update 23 Oct 2022. 5:00-5:01pm
High tide, no activity. Just a few gulls roosting on centre piles.
Update 02 Nov 2022. 1pm.
Photo taken from pole mounted GoPro shows gulls are prospecting the nest boxes.
Two pairs of tarāpunga have nested in the boxes. One of them has really filled it up with material!Tara also look to be nesting in an adjacent boat.
Update 23 Dec 2022. 12pm
The first pair of gulls have a chick, the second nesting gulls have not increased their nest height at all. Maybe because the other pair can keep watch.
Update 15 Jan 2023. 5:30pm
I’m hoping the chick is in one of the nest boxes and the second nest is not being sat on because it is hot, and the nest has a chick. Alternatively there is another adult down in the nest box. If the recent storms had destroyed either nest or pushed the chick off the adults would likely have moved on.
Update 18 Feb2023. 5:00pm
The structure is cyclone proof! Weather stations at St Helier’s and Howick recorded wind speeds of 40 knots (74kph). Despite the roosting gulls in the photo I dont think there were any active nests on the structure today.Additional visit 22 Feb shows nesting material in five of the six boxes. To my knowledge only the two with the most nesting material were used for nesting.
Update 22 Nov 2023. 11:00am
The gulls nested here earlier this year with a chick ready to fledge already. It also looks like at least three of the nest boxes were utilised. There was also a juvenile on a nearby boat and on a pylon under the bridge where tara nested last year.
Update 28 Jan 2024. 2:00pm
The gulls are still using the platform for nesting even though there is space at the main colony. I think the design is just too appealing to gulls.
Update 29 Sep 2024. 3:40pm
Gulls continue to dominate these nest boxes and it looks like three pairs are having a go here this year. Time for Plan B.
Plan B
Matt Rayner had the idea to add concrete tree rings to the tops of the poles. On the 30th of September 2024 we deployed four pairs of tree ring semicircles to the tops of the poles and added shell to encourage nesting tara. They were deployed on the group of poles next out from this group to avoid disturbing the gulls. There are three on the northern side and one in the south where we have seen tara try to nest unsuccessfully in the past.
Nest 1. Northern side, most eastern nestNest 2. Northern middle nestNest 3. Still on the north side of the bridge but further south than the other two nests. We added more shell to this nest to see if that makes a difference.Nest 4. Southern pole had a small metal (rusting) rim
Update 12 Oct 2024. 2:23 pm (windy)
All tree rings had single gulls hunkered down in them. Presumably nesting.All these nest boxes are now full for the first time.
Update 18 Nov 2024. 10:30 am
Also had fledgling gull in the water.Two out of four tree rings had gull nests. A gull is also nesting on and adjacent pole with no tree ring for the first time.
Robertson et al. 2021. Hugh A. Robertson, Karen A. Baird, Graeme P. Elliott, Rodney A. Hitchmough, Nikki J. McArthur, Troy Makan, Colin M. Miskelly, Colin. J. O’Donnell, Paul M. Sagar, R. Paul Scofield, Graeme A. Taylor and Pascale Michel. Conservation status of birds in Aotearoa New Zealand, 2021. New Zealand Threat Classification Series 36. Department of Conservation, Wellington. 43 p.
Mclean 2018. Successful restoration of an unnatural breeding habitat for white-fronted terns (Sterna striata). Notornis, 2018, Vol. 65: 54-58. The Ornithological Society of New Zealand Inc.
It was a joy to work on these tūturiwhatu which were a gift to Alison Stanes QSM for her work at the Tāwharanui Open Sanctuary Society Incorporated. Alison taught me a lot when I began minding dotterel. Sharon Kast and Sally Richardson did a great job of banding the models and adding a shell base.
I enjoyed making these Australian fairy tern replicas for the BirdLife Australia Fairy Tern project in Victoria. They will use them at events to help educate the community and raise awareness of the species to help their conservation.
I do wide angle macro photography underwater which helps me take great photos in yuck conditions. However it’s not so good for bigger fish who tend to not get that close. I tried 3D printing a little decoy for the end of my camera to see if it changed fish behaviour.
3D printed fish decoy that uses the laowa probe lens as an eye
I have only used it once but so far:
Bigeye (which the decoy design was based on, were not even a little interested).
Triplefins are not longer swimming under my lens (thats useful) but might be a bit more timid.
Red moki seem really curious, I’m sure they are doing a ‘double take’.
I’ll adjust my decoy a bit and do some more tests.
I have been helping out Auckland Zoo and the Department of Conservation with important conservation work, and last year Auckland Zoo had an unusual request.
“Can you make flamingo eggs? Our flock of Greater flamingos have a tendency to kick their eggs into the water, so we give them a ‘dummy’ egg whilst we place their precious egg safely in an incubator.”
In the past I have only assisted with endemic or threatened species so I was a little hesitant, that was until I went on a short tour of the Zoo’s flamingo habitat and met the birds. I learnt that in the wild, flamingo habitat is indeed threatened, and I was captivated by these elegant, head-high birds. One of the young females named ‘Otis’ wandered over and gave me a friendly chest bump. Immediately smitten, I have made 21 eggs for the flock. There were two technical challenges:
The eggs have an unusually rough surface, I started off covering the smooth 3D printed models with epoxy but this quickly became laborious. Instead, I sculpted a texture on the 3D model and was impressed how well it printed.
I had to get the weight just right. I achieved this by filling the eggs with sterilised sand, then water to make sure pressure changes from expanding and contracting air bubbles would not stress the resin shells.
One of the eggs has been successfully tested and I hope Otis & co will be happier spending more time sitting on eggs.
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.
This artificial shag roost in Hobson Bay was constructed by Auckland Council to mitigate the effects of a boardwalk being constructed next to an existing shag roost. Nesting materials and a plywood decoy has been added but the birds are yet to show interest in it.
I was recently asked to quickly create some red-billed gull decoys. I joked they might be better of using a decoy picnicker but the reality is this is another native species that is in real trouble (conservation status declining). I posed the decoys with their tails up but with legs so they could be used standing or sitting if they need extra anchorage.
Unfortunately these decoys were snapped off at the leg, we are not sure how, as it would involve a lot of force. So…
I made some more, these have been redesign to bolt on to a 1M long 8mm diameter threaded rod. Here is what they look like installed. We dug holes in the ground and used a little cement to lock them into place. Fingers crossed they work.Photo by Paul KennedyPhoto by Tim Lovegrove.
Update October 2019: Win!Note that the Northland Region Corrections Facility is making wooden Black-billed Gull nesting decoys, I don’t know how much they cost but they look cute!
This was my most challenging project for 2018. After reading about the New Zealand Fairy Tern decoys I was making, the Mangawhai Museum approached me to make them some replicas. As there are only 40 of these birds left in the world they were never going to be able to get a taxidermy one for an exhibition.
I was very ambitious and decided to create a feeding scene where the male is landing with a fish in his bill. This was very challenging and I really pushed my printer to the limits and discovered a few new tricks in the process. I think this kind of model making has advantages over taxidermy where the models can be designed to exhibit a wide range of behaviours. It will be interesting to hear how the public react.
