Rock Wren Recording in Siberia and Upper Wilkin ~ Tiritiri o te Moana

aspiring biodiversity trust rock wren

The Aspiring Biodiversity Trust (ABT) rock wren/ pīwauwau monitoring programme commenced during 2017/2018 summer season with focal alpine basin sites at Lake Crucibel and Lake Castalia/ Upper Lucidus, east of the main divide (Southern Alps/ Tiritiri o te Moana).

This season (2020/2021) the ABT bird monitoring team have been progressing rock wren monitoring, branching out into extended alpine habitat (from the two original monitoring sites) to determine if rock wren are present. This important data is essential to gain a better understanding of current residual populations of this endangered alpine passerine within the project area and measure population changes over time to better inform and guide appropriate conservation management.

Wonderland Valley – view from upper basin

This season the team were fortunate to be able to investigate the North Siberia and Wonderland Valley.

ABT are pleased to report that breeding populations of rock wren were recorded for both the upper Siberia basin and for Wonderland Valley with family groups and fledglings noted.

The upper Siberia and Wonderland Valley have now been identified as new breeding sites for this endangered species, which is promising as Wonderland Valley was not covered by the last aerial pesticide application (during October 2019) as part of the Department of Conservation Battle for our Birds. 

Rock wren fledgling, Feb 2021 Wonderland

Survey methods involve 250m fixed transects identified within suitable rock wren habiatat where all birds seen or heard are recorded (as per DOC survey method based on a 2012 – 2018 rock wren study) and any behavioural observations noted.

Male rock wren with lepidoptera prey item.

At this time of the year rock wren are busy feeding up on plentiful invertebrates (including spiders, moths, butterflies, larvae, flies and some berries) before the winter draws in. At which point they are thought to remain in torpor. Individual birds during March were noted knocking their captured prey items against rocks to make them easier to consume. This could potentially explain some of the bill abrasions noted on a few of the colour banded birds previously captured.

Female rock wren colour banded (med blue, light blue over orange), Lake Crucible March 2021. NB: handling only by NZNBBS L3 Certified bird bander.

This female rock wren was in great condition with a good body weight of 19.5 grams and almost finished post-breeding moult. The females are known to be larger than the male birds which tend to weigh around 15.8 grams. Colour banding assits with identifying individual birds, their territories and provides information on fledgling success and dispersal. We hope to see this female with lots of fledglings next summer!

Upper Siberia home to rock wren and whio

ABT installed and manage a programme of invasive predator control from ridge to river for protection of reminant populations of threatened species such as rock wren and also blue duck/ whio where habitats interconnect. This includes the application of Celium Remote Technology within alpine/ upper river areas to aid trap servicng efficiency in remote areas and provide information on predator activity during the winter. This work is ongoing with improved connectivity of trapline coverage as per funding allows.

Makarora/Wilkin Catchment Threatened Species Project area ~ Ridge To River

The Aspiring Biodviersity Trust threatened species programmes from ridge to river depend on a range of multiple funders, supporters and volunteers and are only viable through positive multi-collaboration (particularly locally but also national and international), dedication and passion for New Zealands indigenous biodiversity.

If you would like to help suport species like the alpine rock wren and see them flourish, please get in touch. We would love to hear from you!

ABT’s rock wren protection and restoration programme forms part of a broader threatened species project for the Makarora Catchment from “ridge to river” and is complementary to the Department of Conservation Predator Control Plan for Makarora and in alignment with NZ Biodiversity Strategy i.e. to maintain and restore viable populations of all indigenous species across their natural range and maintainance of their genetic diversity.

Reference

McNab, B K, Weston, KA (2020). The energetics of the New Zealand rockwren (Xenicus gilviventris): could a passerine hibernate? Journal of Experimental Biology 2020.

Monks J. M, O’Donnell C. F. J, Greene T. C, Weston K, A (2021). Evaluation of counting methods for monitoring populations of a cryptic alpine passerine, the rock wren (Passeriformes, Acanthisittidae, Xenicus gilviventris)

Weston, K A, O’Donnell C F J, van Dam-Bates P, Monks J M (2018). Control of invasive predators improves breeding success of an endangered alpine passerine. International Journal of Avian Science. Vol 160, Issue 4.

The First Makarora Field Course – A Success!

The first  Makarora Field Course was held from the 10 – 16 January 2021. This was the successful result of a partnership between Aspiring Biodiversity Trust and Operation Wallacea (Opwall) with support from LINZ, Birds New Zealand, Makarora Wonderland, local landowners and Wilkin River Jets.

The purpose of the field course was to promote the indigenous biodiversity of the Makarora catchment, create a valuable learning opportunity for students interested in careers based around wildlife management and conservation, contribute to good biological recording, whilst encouraging the future caretakers kaitiakitanga of the natural environment.

Students arrive at Makarora Field Course – yey!
Makarora Field Course Base Camp

Students from Wellington, Auckland and the Coromandel were met at Queenstown Airport, then joined a scenic coach trip over the Crown Range via Wanaka and Lake Hawea to the field course base camp at Makarora. Here the students and teachers were met by the ABT Science team and a representative from Operation Wallacea. The event commenced with a welcomming karikia before entering the learning facility for a welcome presentation and briefing. Students were then  shown to their tents before the first group meal was served at the main Makarora Wonderland Lodge.

Forest vegetation plots
Bird banding and mist netting

The week was divided into a series of applied learning activities focused on biological (fauna and flora) recording survey methods and monitoring with classroom sessions on data analysis, reporting and the use of the R Stats application via an overseas connection with Opwall lecturer’s in the United Kingdom.

Evenings were filled with lectures on geophysiography, protected species detection dog aided surveys (for whio), ABT’s Ridge to River Threatened Species Programme, a forest by night walk and concluded with a session on career’s in conservation and wildlife management with an inspiring and motivational finish for the future from Aspiring Biodiversity Trust patron – Lydia Bradey, recently awarded a New Zealand Order of Merit.

Braided river session including fluvioglacial processes, aquatic inverts and avifauna.

An awesome week of incredible weather and biodiversity concluded with a splendid Wonderland BBQ and a certificate presentation to students on their completion of the field course, plus the awarding of prises (including a NZ bird guide) for various notable achievements over the duration of the weeks activities. A farwell karikia and celebratory cakes completed a most memorable week for all involved.

Protected species survey dog, Hoki.

Thank you  to all funders and supporters who helped enable the first pilot Makarora Field Course. The next Makarora field course dates start from 7-14 January 2022! Get in touch to find out more about the latest itinerary, we look forward to hearing from you 🙂

Lydia Bradey motivational talk following career’s panel.

Commentary from student, staff and parent post 2021 field course:

I would like to thank the team for providing an amazing experience for my son Aditya. He is very grateful to get this wonderful opportunity of working with the best in their fields at such a young age. The communication, management and service has been great fro this trip. Thanks again. Jyoti

Thanks for running such an awesome course here in such a beautiful place. You and your team have provided invaluable insight into the real world – science and ecology. Hope to be back in the future. Dylon

By seeing the banded dotterel chick and other amazing sights, I felt like I was learning in a real meaningful way. Thanks, Fiver

Rachel, we did it! Congratulations on puttng together such an amazing field course you should be very proud of what you have achieved. It has been a real pleasure working with you! Hopefully we can do it again. Jihan

 

 

Braided river bird surveys and the challanges of nature

The fourth annual braided river bird walkover survey was a touch more challanging this year due to unsettled weather conditions with strong winds, sandstorms, downpoors and subsequent rising river and lake levels. This highlights the necessary considerations involved such as timing and weather monitoring before undertaking this important work.

A gusty second day on the river with water levels rising after a night of rain. Image Karthic

The Aspiring Biodiversity Trust team were determined to complete the length of the river walkover from Boiler Flat down to the river delta and with the additional help of a new volunteer Karthic (to the left below), a wildlife and conservation film maker with Natural History New Zealand (NHNZ) from Dunedin. Karthic found the experience “quite an eye opener” and savoured the remoteness of the location throughout his stay. He hopes to return when conditions are more suitable for wildlife filming!

Walkover sections being divided up to help maximise cover of braided river bird habitat by surveyors

The ABT bird surveyors in action (above) planning survey route sections and safe river crossings. All key braided river bird bird species were present however in generally lower numbers with more dispersed distribution in comparison to previous years. Total counts will be analysed and compared with national trends for key braided river bird species. This was the first wrybill pair of the year recorded foraging along the waters edge.

Female wrybill with a more slendar neck collar
Male wrybill with a wider neck collar and black patch to the forehead

The male and the female are very similar, with subtle differences in colouration and markings. Nick Beckwith a regular ABT volunteer captured this pair nicely on the first survey day.

A nest site was later found (below) the pale grey eggs and nest site highlight the incredible cryptic adaptations of these species enabling them to breed in such a harsh environment with considerable threats.

The female had briefly left this nest site (below) to forage on aquatic invertebrates along the nearby waters edge which enabled this image.

A wrybill nest site on the Makarora River

Thanks to Wilkin River Jets who facilitated the lower Makarora River section of the survey and the upper Wilkin River section. Image below shows the view up the Wilkin Valley from the jet boat, with snow capped Mt Aeolus in the background. There was certainly a crisp chill in the wind that day despite the blue, blue sky.

The team were fortunate to be able to stay at Makarora during the surveys especially during the busy production of a new top secret film (due out in March 2021).

As the day came to an end for the wonder that is Makarora, the stars appeared and the familar call of a pair of morepork/ ruru could be heard from the forest alongside the soothing flow of the river. Morepork presence is a positive indication of ecosystem health and this species appearers to be increasing in the valley.

The night sky – looking west over the Makarora River towards the Young Valley. Image Nick Beckwith.

*Thanks to all involved and those who helped enable this work. Including Sarah Forder, Nick Beckwith, Karthic SS, Danyel and Alex at Wilkin River Jets, Mt Albert Station and Dan and Carol Orbell.

Funding support provided by (LINZ) Land Information New Zealand.

 

Threatened Species Protection Expansion with assistance from Bill Day of Seaworks

The Aspiring Biodiversity Trust were out in full force on Tuesday and Wednesday (11 & 12 August), determined to increase the protection of our important threatened Taonga species in preparation for the upcomming breeding season. Bill Day of Seaworks kindly offered his assistance of considerable helicopter time; thanks to Lydia Bradey, ABT’s Patron recently awarded a New Zealand Order of Merit (ONZM).

A crisp early start at Makarora; Bill Day arrives for the initial health and safety briefing before take off into the backcountry. Left to right: Andy Longman, Lydia Bradey, Bill Day (pilot) & Anthony Coote.

Invasive mammal traps fitted with kea proof fixings were assembled locally then transported to Makarora by vehicle. Here the team (Anthony Coote, Lydia Bradey, Rachel Hufton, Karen Day, Andy Longman) were met by Bill Day (Director of Seaworks keen to contribute to indigenous biodiversity protection) in his B0105 helicopter, equiped with plenty of space for transporting predator traps into the backcountry.

The endangered alpine rock wren (juvenile) or pīwauwau, Crucible Basin.

Traps were droped at a number of locations including the upper Siberia, Crucible Basin,  upper/lower  Lucidus and Wilkin Valley. The locations are of particular importance for remnant populations of the alpine rock wren, the ancient blue duck (whio) and kea (as indentified by ABT surveys and monitoring) and will intensify current predator control regimes.

Trap drop at lower Lucidus – where the habitat of rock wren overlaps with blue duck/ whio territories.

Existing traps identified as triggered from Encounter Solution’s remote monitoring Celium technology were serviced.  The new traps will be fitted with detection nodes extending the alpine remote monitoring network. Stoats are currently active within the alpine environment (where rock wren are likely to be particuarly vulnerable in their current state of torpor durung the winter) and down to the river valley (where blue duck frequent whilst foraging for aquatic invertebrates or grazing from algae clad boulders).

Adult blue duck or whio within the upper Siberia Valley (Credit: Nick Beckwith)

The stoat Mustela erminea is a small mammalian carnivore native to Eurasia and North America. The Wilkin was one of the first New Zealand introduction sites back in 1885’s in an attempt to control rabbits. Usually the fur is chestnut brown with a white underbelly; the tail has a black tip and is the most distinguishing feature of this mustelid. Some stoats undergo a white moult during the winter in alpine New Zealand, the tail tip remains black as shown in the example below from our last trip.

An upper Wilkin alpine stoat (a varacious predator of indigeonous wildlife) displaying its pale coat aiding camouflage during the winter months. Note: animal captured humanely with DOC 200 trap.

Lydia Bradey and Bill Day discussing the importance of the work Aspiring Biodiversity Trust have been doing to date and taking a moment to appreciate their incredible homeland in what was optimal weather conditions. 🙂

Lydia Bradey and Bill Day expressing the importance of indigenous biodiversity protection and restoration (Upper Wilkin Valley), fundamental to New Zealand’s cultural heritage.

Aspiring Biodiversity Trust actively contributing to the goals of Predator Free 2050 and working towards local and national Biodiversity Strategys through collaborative engagement.

Acknowledgements

With thanks to all our funders, volunteers and incredible supporters particuarly Perry Brooks and Rich Raynes for predator trap assembly, the Department Of Conservation (DOC) for validation of landing sites and Backcountry Helicopters for remainder of team pickup on Wednesday.

Monitoring the endangered rock wren within the alpine basins of the Makarora catchment

Focused on two alpine study sites; the Crucible Basin within the Siberia Valley and the Upper Lucidus/Castalia Basin within the north branch of the Wilkin Valley with extension into adjacent basins. Rock wren monitoring transects defined and surveyed initially for both sites during 2017/2018. The results of this survey work guided deployment of alpine invasive mammal traps and subsequent installation of Celium remote trap monitoring technology to improve predator control trap servicing efficiency and provide additional information on predator movements (first image above shows a male rock wren in moult, note abraided wing and tail feathers).

Following ABT’s initial rock wren monitoring transect surveys undertaken during summer 2017/2018 and observations during 2018/2019 breeding season ABT have now commenced colour banding of individual birds.

A newly colour banded rock wren at Lake Crucible

This bird monitoring method helps to identify individual birds, confirm rock wren territories and provide information on dispersal and survival of post-breeding juveniles whilst providing an indicator of predator control success. We can also learn about moult strategies for this unique alpine passerine.

Ornithologist Rachel Hufton taking morphological measurements during rock wren colour banding

Specialist mist nets are errected within know breeding territories and a audible lure is used to encourage individuals into the net. The mist net shelves are kept low as rock wren flight is limited and birds often forage close to the ground on terrestrial insects (spiders, moths, beetles and flies) and berries from low growing plants such as Muehlenbeckia axillaris (below).

Succulent fruits of Muehlenbeckia axillaris. Several rock wren have been noted foraging from this plant during February within the Crucible basin.

All birds are carefully extracted from mist nets by a NZNBBS certified bird bander. Three colour bands (two on the right leg, one on the left) are carefuly applied, biometric measurements taken and any observations on moult or body condition are recorded.

A mist net (9m) located within suitable rock wren habitat.

A combination of adult and juvenile birds have been banded during the 2019/2020 season. Images below show an adult male with a prominant supercilium and a weight of 14.6g. This bird appears to have gone through post-breeding moult (moulting is the periodic replacement of feathers by shedding old ones whilst producing new ones).

Male rock wren post- breeding moult (March 2020).
Rear of male rock wren showing new primaries and tail feathers.

 

 

 

 

 

 

 

 

This monitoring work provides addition information on rock wren in an area which has not previously been investigated at this level, complementary to existing study sites such as in Fiordland, and Haast, contributing to overall knowledge to promote effective future conservation management for this nationally endangered species. We look forward to further progressing rock wren monitoring during the next breeding season 2020/2021.

Rachel Hufton
The Crucible basin, one of the Makarora catchment alpine study site for the endangered rock wren. During December a haze of ash and dust from the Australian bush fires could be seen on the top of the lake.

ABT’s rock wren protection and restoration programme forms part of a broader threatened species project for the Makarora Catchment from “ridge to river” and is complementary to the Department of Conservation Predator Control Plan for Makarora as referenced within ABT’s Community Agreement and in accordance with NZ Biodiversity Strategy i.e. to maintain and restore viable populations of all indigenous species across their natural range and maintainance of their genetic diversity.

With thanks to: Otago Regional Council, Perpetual Guardians Ltd, DOC Community Fund, Otago Community Trust, Backcountry Helicopters, Southern Alps Air and all amazing volunteers.

References:

Aspiring Biodiversity Trust (2018). Rock wren protection and enhancement programme. Helping protect and restore Makarora catchment threatened species.

Heath, S M 1989 The breeding biology of the rock wren, Xenicus gilviventris in the Murchison Mountains,
Fiordland National Park, South Island, New Zealand Otago University

Melville, D S (2013 reprint). Moult in birds. British Trust for Ornithology. Guide 19.

Melville, D S (2011). NZNBBS Bird Banders Manual. DOC, Wellington.

Weston, K A, O’Donnell C F J, van Dam-Bates P, Monks J M (2018). Control of invasive predators improves breeding success of an endangered alpine passerine. International Journal of Avian Science. Vol 160, Issue 4.

McNab, B K, Weston, KA (2020). The energetics of the New Zealand rockwren (Xenicus gilviventris): could a passerine hibernate? Journal of Experimental Biology 2020.

Return of the kaka at Makarora

This season has seen the return of the South Island kaka (Nestor meridionalis) in the Makarora valley as recorded in the early days by local residents and as documented partly by the work of the late Peter Child (1980’s).

ABT’s baseline forest bird survey was undertaken on four occassions for the Shrimpton/ Charteris beech/ podocarp forest during 2018/2019. Results recorded a total of 24 species; 14 endemic, 2 native and 8 introduced. A pair of kaka was recorded utilising the forest habitat in spring and summer during the survey. Kaka are seasonal specialists, moving from food source to food source as different fruits, seeds and nectar become available.

South Island kaka
Aspiring Biodiversity Trust 5 minute bird counts undertaken during December 2018 for Shrimpton/ Charteris Forest

Regular sitings of a flock of up to 13 kaka were first reported during this spring by local residents and have been seen and heard reguarly since by many people including myself during several stays in the valley. Historically the highest total in any one valley within the region has been documented as 14 (Child’s 1981).

Their jurassic like raucous sqawks and melodic social calls can be heard most evenings and mornings and are often seen flying between areas of forest, residential gardens, the motor camp and commuting over the highway to further foraging habitat.

Long term resident Gary Charteris “It’s like how it used to be 15-20 years ago”.

Gary a keen nature enthusiast observed all 13 kaka in one of his mature trees on the 11 December and noted the characteristic white head of many, a feature of the South Island kaka. Sarah Forder a more recent resident observed up to 10 kaka feeding on her cherry trees. They have also been noted striping away the the bark of forest deadwood whilst feeding on insect larvae. The local school below the forest have been enjoying the commuting activities of these remarkable birds.

Local resident Gary Charteris sharing his thoughts on the latest kaka sightings in the valley with Linda Hufton an overseas visitor.

The magnificient endemic scarlet mistletoe (Peraxilla colensoi) present in the beech forest is another favourite of the kaka, who enjoy the nectar and the flowers along with small flocks of yellow-crowned karkariki (Cyanoramphus auriceps). Remanent parts can often been seen on the forest floor below where birds have been feeding.

Discarded floral parts of the endemic scarlet mistletoe grazed upon by kaka and other forest birds
Field signs of kaka foraging on insect larvae burrowed within forest deadwood

All though little is know about the kaka population in the area, it is thought that they commute from the West Coast. Numbers appear to have reduced to 3 or 4 since recent sightings so parhaps the remainder of the flock have commenced their journey back towards Haast after the summer forest food peak. More information on the range of kaka and their breeding habits within the region would be beneficial to the future conservaton of this species.

It’s now mid January and the sound of the kaka seems to have simered down. The characteristic dry-thrill call of a long-tailed cuckoo or koekoea noted flying overhead is another species recorded in January for this area of important biodiversity value. Lets hope with the help of ongoing community predator control programmes and forest bird monitoring next spring continues to see the return of the kaka and resident forest bird species continue to flourish!

A yellow-crowned kakariki, a parakeet which appears to be doing well this season with small flocks (3-5) frequently observed.

 

 

Whio (blue duck) breeding confirmed in the upper Siberia Valley

Excited to report a memorable encounter with a whio family of three duckling’s, (two-three weeks old) with their magnificient parents. This is a promising sign for this ancient globally endangered taonga within the Makarora catchment.

The family were observed for a while as they continued dabbling amongst the rapids and jumping between rocks in the riverbed. Hopfully the young whio will fledge within the next 10-12 weeks and establish their own territory nearby their natal grounds.

Third duckling with second adult (24 November 2019), note the distinct bill shape present from a young age.

Whio primarily feed on aquatic invertebrates such as mayfly and caddisfly larvae and also take algae from stones and boulders. Their bill has a unique adaptation to facilitate feeding within the upper river environment. The upper bill has a semi-circular soft flap that helps protect the harder part of the bill from abrasion as the bird pries larvae from rocks in the river. The comb-like structures (lamellae) around the edge of the beak allow the whio to filter out aquatic insects and algae prey.

Proud male (forfront) and female parents

A new invasive mammal trap-line has been installed to help protect whio, particuarly during the breeding season. This is essential in tandem with the Department of Conservation’s periodic pesticide application during beech mast events to help increase fledgling success and restore whio populations.

Whio duckling 2-3 weeks old in the upper Siberia River. Circular bill flaps visible.

Whio are important indicator or Māori touchstone species of environmental condition, if they are present water quality is high as their food source (freshwater aquatic invertebrates) only exists under good conditions. This family really did appear healthy too!

“A day to remember, my first whio experience. Thank you!”

            ~ ABT Volunteer and whio photographer, Nick Beckwith

Typical whio habitat in the upper Siberia Valley and location of new ABT invasive mammal trap-line.

Thank you for visiting 🙂

Wrybill (Ngutuparore) For Bird Of The Year

There is a strong case for Wrybill Anarhynchus frontalis as Bird Of The Year.

The wrybill is an incredible bird with considerable resilience that enables it to survive and breed within the harsh, exposed and dynamic environment of New Zealand’s braided rivers. This unique species, then migrates to the food-rich tidal flats of the North Island where flocks of wrybill congregate for the winter. Both sites instrumental to the survival of this species exhibit considerable threats (invasive mammal and avian predation, damage and disturbance of nest sites from recreation, declines in water quality, avian botulism, flooding of nest sites, climate change increasing severity of flood events, loss of habitat and lack of awareness at breeding sites) to survival rates which accumatively contribute to an overall population decline.

Vulnerable nest site of the cryptic wrybill, two blue-grey eggs within a hollow of braided river gravels (centre of image during incubation swap over). An area often used by vehicles on the Makarora.

Currently the wrybill is listed as Vulnerable under New Zealand and International Union for the Conservation of Nature (IUCN) Threat Classification, however should this species be re-evaluated and its threat status increased?

Currently the global population is estimated at around 4,500 – 5000 individuals but how current is this figure and does it take into account the current threat status. The last published demographic figures are based from 1999 Trend justification.

IUCN Trend Justification: Analysis of wintering flocks indicates a slow decline over the last 40 years (Veitch and Habraken 1999), which is supported by preliminary results from a long-term demographic study (J. E. Dowding in litt. 1999).

The wrybill is the only bird in the world with a laterally curved bill (always curved to the right) which allows it to feed on aquatic insects around the edges of rocks and crevices and also from aquatic biofilms. It relies on cryptic adaptation upon its braided river breeding habitat to avoid predation from invasive mammals and avian predators such as Southern black-backed gull. The wrybill’s neck is able to tilt upwards to the side enabling awareness of preadators from above but also downwards when foraging for invertebrate prey. Typically they lay two blueish-grey eggs within a hollow amongst riverbed gravels (as above image) and incubation is for a period of 30 days.

The characteristic call of the wrybill is integral to the onset of spring on New Zealand’s braided rivers.

Wrybill female at nest site battling sandstorm conditions on the Makarora River

Please vote WRYBILL For Bird Of The Year 2019 along with Pūkorokoro  Miranda Shorebird Centre and Braided River Aid (BRaid).

With thanks 🙂

Rachel Hufton is an ecologist and ornithologist fortunate to have experience of monitoring wrybill at both their wintering (Firth of Thames) and (more recently) braided river breeding sites.

Update: Two days after this article the nest site was washed away by rising flood water due to snow melt and rainfall. Both adults remained at the nest site, showing sign of distress searching for their nearly hatched chicks. Further highlighting the need to raise the profile of this endangered shorebird.

Male wrybill (female close by) looking for the nest recently (8 November) lost to the rising waters of the Makarora River. Eggs would have been due to hatch about now after 30 day incubation.

Spring in the Makarora Catchment – From Ridge to River

Coffee break at Jumboland airstrip (the Coru Lounge)

With this seasons work programme in full swing, spring 2019 marks the installation of ABT’s upper river predator control for whio or blue duck (Hymenolaimus malacorhynchos) protection within the Siberia Valley and the Wilkin Valley. This follows previous walkover survey work with the aid of a protected species dog specifically trained in the detection of whio; New Zealand’s ancient waterfowl species, an important part of Makarora’s indigenous taonga.

A whio pair (also known as blue duck) recorded within the Wilkin Valley Feb 2019

Here remnant populations of whio still remain however numbers are low and fledgling survival is limited by the presence of invasive predators such as stoat and rat. This can often lead to a sex ratio imbalance as females tend to be more vulnerable when nesting and during moult. The new trapping networks join up with alpine trap lines to help extend invasive predator coverage for this globally endangered species.

Predator control traps delivered by Backcountry Helicopters into mid-Siberia Valley. Photo credit Pilot Blair

Spring is also the time to resume alpine predator control operations for rock wren and kea protection. New traps added and a number of stoats, and rodents had been caught over the winter months despite not all traps being accessible at higher levels due to the amount of snow still present (these traps will be serviced next visit).

Invasive mammal trap exposed from the snow at Upper Lucidus (September 2019).
A mummified stoat caught at altitude during the winter months

Rock wren pairs were active at the Crucible Basin but all was quite in the upper Wilkin Valley (where snow cover heavier) suggesting that this population may not of yet stired from their winter torpor. Kea were heard calling above the Siberia Valley  and one in the upper Wilkin.

Crucible Basin trap drop off with Backcountry Helicopters and logistical planning for the day ahead
Snow cover along the ridge of Lake Crucible looking towards Gillespie Saddle (Oct 2019). The characteristic call of the rock wren is often heard here.

Back in the lower river valleys of the Makarora and Wilkin, braided river birds have returned and are starting to nest again. ABT braided river invasive mammal predator control continues on a monthly basis throughout the year with the help of regular volunteers. Stoats, rats, hedgehogs and feral cats are being reduced to help improve fledgling success of endangered birds such as black-fronted tern, wrybill and black-billed gull. The Southern black-backed gull is a avian predator of endangered braided river birds and their chicks. Adaptive management of this species is due to progress this season also.

Makarora braided river habitat showing the Wilkin confluence and the head of Lake Wanaka

Acknowledgements

With thanks to all our volunteers, funders, partners and supporters 🙂

Alpine predator control progress – winter activity indicated

Since the installation of ABT’s alpine predator control programme for the protection of rock wren Xenicus gilviventri, stoats have been recorded in traps at 1200 m elevation (refer to spatial distribution map below) in areas of rock wren habitat and they are still being caught during the winter months.

Adult male stoat caught at 1200 m by DOC 150 (kea proof) trap.

During this winter, Celium remote monitoring technology has shows that invasive mammalian predators are still on the move during the winter and are being caught within the alpine environment where indicative rock wren territories have been identified.

Snap shot of ABT trapping data Feb – April 2019 for Castallia/ Lucidus

The real time data shows current available trap coverage at Lucidus/ Castalia on 8 August 2019 is mostly reduced at lower altitudes and representing a threat to rock wren territory (southern scree area above Lake Lucidus). The red symbols display trap triggers and the green symbols identify the remaining trap coverage available to passing predators. The data illustrate that there is currently no imperative to replace bait (probably due to low temperatures in the alpine environment or lack of predator food source), and that servicing requirements are only determined by available un-sprung trap coverage at this stage (potentially effective rock wren protection).

Real time data provided by Celium remote monitoring technology.

The Celium remote technology provides additional information on alpine predators such as commuting activity and time of capture. Most trap triggers appear to occur at dawn between 06:00 – 08:00 h at 1000 to 1200 metres.

Time and altitude of invasive mammal trap triggers and previous trap servicing occasions

Climate conditions are recorded showing decreasing daily temperatures towards winter at all three Hub Stations. Overall winter conditions are cooler at Castallia/ Lucidus relative to the Crucible Basin.

Celium Hub Station daily temperatures at three alpine locations.

We look forward to servicing alpine traps and resuming rock wren monitoring this coming season, once baseline temperatures have warmed up and the rock wren are out of their winter torpor. Hope to see this juvenile from last year!

Last years (2018/2019) rock wren fledgling

Acknowledgements

With thanks to all our volunteers, partners and the following funders; WWF, the Tindall Foundation, Otago Regional Council, Oceana Gold and the Otago Community Trust.

References

O’Donnell, C F J, Weston K A, Monks J A. (2017). Impacts of introduced mammalian predators on New Zealand alpine fauna. New Zealand Journal of Ecology 41: 01-22.

Weston, K A, O’Donnell C F J, van Dam-Bates P, Monks J M (2018). Control of invasive predators improves breeding success of an endangered alpine passerine. International Journal of Avian Science. Vol 160, Issue 4.