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/ pīwauwau 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.

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.

 

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 🙂