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.
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.
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 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
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.
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.
Please voteWRYBILL ForBird 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.
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 tonga.
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.
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).
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.
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.
With thanks to all our volunteers, funders, partners and supporters 🙂
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.
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.
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).
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.
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.
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!
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.
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.
One of ABT’s core purpose is the collation and updating of threatened species records within the Makarora Catchment to help facilitate and inform appropriate application of invasive predator control.
ABT have been updating records for whio/ blue duck Hymenolaimus malacorhynchos to help ascertain the current status of this ancient endemic waterfowl species within the upper reaches of the Makarora Catchment. No formal inventory has been completed for this species since the work of the late Peter Child during 1970’s/1980’s.
To date a specialist contractor Paul van Klink and his protected species survey dog (Hoki) has been commissioned to undertake walkover surveys for the upper Wilkin, the Siberia and the Young Valley.
From the results of these walkover surveys and the addition of recent incidental records it is promising to see that there remains a remnant population. Numbers are low and in some cases are limited to just male individuals, a high prevalence of unpaired males on rivers without predator control is often common as nesting females are more vulnerable to mammalian predation. However, evidence of breeding success has been recorded with observations of pair bonds and a fledgling bird.
This valuable survey work continues to expand for the region with the future aim of restoring viable, sustainable populations of whio/ blue duck within the upper river catchments of the Makarora for future generations.
Child P, (1981). Birdlife of Mount Aspiring National Park. Scientific Services No.4. Department of Lands and Survey. Head Office, Wellington, New Zealand.
The start of 2019 marks the installation of Celium remote monitoring technology for two key alpine rock wren sites within the Makarora Catchment. We are delighted to be partnering with Encounter Solutions on this innovative approach not yet trialled within the alpine environment.
The Celium platform is a low powered wireless network designed for the purpose of wide-scale rugged management applications. Celium consists of a range of communication devices called Nodes (attached to traps) equipped with sensors. The sensors are designed to monitor parameters such as the status of a pest control trap (below), which the nodes then communicate to the base station called a Hub. The Celium Hub transmits the data via satellite to the Celium cloud programme, which then sends a signal to the user via a notification email or text message.
The Celium Platform can be used for predator control monitoring and also has potential application for monitoring climate/weather and wildlife. On this instance the installation intends to aid trap maintenance servicing efficiency for rock wren protection within remote areas.
Encounter Solutions Director Simon Croft (below) enjoyed his time out in the field with ABT and gained a number of close encounters with New Zealands only true alpine specialist – the endangered rock wren. His technical knowledge was a valuable addition during the North Wilkin installation.
Since installation there have been three invasive mammal trap triggers at the highest trap location points. We look forward to reporting back on what predators have been captured. More soon….
With thanks to sponsors; Otago Community Trust, WWF, the Tindall Foundation, Otago Regional Council and Oceana Gold.
Classified as nationally endangered, the rock wren (Xenicus gilviventris) is New Zealand’s only true alpine specialist remaining in the mountains above the treeline for most of its life. Following the results of ABT’s rock wren survey transect monitoring during Jan/Feb 2018 the team have been installing invasive mammal predator control within two key focal alpine areas. Areas include, the Crucible basin within the Siberia Valley and the upper Lucidus/ Lake Castalia, North Branch of the Wilkin.
Invasive mammalian predator traps (DOC 200 and 150 models) were transported in to both sites on a suspended sling from a Hughes 500 helicopter. The traps were then distributed to designated locations extending and complementing existing predator control efforts within the locality.
Site locations within the Makarora Catchment can be seen from the topograph image below. The North branch of the Wilkin and the Crucible basin are situated to the west of the Makarora River.
Rock wren are at risk from invasive mammalian predation particularly from stoats and rats but also mice. There is increasing recognition that invasive predators are widespread within New Zealand alpine zones. Recent work has found that humane kill trapping of invasive predators can increase rock wren breeding success within the alpine environment (Weston et al 2018).
The national population of rock wren is currently unknown but thought to be around 5,000 mature individuals (IUCN) with severely fragmented populations due to particular habitat requirements. The rock wren belongs to a unique ancient lineage of eight New Zealand wrens now only two species survive. The alpine rock wren and the rifleman Acanthisitta chloris, generally a forest passserine.
During both trips it was encouraging to observe a number of adult rock wren present busy foraging on invertebrate prey. Particularly, at Crucible basin following the late November snowfall. Most birds were male which may indicate females occupied on their nest sites.
Remote trap monitoring
With the aim of optimising alpine trap servicing efficiency and improving understanding of temporal and climate influences on predator trapping ABT have partnered with Encounter Solutions Ltd to install remote trap monitoring technology. The equipment will be installed in January for both alpine sites. This system has been applied to other trapping habitats but will be a first for the alpine environment. If successful other remote rock wren habitats could benefit from use of this technology to aid predator control programmes.
With dedicated effort it is possible that focused rock wren recovery at these sites could result in potential “source” populations of rock wren and expansion/ migration of numbers/ pairs into unoccupied habitat (Weston 2014).
With thanks to Otago Community Trust, Otago Regional Council, Oceana Gold, Backcountry Helicopters Ltd, Tony Zimmerman trap supplies, Central Otago Hunting and Fishing, DOC Wanaka, Backcountry Saddles Expeditions, volunteers Nick Beckwith and Andrew Shepherd.
Aspiring Biodiversity Trust (2018). Alpine predator control plan for rock wren. Makarora Catchment Threatened Species Plan.
IUCN Red List of threatened species
Weston K.A. 2014. Conservation genetics of alpine rock wren (Xenicus gilviventris). Doctorate thesis.
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.
The 2018 braided river bird survey for the Makarora River commenced on the 18 October over a period of three days. The survey area begins at Boiler Flat, includes the lower Willkin and finishes at the Makarora delta where the river meets Lake Wanaka. Endangered braided river birds; wrybill, black-fronted tern, black-billed gull, banded dotterel and South Island pied oyster catcher have returned to breed on the braided river again.
This years survey found six pairs of endemic wrybill (the only bird in the world with a bill that bends to the right) two on nests with eggs and one with two new chicks. During the survey one of the male wrybills was identified with a metal leg band and its unique code was identified thanks to the help of an amazing photo taken by volunteer surveyor Nick Beckwith.
The wrybill was originally banded as a juvenile at Miranda (Firth of Thames) and now as a six year old is found breeding over 900 km away. This bird has probably made the return journey at least five times. A wrybill female was also recorded with a metal band last year and she was found to have been banded on the same day as the male (as an adult) at Miranda during November 2012.
Key nest site monitoring is ongoing throughout the breeding season. Two wrybill chicks hatched on 6 Nov after 30 day incubation period; mainly by the female.
The black fronted terns had formed a number of nesting colonies with eggs at many nest sites along the length of the river. Unfortunately most nests have been lost to high level flooding over the last weekend but signs of re-nesting has already been observed.
Despite the Makarora River flooded “bank to bank” last Friday the adaptation of endemic braided river birds is such that a flightless braid island bound banded dotterel chick somehow survived an extreme natural weather event (image below). Nature never fails to amaze!
Southern black-backed gull populationcontrol commenced this season on the Makarora River and also on a more national scale for Canterbury braided rivers. The numbers of SBBG’s have significantly increased on the Makarora River and on a national scale due primarily to changes in landuse. They are a known predator of braided river bird eggs and chicks, particularly in relation to black-fronted terns. This is evident from trial camera footage at several nesting sites. Invasive avian predator control complements the existing invasive mammal predator control programme for the Makarora River. Similar control measures over time have been shown to increase fledgling success for black fronted terns on the Tasman River.
Fig 1, below summarises this years braided river bird walkover survey.
Other interesting records include a banded and flagged South Island pied oystercatcher. This bird was originally banded at Sand Island near Nelson Airport as an adult during January 2010. This is an interesting record as little is currently know about the migrational movements of this species.
In the news, ABT are delighted to feature in the latest Otago Regional Council (ORC) Eco Fund promotional video (above screenshot of the Makarora River with the Wilkin valley in the background) and were asked to supply threatened species survey images from last season (top left and top right below) which have been used to feature in the new promotional brochure. The video provides a short clip on a number of valuable environmental projects happening across Otago. There is nice drone footage of the Makarora braided river habitat. The video aims to encourage projects that protect and enhance the environment and the community.
Makarora Catchment Threatened Species Programmes
We may have been quite but behind the scenes ABT are busy implementing and progressing Makarora threatened species programmes for endemic braided river birds, rock wren, blue duck / whio and forest birds. This also includes biodiversity education an integral part of connecting people with nature.
Invasive mammalian catch effort on the Makarora braided river has removed a number of stoats, hedgehogs, rats and mice in preparation for the spring bird breeding season. Feral cats and the Southern black-backed gull (an avian predator of endemic braided river bird chicks) are also part of the braided river bird restoration programme and will be addressed this coming season. Volunteer help has been essential to this progress.