Ducks Unlimited
Tuesday, 27 August 2019 05:41

Operation Duck Pond

With about 90 percent of New Zealand’s wetland lost over the past 150 years, Fish & Game NZ realises there’s a compelling need to assess the role that ponds play in successfully managing waterfowl.

Ponds have been established across the New Zealand landscape for  various purposes including stock watering, irrigation, storm water  capture, effluent ponding, waterfowl habitat and simple aesthetic values. Currently, there’s little scientific information on what, and how big a role these ponds play as habitat for waterfowl populations.

The aim of this ‘citizen science’ project is to determine what pond habitat features provide good breeding for waterfowl, and promote good pond management practices for breeding these birds. Fish & Game has launched an appeal for people who want to monitor waterfowl  populations on ponds around their area. The aim is to establish a network of ponds to be closely monitored over the breeding season.

You don’t have to be a scientist! All volunteers will be given a set of simple instructions on how to go about monitoring. Fish & Game will supply a manual with simple instructions on how to run their surveys – so everyone round the country is tackling the project the same way, and volunteers gather the best data possible.

If you’re keen to help with collection of data and are prepared to monitor a pond, a fun and fulfilling project that will help New Zealand’s waterfowl and other native water dependant birds, this project is for you. Don’t forget – we are keen to hear from a wide range of people,  including youngsters. Kids – depending on your age, you may need to line up support from mum and dad, a friend or relation.

Your help in this project will not only provide data to drive management decisions, but will give waterfowl enthusiasts, hunters and landowners a unique opportunity to get involved and make a real hands on  contribution to our efforts to manage waterfowl – and keep their numbers up!


To get involved please contact: This email address is being protected from spambots. You need JavaScript enabled to view it.
Nathan Burkepile, Fish and Game Officer, Northland Fish and Game
Published in Issue 158

Change attitudes and improve the environment

The Mangaone West region is typical of many farming districts where remaining indigenous cover is very limited and the balance is in productive farmland.

Into this area a few years ago stepped Ducks Unlimited member Ossie Latham, and his conscious was pricked by the degradation he saw in the waterways near his home.

Growing up on the banks of the Oroua River downstream from Feilding, part of a third generation on both maternal and paternal sides of his family he remembers: “During that time the Oroua had gone from a pristine small river where kids could swim in deep holes, dive off the road bridge, catch eel, trout and flounder, to a gravel choked conduit for industrial, town and farm waste. A dead waterway, the greatest degradation happened in my time as a kid,” said Ossie.

Then came concern for the Manawatu River and its’ tributaries of which the Oroua is one. The Manawatu River Accord was set up and out of that spun the Oroua Catchment Care Group. Ossie attended their meetings and the Oroua Group decided the best way to tackle the problems was to think catchment wide
but act local to address whatever issues may be in any given area. The Mangaone West stream where Ossie and wife Mary live is a tributary of the Oroua. Ossie volunteered to be champion for that area.

As a local champion his job was to gage the support of residents for a collective effort to address issues of farming and lifestyle practises that degrade the environment.

“Once sufficient interest was identified, we called a community meeting and established the Mangaone West Landcare Group.
Knowing that what we do on our land eventually affects water quality in our area
and downstream, we chose to take a holistic view of our catchment and deal with our habitat as a whole, be it farming practises or lifestyle choices.”
Ossie said it was fortunate that some residents in the lower catchment had come together 15 years ago and as a group had investigated and in many cases implemented, more sustainable farming practises.
This group ran out of puff after four years but two of the group’s successes were a widespread possum control programme that is still going today, and the other was recognising the detrimental effect of pugging by wintering mature cattle on wet soils.

Neil Managh, coordinator of the original group gave his support to Ossie who
then called on the leading farmers in the area, the local school principal, known 
environmentalists, friends and acquaintances and got their commitment to the scheme.

“We organised a community wide pamphlet drop calling a public meeting and away we went,” Ossie said.
Is this something DU members should get involved with? Ossie said: “Given that 
whatever we do to our landscape sooner or later affects our wetlands and waterways, I think it is worth DU members thinking about what happens upstream from their favourite dam, wetland or waterway.
“The primary benefits are thinking of being more sustainable in what we do for the benefit of the habitat as a whole. This includes the best way to keep our soils in situ, the nutrients on the property and a flourishing diversity of which we are part.”
Although initial funding came from the Government through the Ministry for the 
Environment to the Regional Council to the group; they also applied to Trusts with an interest in what they are doing and they asked Landcare to come on board to provide the governance and institutional expertise.

About 60 percent of landowners are part of the group. All major farmers bar two are committed and interest is growing. There is a diversity of views on what best practise is and just what is sustainable but Ossie said they cope with this by agreeing that “Sustainability is the ability of the current generation to meet its needs, without compromising the ability of future generations to meet theirs.”
“I’m not sure where I got the quote from but it gained widespread acceptance to what we are on about.

“We recognise it’s taken over 100 years to get where we are now, so we expect our work to improve our chosen living spaces to be intergenerational. While the stream is our common bond, we love our landscape which the stream and we are part off.” 

“After doing the question and answer bit for you I got to thinking, what is the key for many of the settler families who are part of our group? Many of them are 3rd and 4th generation; they have a strong sense of stewardship, a concept that is evolving as our knowledge of interdependence grows. It’s good to be part of their efforts.”


Published in Issue 159
Sunday, 25 February 2018 09:33

Joining the dots on Watermouse

WetlandCare Australia has obtained funding through various local government grants to try and locate the vulnerable water mouse, Xeromys myoides. Working with consultant and Sunshine Coast based water mouse researcher, Janina Kaluza UQ, WetlandCare Australia will be out in the mangroves and saltmarsh from Jacobs Well to Beachmere on the hunt for signs of the water mouse.

With support of several organisations, Janina Kaluza has been surveying, monitoring and researching the water mouse in a number of locations throughout the Wide Bay and South East Queensland region since February 2012. This work has expanded and built on previous research in the past 15 to 20 years by scientists within State Government and the broader community. However, gaps remain on information that Janina aims to fill.

The water mouse inhabits coastal areas of central and south east Queensland, Northern Territory and New Guinea, and is typically found in coastal saltmarsh and mangrove areas. A key sign of their presence is their nesting mounds that range from free-standing mounds in saltwater couch grasslands to sheltered mounds in sites such as the base of old grey mangrove trees (Avicennia marina) located within the intertidal zone. The water mouse forages in the mangroves at night, feasting on invertebrates such as crabs, shellfish and snails. Loss, fragmentation and degradation of their habitats are key threats to their survival.

Working with local councils, WetlandCare Australia has been awarded funding to undertake a number of small local projects to survey potential water mice habitat areas. The combined information from these projects will contribute towards completing the jigsaw puzzle on water mice in south east Queensland.
Not much is known about this Australian native rodent, with the data collected being an important step in assisting the implementation of the ‘National Recovery Plan for the water mouse (false water rat) Xeromys myoides’ and the delivery of a coordinated approach to its conservation.

Another project focuses on surveying key habitat areas on Russell Island, one of the Southern Moreton Bay Islands, with funding support from a Redland City Council’s Conservation Grant. The water mouse was recorded on the island in the 1990s. The project aims to determine if the water mouse is still present and identify current threats to its habitat and survival. Surveys undertaken over three days in May this year and the data and survey results are currently being collated.

Funding through the City of Gold Coast’s Community Grants Program, WetlandCare Australia will be focussing water mouse survey effort in the Jacobs Well area in early 2016. Survey work will build on knowledge obtained in the 1990s that recorded the presence of the water mouse in this area. Logan City Council, through their Enviro Grants allows for surveying potential habitat areas on the Logan River in search of the water mouse. Approximately 40ha of mangrove areas will be surveyed in early 2016 to record the presence or absence of nests.

Water mice surveys will also be undertaken in early 2016 over 80ha of mangrove vegetation near the mouth of the Caboolture River with funding through the Moreton Bay Regional Council’s Community Grants Program. This project aims to identify the presence or absence of the water mouse in this area. The water mouse has been recorded previously at nearby Donnybrook.
Published in Issue 165
Friday, 23 February 2018 08:23

Mute swans on site

Having their own water feature right in front of their home is a rewarding and entertaining result for hard work for Steve Clarkson and Lyn Watson.

Several years ago they built their attractive home that sits right on the edge of their main pond, and now after years of toil they have a  grand vista as a backdrop to their everyday living.

Just last year they acquired two Mute Swans. The pair settled in well, and add another interesting touch to the scenery. With luck there will be more than two white swans on that pond.

Steve and Lyn also run a few black and coloured sheep and Lyn takes full advantage of  using their wonderful wool to make a variety of garments and useful items.

Published in Issue 166
Friday, 23 February 2018 08:16

Crayfish (Koura) anyone

When I was a kid (and that was a while ago), there was a stream a couple of gullies away from our place with freshwater crays (koura) living there. They were not big but they did taste good.

On a camping holiday at Taupo there was the  opportunity to head off to the lake outlet and dangle tempting tit bits on string and pull up a few koura, and they were slightly bigger than the ones at home.

So it was with interest that recently I read  about a South Island forestry company who decided to stock their fire-fighting ponds with  fresh water crayfish. What a smart idea. They now have 400 ponds.

Takes a while for the little koura to get big enough to provide a good meal, and I don’t know how they would co-habit with ducks, but for those with a good sized pond/lake it just might be a new idea.

It seems their distribution is shrinking through loss of habitat. So this could be an interesting venture or hobby it you have the right sized water area. The Department of Conservation  regard them as a threatened species, so if you lean more toward conservation than a good  meal, this could be an opportunity to do a bit for their survival.

Koura may possibly prefer free flowing water so a quiet pond might not be their home of choice.

But don’t be in a rush to eat them – it takes a while for them to reach eatable size. Feeding them might help. Oh - and you do need a permit if you consider farming them as a commercial venture.

Liz Brook

Published in Issue 166

Southland has long been recognised for its duck population and the associated buzz around the district during the first weekend in May!

However, the combination of several poor mallard breeding seasons in a row and in response to hunters concerns about the struggling North Island population, the Southland Fish and Game Council funded a national mallard research project. I was fortunate to have my Master’s research funded as part of this wider project.

The Southland Council had expressed concern about continual dairy conversions and the associated changes in pasture management that might affect duckling survival. Consequently, for my research I focused on female habitat selection and factors that may impact duckling survival.

In terms of pasture management, I found that duckling survival is comparable between dairy and sheep/deer pastoral grazing systems. This is good news for mallards in Southland, as we readily see our landscape convert to dairying systems. However, first and foremost, broodrearing females in Southland are selecting for ‘unmanaged habitat’ i.e., everything that is not pasture (hedgerows, shelterbelts, rank grass). This may not seem like an unexpected result, but alarmingly, these types of habitat are associated with lower duckling survival.

In our landscape, these habitats are typically thin and linear in configuration, creating ideal travelling corridors for predators. While broods may feel safe and protected tucked up in a hedgerow, predators that rely on their olfactory sensory system to track prey can easily run along the downwind side of these strips and pick up the scent of a sitting duck.

Additionally, I found that duckling survival is reduced for broods that spend their time closer to houses and roads, with both being structures that tend to be associated with a higher predator presence. Over the two year study period, 15-25 percent of our breeding females were killed on the nest by predators. To put this figure in context, this is similar to the proportion that we, as hunters, shoot each year. Further, an additional 30 percent of nests last season were abandoned or destroyed due to predators. At necropsy (post mortem examination), many of these females had evidence suggesting both mustelids and cats were the main perpetrators. While more research is needed, these results suggest that predators are having a much bigger impact on our mallard population than we originally suspected. Luckily, predator abundance is a factor that we can all influence. Further, in reducing the predator guild, you may be surprised in what other wildlife you attract!

Operation duck pond

After chasing ducks through the 2014  breeding season, staff noticed definite differences in ponds that were used by ducks and broods. Consequently, over the 2015 breeding season, we deployed 21 game cameras on ponds throughout the region that captured images every five minutes during daylight hours. If you do the math, that means I have roughly 250,000+ photos to wade through! As a result, I have not quite made it through all these photos to run the analysis. However, I can make a few comments on factors that seem to have an impact on the ponds I have made it through thus far.

Typically, the shallower ponds with plenty of feeding bottom (at least 43cm deep) have had hundreds of headless, ‘bums-up’ photos. Another example is a pond that only has water in it during the breeding season. These seasonal bodies of water tend to be the most productive in terms of invertebrate presence, and this may flow through into brood use. In last year’s study, I found that the presence of ephemeral water (short-lived bodies of water) during the first 10 days of a ducklings life, had a huge impact on survival. For Southland, cumulative duckling survival to 30 days of age without ephemeral (lasting only a short time), water present was only 11 percent for broods raised by yearling females compared to 26 percent for broods raised by adult females. However, with the presence of ephemeral water, duckling survival dramatically increased to 28 percent for broods raised by yearling females and 46 percent for broods raised by adult females. Initially, ducklings require a high protein food source, which is readily available in ephemeral water, particularly in the form of earthworms that are forced to the surface. Hence, this may be why Southland is recognised as a duck factory, and as duck enthusiasts, we shouldn’t be complaining about the weather! Consequently, management of pond water levels to mimic a seasonal body of water might be one way to encourage duck use of ponds.

Another observation that might be important to brood use is the degree of exposure of the pond to the elements. The more barren-like ponds lacking any edge, bank, or overhead cover tend to have very limited use by any mallards, and none by broods. It will be interesting to see what factors come out of the data, but my gut feeling is pond use by broods is a combination of factors that create a sheltered, food-laden haven…. Watch this space! After chasing ducks through the 2014 breeding season, staff noticed definite differences in ponds that were used by ducks 

Erin Garrick

Published in Issue 167
Wednesday, 07 February 2018 01:00

Hunter Wetlands - Porangahau

Published in Issue 169
Tuesday, 31 October 2017 03:31

DU Flight NZ Game Bird Habitat Trust

The NZ Game Bird Habitat Stamp programme and the Game Bird Habitat Trust Board play an important role in the protection, enhancement and creation of game bird habitat in New Zealand. While the major focus has been on wetlands, upland game bird habitat is also included. In addition, any improvement of wetlands is also of benefit to a wide range of other wetland birds and fish.

The NZ programme was initiated in 1993 and was based on the programmes operating in Canada and the USA. DUNZ actively supported its establishment. The programme is ably administered by Fish and Game NZ who process the funding applications and provide the secretarial support for the Trust Board.

Board Members

Board members are appointed by the Minister of Conservation on the recommendation of Fish and Game (4 members), Ducks Unlimited (1 member) and a member nominated by the Director General of Conservation.

Current members are:

Andy Tannock – Chairperson (Manawatu), Ian Hogarth (Canterbury, formerly Northland), Mark Sutton (Southland), Steve Cragg (Gisborne), John Cheyne, DU representative (Hawke’s Bay), Susan King, DOC nominee (Malborough).


The functions of the Trust Board are set out in Section 44D of the Wildlife Act 1953. The Board’s primary focus is applying funds obtained from the Habitat Stamp programme as grants to applicants for the protection, restoration, improvement, creation, or procurement of game bird habitat.

The Board can also:

  • Identify and evaluate areas for protection or restoration of habitat
  • Negotiate with landowners and other agencies for the protection and restoration of habitat
  • Promote or provide advice on protection and restoration of habitat
  • Promote the sale of game bird habitat stamps and associated products
  • Recommend the game bird or other wildlife species to be depicted on stamp.

NZ Game Bird Habitat

NZ Game Bird Trust StampNZ Game Bird Trust Stamp


Funding for the Trust comes from the $3 Game Bird Habitat Stamp, recently increased from $2, from every game bird hunting licence and a proportion of the external sale of stamps to collectors and prints of the annual bird painting. The money raised each year from game bird habitat stamps is transferred from Fish and Game Councils to the Game Bird Habitat Trust. Currently this is approximately $100,000.

Major Projects

The Trust Board is working with wider community interests in implementing a wetland management plan involving a small number of large projects in both the North and South Island. This has included the Para Wetland near Blenheim and Taikitakitoa Wetland near Dunedin

 It is currently considering how to help with the JK Donald Block on the north-eastern edge of Lake Wairarapa and the Underwood Wetland near Dargaville. These projects are ranked highly by the Habitat Trust Board for development of a sponsorship package on the basis of game bird and other wildlife habitat enhancement potential.

DU received significant financial assistance from the Trust in developing the Wairio wetland.

Annual Grants

Applications for grants from the Trust close on 30 June each year and are open to anyone with support from the landowner and a recognised habitat referee. Information and forms are available from the Fish and Game NZ website.

This year (2017) the Trust has received 30 applications and these will be considered by the Board when they meet in the Wairarapa 24-25 August. They will also be visiting Wairio wetland during their visit.

Supplied by John Cheyne.

Published in Issue 172
Monday, 04 September 2017 12:29

Why Wetlands are Important

Wetlands are important features in the landscape that provide numerous beneficial services for people & for fish and wildlife. Some of these services, or functions, include protecting & improving water quality, providing fish & wildlife habitats, storing floodwaters and maintaining surface water flow during dry periods.
These valuable functions are the result of the unique natural characteristics of wetlands. To access more information about wetlands, please visit the Wetland Factsheet Series. At
Wetlands and Nature.
Wetlands are among the most productive ecosystems in the world, comparable to rain forests and coral reefs. An immense variety of species of microbes, plants, insects, amphibians, reptiles, birds, fish and mammals can be part of a wetland ecosystem. Climate, landscape shape (topology), geology and the movement and abundance of water help to determine the plants and animals that inhabit each wetland. The complex, dynamic relationships among the organisms inhabiting the wetland environment are called food webs. This is why wetlands in Texas, North Carolina and Alaska differ from one another.
Wetlands can be thought of as “biological supermarkets.” They provide great volumes of food that attract many animal species. These animals use wetlands for part of or all of their life-cycle. Dead plant leaves and stems break down in the water to form small particles of organic material called “detritus.” This enriched material feeds many small aquatic insects, shellfish and small fish that are food for larger predatory fish, reptiles, amphibians, birds and mammals.
The functions of a wetland and the values of these functions to humans depend on a complex set of relationships between the wetland and the other ecosystems in the watershed. A watershed is a geographic area in which water, sediments and dissolved materials drain from higher elevations to a common low-lying outlet or basin a point on a larger stream, lake, underlying aquifer or estuary.
Wetlands play an integral role in the ecology of the watershed. The combination of shallow water, high levels of nutrients and primary productivity is ideal for the development of organisms that form the base of the food web and feed many species of fish, amphibians, shellfish and insects. Many species of birds and mammals rely on wetlands for food, water and shelter, especially during migration and breeding. Wetlands’ microbes, plants and wildlife are part of global cycles for water, nitrogen and sulfur. Scientists now know that atmospheric maintenance may be an additional wetlands function. Wetlands store carbon within their plant communities and soil instead of releasing it to the atmosphere as carbon dioxide. Thus wetlands help to moderate global climate conditions.
Wetlands and People
Far from being useless, disease-ridden places, wetlands provide values that no other ecosystem can. These include natural water quality improvement, flood protection, shoreline erosion control, opportunities for recreation and aesthetic appreciation and natural products for our use at no cost. Protecting wetlands can protect our safety and welfare.
Environmental benefits of water quality
Wetlands improve water quality. As water moves into a wetland, the flow rate decreases, allowing particles to settle out. The many plant surfaces act as filters, absorbing solids and adding oxygen to the water. Growing plants remove nutrients and play a cleansing role that protects the downstream environments.
Flood control
Wetlands can also reduce the impacts of flooding, as they can absorb heavy rain and release water gradually. Downstream water flows and ground water levels are also maintained during periods of low rainfall. Wetlands help stabilise shorelines and riverbanks.
Wildlife habitat
Many wetland plants have specific environmental needs and are extremely vulnerable to change. Some of our endangered plant species depend totally on wetlands. Wetlands support great concentrations of bird life - far more species than a similar forest area. The survival of threatened species such as the Australasian bittern, brown teal, fernbird, marsh crake and white heron relies on remnant wetlands.
Native fish need wetlands too. Eight of New Zealand’s 27 species including inanga, short-finned eels, kokopu and bullies are found in wetlands, while the whitebait fishery depends on the spawning habitat offered by freshwater wetlands. The decline in native fish populations is directly related to massive reductions in freshwater habitat.
Published in Issue 170
Monday, 04 September 2017 11:58

On the Scent - Bittern

On the trail
It’s a beautiful morning on Lake Whatumā. As the last of the fog lifts and disperses, leaving the lake’s clear water exposed, Kimi and I float along the edge of the western shore quietly in our kayak. We’re looking for bittern nests and listening for the tell-tale bubbling call of chicks.
Nearby, peering out of two separate maimais are the heads of Finn McCool and Bernie Kelly. They’re watching careful for any signs of movement within the Raupo – an important job. Kimi and I can’t see more than a few metres in front of us as we move through the Raupo so we always need ‘spotters’ to detect the birds that are present but try to sneak away from us.
Suddenly, Kimi’s black Labrador nose begins to twitch. She’s picked up some scent. Her tail flicks up and begins to bounce from side to side as she reaches forward across the kayak. I slip off the kayak giving her permission to do the same. It is at this moment that we transform into our swamp alter egos. Kimi becomes an elegant torpedo - her otter-like tail propelling her beautifully through the water, until she silently disappears into the Raupo.
And me? Not so much.
My transformation is somewhat less fortuitous. Knee deep in mud, one foot already stuck and water up to my waist - my movements are best described as cloddish and ungainly. I slosh awkwardly after her trying my best not to sound like a heffalump bombing in a swimming pool. As I enter the Raupo, my radio crackles and Bernie announces that a bittern has flushed south of our location. We can never be sure of the sex of a bittern when we see one, but there are a few tell-tale signs that give us a clue.
Firstly, females are noticeably smaller than males, and secondly, in the case of Lake Whatuma, we know that none of the females are wearing radio-transmitters (yet!). Both Bernie and Finn carry radio-receivers. These devices detect the pulse-like signals emitted from any bird that’s been caught and still carries a Ducks Unlimited transmitter. If a radio-signal is detected, Finn and Bernie can identify the bird and follow its movements even if they can’t see it in the thick Raupo – so when a relatively small bittern flushes and they don’t get a signal on their receivers they know it’s likely to be a female.
The excitement in Bernie’s voice tells me this bird fits this criteria even before his words confirm it. Another female is great news. We’ve been searching bittern territories at Lake Whatuma for females and nests for a while now. We started unobtrusively by watching over known territories in October for something known as a ‘female foraging flight’. These flights are supposedly undertaken by females when they leave the nest to find food, a behaviour they have to do regularly because the males don’t feed them or the chicks. Such flights are noticeable and have enabled researchers to find nests overseas. By November, we have only witnessed a handful of these flights, and after investigating them further none suggested the presence of a nest. This surprised us. In previous years we’ve found nests by accident and all of them were (or would have been) at chick stage by November.
It was time to up the ante…and go in with the dog. Since November we’ve swept every known territory on foot looking for evidence of nesting. Up till now, and with the help of spotters like Bernie and Finn, we’ve been able to find at least four small unmarked birds (females), but none of them appear to show any interest in breeding. This latest bird would be the fifth. Bitterns are polygynous, meaning males often have more than one female. So it’s reasonable to expect up to five females to every male. To only find five on the whole lake – a site with at least twelve booming males – is somewhat concerning. If not down-right depressing.
To add to our concerns – the five males that still carry Ducks Unlimited transmitters at Lake Whatuma have been very unstable in their territories. They started off well, with all five returning to the lake in August to boom as usual and fight over the usual patches of real estate. Yet by October only two appeared to have claimed a Raupo patch. The others had spent all their time interfering with their neighbours before leaving to try elsewhere. Why are they not finding what they need at L. Whatuma?
So when Bernie confirms a fifth female. I think we can be forgiven for thinking we’d won the lottery. He immediately directs me southwards towards where the bird came up...but Kimi has different plans and starts heading northwards into the breeze. I pause for a second. On one hand I have a confirmed sighting to the south. A rare opportunity to reward the dog on fresh scent and a possibility that there was a nest nearby. On the other hand my dog clearly thinks she’s onto something better, and as I can’t be sure what the dog nose knows and John Cheyne is always telling me to ‘always trust your dog’…I decided to abandon the sterling advice of the spotter and follow Kimi’s lead.
I wasn’t disappointed. It took us awhile to find the four perfectly formed olive eggs that were tucked away on a carefully constructed platform in the thick Raupo. We think the nest belonged to the same bird that the spotter saw. Kimi has been trained on feathers and the live bird’s scent, and in this case the wind would have been wrong for her to detect the flushed female. Instead we suspect that the female moved south to evade us as we entered the Raupo. Kimi hit its scent track and was able to follow it back through the vegetation. It was definitely a team effort requiring all parties - the spotters, dog and handler.
Finding Nests
There are several reasons why we’re particularly interested in finding nests this season. We have little knowledge of how successful bitterns are in breeding and whether chicks survive to adulthood. Nests are notoriously difficult to find and this is part of our problem. To date we’ve had great success in developing methods for monitoring male bitterns (through their conspicuous booming call) but have no means for detecting females and chicks. Yet it’s the females and chicks that are our capacity to save the species. Just like money in the bank, the more we start with, the greater the capacity to grow our fund (or bittern population). One male can fertilise several females, so it’s the females that limit the size of our deposit. The more eggs she lays the higher the interest rate, and the more chicks that survive the greater the deposit in the following year.
…and of course to achieve this you have to prevent your significant other from hammering your credit card (prevent threats) in the meantime – this is tricky for bitterns as we’re still working out how many we’ve got, who’s hammering the bittern credit card and how much they’re spending…and there are so many potential spenders out there i.e. predators, poor water clarity, fluctuating water levels, poor food availability. We have many reasons to believe our bittern credit card is out of balance. In the last 12 months five starving nestlings have been found by members of the public right in the heart of urban areas – two females in Christchurch, and two males and a female in Tauranga - unusual behaviours for a secretive wetland specialist species. What happened to the parent that caused these birds to wander? Why were they nesting near to such accessible, high-disturbance areas in the first place? All five birds went into captive care and four survived to be released later in the year with healthy weights. We followed these birds post-release using Ducks Unlimited transmitters. To date two have died of starvation, one is missing – leaving a lone female surviving in Tauranga as our starting deposit.
Extinction Looms
As recently as 2010, surveyors at Whangamarino wetland – a site touted to be the national stronghold for bitterns – regularly recorded 50 + bittern calls within 15 minute long surveys. The number of birds calling could be as many as 12 individual birds per listening post and there were 40
listening posts – that was a lot of noise and a lot of birds. So many that observers regularly complained that they couldn’t keep track of them all.
Sadly these days are gone. Now the same locations are eerily silent, and observers are lucky to find seven birds across the whole wetland. The Australasian bittern is no longer Nationally Endangered. It is now Nationally Critical - the same threat classification as Kakapo – and the last threat classification before Extinction. The clock ticks…all year around multiple threats hammered away at the bittern credit card…and once a year there’s a short opportunity for bitterns to make their deposits. …how much longer before the balance turns red?
Emma Williams
Published in Issue 170