Ducks Unlimited

Displaying items by tag: Tracking

Sunday, 20 January 2019 03:35

Hunt for the puweto

The spotless crake or puweto is only half the size of a blackbird and extremely shy but Dr Emma Williams and DOC ranger Rose Graham are experts at getting them to reveal themselves. Emma and Rose teamed up this year on a project to monitor spotless crakes in Waikato’s peat lakes Rotomanuka, Ruatuna and Areare where restoration work is being carried out by DOC and Fonterra’s partnership, Living Water.
 
DOC’s Arawai kakariki restoration programme has been investigating whether the species is a suitable indicator species for wetland restoration. Spotless crakes are thought to be suitable because they have large clutch sizes of up to five eggs – sometimes producing two clutches per season. They’re also very vulnerable, with nests and chicks being easy prey for a range of wetland predators. 
 
The crakes need specific plants and good water quality for their habitat and food to survive. Theoretically, these specific requirements suggest crake numbers will increase quickly (within a few generations) at any sites that have good predator/weed control and have been restored with the right plantings. As long as wetland restoration efforts cover their home ranges adequately, more crakes should tell you that your restoration efforts have been a success.
 
Monitoring so far suggests this is true. To date, all three Waikato peat lakes have had three years of management and crake monitoring. During this time, the number of birds detected at listening stations (areas where puweto calls are played) have increased from 11 per cent to 42 per cent of the time. Crakes also rely on habitat that is important for other endangered species, such as the nationally critical Australasian bittern (matuku), suggesting their presence can indicate conditions are good for these species too. 
Spotless crakes are a challenge to work with though. Many crake and rail species are difficult to sex as males and females often look similar puweto are no exception. So little is known about the species, even attempts to sex them using their DNA is a challenge. This is because there is no baseline information to confirm which DNA testing methods are most appropriate to use. Unless you have a known male and female to test your DNA methods on, then you can’t tell whether the results you get are true or not. 
 
To help with this, Arawai kakariki and Massey University are taking DNA samples from dead crakes found in museums or DOC freezers. The sex of these samples is known because internally the reproductive organs of male and female birds are distinct, and this information is recorded during the autopsy. The DNA test results from these samples can then be used to interpret DNA results taken from the live crakes captured in 2017 and 2018.
 
To monitor crakes, observers sit out and listened for 10 minutes at each station, three times each summer, in the morning or early evening. Each observer plays local puweto calls intermittently and records any sightings or sounds  heard. They are shy so are rarely seen during surveys but are often heard calling back in response to calls.
 
To radio-track the crakes, Emma and Rose first had to catch them. To do this they trialled cage traps and a hinaki-type net (also known as a fyke net).
The net is usually suspended in water to catch fish. It has a series of funnelshaped openings, which makes it hard for fish or birds to escape.
However, to catch puweto on land, the net must be properly suspended above the water by using twisty ties, string, and stakes. Placed in naturally occurring tunnels among the raupo, and channelled with weed matting, this style of trap has  proven the most successful to date,  having caught four so far.
 
Once a bird has been caught, Emma  bands it and attaches a transmitter to the bird’s back. They are so small that only tiny transmitters (the size of a jelly-bean) can be used – each lasting been four to seven weeks, and weighing less than a gram. Once the transmitter is attached, the bird can be released. 
 
After that, Rose and Mark Lammas use the signal from the transmitter to refind birds. They follow each bird carefully for three hours a day in all weather conditions every day until the battery life on the transmitter has expired. To refind birds, Rose and Mark listen to the signal produced by the transmitter  using a hand-held radio antenna. 
 
Often the tracker gets  within 10 to 15 metres of the bird, which usually stays out of sight in the dense lakeside vegetation. “It would appear one of the survival techniques of crake is that you can be right next to them and never know they are there. They can sneak across  small open spaces without you seeing them at all,” says Rose. 
 
The project was funded by the Living Water partnership (DOCFonterra).
Transmitters were purchased  by DOC’s Arawai kakariki restoration  fund.
 

 

Published in Issue 175
Thursday, 12 April 2018 04:10

The secret life of male bitterns

Finally revealed by DU transmitters

Last issue I introduced Australasian bitterns, a rare, secretive wetland bird that often lives within a stones’ throw of people’s houses – yet only the lucky few who spend time in wetlands know this species exists!
As our  bittern is the rarest in the world, we have  several reasons to be concerned about the population here in New Zealand.
 
In the last DU issue I discussed several threats known to limit bittern populations overseas - threats that are unfortunately also present in New Zealand. These threats include habitat loss (here in NZ this loss amounts to a shocking 90 percent!), introduced predators, modified water levels, poor water quality and inconsistent food availability. Unfortunately, despite knowing this, we still have little information about what’s happening with the bittern population here in New Zealand.
This is mainly because bitterns are almost impossible to find and study due to their camoflage plumage and elusive behaviour. Not being able to find this species also means conservationists can’t tell if their efforts to save the species are working.
 
To solve this problem we’ve been developing several monitoring methods that can be used to detect and count breeding male bitterns. This year we wanted to measure how well these methods work.
To do this we needed to catch and ‘mark’ as many male bitterns  as possible on Lake Whatuma, in Central Hawke’s Bay. We knew this would be tricky because to-date few bitterns have been caught.  However, as a team we collectively had several years of bird catching experience using a variety of methods…knowledge of two methods that had been used successfully to catch bitterns overseas…an ability to adapt as we went…and a ridiculous amount of dogged determination… And it worked!
Since September we’ve been able to catch six  male bitterns at Lake Whatuma. We caught all six birds by luring them into cage traps using a combination of calls and mirrors.
 
Playing bittern booming calls within a bird’s territory worked because it tricked the resident male into thinking that a rival male is challenging it. The resident male tries to creep up on this fake rival male intending to see it off. Eventually it sees its own reflection in the back of the cage trap, which it mistakes for the intruding bird, causing it to enter the trap. As soon as the resident male steps on the treadle plate inside the trap, it’s weight releases a catch, dropping the cage door shut, and capturing the bird.
 
Once caught, we banded each bittern with a metal M-band to make them uniquely identifiable in the hand. 
We also attached the radio transmitters provided by Ducks Unlimited sponsorship to help us locate and  identify the bird even when it was hidden from  us in the thick vegetation.
 
Before releasing the bird we weighed it, took a range of measurements (such as length of tarsus, bill, wing and tail), and some photos of its bill and feather patterns.
Photos and measurements can be used to crudely determine the health of the bird and as a general guide to help us confirm its age and sex. Each captured bittern was named in the honour of a deceased crooner – so by November we had caught Barry White, Bing Crosby, Tama Tomoana, Prince Tui Teka, Howard Morrison and Elvis Presley.
 
Once we’d finished processing each captured bird we released them back into their territories.
After that we regularly located birds using the signals emitted from their transmitters. Locations of marked bitterns were plotted to map their territories. We also checked where birds were located during our monitoring sessions and noted if a bird called during monitoring periods, and for those birds that did call we looked to see if observers had succeeded in detecting them. 
 
The results of our monitoring trial are still being analysed but preliminary results already show that breeding male bitterns have high site fidelity during the breeding season, meaning they always boom from the same area.
This is good news for our monitoring methods as it allows us to assume that booms heard at the same location at different times during the breeding season were produced by the same bird.
 
There was one exception. Bing Crosby, a bird caught in the northern end of the lake, permanently left his territory in October (midway through the breeding season). However, we have reason to believe that Bing was not as popular with the opposite sex as his namesake – and therefore does not count as a breeding male. Indeed we suspect he left the lake because he was single and  wanted to try his luck at wooing a female  elsewhere. There are several reasons why we suspect this. Firstly, the quality of Bing’s booming, something that’s associated with mate attraction, dropped steadily throughout the breeding season. This was not observed with the other marked males. Secondly, we had fewer observations of unmarked non-booming birds (females?) within Bing’s territory compared to some of the other booming males. This causes us to suspect that any visiting females were not staying for long. 
Thirdly, in the final days leading up to Bings disappearance he became more transient, often appearing in places that seemed well outside of his usual territory.
 
For example, two days before his disappearance he was found in the heart of his neighbour’s territory cavorting with two unmarked non-booming bitterns. His neighbour was booming within 100 metres of these liaisons - A final desperate attempt at securing a Lake Whatuma female perhaps??
 
Finally, after Bing’s disappearance we searched his territory for evidence of nest  attempts and were unable to find anything  to suggest he had attempted to mate with a female. We believe he was a single male trying his luck, but still can’t say this with certainty because many of the birds interacting with Bing were still unmarked and the sex of bitterns is difficult to determine from plumage alone.
Still, if we had not had the transmitter on him we would have never known that about these behaviours. Interestingly we observed similar transient behaviours with the other five marked bitterns. Although for them these observations occurred much later in the season and coincided with the time when we were expecting bittern chicks to fledge.
At this time of year (December/January), it makes sense for males to be more mobile, as chicks are supposed  to be relatively independent after fledging,  leaving few reasons for males to invest time and effort in maintaining their territories.
 
As you can see we still have much to learn about bitterns, their needs and behaviours. However, just in these last six months, through the use of the transmitters provided by Ducks Unlimited, we’ve been able to associate some of our observations with individual birds allowing us to put these observations into greater context.
 
All six of our marked bitterns have now left Lake Whatuma – again something we did not (and could not) have known would happen if our marked birds were not carrying transmitters.
We plan to continue following these six bitterns over the next six months. Hopefully the more we learn about them, their movements and habitat requirements, the more these observed behaviours will start to make sense.
 

 

Published in Issue 163
Sunday, 25 February 2018 09:06

It’s not all boom and gloom

The fallen leaves crunch below our feet as Kimi, my canine sidekick and I approach the top of yet another hill.

It’s autumn and we’re hunting for Australasian bitterns – but not in the thick raupo or out in the shallow waters along wetland edges as you would expect.

No, we’re on farmland - the last place you would think to look for an endangered bird that is rarer than the kokako.

Yet this is where my telemetry gear tells me we need to go. A loud beep pulses out from the little box that hangs from my neck, and I know from the frequency that Prince Tui Teka is close.

It is hard to imagine Prince in this environment. His streaky dark-brown and beige plumage contrasts markedly against this sea of emerald green - so that instead of blending perfectly into the raupo, as he does in his breeding territory at Lake Whatuma, he stands out like a gangly teenager with stage fright - or worse, a possum in the headlights.

We have long suspected that bitterns forage in farmland drains and small spring fed creeks. After all, this is where members of the public report seeing them. Yet bitterns are also easier to spot in these environments, and the habitat is far removed from what the species is reported to like. This is why these sightings have always seemed like fortuitous interactions rather than something of the norm.

The same can be said for bitterns leaving Lake Whatuma. We always thought it was possible, but somewhat unlikely. In the 1980s, a few bitterns carrying transmitters at Whangamarino wetland in the Waikato left their breeding site and were never re-found. Yet other bitterns marked in the same study were known to remain within the area. There are multiple reasons why we might lose the signal of a transmitter carried by a bittern and not all reasons relate to the bird leaving the area. For one, the thick raupo they live in has a high water content, and therefore dampens the radio-signals emitted by our transmitters. So if one has no idea where a bird has gone, and there’s a chance it is in thick raupo, thorough searches of the area are needed to be sure it has left.

So when the signals of all six of my marked bitterns suddenly disappeared in late December, and thorough searches at Lake Whatuma revealed nothing, I have to admit that I was a little surprised. One or two birds leaving the lake was expected, all of them leaving was not. At the same time it was also logical.

The departure of these birds coincided with a dramatic drop in water levels at Lake Whatuma. For most wetland birds this was a god-send – fish and other small prey items become concentrated in the centre of the lake where several wading birds, like pied stilts, congregate to feed in large numbers. But this is not good for bitterns. Of all the species in the heron family, bitterns are known to be the least behaviourally adaptable.They like what they like and that’s it. They’re not one of those gregarious flighty species that can opportunistically flit between people’s gardens, like the silver-eye. And they are not interested in probing around with yappy pied stilts. They’d much rather stalk and stab their food in peace - preferably somewhere that there’s cover and low water levels. If they can’t do that, they leave.

So they left.

Initially it took us a little while to track them down. Kimi and I spent a lot of time out on the top of hills where it’s easier to get a signal.This is because the angle means there’s less vegetation between us and the bird. I met a lot of farmers and landowners during these quests. Some landowners already knew what a bittern was because they’d flushed them from time to time, and others had no idea -but everyone was equally excited to learn that they have the rarest bittern in the world living on their land. I was overwhelmed by the response of these locals and the appreciation they have of their land and their environment.

Yet finding my birds in these areas also troubled me. Sometimes I would find my bitterns foraging happily on gambusia soup or an army of frogs with lots of cover around them. But more often than not I’d find them wandering along a deep drain looking lost and dispirited. There will have been a time when this happened with brown kiwi. When they were still on peoples doorsteps, being seen by locals who loved and adored them. Yet their habitat was still in decline. They were visible not because they were plentiful, but because they couldn’t find what they needed, and were out and about looking for it…and then one day they were gone.

I believe we’re at this unique position with bitterns. The birds are still around but don’t have everything they need for the population to increase. This is a concern because there will be multiple factors driving the decline of bitterns and many of these factors are still poorly understood. The longer a species remains endangered the harder it is to reverse the decline. If you need any more evidence to convince you of this, you only have to look at how intensive (and expensive) the kakapo recovery program is – a species that is currently only one threat classification rarer than bitterns.

The signal emitted from the transmitter carried by Prince Tui Teka gets stronger and suddenly he flies up out of a tiny raupo patch at the edge of a stream. I know that he saw us long before we saw him. As soon as we came over the brow of the hill he will have been tracking us – just as we were tracking him. He will have been standing in the raupo with his beak pointing towards the sky and only his eyes moving as he watched us across the paddock. He will have seen us pause several times to visually scan the raupo patch. The same patch he was hiding in. Who knows he may have seen us look right at him. Yet until this moment we had not spotted him, and even if we had his plumage makes him look exactly like all of the other raupo stems in the same patch.

He has only flushed now because he knows the game is up.Thanks to the transmitter he carries his camouflage no longer prevents us from re-finding him. I watch him land further down the stream before placing my boot in the water where he was previously standing – the stream is shallow and several small fish and amphibians dart away from me and disappear into the aquatic vegetation. This is one of the better places I’ve found him. There is some cover for him so that he can hide while he forages and the water is clear and shallow enough for him to see his prey. I leave him in peace and head off to find the landowner and congratulate them on this discovery. It’s not all boom and gloom – this landowner likes bitterns and has already said he will not remove any of the habitat Prince uses. 

I still suspect Prince doesn’t have everything he needs but at least this site is better than the empty drain he was wandering along last week.Upon returning to my van on the top of the hill I have a quick listen for the bittern Tama Tomoana with my tracking gear. Members of the local hapu named this bittern after one of the grandsons of Henare Tomoana, a prominent Maori leader in the Hawke’s Bay region in the late 1800s. 
Tama’s father, Paraire Tomoana, composed a number of well known waiata including ‘Po Karekare Ana’. Tama himself was renowned for his rich baritone booming voice – just like our Tama. (And the leadership and musical genes were passed on to Tama’s son, Ngahiwi, who currently chairs Ngati Kahungunu Iwi Inc.). Yet it’s been a while since we’ve heard anything from Tama the bird.

Tama has been missing for seven months now. During the breeding season he was one of our most site-loyal birds and he was regularly found booming within a small area of less than 2 hectares in size - basically one small raupo patch. This was in contrast to some of the other bitterns, like Barry White, who boomed from lots of locations within a 15 hectare area.

This previous site-loyalty left us extra surprised when Tama disappeared and then could not be found. By now all of the other bitterns were accounted for – even Bing Crosby, who had originally flummoxed us last year by disappearing mid-way through the bittern breeding season. In late January we happily rediscovered Bing at Wanstead swamp, a site that’s about 15 kms from his breeding site. Of all of our wandering bittern, Bing was found the farthest from home. We looked for Tama in all of these areas too and nothing was heard.

Colleagues in Australia had recently attached a satellite transmitter to a juvenile male bittern and found that this bird moved farther than 550 kms after breeding had finished, crossing two state borders. Clearly our bitterns could physically move long distances if they want to - this got us thinking that perhaps Tama has done something similar? Five months after he went missing we decided we needed to broaden our search, so we put out a national plea asking anyone with access to telemetry gear to check their wetlands and listen for his signal. People looked for him at wetlands across the country - from Northland down to Waituna lagoon in Southland. His signal was still not found.

In June, all five of our autumn wanderers came back to Lake Whatuma. We waited with baited breath to see if Tama would also return - but his signal remained silent. By July 28, local landowner Max Lyver reported hearing the first bittern boom on the lake. The breeding season had begun, but still Tama was missing. We’d given up hope. Then on August 12, eight months after he’d left the lake, and over one month later than all the other marked male bitterns, Tama’s signal was once again heard beeping from his usual breeding territory. He was back and booming again. Where he went we will never know. He clearly still has a story to tell. This year we hope to recapture him so that we can replace his radio transmitter with a satellite transmitter - kindly donated by Ducks Unlimited, NZ. This will allow us to track him regardless of where he goes, meaning we will be able to get a complete story of his autumn adventures next year.

To me, Tama’s return to Lake Whatuma highlights just how much we’ve learned about the habits and behaviours of these birds over the 12 months they have been carrying transmitters – and yet how many mysteries still remain.

Without Ducks Unlimited, NZ’s continued financial support of this project we would not have been able to unlock these bittern secrets. Knowledge gained by this project is being used to help inform bittern conservation projects nationally.

Emma Williams
Published in Issue 165
Tagged under
Tuesday, 31 October 2017 01:07

Tracker dog helps find and protect birds

Emma Williams and I are helping the South Wairarapa Schools - Martinborough, Pirinoa and Kahutara - to achieve some of their environmental studies assignments and general objectives.

Emma has visited Kahutara School once already and her talk was very successful, she had her dog Kimi with her and the children loved that.

Then Emma went up to Hawke’s Bay and further north where she worked with older young people. Emma has developed a package for schools on wetlands and wetland birds with bitterns in particular, and where they are in the habitat.

Emma’s lovely black labrador Kimi, helps with her work and accompanies her on visits to schools.

We will start another series of school visits in the South Wairarapa during August and plan to visit Wairio wetlands at some stage and track bitterns that have radio transmitters attached to them.

The overall plan is to introduce pupils to wetland conservation and so attract some new young members for Ducks Unlimited!

Gill Lundie

Published in Issue 172