Search Results For Landsborough bird counters

For 25 years a small team of bird experts have flown into the Landsborough valley in South Westland most summers to count birds. It’s one of the Department of Conservation’s longest running monitoring projects.

DOC Principal Scientist Colin O’Donnell has been involved in this work from day one, joined by the same few counters who return each year. Together they have counted over 100,000 individual birds.

The Landsborough valley campsite the team call home during bird counts | 📷 DOC.

Some things haven’t changed over that time. They still fly in by helicopter and camp in small tents in the beech forest with a view of the Dechen Glacier. In the evening they sit on their folding chairs and cook on small camping stoves under a fly for shelter.

“If we’d known we’d be doing this for 25 years we might have set up a more permanent camp,” laughs Colin.

During the day, they do five-minute bird counts at 174 stations along lines through the forest. Each observer listens to and records all individual birds calling around them over five minutes.  It requires top notch bird call identification skills (for more on this see: Bird counting in the Landsborough valley).

In 1998, when the monitoring began, its purpose was to measure how bird populations fared as DOC began managing introduced predators – first possums, then later rats and stoats.

Today this is still the aim – but much has been learnt over the past quarter of a century.

Colin and Hannah during a bird count | 📷 DOC.

Fresh from university, Colin first surveyed mohua (or yellowhead) in South Westland in the mid-1980s, for the former Wildlife Service. He found very few birds – the first warnings that this species wasn’t doing well.

Later, studies confirmed stoats were preying on mohua and trapping made a difference. Further research using cameras on nests revealed rats were also a problem.

Mohua had hung on in the Landsborough, along with a good range of other native forest birds. It was a priority to try to protect them. 

Colin says they first set out to measure the benefits of trapping over just 50 ha of forest.

“It’s something I’m most proud of – it was a proof of concept that worked – showing that we could increase breeding success of birds like mohua and save the breeding females from predation.”

A mohua spotted during a recent bird count in the Landsborough valley | 📷 DOC.

“At first, we naively thought that trapping alone over the 50 km-long Landsborough valley would be enough to recover the birds. The first 1080 operation was to control possums, and we later learnt how effective this would be at controlling rats and stoats as well.

“We designed the bird monitoring to be repeatable and practical for such a large valley. The 174 monitoring points give us enough data to be able to detect change in bird populations.”

That first year just 14 mohua were heard; last November the number was 485.

Mohua is now the most common bird, as it once would have been throughout South Island forests before introduced predators invaded.

Over this time, seven other native bird species have also steadily increased in number – tūī, bellbird/korimako, brown creeper/pīpipi, rifleman/tītitipounamu, grey warbler/riroriro, fantail/pīwakawaka and yellow-crowned parakeet/kākāriki kōwhai.

Six other native species have stayed stable or only very slowly increased – kākā, kea, tomtit/ngirungiru, wood pigeon/kererū, New Zealand falcon/kārearea and shining cuckoo/pīpīwharauroa.

Just two native birds have declined – silvereye/tautou and long-tailed cuckoo/koekoeā, which migrates to the Pacific Islands each winter.

Silvereye may be being outcompeted by the larger and more aggressive honeyeaters, tūī and bellbird, which have dramatically increased. Long-tailed cuckoo rely on mohua and brown creeper to raise their young, so may have been affected by earlier declines in these species. They could also be impacted by conditions during their Pacific over-wintering. We don’t know for sure.

In total, native birdlife has more than doubled.

The stunning mountain landscape of the Landsborough valley | 📷 DOC.

In contrast, introduced birds such as hedge sparrow, chaffinch, thrush and blackbird have declined, their fortunes reversed as competition for food and space has grown.

Overall, the results have been phenomenal, Colin says.

“It’s beyond what I imagined but not beyond what I hoped.

“When mohua became the most common bird in 2019, I thought, yes, we’ve done it!”

Over time, the counting has got more difficult with more birds and a chorus of overlapping calls.

The results of monitoring and knowledge gained have been used to adapt the predator control programme over the years. Now extensive trap lines snake for 56 km either side of the river, and aerial 1080 operations are carefully timed with the cyclic beech forest seeding or masts, which cause rat numbers to spike.

However, things are always changing in nature, especially with climate change and warmer temperatures favouring rats by allowing them to better survive over the winter months. 

Ongoing monitoring is important, to detect future changes in birdlife and check predator control remains effective.

“In 2010, there was a year where we missed controlling rats after a beech mast, and we noticed a drop in mohua numbers. It took six years before they recovered to their former levels,” says Colin.

“If we detect a decline in some birds this could be the first early warning. If it was the start of a trend or pattern, we’d need to look at adapting our management.”

Over the years new bird counters have been trained but the original team is still going.

Colin says these days his knees get sore, but he still enjoys his annual trip into the valley.

“My dream day is just going off to have time by myself to count birds.”

Have a watch of the below video to see Colin and the bird count team in action and learn more about the Landsborough valley.

For 20 years our ‘bird counters’ have been flying into the remote Landsborough valley in South Westland to monitor the effects of sustained predator control on bird life. This work has contributed to a long-term picture of the health of the bird community in Landsborough Valley that includes more than a dozen native species. Christchurch-based Media Advisor Fiona Oliphant chats to scientist Colin O’Donnell and contractor Paul van Klink about the art of counting birds and the results of their work.

Our scientists set out to chart the recovery of forest birds in the Landsborough valley after trapping and aerial pest control began there in 1998. This large, forest-clad valley runs for 50 kilometres, from north to south, shadowing the Southern Alps/Kā Tiritiri o Te Moana before joining the mighty Haast River. Apart from rafters on guided trips and hunting parties, few people venture there.

The remote Landsborough Valley in South Westland. 📷: Neil Sloan

The Landsborough has one of the most diverse native bird communities in Westland and is a stronghold for the rare mohua or yellowhead. But in the early 1990s bird numbers were seen to be steadily falling due to the regular spike in rat and stoat numbers following beech forest seeding. Possums had also made inroads.

It was assumed that controlling these pests would benefit the bird populations, but our scientists wanted to measure this response.

Each spring a team of four expert bird observers camp in the forest, in view of the Dechen Glacier, and spend fine days doing five-minute bird counts at regular points along set lines on one side of the river.

The five-minute bird count is the most commonly used bird counting method and gives an index of bird activity and relative bird numbers. It may sound easy but it’s demanding work, says Colin O’Donnell, who leads the programme and has done about half of the annual surveys.

“Each observer must identify the calls of all individual birds in the forest around them in a five-minute period and record this on a notepad.”

“They need to be able to distinguish the range of calls each species makes as well as differences between male and female birds.”

A team of four expert bird counters have been flying into the Landsborough Valley to measure the effects of predator control. 📷: Colin O’Donnell

Birds are most vocal at dawn, but the observers start at nine in the morning to avoid being drowned in bird sound. Together they do 175 bird counts, which represents more than 14 hours of concentrated listening.

Paul van Klink has been counting birds in the Landsborough for 19 out of the last 20 years, the lure of this “legendary valley” drawing him back each time. The challenge when counting, Paul says, is to be truly in the moment; tuning in to every bird call in the area around you. It can be intense and takes a while to come back into the zone when you start out, he says.

“Some days—when it’s cloudy and not too hot—the birds are really going for it and it’s difficult to work out who’s who and where they are.”

In high counts there might be 30-40 individual birds identified within a 5-minute period.

Paul says he’s a “conservative” counter, which Colin confirms. But it’s consistency that’s important, which is why the same four observers have been used to carry out 90% of the bird counts.

The results of this painstaking monitoring are impressive. Overall, native bird numbers have doubled since 1998 when the first trapping and aerial 1080 operation began.

Predator-sensitive mohua has steadily increased in the monitoring area from 14 birds to 338. 📷: James Reardon

In this time the predator-sensitive mohua—the ‘canary of the coalmine’—has steadily increased in the monitoring area from 14 birds to 338. Prior to pest control, this vulnerable tree hole-nester, had declined significantly in the valley.

More common birds—tuī, bellbird, brown creeper, rifleman, grey warbler and kākāriki—are also on an upward trend.

Other species—kākā, fantail, tomtit and kereru—have stayed stable.

Two native species—silvereye and the migratory long-tailed cuckoo—have declined, although it’s not sure why. Silvereyes may be being outcompeted for food by tuī and bellbirds, which have swelled in numbers.

Interestingly, introduced birds like chaffinch, blackbird and redpoll finch have also declined, again perhaps due to competition for food from more native birds.

The results are heartening and show the benefits to this native bird community of decades of careful and consistent predator management, says Colin.

“But the exciting thing is that we don’t know how numerous the bird populations will get.

“Each year I look forward to analysing the results and seeing how they contribute to the trends.”