In Aotearoa there are 67 threatened species, including the blue duck / whio. Photo: Tony Green
New Zealand has the fifth largest proportion of birds at threat of extinction globally, in the grimmest release of The State of the World's Birds report yet.
Globally, around half of all bird species are declining, one in eight are threatened, and 187 species are believe to have vanished since the 1500s.
Dr Stuart Butchart is the chief scientist at BirdLife International, which released the four-yearly report.
He said a large number of bird species were threatened and those not yet at risk of extinction were in decline.
"That has consequences for all of us and the ecosystems they inhabit."
In Aotearoa there were 67 threatened species - about 30 percent of the country's bird population - which made up the fifth highest proportion in the world.
Dr Butchart said this was due to the introduction of rats, cats and possums which had devastated bird numbers.
The introduction of rats, cats and possums has hit bird numbers in Aotearoa. Photo: Aneta Foubikova/ Unsplash
Worldwide the four most negative impacts on bird numbers were: intensification of agriculture such as conversion of grasslands to croplands; unsustainable logging, particularly in the Amazon and South-East Asia; the trapping of birds and the presence of invasive species.
Climate change was the fifth most important threat to the world's birds but was rapidly becoming more important, Dr Butchart told Morning Report.
"Of course we're all aware how quickly our climate is changing driven by greenhouse gas emissions through industry and it's causing all sorts of issues with species being forced to shift their distributions as temperatures rise and weather patterns change.
"Sea level rise is impacting those species that occur on small islands or coastal distributions and changes in the frequency of extreme events affect many species."
While the report painted a worrying picture of the state of the world's birds and detailed all the threats that were affecting them, birds "pointed the way" to the solutions that were being implemented in some countries.
The South Island takahē is among threatened species while the North Island species is extinct. Photo: / CC 2.0
The work of organisations such as Forest and Bird was vital, Dr Butchart said.
"They also show that when the appropriate actions are implemented, where there's sufficient resources and political will, we can turn things around. They provide hope because they show species can be saved and ecosystems recover."
The report estimated that between 21 and 32 bird species would have become extinct in recent decades without the conservation efforts that went into saving them.
"Sea level rise is impacting those species that occur on small islands" - BirdLife International chief scientist Dr Stuart Butchart