This video from New Zealand is called Chatham Island Pigeon (Parea) hopping – Chatham Island.
From Scoop in New Zealand:
Besieged bird species recovers
Wednesday, 19 August 2009
Scientists surveying endangered Chatham Islands parea (Chatham Islands pigeon) last week were were surprised to find that the population had increased to around 500, from a population low of 40 in the late 1980s.
Protection of their habitat through fencing, predator control and covenanting has reversed the decline of parea. The positive survey results could see its threat status being lowered when it is next assessed, Department of Conservation scientific officer Ralph Powlesland said. …
“It’s a 66 per cent increase in the past four years. We counted 234 birds in the core area of the forest (compared with 141 during the previous survey in 2005). When we extrapolated the information we collected over the full area of protection we realised the population was around 500.”
Predation of parea eggs, nestlings and adults by feral cats, and the degradation of some favoured parea food species, such as hoho (Pseudopanax chathamicus), through feeding by feral stock and possums led to a decline in parea numbers during the 1980s.
But their population increased dramatically over the next 20 years, after the forest was protected by fencing to exclude stock, possum and cat populations were controlled to low levels, and forest patches were covenanted by landowners; the Tuanui, Seymour, Holmes and Day families.
Birds [crested pigeons] make a unique “whistling” sound with their wings when they flee a predator in order to alert other members of the flock to the danger, new research shows: here.
Crested pigeons sound the alarm with their wings. Specialized feathers produce high and low tones when the birds flee in a hurry. By Helen Thompson, 1:28pm, November 9, 2017.
Dear Kitty. Some blog 
Birdlife explosion as possum numbers slashed
By PAUL EASTON – The Dominion Post
Last updated 05:00 27/11/2009
A dramatic drop in the estimated possum population is good news for native birds.
New research shows possum numbers have plummeted from between 60 and 70 million during the 1980s, to about 30 million.
The Wellington region recorded the biggest drop, of 87 per cent.
The region has about 200,000 possums, but without possum control the number would have been between 1.3 and 1.5 million.
Forest and Bird spokeswoman Helen Bain said the drop was a factor in exploding numbers of tui in the Wellington area. “We’re getting a lot of anecdotal reports that numbers are up. I was in town the other day and I would have seen about 20 of them.”
Possums would raid the nests of native birds, such as tui, taking eggs, chicks and sometimes even adult birds, she said. “If we get possum numbers down, native birds and plants come back big time.”
The study, by Landcare Research wildlife biologist Bruce Warburton, used satellite-imaging technology to analyse 52 vegetation types, which helped show how many possums each area could accommodate.
The Conservation Department and regional councils also provided information.
The study found the forests could host 48 million possums, with no pest control. But when efforts to beat possums were included, that figure dropped to 30 million. “New Zealanders have been fascinated by how many possums there are, ever since the estimates of 60 to 70 million were generated in the 1980s.”
Australian brush-tailed possums, introduced in 1837 to establish a fur trade, have become New Zealand’s main pest in both ecological and economic terms.
Among their favourite foods are the leaves of natives trees such as pohutukawa and totara.
Possum control is carried out on about 13.3 million hectares – about half all vegetated land – for conservation and to stop the spread of bovine tuberculosis. The Conservation Department spent $14.9 million on it last year, mainly using 1080 poison.
The results of the study did not mean the war against possums was over, DOC spokesman Rory Newsman said. “We are getting some good results in places, but there is constant re-invasion by possums.”
http://www.stuff.co.nz/environment/3101308/Birdlife-explosion-as-possum-numbers-slashed
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