Distinguishing Manumea's call is key, says ecologist
Identifying the difference in the bird calls of the Lupe or Pacific Pigeon and the critically endangered Manumea, could be the key to confirming the existence of Samoa’s national bird, says Italian ecologist, Dr Gianluca Serra.
Dr Serra – who has done a five-year study titled “Traditional ecological knowledge about critically endangered Tooth-billed Pigeon (Didunculus strigirostris) endemic of Samoa” on the Manumea and worked with Samoa’s Ministry of Natural Resources and Environment as well as the Samoa Conservation Society (S.C.S.) – told the Samoa Observer on Wednesday that the study tried to use ecological knowledge to identify the calls of the Manumea, which is scientifically called Didunculus Strigirostris and is said to be a critically endangered endemic tooth-billed pigeon.
He said the main issue with the manumea’s call was only discovered in 2016, until then its call was not recognised as an issue, which he said led to some mistakes or biased estimates of the Manumea population, as in the past the Lupe might have been counted together with the Manumea.
"There was no awareness that there was this issue of the difference between the call or the overlap between the two calls so it was only 2016 that we finally identified the problem, and we stated clearly on scientific papers that there was an issue of identification of the Manumea call and so since then we have struggled to find the solution and but it’s quite complex problem," he said.
Dr Serra added that Manumea experts, Ulf and Sabine Beichles of Germany who did a doctorate on the pigeon species in the 1980s, agreed that there was an issue and he also ran a sound analysis in parallel to the work that Dr. Serra has done.
The Beichles’ approach is more scientific and western science-based, according to Dr Serra, while he more is more specialised in using traditional ecological knowledge, which is going to the village and working with indigenous hunters due to their knowledge about nature.
In 2015 the M.N.R.E. was approached and the Italian ecologist worked with the Ministry’s Assistant Chief Executive Officer (Environment Conservation), Seumalo Afele Faiilagi who supported and travelled with him throughout the study to interview hunters in the villages on both Upolu and Savai’i, collect information on the Manumea, and recorded 1200-plus hours of forest sounds using automatic devices.
S.C.S. President James Atherton confirmed that the society supported Gianluca with his research through the provision of grants as well as project coordination assistance.
“S.C.S. for years has been working with M.N.R.E. on Manumea conservation and this is one of the number of projects that we have been supporting," Mr Atherton said. "So we supported Gianluca to do his research, help him with grants , and help coordinate his work looking at the call issue of the Manumea.
It's a partnership, just like everything we do it's a partnership with M.N.R.E.
“We have been working with Gianluca ever since he was living here four or five years ago on his manumea work and helping him with fieldwork.
"And also we coordinated the Manumea recovery plan with M.N.R.E. which his field work and his research links to so it's all part of our longer-term project to save the manumea from extinction."
Dr Serra told this newspaper that it took several years to analyse the data collected during the study, but the mystery behind the disappearance of the Manumea remains unresolved due to the bird’s complex behaviour, though he said the study shed some light and provided a breakthrough.
"The main result was that the call of Lupe and Manumea may differ in some sonographic parameters," he said.
The call of the Manumea and Lupe are basically a repeated sequence of a "coo call", which Dr Serra said is repeated several times, and their sonographic analysis has found a difference in the interval between each coo call in the two pigeon species.
"Basically in Manumea, these intervals are shorter and probably more regularly spaced than in Lupe.
“In Lupe they are longer and more variable so this might be the key to, you know, to crack the mystery and find the solution.
“And I am saying that because the other study run in parallel by the Germans found the same result using a completely different approach and using completely different data.”
And while the Italian ecologist and his M.N.R.E. colleagues had gotten other results from their study, Dr Serra said the results were not consistent with the study by the Beichles, but he thinks the most promising approach in the future is to focus on the issue of the coo calls intervals.
Dr Serra said the Manumea is elusive and shy and difficult to find, and he believes that there are very few individuals, probably a few dozen left in Samoa, which puts the species on the brink of extinction.
Having lived in Samoa for six years, the Italian ecologist said he has only seen the Manumea once and the other three or four times he wasn't sure of the species.
He added that the problem is that the bird lives in the dense forest and is very shy.
"Even the hunters that I have interviewed, they have seen Manumea only a few times in their life, some of them have never seen them," added Dr Serra.
The Italian ecologist added that he found older hunters who have seen the Manumea, due to the fact that they were common many years ago, but the younger generation have never seen the bird.
In order to save the Manumea, Dr Serra is of the view that a solution for the identification of the bird’s call should be found, then M.N.R.E will be able to run a comprehensive survey all around Samoa and identify the last strongholds of the birds, and work with villages to conserve those forests to save the Manumea.
But he emphasised that the mystery of the call still needs to be solved, in order to run a complete survey all over Samoa and have reliable estimates on how many birds are left, because a species cannot be saved without knowing how many are left or where they still live.
Dr Serra explained that the Manumea is a stout pigeon with a mix of colors, has a hooked bill that is yellow and red, and the plumage of its body is a mix of brown and blue.
He added that it is a beautiful bird and he was lucky to have seen it in the Uafato forest, and it looked like a big parrot.
Based on his observations of the bird, he says that one diagnostic feature to identify the bird from a distance is the flight, as pigeons usually fly in a very straight line, are strong and high, while the Manumea’s wings flap slowly which he described as something of a clumsy flight.
The Italian ecologist also said people usually confuse the Manumea for the Fiaui bird (metallic pigeon or white-throated pigeon), which is a bit shy and flys low like the Manumea and is also dark in dark.
• This story was edited on 27 January 2020 incorporating comments from the Samoa Conservation Society which also supported the work of Dr Gianluca Serra in Samoa.