It is a good half hour before dawn. I’m on Ambrym, just down the coast from Craig Cove and standing in a bush garden surrounded on three sides by steep-sided slopes covered in bush. There are six of us – each standing about 100m apart waiting for the first calls. Just as the first rays of daylight start to appear the song starts, ‘Whuap, wah, wah, wow, wahahahu’ the last phrase sounding like a chuckle. Immediately, another bird responds and soon the slopes are alive with a chorus of early-morning singing ‘Namalao’, in English, Megapodes or Scrubfowl. The chorus continued for ten to fifteen minutes and then, as quickly as it started, it subsided back to the ‘normal’ Vanuatu dawn chorus of parrots, pigeons and doves, honeyeaters and fantails. One of those fantastic experiences of the natural world.
Endemic to Vanuatu, from Efate to the to the Banks Islands in north, Vanuatu Megapodes are listed on the IUCN Red List as a Vulnerable species. Surveys such as above suggested that, in favourable areas of forest, Megapodes could reach densities as high as seven pairs per square km which, if extended across Vanuatu, suggests somewhere between 3,500 and 15,000 birds. In the past there were probably numerous colonies associated with volcanic soils. Overharvesting means that probably only a handful of these colonies remain – although the birds remain at low densities in lowland forest areas. The birds lay an egg every 10 days in a burrow in warm soil (either due to volcanic activity, or composting of dead tree roots) which provides a constant temperature for incubation. Burrows can be up to a metre in depth or more. The birds dig down into the soil, lay an egg, and then backfill the soil – burying the egg at depth. The chicks hatch out around 60 days later, having to dig their own way out of the burrow and disappear into the bush without ever having seen their parents. Key threats are habitat loss, over-harvesting of eggs and the effect of predators such as cats, dogs, pigs and even rats.
After our visit to the Craig Cove colony, our ultimate destination on Ambrym was another colony of Megapode burrows on the north coast. We estimated that the colony held around 150 active burrows in the volcanic sand. The extraordinary thing was that we spent two days at the site and heard maybe just one bird call on one occasion. I guess the birds around Craig Cove are territorial, and so advertise their presence, while the birds at the north coast site are colonial, and so don’t need to defend their own patch.
I was on Ambrym in 2001, my first visit to the Pacific. This year, I’m reprising the Megapode work, but this time on the island of Tongoa. Here, there is another colony of maybe 300 active burrows associated with volcanic soils. The local community are keen to understand better how to harvest the eggs at a sustainable rate, so we are using automatic cameras to record the activity at twelve of the burrows. In addition the community have established a tabu, to minimise disturbance at the site, which the community actively controls through the employment of rangers. The cameras have not only recorded some great shots of the Megapodes, but also interesting behaviour from the local cats that sit for considerable lengths of time on the burrow perimeter. Can they hear the chicks digging their way out of the burrows? We have not yet recorded a cat catch a newly-emerging chick – but it seems a likely scenario.
Armed with a lot of the traditional ecological knowledge gathered over generations by the local community and a bit of scientific data, our mission during 2017/18 will be to sit together to work out how best to manage the egg harvesting in a sustainable manner on Tongoa. We will also consider the extent to which this might be repeated at other colony sites on Vanuatu and so hope to perpetuate a tradition that has lasted for as long as man has occupied these islands.
Our new regular column by bird expert Dr Mark O’Brien, Regional Program Coordinator for BirdLife International.