Once muttonbirds have been caught and killed they are transported to the workhouse for processing. About five chicks are tied to each end of a length of flax or twine and either carried back to the workhouse or, where possible, sent down wires running from the hillsides to the workhouses. Processing is highly labour intensive, and the methods used vary between families. The following is a general description of the main procedures.
Chicks are plucked as soon as possible after they have been caught – the feathers are easier to remove while the birds are still warm. For this reason some muttonbirders like to pluck their birds while still out in the birding ground. Plucking is done by hand, or by a purpose-built machine powered by a generator. Machine plucking puts less strain on hands and fingers and is marginally faster. By way of comparison, an experienced muttonbirder can usually hand-pluck a chick in about 46 seconds, and a machine in 40 seconds. Care is taken not to rip the birds’ skin as this reduces its value.
When the feathers have been plucked, a layer of fine down and pin feathers (new growth) remains. These are usually removed with hot wax. After the birds’ wings and feet have been cut off, their bodies are dipped into a copper vat of molten wax floating on hot water. When the wax has cooled and solidified around the bird, it is cracked and peeled off, taking the downy feathers with it and exposing a clean white body. The wax is recycled every season. In the past, muttonbirders would dip the chicks into large pots of hot water and rub off the down by hand.
The clean chicks are hung for a period. They are then split longitudinally through the breastbone and their internal organs are removed. Each chick is graded by size, covered with salt, and packed into 10-litre plastic buckets for storage. Preserved in this way and kept cool, the birds can keep for a year or more.
Before plastic buckets were common, different types of storage containers were used, including large tins and wooden barrels. More traditional are pōhā – bags made of hollowed, inflated blades of bull kelp, enclosed in strips of tōtara bark and placed in flax baskets. A few Māori still use kelp bags, some using the birds’ own fat instead of salt as a preservative; this is called tītī-pōhā or tītī-tahu. On occasion the chicks are preserved without having their stomachs removed – these birds are known as tītī-puku.
The future of muttonbirding
Rakiura Māori have initiated a long-term research programme with the University of Otago to monitor the birds and assess the effects of harvesting. Studies carried out in 1999 and 2002 have indicated that on some harvested and unharvested islands populations have fallen by 30–40% over the last two decades. The decline has been partly linked to climatic phenomena such as the El Niño Southern Oscillation, a periodic warming of the ocean. Also, muttonbirds are often killed as by-catch in commercial fisheries in the northern Pacific. Preliminary estimates of sustainability and management recommendations will begin to emerge from the studies by 2008, guiding the practice of muttonbirding to ensure the birds remain plentiful.